A Planar End-fire Array in S-band for Airborne Applications

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A Planar End-fire Array in S-band for AirborneApplicationsAbhijit Sanyala, Ananjan Basua, Shiban Kishen Koula, Mahesh Abegaonkara, Suma Varughesea

& P. B. Venkatesh Raoba Centre for Applied Research in Electronics, I.I.T. Delhi, New Delhib Centre for Airborne Systems, Defence R and D Organization, Bangalore, IndiaPublished online: 01 Sep 2014.

To cite this article: Abhijit Sanyal, Ananjan Basu, Shiban Kishen Koul, Mahesh Abegaonkar, Suma Varughese & P. B. VenkateshRao (2012) A Planar End-fire Array in S-band for Airborne Applications, IETE Journal of Research, 58:1, 34-43

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34 IETE JOURNAL OF RESEARCH | VOL 58 | ISSUE 1 | JAN-FEB 2012

A Planar Endfire Array in Sband for Airborne Applications

Abhijit Sanyal, Ananjan Basu, Shiban Kishen Koul, Mahesh Abegaonkar, Suma Varughese1 and P. B. Venkatesh Rao1

Centre for Applied Research in Electronics, I.I.T. Delhi, New Delhi, 1Centre for Airborne Systems, Defence R and D Organization, Bangalore, India

ABSTRACT

Planar endfire arrays can be used in airborne radar applications for forward and rear vision. The purpose of this work is to demonstrate the viability of constructing endfire arrays with good bandwidth and fronttoback (f/b) ratio. The array so constructed must be extendable to a large number (possibly >1 000) of elements depending on the platform. In this work, starting from a basic Sband 22 array, arrays with higher number of elements have been studied through simulations such as 44, 48, and 216 configurations. An endfire array comprising 48 elements (uniformly excited) has been successfully fabricated and tested giving a f/b ratio of 15 dB, and directivity 15 dB and an array comprising 48 elements excited by coefficients of Chebyshev polynomials has been simulated which gives a f/b ratio of 25 dB and similar directivity. Beam steering simulations show that the 48 array can be steered to 25 degrees with acceptable side lobe levels.

Keywords: Airborne radar, Dipole antenna, Endfire antenna, Planar array.

1. INTRODUCTION

In airborne radars, there is a restriction on the antenna orientation as it should not obstruct the airflow during flight. In order to effectively cover the forward and rear directions, such radars can use a planar end-fire array. Very little information about such antennas or systems which are operational can be found. As far as we know, the only airborne radar which uses such an antenna array, called the top-hat antenna is described in the study by Hendrix [1], and here too, the antenna elements are not planar. An effort to develop such an antenna array at S-band, using planar elements, is described here; the benefits of using planar technology are of course well-known. The typical approach to mounting such an array on an aircraft (similar to [1]) is shown in Figure 1. The coordinate system for describing radiation patterns in this work is also shown in Figure 1.

Since element spacing is an important factor in an end-fire array, an antenna element needs to be compact (less than half wavelength in length and breadth). An angled dipole antenna [2] is useful since the dipole length of half wavelength can be accommodated in a smaller width.

In addition to the above, the beam of the array should be electronically steerable within a certain angle (typically 30) for practical use in searching and tracking.

Planar Yagi-Uda antennas [3-5] have generated a lot of interest in phased array applications due to its suitability for a wide range of applications such as wireless

communication systems, power combining, phased arrays, active arrays as well as millimeter-wave imaging arrays. It is of particular interest in this case because of the ease with which the angled-dipole antenna can be converted to a Yagi-Uda end-fire type. A suitable antenna must not only have an end-fire beam pattern, but must also have a good bandwidth (in excess of 25% of the full S-band is desirable) as well as have a small dimension of around 0.35 0.35 (to allow elements to be placed very close to each other in the array).

In this paper, we present an S-band (2-4 GHz) end-fire array designed to operate from 3 to 4 GHz (the measured bandwidth was about half of this, due to limitations in the test procedure, as will be described) and with front-to-back (f/b) ratio exceeding 15 dB. The array consists of angled dipole antenna elements with microstrip feed designed on a 0.03 thick, er=2.2 substrate.

The antenna element is detailed in Section II and Section III deals with design fabrication and testing of small arrays (up to 44). Section IV reports the experimental validation of an 84 array, and is the most important part of this work. Section V gives simulated data for azimuthal beam-scanning capabilities of the 84 array.

2. THE ANTENNA ELEMENT

2.1 Antenna Element Design

The design used in the antenna element is an angled dipole antenna. Prior to this, a dipole antenna with

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35IETE JOURNAL OF RESEARCH | VOL 58 | ISSUE 1 | JAN-FEB 2012

Figure 1: Conceptual mounting of the proposed endfire arrays (one for front and another for back), and thereference coordinate system used.

balun [6] was investigated which gave excellent characteristics but was marginally oversized for the application. The concept of the angled dipole was retained in the current design. This particular design reduces the width of the antenna element by using an angled dipole which also gives added advantages of a wider frequency response and reduced mutual coupling [2]. The design dimensions are shown in Figure 2. It will be noticed that in addition to the basic design of [2] this uses two directors, and the truncated ground plane as a reflector. The main difference with the antenna in [2] comes from the directors, which are necessary to maintain a f/b ratio of 10 dB, in spite of the much smaller ground plane size (dictated by a limit of 0.5l spacing in end-fire arraysnote that the antennas in [2] were not used in end-fire arrays). This structure was finalized after numerous simulations (e.g., more directors and reflectors, distributed on top and bottom layers, etc.). Even better f/b ratio would have been desirable, but could not be achieved, given the size constraint.

Both the parasitic elements (directors) are of identical dimensions. The feed lines and dipole elements in the front and reverse sides of the PCB are of identical dimensions. The ground plane acts as a reflector, whereas two identical directors help in increasing directivity in the end-fire direction. An initial estimate for the radiating element length is given by L=2L1=L1+L4=0.49eff,

where, eff is an effective wavelength [7] (the term wavelength is used loosely here, as the dipoles are not guiding structures, but this terminology is fairly standard, inspired by wire antennas). We have used 0 for eff.

For f=3.5 Ghz, this gives L=42 mm. Hence, the length of the resonating dipole on each side of the substrate should be 21 mm. However, after optimizing the design in CST Microwