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PROJECT FINAL REPORT Grant Agreement number: 224197 Project acronym: TUMESA Project title: MEMS Tuneable Metamaterials for Smart Wireless Applications Funding Scheme: Collaborative Project Period covered: from 1.6.2008 to 30.9.2011 Name of the scientific representative of the project's co-ordinator1, Title and Organisation: Antti Räisänen, Professor, Aalto University Tel: +358-9-47022241 Fax: +358-9-47022152 E-mail: antti.raisanen@aalto.fi

Project website address: http://radio.tkk.fi/tumesa/

1 Usually the contact person of the coordinator as specified in Art. 8.1. of the Grant Agreement.

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Contents Contents ................................................................................................................................................. 2 1.  Executive Summary ....................................................................................................................... 3 2.  Project context and objectives ....................................................................................................... 4 

2.1.  Context .................................................................................................................................... 4 2.2.  Objective ................................................................................................................................. 5 

3.  Main S&T results/foregrounds ...................................................................................................... 6 3.1  MEMS-based high impedance surfaces (AALTO) ................................................................. 6 

3.1.1  Objectives ....................................................................................................................... 6 3.1.2  Overview of the concept .................................................................................................. 6 3.1.3  Theory and numerical analysis ........................................................................................ 7 3.1.4  Reflection type phase shifter based on a metal waveguide .............................................. 7 3.1.5  Transmission type phase shifter based on a dielectric rod wave-guide ........................... 8 3.1.6  Smart beam steering surface ............................................................................................ 9 

3.2  Waveguide antenna array (UR1) ........................................................................................... 10 3.2.1  Definition of the antenna array element ......................................................................... 11 3.2.2  Definition of the 2-D antenna array size ........................................................................ 11 3.2.3  Phase quantization study ................................................................................................ 11 3.2.4  Phase shifter design, optimization and prototyping ....................................................... 12 

3.3  Leaky wave antennas ............................................................................................................ 19 3.3.1  MEMS-based coplanar waveguide leaky-wave antenna ............................................... 20 3.3.2  MEMS-based dielectric rod leaky-wave antenna .......................................................... 21 3.3.3  MEMS-based coupling leaky-wave antenna ................................................................. 23 3.3.4  Conclusions .................................................................................................................... 26 

3.4  MEMS Technology: Design, Fabrication and Evaluation (KTH) ........................................ 26 3.4.1  Objectives ...................................................................................................................... 26 3.4.2  Overview of fabrication technology .............................................................................. 27 3.4.3  MEMS-based high impedance surfaces ......................................................................... 28 3.4.4  Wave-guide antenna array ............................................................................................. 32 3.4.5  Coupling leaky wave antenna ........................................................................................ 33 Conclusion ................................................................................................................................... 35 

4  Potential impact ........................................................................................................................... 36 4.1  Strategic impact ..................................................................................................................... 36 4.2  Dissemination and usage of the project results ..................................................................... 37 4.3  Plan for further dissemination and usage of the project results ............................................ 47 

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1. Executive Summary This Report consists of the following sections. Section "Project context and objectives" provides explanations of necessity of carrying out research on novel millimetre wave beam steering solutions for various applications and especially for automotive radar at 79 GHz. The main objectives of the project are to develop novel on-chip phase shifting and beam-steering devices based on MEMS tuneable high-impedance surfaces; to integrate developed phase shifting components in novel space-efficient antenna arrays on a single chip; to elaborate novel concepts of implementation the beam-steering devices and antenna arrays in cost-efficient radar sensor and future high-capacity wireless communication systems and evaluate fabricated prototypes at a system level.

Section "Main S&T results/foreground" describes results attained by TUMESA in the following development directions: 1. MEMS-based high-impedance surface: We have designed, analyzed analytically and

numerically, fabricated and measured several prototypes of MEMS-based high-impedance surface. Measurement results showed clear resonant behavior and phase transition to 0 degrees at the resonance frequency. Transmission type phase shifter based on a dielectric waveguide showed an analog-type phase shift at W-band.

2. Waveguide antenna array: We have designed, analyzed, fabricated and measured phased array unit cells based on rectangular metal waveguide WR-12 of two different configurations and a phased array antenna with 20x10 unit cells.

3. Leaky wave antennas: We have designed, analyzed, fabricated and measured leaky wave

antenna based on a dielectric rod waveguide. In addition, we have designed, analyzed, fabricated, and measured another microstrip-based MEMS leaky-wave antenna prototype.

4. MEMS technology: We have elaborated novel microfabrication process, carried out several

runs of high-impedance surface fabrication, phase array element fabrication and coupling elements for leaky wave antenna. We also performed reliability measurements, which showed no degradation of MEMS varactor properties over 100 million actuation cycles.

The project total personnel effort exceeds the planned amount of person-months by 16 % because TUMESA targeted several ambitious, challenging and risky objectives. Besides, many additional results were attained during each period of the project. Section "Potential impact" discusses scientific and societal impact of the project results, describes publications and dissemination activities, and provides plan for use and dissemination of foreground. Report on societal implications finalizes the report.

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2. Project context and objectives

2.1. Context EU authorities have launched a program to reduce fatal road accidents by 50% by 2010, with focus on driver assistance and on-board safety systems for accident reduction, including automotive radar. For this purpose, the European Telecommunication Standard Institute ETSI has already produced a standard for automotive radar in the 79 GHz range (EN 301 091). However, current technology is not mature enough to implement cost-efficient radar front-ends in the millimetre wave range. Therefore, the European Commission has approved the allocation of the 24 GHz band in January 2005, to allow for the faster implementation and usage of automotive radar. Due to the fact that this band is interfering with other applications, it was seen only as a transitional solution until 2013, when the technology for 79 GHz was thought to be mature enough for cost-efficient implementation of radar sensors in cars. However, in December 2010 EC issued a call to stakeholders for their views on the proposed amendment to this Commission decision, emphasising that SRR technology at 79 GHz is not progressing in such a way as to guarantee availability even by July 2013. One of the main components of a radar sensor is a beam-steering device that scans surroundings for objects looked for. Another application that requires implementation of the same technology is point-to-point wireless communication systems. If beam steering is implemented in receiving and transmitting antennas, a self-adapting mechanism can be elaborated for innovative performance of the future secure high-capacity communication links. As far as the RF spectrum at microwaves is highly populated with different communication standards, a possible frequency range for high-capacity communication systems, which require a wide bandwidth, can be found at millimetre wavelengths, e.g. at 60 GHz. Beam steering can be achieved by phased array antennas, where the phase of each antenna element is controlled with a dedicated phase shifter. Existing millimetre-wave phase shifters change the phase by adjusting either the geometrical parameters of the device (e.g. changing the length of a transmission line using semiconductor switches), or material properties of its components (e.g. by applying magnetic or electric field). Mechanically controlled phase shifters are not convenient, e.g., in phased arrays. Existing materials with controllable parameters (e.g. ferroelectrics) are usually very lossy at millimetre wavelengths. That is why we propose a novel approach that combines the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Tuneable metamaterials proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable metamaterials allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level. In general, metamaterials provide a way to design materials and surfaces with unique and engineered electromagnetic properties. According to the definition adopted by the Metamorphose Network of Excellence, metamaterial is an arrangement of artificial structural elements, designed to achieve advantageous and unusual electromagnetic properties. This concept includes also artificial surfaces with engineered electromagnetic properties. Within the scope of this project, tuneability and low losses in the targeted frequency range should be the main design goals.

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2.2. Objective The objective of the project is to develop components and sub-systems based on microelectromechanical systems (MEMS) in order to provide a cost-efficient and high-performance technology platform for millimetre-wave automotive and industrial radar, and future high-capacity communication systems. The beam-steering unit is the bottleneck for large-scale commercialisation of radar sensors, since it requires large area components (patch antenna arrays) that cannot be integrated, which increases the cost of the system. This project investigates new concepts for beam steering with the goal of reducing the size and ultimately targeting a complete on-chip reconfigurable antenna. The aim is develop a dielectric rod antenna with embedded analogue type phase-shifters, smart beam-steerable reflective surface, steerable leaky wave antenna, and phased array antenna, all based on MEMS tuneable metamaterials and metasurfaces. The advantage of convergence between MEMS and metamaterials is ability to create novel miniaturised reconfigurable devices that can substitute larger subsystems, which allows developing novel cost-effective small size and high performance multifunctional wireless systems. Special attention should be paid to decreasing power consumption required for the devices’ operation during design phase and to elaborating novel fabrication techniques. Low loss MEMS technique is one of the factors of low power consumption. Novel concepts of implementation of fabricated prototypes in cost-efficient radar sensor and future high-capacity wireless communication systems should be elaborated, tested and evaluated. Volume manufacturability should be investigated. Our main objectives were the following: to develop novel on-chip phase shifting and beam-steering devices based on MEMS tuneable high-impedance surfaces; to integrate developed phase shifting components in novel space-efficient antenna arrays on a single chip; to elaborate novel concepts of implementation the beam-steering devices and antenna arrays in cost-efficient radar sensor and future high-capacity wireless communication systems and evaluate fabricated prototypes at a system level. One of the main components of smart automotive radar sensors is the beam-steering antenna that scans surroundings to localize, identify and even classify targets. For such applications, low-cost and highly-integrated multiple beam antennas must be developed to design reconfigurable front-ends for short-range and long-range automotive radars. Mechanically-scanned antennas cannot be used since the scan rate is too slow and reliability might be an issue. Electronic beam steering is thus preferred.

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3. Main S&T results/foregrounds

3.1 MEMS-based high impedance surfaces (AALTO)

3.1.1   Objectives 1. To study analytically and numerically novel MEMS tuneable high-impedance surface. 2. To develop, analyse and measure:

- novel single chip analogue type phase-shifters for dielectric rod antenna based on MEMS tuneable metamaterials

- novel phase shifter integrated in a micromachined metallic waveguide - novel single chip smart beam-steerable reflective surface based on MEMS tuneable high-

impedance surface

3.1.2  Overview of the concept One of the examples of metamaterials and metasurfaces is a high-impedance surface. In the electronically reconfigurable MEMS-based HIS, an array of MEMS varactors, biased by an applied voltage and arranged on an electrically thin dielectric substrate with a ground plane, see Fig. 1, is used to provide tuneability of the surface impedance. A MEMS varactor is formed by a metal patch (black on Fig. 1) placed on the substrate and a membrane (grey) supported by four stems with springs. The period of the structure and the size of capacitors are much smaller than the wavelength, hence the surface can be analysed in terms of its effective input impedance. The input impedance is related to equivalent resonant circuit parameters of the structure: inductance (due to the input impedance of the dielectric spacer with a ground plane) and capacitance (due to the array of MEMS capacitors). Applying an actuation voltage to the capacitors connected in rows changes the input impedance of the structure. At the resonant frequency, which is determined by the dimensions of the structure and materials it consists of, the impedance of the structure becomes very high. Electronic tuning of the input impedance of the structure introduced to the waveguides can result in change of the propagation constant of the waveguide, or in change of the reflection coefficient of an incident wave.

Fig. 1. Possible design of a MEMS tuneable high-impedance surface.

Upper membrane

Lower patches and wiring

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3.1.3  Theory and numerical analysis Analytical study of a basic high-impedance surface (so called mushroom structure) was already carried out before the project. In TUMESA we developed advanced analytical model for a multilayer high-impedance surface, including analysis of losses. Thorough numerical analysis was carried out in order to validate the developed analytical model and better understand the structure behaviour, for realistic (i.e. as to be fabricated) device models, for example: supporting stems and springs of different sizes, bias wiring, triple-layer MEMS-membrane structure, etc. The model and numerical results are described in deliverable D1.2, D1.4, publications and D. Chicherin’s thesis.

3.1.4  Reflection type phase shifter based on a metal waveguide The reflection type phase array unit cell consists of the WR-10 rectangular metal waveguide with a MEMS tuneable HIS placed as a backshort of the waveguide. The design, analytical and numerical analysis of the MEMS tuneable HIS and the phase shifter are described in deliverables D1.1, D1.2, D1.4. The size of the HIS is 1.2 x 2.4 mm2 to fit WR-10 rectangular metal waveguide, see Fig. 2. The period is 250 μm. The structure was fabricated in KTH. The details on MEMS fabrication and tests are given in the deliverable D4.1 and further in this report.

Fig. 2 SEM image of the fabricated MEMS tuneable HIS.

The fabricated MEMS tuneable HIS was placed as a backshort of a rectangular metal waveguide WR-10 forming this way a reflection type phase shifter. The S11 parameter of the structure was measured with a vector network analyzer over W-band, see Fig. 3. The reflection phase of the MEMS tunable HIS changes gradually from nearly 180º to 0º at the resonance frequency 83.4 GHz and then to -180º, showing that the structure has high input impedance at the resonance. As soon as the MEMS varactors are actuated, the resonance shifts toward lower frequencies and the reflection phase changes dramatically for an operation frequency near the resonance. Analogue phase shift up to 240º is estimated for a fabricated tuneable HIS with high MEMS capacitance ratio. Typical insertion loss at the resonance referenced to the waveguide loss is 3.5 dB, whereas minimal insertion loss outside the resonance is as low as 0.7 dB. This loss can be further decreased by higher integration to the waveguide.

Fig. 3 Measured S11-parameter of the reflection type phase shifter with MEMS tunable HIS over W-band.

Contact pad HIS 200 μm

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MCNAB has designed and manufactured waveguide assemblies for characterising the fabricated MEMS chips. Two different sets have been developed and manufactured: one is an end launch version for reflection measurements, and one is a dual launch version that is going to be used in through measurements. The last unit has been verified that full parallel is meeting through pressurising the waveguide assembly without any leakage. MCNAB waveguide assemblies have been tested with good success, and use of sticky material by KTH in order to attach the substrate to the waveguide has proven to be a reliable process for development.

3.1.5  Transmission type phase shifter based on a dielectric rod wave­guide Analogue type phase shifter for dielectric rod antenna consists of a MEMS tuneable high-impedance surface placed adjacent to the dielectric rod waveguide, see Fig. 4. Applying bias voltage to MEMS varactors of the HIS leads to gradual change of the phase factor of propagation constant of the field above the structure, i.e. in the section of the dielectric rod waveguide adjacent to the HIS. The structure can perform as a phase shifter or a dielectric rod antenna with an embedded phase shifter.

Fig.4 Phase shifter based on a dielectric rod waveguide (DRW) with adjacent at a distance d MEMS tuneable

high-impedance surface (HIS) of width w (3D view). A prototype of the MEMS tuneable HIS with 24x120 MEMS varactors placed on a silicon substrate with the period of 250 µm and total size of 6 x 30 mm2 has been fabricated, see Fig. 5. All varactors are connected by bias voltage lines to two contact pads.

Fig. 5. SEM image of the fabricated prototype of MEMS tuneable high-impedance surface.

The MEMS tuneable HIS is placed adjacent to the silicon DRW matched to WR-10 waveports of a vector network analyser for measuring S-parameters. The bias voltage from 0 V to 40 V is applied to all MEMS varactors simultaneously. An analogue type phase shift is detected at Port 2 of the DRW, see Fig. 6, where the phase of S21 of biased phase shifter is referenced to the S21 at 0 V. The measured frequency dependence of the phase shift at, e.g. 40 V bias voltage, corresponds to the simulated results. Dependence of the phase shift on the bias voltage is shown in Fig. 6 for 75 GHz and 110 GHz, where the value of the phase shift is largest on the measured frequency range. The phase changes gradually from 0° to 13° and -32°. Larger phase shift value can be expected with higher bias voltage, and in case the HIS is optimised so that the minimum phase shift would appear, e.g., at 110 GHz.

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Fig. 6. Measured analogue type phase shift with respect to frequency for the DRW with adjacent MEMS tuneable HIS, and measured dependence of the phase shift on the bias voltage.

The S21 of the DRW and DRW with adjacent HIS is given in Fig. 7 showing that the insertion loss of MEMS tuneable HIS as a phase shifting element is between 3 dB and 5 dB. Second fabricated prototype, showing larger phase shift of up to 70°, exhibited higher insertion loss. The losses can be decreased by optimised fabrication procedure, choosing better material of the DRW and improving matching of DRW to the WR-10 ports of the VNA.

Fig. 7. Measured insertion loss of the phase shifter.

3.1.6  Smart beam steering surface MEMS tuneable HIS can be used for electronic reflective beam steering by inducing reconfigurable surface impedance through applying different bias voltage to different rows of elements of the MEMS varactors array, see Fig. 8. Since full-wave simulation of electrically large reflective surface with electrically small features of MEMS varactors is practically computationally impossible, a simplified model of a surface with 40 impedance strip lines of 0.35 x 0.35 mm2 is used. If all strips have the same impedance, the angle of the reflected beam is equal to the angle of the incident beam. Configuring the surface so that different strips have different impedances and different phase of the reflection coefficient, the reflected beam can be steered by changing the gradient of the surface impedance, see Fig. 9.

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Fig. 8. MEMS tuneable HIS for electronic reflective beam steering

Fig. 9. The normalized radiation pattern of the surface at 80 GHz with incident angle from 45° which is programmed for -30° (lhs), 0° (rhs).

Several prototypes of the large high-impedance surface with 52x200 were fabricated. Due to the fabrication challenges and refocusing of the resources during last year of the project according to the recommendation from the second year review, reliable tuning of the whole array, which is needed for demonstrating beam steering, was not achieved. However, S11 of those prototypes were measured with a VNA by placing them as a backshort of the WR-10, showing clear resonance and smooth frequency dependent reflection phase transition from 180° to 0° and back to -180°, in agreement with the designed performance.

3.2 Waveguide antenna array (UR1) There are many known antenna technologies for automotive radar applications, like Rotman lenses or multilayer planar phased arrays. However, they suffer from many limitations such as low efficiency and radiation performance for large beam deviations. To alleviate this problem an alternative solution could be based on transmit-arrays using waveguides as unit-cells. It is well known that the use of phase-reconfigurable waveguide apertures is one attractive solution for beam

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scanning over a wide field of view. One of the key points in the design of such a structure consists in integrating an active phase shifter in a metallic waveguide. To this end, the work has been organized into several sub–problems, namely:

• Definition of the antenna array element; • Definition of the 2-D antenna array size; • Phase quantization study; • Design, optimization, prototyping and measurements of the phase shifters; • Design optimization, prototyping and measurements two phased array antennas.

3.2.1 Definition of the antenna array element  WR-12 metallic waveguides (3.09×1.55 mm2) have been selected as antenna array element. Compared to WR-10 waveguides, this choice is motivated by the following reasons:

• For a given antenna size (i.e. antenna directivity), we need less waveguides in the array, i.e. less active phase shifters, in contrast to WR-10 waveguides for example;

• This waveguide configuration is better for MEMS integration due to the larger size of the unit-cell;

• The WR-12 waveguide operational bandwidth is between 60GHz and 90GHz, and perfectly suits with the target frequency of the future generation of millimeter wave automotive radars (77GHz).

• This waveguide configuration suits with the experimental facilities available at AALTO.

3.2.2 Definition of the 2­D antenna array size Starting from initial guess of antenna array specifications, namely:

i) Long-range gain: 27 dBi (full half-power beam width (FHPB) equal to 3 deg.); ii) Short-range gain: 15 dBi (full half-power beam width equal to 8 deg.); iii) Field of view equal to +/-10 deg. in long-range mode, and +/-30 deg. in short-range

mode), 2D arrays have been studied using ideal electromagnetic modeling: each waveguide element is excited by a wave port which controls the phase of the radiated wave. No amplitude tapering is taken into account here. This strategy enables one to define the minimum radiating area of the antenna so as to achieve the above-mentioned specifications assuming an ideal phase distribution over the antenna array. Based on our simulation results we can conclude that it should be enough to have approximately 20 WR-12 elements in E-plane and 10 elements in H-plane to achieve a 6 deg. FHPB. In practice, waveguide walls have a finite thickness. Increasing the waveguide wall thickness (starting from 0.1mm) decreases the FHPB. Our results have shown that 0.5mm or less wall thickness is acceptable to avoid parasitic radiation (high level grating lobes). Due to technological constrains we will use 1mm-thick waveguide walls.

3.2.3 Phase quantization study By controlling the phase and amplitude of excitation of each element, we can control the direction and shape of the beam radiated by the antenna array. Using a linear phase law is impossible in real life due to challenges in implementation of high-resolution phase shifters in array systems. Therefore, the most suitable bit resolution for the phase shifter (2-bit, 3-bit, etc.) has been defined so as to achieve the best trade-off between radiation performance and complexity/loss of the phase shifter. An n-bit digital phase shifter has 2n phase states. Comparison of the antenna radiation performance (directivity, scan angle, side lobe level) for different bit resolutions (ideal case, 2-bit, and 3-bit) has shown that a 3-bit resolution is very close to

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the ideal case (as expected), and that the directivity decrease for 2-bit phase shifters is around 1dB (Fig. 10). For small scan angles, using 2-bit phase shifters is an acceptable compromise between complexity and loss of the phase shifter and radiation characteristics. Nevertheless, for scan angles larger than 25 deg., a 2-bit resolution might not be fine enough (beam distortions and high sidelobes level). For such cases, it might be better to decrease the unit-cell size (WR-10 waveguide, instead of WR-12 waveguides) and keep a 2-bit resolution, instead of using 3-bit phase shifters integrated into WR-12 waveguides.

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(a) (b) Fig. 10. Main features of 2-D array radiation pattern: main lobe (a) and FHPB (b).

3.2.4 Phase shifter design, optimization and prototyping  Based on a detailed bibliographic study, two phase shifter solutions for waveguide integration have been selected from a decision matrix table. These are based on finline and inductive iris band pass filters. Finline-based phase shifters. Finline structures allow integrating millimetre-wave active and passive devices together and enable to form the compact and light-weighted millimetre wave components. A finline taper is similar to a ridged waveguide with dielectric backing as shown in Fig. 11a. It is inserted in a metallic waveguide to form a completed circuit. Our second choice is based on inductive irises. This particular filter configuration is attractive due to its very good performances in terms of filtering property. Inductive irises are often used as coupling elements in rectangular waveguide band pass filter (BPF). Inductive coupling irises are shown in Fig. 11b. One of the possible drawbacks of these two phase shifter configurations is their manufacturing and assembly complexity.

We have designed and optimized two tunable phase shifters for waveguide integration at 77GHz. These are finline-based (rectangular and X-shaped) and inductive iris-based phase shifters. The proposed phase shifters demonstrate good performance in terms of phase shifting (bit resolution close to 2-bit) and insertion loss (S21<-0.7dB) over the desired frequency band. A fully-tunable finline phase shifter taking into account all the material properties and technological constraints

(a) Finline taper

(b) Inductive coupling irises

Fig. 11. Phase shifter solutions.

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defined with KTH has been designed (Fig. 12). The finline phase shifter is symmetrical: there are two identical fin structures, one on each side of the dielectric substrate. Due to technological constraints, the device is fabricated in two separate parts; each of them comprises 11 MEMS cantilevers fabricated on a 300µm-thick Silicon substrate. Both substrates are fixed to each other by non-conductive glue so as to obtain a single bilateral finline phase.

-Silicon (ε =11.9; tgδ=0003)-Gold (Fins)

-Gold (MEMS: cantilevers)

(a) Finline chip integrated into the WR-12 waveguide

(b) Side view of one fin with MEMS and comb-like fixed fin slot pattern (ground layer)

Fig. 12. Finline MEMS-based phase shifter. A cross section view of the cantilever is provided in Fig. 13. In this design, the whole plate below the cantilever is used as an electrode. The gold layer thickness for the electrode is 0.5µm, and 0.2µm for the silicon covered layer. For actuation, the bottom plate (biasing line) is connected to V+, and the cantilever electrode through the fin layer to ground. The contact thickness is 0.3µm and enough to provide safety distance and to avoid any insulating layer. To have an access to the cantilever actuation electrode we made a hole in the anchor. Thus the biasing line can be easily connected to the cantilever actuator layer. In the open state, the distance between the cantilever contact and the finline is only 1.5µm (Fig. 14).

(a) Finline fabricated into two separate parts, and assembly.

(b) MEMS actuation

Fig. 13. Cross section view of the cantilever.

Open state

Close state Fig. 14. Cantilever contact states.

Due to strong technological complexity and limited time resources, the MEMS-based finline phase shifters have been prototyped in “frozen” MEMS state. The layout of the prototyped bilateral finline-based structure is represented in Fig. 6. The fins are placed on both sides of a Silicon substrate

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Fig.18. Computational results for the X-shape shape finline chip at 77 GHz (HFSS).

The rectangular and X-shaped finline-based phase shifter chips fabricated by KTH are shown in Fig. 19.

(a) Wafer with chips (b) Rectangular chip (c) X-shaped chips Fig. 19. Finline-based phase shifter prototypes.

The performances of the finline phase shifters have been confirmed experimentally at AALTO. A special waveguide (WR-12, 1.55×3.09×120mm3) measurement set-up has been designed by UR1 and MicroComp Nordic (Fig. 20). For rectangular and X-shaped chip types, a slot is fabricated in the middle of the waveguide. In this area, we make another cut for the chip footprint.

(a) Model (b) Prototype (rectangular chips) (c) Prototype (X-shaped chips)

Fig. 20. WR-12 waveguide model for testing the chip performance. The latter guarantees the chip position to be exactly in the middle of the waveguide aperture. For chip fixation in the waveguide, we used a lid (green part in Fig. 20). Once the chip is inserted into its place in the waveguide and lid is covering the chip, we fix all the structure with two clamps. The proposed waveguide structure provides easy and fast access to the chip. Some experimental results (measured S-parameters in phase) are shown in Fig. 21. The measured data are shifted to higher frequencies in comparison with the theoretical results. This frequency shift is about 5GHz-6GHz. At the same time, the measured insertion loss level is 2-4 times higher than expected (1.5dB-4dB). The

16

measured phase value is slightly different from the predicted one (Fig. 21). This is mainly due to the fact that our resonance frequency is shifted (the chip dimensions are different from the nominal ones). The reproducibility and bit resolution of the phase shifters are been discussed in detail in the first Periodic Report.

(a) Rectangular-shaped chip (b) X-shaped chip Fig. 21. Example of finline chips phase response.

Iris-based phase shifters. The design and optimization of inductive iris phase shifters has been considered at 77 GHz as an additional work that enables us to go beyond the description and work of the TUMESA project. For complexity and manufacturing cost reduction, prototyping of the inductive iris-based phase shifters lower was launched at 10GHz (scaled prototypes integrated into WR-90 (10.16×22.86mm2) waveguides). The designed 3-pole asymmetrical iris-based filter includes four asymmetrical iris sections printed on a RT/Duroid 5880 dielectric substrate (εr=2.2, h=0.58mm) and is integrated into a WR-90 waveguide as shown in Fig. 22 (D1=D4 and D2=D3).

(a) (b)

(c) Different iris states configuration Fig. 22. Iris-based model.

The transmission phase is controlled by changing the iris slot length, as shown in Fig. 22c. Instead of using switchable MEMS, the iris slot is controlled by rectangular patches. These patches are represented in yellow in Fig. 22a and are marked with numbers (1, 2 and 3). The size of each individual patch is 1.6×1.6mm2. For each iris, the total patch number is equal to three. The phase response of a 2-bit phase shifter is represented in Fig. 23.

9-2,0

-1,5

-1,0

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18

3.2.5 Antenna array optimization, prototyping, and measurements 

A 10×21 element antenna array (54.55×41.9×10.205 mm3) fed by a 11-dBi pyramidal horn has been designed to radiate its main beam at broadside (Fig. 27). The four rectangular phase shifters represented in Fig. 16 are used to compensate for the different electrical path lengths between the horn and each unit-cell of the radiating aperture. In the antenna array model, the waveguide wall thickness equals 1mm.

 

(a) (b)

Fig. 27. (a) Phased antenna array model. The unit-cell is a rectangular finline-based phase shifter chip model. (b) Feed pyramidal horn antenna.

Two antenna arrays have been fabricated in bronze. Each array is divided into 11 parts. There is a footprint inside each antenna array part to accommodate for the chip and keep it fixed inside the waveguide. Long bolts are put through the antenna array walls to pull together all array parts. Fig. 28 shows one of the two arrays once assembled.

(a) One array section (b) Array once assembled Fig. 28. Antenna array.

The far-field patterns of both antenna arrays have been measured at UR1. The measured antenna gain is lower than the theoretical value (by 6dB). This is mainly due to the chips performance that exhibit higher insertion loss, as described in the Final Periodic Report. The measured antenna array patterns are in good agreement with the numerical predictions (Fig. 29).

19

-90 -60 -30 0 30 60 90-60

-50

-40

-30

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-10

0

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m G

ain

[dB

]

Angle [degree]

Co-pol Theor Co-pol Meas X-pol Theor X-pol Meas

77 GHz E-plane

-90 -60 -30 0 30 60 90-60

-50

-40

-30

-20

-10

0

Nor

m G

ain

[dB

]

Angle [degree]

Co-pol Theor Co-pol Meas X-pol Theor X-pol Meas

77 GHz H-plane

E-plane – 77 GHz H-plane – 77 GHz

Fig. 29. Measured and computed radiation patterns. The antenna array ability for beam scanning by moving the feed in E-plane in a plane parallel to the antenna array is presented in Fig. 30. In this case, all phase shifter are tuned to have maximum radiation at broadside.

-90 -60 -30 0 30 60 90-30

-25

-20

-15

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0

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ain

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0

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m. G

ain

[dB

]

Angle [degree]

0 4mm 8mm 12mm 16mm 20mm

Second antenna array Offset feed position84GHzE-plane

Fig. 30. Antenna array beam steering radiation patterns at 77 GHz and 84 GHz.

3.3 Leaky wave antennas

AUTOCRUISE contributed to the TUMESA project by providing system & antenna specifications for the different scenarios which occur in vehicular traffic. A PhD student was specifically hired to investigate candidate antenna solutions which are suitable for fixed-frequency electronic beam steering, with the academic support from UR1 while taking into account the technology available from the TUMESA partners (KTH, AALTO). This research work resulted in investigating an original beam-steering solution (coupling leaky-wave antenna (CLWA)) which was finally fabricated and measured. In addition to their frequency scanning capability, periodic leaky-wave antennas are

20

also capable of fixed-frequency beam steering either by varying the guided wavelength or the perturbation spacing. In this section, we overview the different LWA solutions, which were investigated in the frame of TUMESA, as well as the fabricated CLWA prototype.

3.3.1  MEMS­based coplanar waveguide leaky­wave antenna One the antenna solutions suitable for fixed-frequency electronic beam steering is the coplanar waveguide LWA proposed by Xiao et al. The fixed-frequency beam steering can be achieved by controlling the states of MEMS switches which are integrated within the ground plates in the CPW plane. The structure is Fig. 31. Although designed at 35 GHz, we simulated this type of antenna on FEKO in order to investigate its performance as well as the possibility of implementation at 77 GHz.

Fig. 31. MEMS-based CPW leaky-wave antenna.

The perturbation spacing is formed by making one MEMS switch open (OFF-state) following (p-1) MEMS switches in the closed (ON) state. Two configurations (d1 = 4mm : 9OFF-1ON) and (d2 = 3.6mm : 8OFF-1ON) were tested. The results are shown in Fig. 32.

Fig. 32. Radiation characteristics of the two CPW LWA configurations at 34.16 GHz (FEKO).

According to our FEKO simulations, the CPW LWA demonstrates a fixed-frequency beam scanning capability, however the antenna performance are degraded when switching between the two tested configurations. In addition, the antenna efficiency is significantly degraded in configuration 2, which raises concerns on the possibility of implementing this antenna concept at 77 GHz. For this reason, we decided to turn our attention to the dielectric rod LWA concept.

21

3.3.2  MEMS­based dielectric rod leaky­wave antenna Taking into account the silicon technology available at KTH, we decided to investigate silicon rod LWAs at 77 GHz. This type of antenna consists of a silicon rod with periodic metal grating on top and a metal plate on the bottom to avoid backward radiation (see Fig. 33). The design guidelines have been reported in details in the previous TUMESA deliverables. By varying the distance between two consecutive metal strips (perturbation spacing), the fixed-frequency beam-steering capability of this type of antenna is clearly shown in Fig. 34. It has been shown by FEKO simulation that the main beam of the antenna is scanned from -30° to 15° while varying the perturbation period from 1.1 mm to 1.4 mm. Over this angular region, the sidelobe level is kep below -12 dB and the mean value for the directivity is 15.6 dBi with a variation of ±0.7 dB.

Fig. 33. Dielectric rod LWA with metal grating.

Fig. 34. Silicon rod LWA: fixed-frequency beam steering capability at 76.5 GHz (azimuth).

However, as it was shown via simulation and confirmed by theory, the main beam of the silicon rod LWA is highly sensitive to frequency, and exhibits an undesirable frequency scanning of 3°/GHz in the frequency band of interest (76 – 77 GHz). This problem was mainly due to high permittivity of the silicon rod waveguide. In order to reduce the undesirable frequency scanning, we decided to redesign the same antenna concept using a dielectric rod waveguide with lower dielectric constant (quartz). The radiation characteristics in the azimuth plane of the quartz rod LWA are illustrated in Fig. 35. This antenna

22

demonstrated a fixed-frequency beam steering capability with improved performance in comparison with the silicon rod LWA, and main beam is less sensitive to frequency in the 76 – 77 GHz band. Furthermore, in order to take into account the MEMS integration for electronic beam steering at 76.5 GHz, we proposed to break each metal strip into several elementary strips, as shown in Fig. 36. In the “ON-region”, the elementary strips are connected with metal pads (MEMS in the ON-state) while the “OFF-region” consists of unconnected elementary strips (MEMS in the OFF-state) to simulate the dielectric gap.

Fig. 35. Quartz rod LWA: fixed-frequency beam steering capability at 76.5 GHz (azimuth).

Fig. 36. Quartz rod LWA with MEMS integration.

23

The simulation results of the quartz rod LWA with elementary strips demonstrated similar radiation characteristics to Fig. 35. However, from technological feasibility point of view, the proposed structure cannot be fabricated in the frame of TUMESA as the MEMS switches shall be implemented on high-resistivity silicon wafers (cf. D5.2b). For this reason, we decided to use a different concept where the dielectric rod waveguide and perturbation strips are implemented separately.

3.3.3  MEMS­based coupling leaky­wave antenna The coupling LWA is shown in Fig. 37. It consists of a circular dielectric rod (quartz) positioned inside a metallic packaging with a radiating aperture at one side and a 300µm-slot at the other side. The perturbation strips are etched on top of a separate silicon substrate and coupled to the dielectric rod via the slot.

Fig. 37. Coupling leaky-wave antenna.

The diameter of the dielectric rod was chosen to ensure the propagation of only one mode in the structure (HE11) and the rod was chosen long enough to radiate 90% - 95% of the propagating energy. As for the other design parameters (dimensions of the packaging, coupling distance between the silicon substrate and the dielectric rod etc.), they were chosen via a 2D-study of the effective permittivity. Indeed, the latter must be as close as possible to 1 in order to reinforce the leaky-wave behaviour in the proposed structure. The design guidelines for this type of antenna are described in details in previous TUMESA deliverables.

The perturbation period shall be controlled by the states of the MEMS switches. The ON-state of the MEMS is represented by metal patches while the OFF-state is represented by dielectric gaps in CPW technology. The 5OFF-5ON configuration is illustrated in Fig. 38.

Fig. 38. CLWA: perturbation period in the 5OFF-5ON configuration.

In order to validate the capability of fixed frequency beam steering, we simulated the CLWA in different configurations of the perturbation period. As the simulation results were very promising and the frequency scanning in the frequency band of interest was very low (1°/GHz), we decided to fabricate a CLWA prototype. The fabricated CLWA prototype developed at AUTOCRUISE consists

Slot

24

of the assembly of the following parts: the dielectric rod (quartz), the silicon chips, the metallic packaging, the dielectric lens (focusing in the elevation plane) and WR10-compatible transitions (for antenna excitation/measurement). The antenna prototype was measured at UR1 in the 72 – 80 GHz frequency band (see Fig. 39). Four lengths of the perturbation period were measured, as indicated in Table 1. Each perturbation period corresponds to a determined configuration of the MEMS switches.

Fig. 39 CLWA in the measurement chamber.

Table 1 – Tested configurations of the perturbation spacing.

Configuration Code Period length[mm]

Azimuth beam angle [°] @ 76.5 GHz / broadside

1 5F_6N 3.74 -12°2 7F_5N 4.08 -5°3 8F_6N 4.76 2°4 8F_7N 5.1 5°

The measured radiation patterns of the CLWA in the 5F_6N configuration are compared to HFSS simulations in Fig. 40 in the 72 – 80 GHz frequency band. We notice that the measurement results agree well with HFSS simulations, notably when it comes to the angular position of the main beam. As expected, the measured beam angle at 76.5 GHz is 12° and the -3dB beamwidth is 7.5°. As for the sidelobe level, the latter increases at higher frequencies and the beam shape degrades as well. Finally, the measured |S11| is kept below -12 dB over the frequency band of interest. In addition, the effect of the coupling distance as well as the position of the first strip was validated by measurements. (cf. D2.4 & D3.6 for more details).

Matched Load

25

Fig. 40. Measured (Blue) and Simulated (Red) azimuth radiation patterns [dB] vs. azimuth angle [°] in the

[72 GHz – 80 GHz] frequency band.

More importantly, the capability of the CLWA of fixed-frequency electronic beam steering was also validated by measurements. The azimuth radiation patterns corresponding to the four tested configurations (Figure 10) illustrates the variation of the main beam of the antenna at 77 GHz, accordingly with the perturbation period.

26

Fig. 41. Measured azimuth radiation patterns at 77GHz vs. azimuth angle for each tested configuration.

3.3.4  Conclusions Following the investigation of several LWA concepts in the frame of TUMESA, a coupling leaky-wave antenna was designed, simulated, optimized, fabricated and measured. The prototype has been characterized and validated; the measurement results agree with the HFSS simulations, notably for the estimation of the azimuth angular position of the main beam. The prototype capability of fixed-frequency electronic beam steering has been validated: for a periodic leaky-wave antenna, the beam angle varies accordingly with the length of the perturbation period (at a fixed frequency). In addition, the effect of the coupling distance and the lens on the antenna performances has been observed. The side lobe levels can be improved with further optimization of the coupling distance, the position of the first strips for each chip configuration and finally by using non-uniform periodic configurations to modulate the antenna effective aperture. The overall good performances achieved with this “passive” CLWA prototype (different chip configurations) open the door to the implementation of an “active” CLWA prototype where the perturbation period can be varied electronically via integration of MEMS switches on the silicon substrate to realize electronic beam steering. Finally, the CLWA offer the advantage of using simple monostatic RF transceiver when integrated within the 77 GHz radar front-end, as it requires only one RF-channel in RX. The different issues regarding the antenna implemented in the 77 GHz radar front end are discussed in D3.6.

3.4 MEMS Technology: Design, Fabrication and Evaluation (KTH)

3.4.1  Objectives The objectives of KTH in the project have been the following:

• Developing concepts and designs for MEMS devices. This involves mechanical design, actuator design, material selection and process development. Most of the RF design has been done by other partners.

• Prototype fabrication in cleanroom facilities. This includes photolithography mask layouting, ordering of materials and then a number of test and sharp fabrication runs in the cleanroom to tune the fabrication process.

• Evaluation of prototypes by reliability and mechanical characterization. Most of the RF measurements have been done by other partners

27

3.4.2  Overview of fabrication technology The microstructures designed within the TUMESA project has been fabricated by KTH at the Electrum Laboratory cleanroom facilities. The fabrication activities are divided into three main tracks by the underlying process designs, as shown in 2, which are then used by the different device designs. Each process design corresponds to a main partner in the project. For each of the three fabrication tracks, a complete microfabrication process was developed and tuned by KTH. The first track (A) was the most complex process to develop, and thus consumed the most time in the fabrication activity. It uses 8 photolitography masks and employs full-wafer adhesive transfer bonding to integrate monocrystalline silicon layers from 3 different wafers with micron scale lithographically defined features. The second track (B) uses 2 photolithography masks and high-aspect ratio deep reactive ion etching to create irregular shaped silicon chips with precision aligned metal patterns on both sides. Final assembly of the chips inside waveguides was done at UR1. The third track (C) uses 3 photolithography masks and deep reactive ion etching of 150 mm diameter silicon on insulator wafers to create chips with thin overhanging silicon structures with fine metal patterns on the surface. In the rest of this section, the activities in each of the three fabrication tracks are outlined. Table 2. Major fabrication process designs in the project and their respective main partner.

Design Technology description Application A) Transfer bonded distributed

MEMS tuning technology (AALTO)

Metallized monocrystalline silicon core membranes (1 µm thin) are transferred onto a patterned substrate by a full wafer bonding technique, allowing large arrays with perfect mechanical performance.

1) High impedance surface stub line phase shifter (5×10 array elements)

2) Dielectric rod waveguide HIS phase

shifter (24×120 array elements)

3) High impedance surface for beam

steering (200×52 array elements)

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antenna (30 linear elements)

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28

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29

3. Erecting thin movable membranes above the surface of the dielectric film, connected to the metal lines and with thick metallization above the skin depth at 77 GHz. This was done by transfer bonding of a thin monocrystalline silicon layer, for perfect mechanical performance, which was symmetrically metalized on both sides for stress compensation.

Process flow showing the wafer-scale multi-layer fabrication process for the high-impedance surface.

In the rest of this section, the chronological development of the fabrication process is outlined with respect to the different fabrication runs performed. In total, 2 test runs and 6 sharp runs were done. Background to the test runs The high impedance surface arrays require processing on a substrate consisting of three layers: a handle wafer, a metal ground plane and a 100 µm thick dielectric layer of a microwave compatible material. From previous work at KTH came the process of using adhesive wafer bonding of 100 µm AF45 glass wafers with BCB polymer. To compensate stress due to thermal mismatch, one glass wafer is bonded on each side. The process of transferring a thin monocrystalline silicon membrane has also been previously used. However, it works less well on glass due to the waviness of glass substrates. Thus polishing of the glass was first track in the project, before the alternative technology using high resistivity silicon dielectrics was employed. Test run 1 Date of completion: 2008-07 Substrate stack: AF45 – BCB – Si – ground – BCB – polished AF45 Mask set: #1 Description: experiment with post-bonding polishing of top glass to overcome waviness Objective: produce a flat substrate for subsequent processing Outcome: didn’t work due to cracking or release of glass bond Conclusion: adhesively bonded glass was not stable enough to polish in this way, likely due to thermally induced stress during the bonding Test run 2 Date of completion: 2008-09 Substrate stack: AF45 – eutectic Si18.6Au71.4 – 500 µm Si – eutectic eutectic Si18.6Au71.4 – polished AF45 Mask set: #1 Description: experiment with eutectic bonding of glass to overcome failure during polishing Objective: making a stronger glass-to-silicon bond, using the gold layer already present in the design, so that the glass wafer would survive polishing Outcome: failed due to unsuccessful bonding, or cracking of the glass when polishing Conclusion: The eutectic bonding of AF45 glass to silicon did not prove a viable way to create a bonded polished glass surface, despite the stronger bond strength. Further experiments were not done on this technique due to high resistivity silicon being used instead (see next section).

30

Background to the sharp runs Due to the problems caused by the glass substrate being wavy and having a significantly different thermal expansion than silicon, high resistivity silicon was considered as an alternative material for the 100 µm dielectric layer. Microwave measurements showed that the loss tangent at the working frequency was as least as good as the AF45 glass, and an all-silicon design meant no thermal mismatch. Sharp run 1 Date of completion: 2009-03 Substrate stack: Si – ground – BCB – HRS Mask sets: #1 Description: experiment with high resistivity silicon instead of glass for perfect CTE match Objective: create a silicon-silicon stack more suitable for further processing than silicon-glass Outcome: membrane bonding still poor due to high electrode topography Conclusion: high resistivity silicon is a good material for the dielectric layer, only some additional problems remain to be solved for better bonding Sharp run 2 Date of completion: 2009-07 Substrate stack: Si – ground – BCB – HRS Mask sets: #1 Description: resist based planarization of electrode layer for perfect membrane bonding Objective: improve adhesion of silicon membrane until it has been fixated by creating the electroplated post structures Outcome: problems with plating due to wet etching of plating base Conclusion: the planarization was useful to improve bonding, further work needed to make the electroplating robust structurally Results: spot measurements of large arrays to prove high impedance surface behavior Sharp run 3 Date of completion: 2009-08 Substrate stack: Si – ground – BCB – HRS Mask sets: #2 Description: new masks with larger drawn dimensions for safer wet etching, also test structures for determining membrane stress Objective: increase adhesion of electroplated posts to substrate Conclusion: increasing the mask dimensions and thus the plating base made the structure stronger Results: reliability data for movable membranes Sharp run 4 Date of completion: 2010-01 Substrate stack: Si – ground – BCB – partially etched HRS Mask set: #3 Description: new mask set with openings in the dielectric layer for contact between ground and waveguide in RT devices Objective: provide better integration of reflective chips with the waveguides by contacting the waveguide to the ground plane using patterned conductive adhesive Outcome: problems during the processing with underetching of metal layers on the backside of the transfer bonded membranes

31

Conclusion: etching down to the ground plane was feasible and provided lower loss Results: measurement data on waveguide integration of phase shifter arrays Sharp run 5 Date of completion: 2010-07 Substrate stack: Si – ground – BCB – partially etched HRS Mask set: #4 Description: new mask set with more compact layout and new transmission line LWA structures Objective: fit more devices on the wafer to overcome yield issues and introduce new variations Outcome: some structures destroyed by overetching in ground etch step Conclusion: better protection resist layer needed in the final step Results: tuneable dielectric waveguide high impedance surface phase shifter delivered Post processing of sharp run 5 for leaky wave antennas Date of completion: 2010-10 Substrate stack: Si – ground – BCB – partially etched HRS – wirebonds to ground Description: final wirebonding of the transmission line leaky wave antenna structures to connect the membranes to the ground of the microstrip line Objective: connect the membrane layer to the exposed ground layer by wirebonding Conclusion: wirebonding was a feasible way of connecting upper and lower layers Results: measurements of transmission line leaky wave antennas Sharp run 6 Date of completion: 2011-09 Substrate stack: Si – ground – BCB – partially etched HRS Mask set: #5 Description: new mask set that fits three BS chips without any DW chips, and many RT chips Objective: produce chips with higher yield for beam steering arrays Outcome: two independent issues with the gold plating setup and the dry etching of metals ruined the last two sharp wafers Conclusion: yield management is still an issue, as is process stability Results: beam steering and stub line devices delivered for additional measurements Conclusions Two test runs and six sharp runs of the microfabrication process were performed by KTH during the development of the transfer bonded distributed MEMS tuning technology. Fabricated chips have been sent to AALTO for measurements and characterization.

SEM image of a perfectly flat released membrane

Life-cycle measurement over 100 million cycles

32

MEMS chip with free-etched ground layer and DC interconnection lines, shown with unmounted waveguide stub. SEM image of a leaky wave antenna chip.

3.4.4  Wave­guide antenna array Concept The final goal of this track is to create an antenna array consisting of rectangular waveguide aperture array elements, where each one has a microfabricated chip inserted in fin line configuration. On the chip is a metal pattern that affects the phase of the wave, and by configuring the array according to certain patterns beam steering can be achieved. The chips have been fabricated by KTH while the final assembly of the waveguide array has been done at UR1. A single waveguide fixture for testing the individual chips was made by MCNAB and measured by AALTO. The rest of this section outlines the fabrication performed by KTH. Fabrication The table below explains the fabrication process developed by KTH for the fabrication of the irregular shaped double-side metalized and patterned silicon chips:

1. Coating of two wafers by BCB adhesive

2. Bonding at 250°C

3. Pattern metal on front and back side by lift off, using backside alignment to align the patterns

4. Etch the chip with deep reactive ion etching from front and back side, mounting the wafer on a thermal release tape for final etch

33

Conclusion In total 500 individual chips was created by the fabrication process on four wafer pairs. Six chip configurations are realized of each chip type, for different phase shifts. Pictures of the fabricated chips are shown below.

3.4.5  Coupling leaky wave antenna Concept This concept for a steerable leaky wave antenna has a thin (100 µm) silicon substrate inserted close to a dielectric rod waveguide (illustrated below), coupling perturbations etched in a metal layer on the silicon to the waveguide which affects the outgoing angle of the radiation. Challenges in the fabrication include how to create a stable support for the thin silicon part, and to create well-defined thicknesses of the metal patterns and the silicon parts. The solution employed is to use a silicon on insulator wafer with a 100 µm device layer, and then patterning the handle wafer to create an overhanging structure. The metal layer is patterned beforehand using lift-off. Finally a tapered outline of the chip is achieved by etching the device layer to release the chips.

Concept of the microfabricated silicon overhanging structures with metal layer perturbations close to a rod waveguide

Picture of the perturbations in the metal on the chip edge on a fabricated chip

34

Process Flow In this section the fabrication procedure of the chips is outlined. The chips were fabricated on a 6 inch high resistivity SOI (silicon-on-insulator) wafer using a three mask process. The fabrication started with the high resistivity SOI wafer with device layer of 100 µm, handle wafer of 500 µm and the buried oxide layer of 2 µm. Figure 1 shows the SOI wafer.

Figure 1. High resistivity SOI wafer with 100 µm device layer, 500 µm handle wafer and 2 µm buried oxide layer

1 µm gold was then patterned on the wafer by lift-off, and subsequently protected by a resist layer.

Figure 3. Antenna pattern defined by 1 µm of gold on top of device layer of high resistivity silicon

The handle wafer was then DRIE etched to form the back support of the antenna chips as shown in Figure 5.

Figure 5 – Backside etching of the handle wafer using STS ICP

The wafer was then placed on a 6 inch silicon wafer carrier using a thermal release tape. The front side was DRIE etched as shown in Figure 6. The chips were finally released from the thermal release tape by placing the carrier on a hotplate at 120°C for 15 seconds and finally the remaining photoresist was removed with the combination of acetone and oxygen plasma at reduced power. The silicon dioxide was then dry etched as shown in Figure 7.

Figure 7 – Etching of the buried oxide layer

SEM Pictures The SEM pictures of the fabricated devices are shown below. Figure 8 shows a SEM picture of the antenna chip showing the slots. Figure 9 shows the closeup of one of the slots where 1 µm of gold is seen above the silicon device layer. Figure 10 shows the SEM image of the taper of the fabricated CLWA chip. Figure 11 shows the fabricated chip where the device layer, handle wafer and the gold layer on the top is clearly seen. Also the taper of the chip can be seen in this figure.

35

Figure 8. SEM picture of the antenna chip showing the slots Figure 9. Closeup of one of the slots of the fabricated CLWA chip

Figure 10. Taper of the fabricated CLWA chip Figure 11. SEM picture of the fabricated CLWA chip from the side

Conclusion Multiple configurations of the CLWA chips were fabricated on a 150 mm wafer and delivered to AUTOCRUISE for measurements. The yield on chip level was 75-80% once the fabrication process had been fully developed.

36

4 Potential impact

4.1 Strategic impact One of the most important aspects of life is safety in general and road safety in particular. In 2005, almost 45000 fatalities were caused by road accidents in the European Union (27 countries). European Commission has set in White Paper on the Common Transport Policy an ambitious target to halve this number by 2010, but a decrease of only 20 % has been achieved during 2000 – 2005, which is unacceptable according to a recent communication from the Commission in the frame of Intelligent Car Initiative. Consequently, more decisive measures have to be introduced in nearest future in order to improve road safety. The European Commission has identified that introduction of advanced surroundings perception devices, i.e. automotive radars, is the first priority for vehicle safety, together with a wide penetration of electronically controlled stability program (ESP). The European Conference of Postal and Telecommunications Administrations (CEPT) has identified the 79 GHz range as a most suitable band for long term and permanent development of automotive radars. However, in December 2010 EC issued a call to stakeholders for their views on the proposed amendment to this Commission decision, emphasising that SRR technology at 79 GHz is not progressing in such a way as to guarantee availability even by July 2013. The goal of this project is to develop smart wireless communication components and systems for short range and long range automotive radar sensor in order to increase road safety and improve driving comfort. The concept is integration of advanced metamaterials and microelectromechanical technologies to enable significant progress in automotive radar development, including miniaturisation, higher functionality and integration, reduced power consumption. One of the most important factors restraining implementation of automotive radar in mass production is high cost. That is why the special focus of the project is to reduce cost of the final product. Proposed MEMS tuneable metamaterials are devices fabricated on a single chip that can substitute larger beam steering subsystems, e.g. conventional phased array, and consequently reduce cost of the whole radar system. Besides, the chosen MEMS technology helps to develop cost-effective devices thanks to the batch manufacturing possibilities. As far as the potential of the automotive radar market is counted in millions, this is a very expedient solution. The expertise of the partners in such fields as metamaterials, MEMS, antennas, millimetre wave measurements, and automotive radars, which are necessary for achieving the objectives of the project, allowed working on the whole value chain including design, analysis, fabrication, characterisation and system integration of the proposed components and devices. The European approach to such a challenge as development of high performance automotive radar based on MEMS tuneable metamaterials is needed because none of the European countries host a set of organisations with a competence in the abovementioned fields on the cumulative level of the consortium partners’ competence. The consortium enjoys the participation of AUTOCRUISE, a leading European automotive radar manufacturer, which enables the pre-industrial evaluation of developed prototype performance on a system level and validation of new manufacturing concepts suitable for mass production as well. We believe that this also shorten time-to-market needed for the automotive radar system developed after the end of this project. AUTOCRUISE is based in France, its main customers are German, Swedish and English companies, and technical components are supplied from European suppliers. Therefore, the successful implementation of the developed devices in industrial production will allow increasing market share of European companies manufacturing vehicles and their components by delivering in time a cost-

37

efficient and high performance long-awaited solution for improving road safety. Taking into account the market potential, this implementation may result also in creation additional jobs in Europe.

4.2 Dissemination and usage of the project results The millimetre wavelength region is of increasing interest for many applications such as radio radar, secure high-capacity communication systems, astronomy and atmospheric remote sensing, spectroscopy, medical diagnostics, etc. An automotive radar standard in 79 GHz range is already produced by European Telecommunication Standard Institute ETSI and according to the European Commission is to be implemented in collision avoidance system in the nearest future. Also, high-capacity communication systems (57-64GHz) and Road Traffic & Transport Telematics (RTTT, 63-64GHz) are targeting millimetre wave ranges due to the strict requirements of wide bandwidth. The research described in the current proposal is triggered by lack of low loss, inexpensive and space-efficient components for millimetre-wave automotive and industrial radar and communication systems. We aim to develop novel on-chip phase shifting and beam-steering devices, space-efficient antenna arrays, and to elaborate novel concepts of cost-efficient radar sensor and future high-capacity wireless communication systems.

Consequently, research institutions and industrial companies which deal with the abovementioned applications can be interested in the results of the project. More precisely, the target audience for exploitation project results is presented in table below. Level Result Target audience Component MEMS-based tuneable

high-impedance surface Research organisations developing smart metamaterial-based devices and miniaturised/highly integrated devices such as: antennas, phase shifters, frequency-selected surfaces.

Component MEMS capacitor with large continuous tuning range

Research and industrial organisations focused on electrical and communication engineering, automotive applications, bioengineering, etc., developing miniaturised tuneable devices on a chip such as phase shifters, accelerometers, pressure and flow sensors and components such as filters, impedance tuners, resonators, oscillators, amplifiers, power dividers etc.

Component Low-loss analogue phase shifter

Research and industrial organisations developing low-cost and phased antenna arrays with high radiation efficiency

Sub-system Smart beam-steering reflective surface

Research and industrial organisations focused on communication engineering and automotive applications, developing novel technologies for next-generation reconfigurable sensor front-ends in radar, high capacity communications systems, remote sensing, etc.

Sub-system Steering leaky wave antenna

Sub-system Antenna array

System Novel concept of reconfigurable short range / long range radar sensors

Automotive companies

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TEMPLATE A1: LIST OF SCIENTIFIC (PEER REVIEWED) PUBLICATIONS, STARTING WITH THE MOST IMPORTANT ONES

NO. Title Main author Title of the periodical or the series

Number, date or

frequency Publisher Place of

publication Year of publica

tion Relevant

pages

2Permanent identifiers[1]  (if available) 

Is/Will open access[

2] provided to this 

publication? 

1 “Analogue type millimetre wave phase shifters based on MEMS tuneable high-impedance surface and dielectric rod waveguide”

D. Chicherin International Journal of Microwave and Wireless Technologies

Vol. 3, Special Issue on RF MEMS

Camb. Uni. Press 2011 pp. 533-

538 No

2 “Microwave MEMS devices designed for process robustness and operational reliability”

M. Sterner International Journal of Microwave and Wireless Technologies

Vol. 3, Special Issue RF MEMS

Camb. Uni. Press 2011 pp. 547-

563 No

3 “Iris-Based 2-bit Waveguide Phase Shifters and Transmit-Array for Automotive Radar Applications”

A. Vorobyov European Conference on Antennas and Propagation EuCAP 2012

2012 No

4 “Antenne à ondes de fuite à balayage angulaire à fréquence fixe à 77GHz”

G. El Haj Shhade

17èmes Journées Nationales Microondes JNM 2011

May 18-20 Brest, France 2011 No

2 A permanent identifier should be a persistent link to the published version full text if open access or abstract if article is pay per view) or to the final manuscript accepted for publication (link to article in repository). 2 Open Access is defined as free of charge access for anyone via Internet. Please answer "yes" if the open access to the publication is already established and also if the embargo period for open access is not yet over but you intend to establish open access afterwards.

39

5 “Leaky-wave antenna based on microelectromechanical systems-loaded microstrip line”

T. Zvolensky IET Microwaves, Antennas and Propagation Vol. 5, no. 3 IET 2011 pp.357-363

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5714046  

No

6 “Analog type millimeter wave phase shifters based on MEMS tunable high-impedance surface in rectangular metal waveguide”

D. Chicherin IEEE International Microwave Symposium 2010 Digest

May 23-28 IEEE Anaheim, CA, USA 2010 pp. 61-64

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5515937  

No

7

“Monocrystalline-silicon microwave MEMS devices: multi-stable switches, W-band phase shifters, and MEMS tuneable frequency-selective surfaces”

J. Oberhammer

Book Chapter in “Advanced Materials and Technologies for Micro/Nano-devices, Sensors, and Actuators”

Springer 2010 pp. 89-100

http://www.springerlink.com/content/l11qut2mr24136n5/  

No

8 "Mm-wave antennas for automotive radars: review and needs"

R. Sauleau Proceedings of the 4th European Conference on Antennas and Propagation, Workshop ARTIC

April 12-16 IEEE Barcelona, Spain 2010 No

9

“Nanometer-scale flatness and reliability investigation of stress-compensated symmetrically-metallized monocrystalline-silicon multi-layer membranes”

M. Sterner IEEE Nano Electro Mechanical Systems 2010 Jan. 20-23 IEEE Xiamen,

China 2010

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5592249  

No

10 “MEMS based waveguide phase shifter for phased array in automotive radar applications”

A.Vorobyov Proceedings of the European Conference on Antenna and Propagation 2011

April 10-15 IEEE Rome, Italy 2011 pp. 2087-2090

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5781980   

No

11 “Millimeter Wave Beam Steering with a MEMS-based High Impedance Surface”

Z. Du Proceedings of the 41st European Microwave Conference

Oct. 9-14 IEEE Manchester, UK 2011 pp. 1043-

1046 No

12 “Leaky-wave regimes on MEMS- T. Zvolensky Progress in Vol. 13 PIER 2010 pp. 157- http://www.jp Yes

40

loaded transmission lines for mm-wave applications”

Electromagnetics Research M

171 ier.org/PIERM/pier.php?paper=10050605  

13

“Reliability investigation of stress-compensated metal-coated monocrystalline-silicon membranes for MEMS tuneable high-impedance surfaces”

M. Sterner MEMSWAVE 2010 Conference June 28-30 Otranto,

Italy 2010 No

14 "MEMS based high-impedance surface for millimetre wave dielectric rod waveguide phase shifter"

D. Chicherin European Microwave Conference 2010 Sep. 28-30 IEEE Paris,

France 2010 pp. 950-953

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5616114  

No

15 “RF MEMS high-impedance tuneable metamaterials for millimeter-wave beam steering”

M. Sterner Proceedings of the IEEE MEMS Conference 25-29 Jan. Sorrento,

Italy 2009 pp. 896-899 No

16 "Reconfigurable phased antenna arrays for automotive radar application"

A. Vorobyov Young Scientists Conference YSC 2011

Nov. 28-Dec. 2 Kharkov,

Ukraine 2011 No

17 “Leaky-wave antenna at 77 GHz” T. Zvolensky Proceedings of the 41st European Microwave Conference

Oct. 9-14 IEEE Manchester, UK 2011 pp. 1039-

1042 No

18 “Millimeter wave phase shifters based on dielectric rod waveguide”

D.V. Lioubtchenko

Proceedings of Int'l IEEE Conf. on Electromagnetics in Advanced Applications & IEEE-APS Topical Conf. on Antennas & Propagation in Wireless Communications 2011

Sep. 12 – 17 IEEE Torino, Italy 2011 pp. 789-

791

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6046447  

No

19 “MEMS-based High Impedance Surface for Beam Steering at 80 GHz”

Z. Du The Millimetre Wave Days: The 6th ESA Workshop on Millimetre-Wave Technology and

May 23 – 25 Espoo, Finland 2011 No

41

Applications

20 “MEMS tunable metamaterials surfaces and their applications” D. Chicherin

Proceedings of the Asia Pacific Microwave Conference 2010

Dec. 7-10 IEEE Yokohama, Japan 2010 pp. 239-

242

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5728690  

No

21 "Integration of microwave MEMS reconfigurable reflective surfaces in rectangular waveguide stubs for W-band phase-shifters"

M. Sterner Proceedings of the Asia Pacific Microwave Conference 2010

Dec. 7-10 IEEE Yokohama, Japan 2010 pp. 1825-

1828

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5728282  

No

22 “Beam-steering MEMS-loaded antenna based on planar lines" T. Zvolensky

Proceedings of the 4th European Conference on Antennas and Propagation

April 12-16 IEEE Barcelona, Spain 2010 pp. 1-4

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5505310  

No

23 “Microwave MEMS activities at KTH-Royal Institute of Technology”

J. Oberhammer

Micro Structure Workshop 2010 May 4-5 Stockholm,

Sweden 2010 No

24 “RF MEMS Tuneable High-Impedance Metamaterial Surfaces for Millimeter Wave Applications”

M. Sterner Micro Structure Workshop 2010 May 4-5 Stockholm,

Sweden 2010 No

25 "MEMS tunable metamaterials for beam steering millimeter wave applications"

D. Chicherin

Proceedings of NATO Research Workshop on Advanced Materials and Technologies for Micro/Nano-devices, Sensors, and Actuators: From Fundamentals to Applications

June 29-July 2

St. Petersburg, Russia

2009 p. 45 No

26 “Monocrystalline-silicon microwave MEMS devices multi-stable switches, W-band phase

J. Oberhammer

Proceedings of NATO Research Workshop on Advanced Materials and

June 29-July 2

St. Petersburg, Russia

2009 pp. 21-22 No

42

shifters, and MEMS tuneable frequency-selective surfaces”

Technologies for Micro/Nano-devices, Sensors, and Actuators: From Fundamentals to Applications

27

“MEMS switching devices as promising solution for electronically controlled phase shifter in automotive radar applications: a review"

A. Vorobyov Conference on Electromagnetics, Photonics and Biophysics

Dec. 1-3 Kharkov, Ukraine 2009 No

28 “RF MEMS high-impedance tuneable metamaterials for millimeter-wave beam steering”

M. Sterner Proceedings of GigaHertz Symposium Mar. 9-10 Lund,

Sweden 2010 p. 29 No

29

“Wafer counter-bonding for integrating CTE-mismatched substrates and its application to MEMS tuneable metamaterials”

M. Sterner

Proceedings of the 15th International Conference on Solid-State Sensors, Actuators and Microsystems

June 21-25 Denver, CO, USA 2009 pp. 1722-

1725

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5285734  

No

30 “Rectangular metal waveguide phase shifter controlled with MEMS high-impedance surface”

D. Chicherin

Proceedings of the XXXI Finnish URSI Convention on Radio Science and Electromagnetics 2008 Meeting

28 Oct. Espoo, Finland 2008 pp. 27-28 No

43

TEMPLATE A2: LIST OF DISSEMINATION ACTIVITIES

NO. Type of activities3 Main leader Title Date Place Type of audience4

Size of audience

Countries addressed

1 RF-MST Cluster (EU FP6 and FP7 projects) Workshop and MEMSWAVE conference

D. Chicherin Project presentation June 30 – July 3, 2008

Heraklion Scientific Community

50 Greece

2 TUMESA web-site; (opening) D. Chicherin TUMESA web-site; (opening) July 14, 2008

3 International Conference on Infrared, Millimeter and Terahertz Waves, Keynote speech

A. Räisänen September 15 – 19, 2008

Pasadena, CA,

Scientific Community, Industry

200 USA

4 Research seminar Presentation

J. Oberhammer

Research seminar September 2008

Kyoto University, Dept. of Electrical Engineering

Scientific Community

30 Japan

3 A drop down list allows choosing the dissemination activity: publications, conferences, workshops, web, press releases, flyers, articles published in the popular press, videos, media briefings, presentations, exhibitions, thesis, interviews, films, TV clips, posters, Other. 4 A drop down list allows choosing the type of public: Scientific Community (higher education, Research), Industry, Civil Society, Policy makers, Medias ('multiple choices' is possible.

44

5 Poster Presentation D. Chicherin Annual research seminar of SMARAD Centre of Excellence

October 15, 2008

Espoo Scientific Community

60 Finland

6 Industrial workshop on Microsystem Technology

J. Oberhammer

RF and microwave MEMS at KTH

October 2008 Yoshida Campus, Kyoto University

Japanese MEMS industrial audience

20 Japan

7 XXXI Finnish URSI Convention on Radio Science

Oral presentation of TUMESA project

October 28, 2008

Espoo Scientific Community, Industry

40 Finland

8 NORDITE technology program Conference

J. Oberhammer

November 19, 2008

Stockholm Scientific Community

35 Sweden

9 Special meeting with potential partners

J. Oberhammer

Discussion on possible collaboration with VTT researchers

January 9, 2009

Espoo Scientific Community

15 Finland

10 Invited oral presentation J. Oberhammer

Vestfold University College, Tønsberg

Scientific Community

40 Norway

11 XXII International Conference on Microelectromechanical systems, MEMS

M. Sterner poster presentation January 25-29, 2009

Sorrento Scientific Community, Industry

200 Italy

12 15th International Conference on Solid-State Sensors, Actuators and Microsystems

J. Oberhammer

Oral presentation June 21 - 25, 2009

Denver, CO

Scientific Community, Industry

100 USA

13 NATO Research Workshop on Advanced materials and technologies for micro/nano-devices, sensors and actuators: From fundamentals to applications

J. Oberhammer; D. Chicherin

Oral presentation, poster June 29-July 2, 2009

St.Petersburg

Scientific Community, Industry

50 Russia

14 RF-MST Cluster (EU FP6 and FP7 projects) Workshop and MEMSWAVE conference

D. Chicherin Project presentation, poster July 6-9, 2009 Trento Scientific Community

50 Italy

45

15 MEMS reliability workshop given at the IEEE European Microwave Conference

J. Oberhammer

September 30, 2009

Trento Scientific Community

20 Italy

16 Annual research seminar of SMARAD Centre of Excellence

AALTO October 28, 2009

Espoo Scientific Community

60 Finland

17 Seminar J. Oberhammer

RF/microwave MEMS development at KTH

November 3, 2009

VTT, Espoo

Scientific Community

30 Finland

18 IX Kharkiv young scientist conference on electromagnetics, photonics and biophysics, YSC 2009

A. Vorobyov oral presentation Dec. 1-3 2009 Kharkiv Scientific Community

50 Ukraine

19 IEEE Nano Electro Mechanical Systems 2010

M. Sterner Nanometer-Scale Flatness and Reliability Investigation of Stress-Compensated Symmetrically-Metallized Monocrystalline-Silicon Multi-Layer Membranes

Jan. 20-23, 2010

Xiamen Scientific Community, Industry

100 China

20 A kick-off meeting of a national Swedish project focussing on future communication systems (TNG-The Next Generation)

J. Oberhammer

recent TUMESA results February 23, 2010

Stockholm University

Scientific Community

20 Sweden

21 Proceedings of GigaHertz Symposium

M. Sterner RF MEMS high-impedance tuneable metamaterials for millimeter-wave beam steering

March 9-10, 2010

Lund Scientific Community, Industry

50 Sweden

22 4th European Conference on Antenna and propagation

T. Zvolensky Beam-steering MEMS-loaded antenna based on planar lines

April 12-16, 2010

Barcelona Scientific Community

100 Spain

23 Workshop ARTIC, European Conf. on Antennas and Propagation, EuCAP 2010

R. Sauleau Mm-wave antennas for automotive radars: review and needs

April 12-16, 2010

Barcelona Scientific Community

100 Spain

24 A kick-off meeting of the METU-MEMS project (EU FP7)

J. Oberhammer

recent TUMESA results April 29, 2010 Ankara Scientific Community

20 Turkey

25 Micro Structure Workshop 2010

M. Sterner RF MEMS Tuneable High-Impedance Metamaterial Surfaces for MillimeterWave Applications

May 4-5, 2010 Stockholm Scientific Community, Industry

30 Sweden

46

26 Advisory Board meeting of SMARAD Centre of Excellence

AALTO May 21, 2010 Espoo Scientific Community

15 Finland

27 RF-MST Cluster (EU FP6 and FP7 projects) Workshop

D. Chicherin Project presentation 2010 Otranto Scientific Community

50 Italy

28 MEMSWAVE 2010 Conference M. Sterner Reliability investigation of stress-compensated metal-coated monocrystalline-silicon membranes for MEMS tuneable high-impedance surfaces

June 28-30, 2010

Otranto Scientific Community, Industry

50 Italy

29 European Microwave Conference 2010

D. Chicherin MEMS based high-impedance surface for millimetre wave dielectric rod waveguide phase shifter

September 28-30, 2010

Paris Scientific Community, Industry

100 France

30 Proc. Asia Pacific Microwave Conference 2010

M. Sterner Integration of MEMS reconfigurable reflective surfaces in rectangular waveguide stubs for W-band phase-shifters

December 7-10, 2010

Yokohama Scientific Community, Industry

100 Japan

31 INVITED Talk, Proc. Asia Pacific Microwave Conference 2010

A.V. Räisänen MEMS tunable metamaterials surfaces and their applications

December 7-10, 2010

Yokohama Scientific Community, Industry

100 Japan

32 Proceedings of of the Global Symposium on Millimeter Waves 2011

Z. Du MEMS-based High Impedance Surface for Beam Steering at 80 GHz

May 23-25, 2011

Espoo Scientific Community, Industry

100 Finland

33 RF-MST Cluster (EU FP6 and FP7 projects) Workshop and MEMSWAVE conference 2011

J. Oberhammer

Project presentation Athens Scientific Community

50 Greece

34 Int'l IEEE Conf. on Electromagnetics in Advanced Applications & IEEE-APS Topical Conf. on Antennas & Propagation in Wireless Communications

D.V. Lioubtchenko

Millimeter wave phase shifters based on dielectric rod waveguide

September 12 – 17, 2011

Torino Scientific Community, Industry

50 Italy

47

4.3 Plan for further dissemination and usage of the project results The consortium has plan for further dissemination and usage of the project results in different ways, which include, but are not limited to, the following:

1. Active participation of TUMESA members at the following events after the end of the project: 1.1 European Conference on Antennas and Propagation 1.2 European Microwave Week 1.3 IEEE International Microwave Symposium 1.4 IEEE MEMS Conference 1.5 MEMS Wave Conference 1.6 GHz Symposium 1.7 Asia Pacific Microwave Conference 1.8 Global Symposium on Millimeter Waves 1.9 ESA Antenna Workshops 1.10 Other conferences, workshop and seminars

2. Elaboration of joint publications:

2.1 Few publications on recent TUMESA results 2.2 Large review publication describing all significant TUMESA results attained during

the project 2.3 A book chapter “RF MEMS for automotive radar”

3. Public PhD thesis defence of the project members and following public availability of the theses based on the project results: 3.1 Dmitri Chicherin, AALTO, 02.12.2011 3.2 Ghayath ElHaidShade, AUTOCRUISE, winter 2011/2012 3.3 Mikael Sterner, KTH, Spring 2012

4. Giving an interview to an IEEE Spectrum journalist (D. Chicherin, November 2011)

5. Including project results in the scope of courses given to students in AALTO, KTH and UR1

6. Lectures given in the courses of the European School of Antennas (ESoA)

7. Maintaining TUMESA web-site, which describes 7.1 Project objective, concepts 7.2 Description of work and results done in all workpackage 7.3 List of publication 7.4 Contact details

8. Further development of more advanced devices and systems based on the project results: 8.1 Phased array antennas 8.2 Leaky wave antennas 8.3 Large array of MEMS varactors with high yield, reliability and tuning range 8.4 Smart antenna systems

48

9. Studying possibilities of technology transfer towards prototype demonstrations and large scale production

10. Identifying potential user group and raising their awareness of the project results in order to speed up potential industrial use of the project results.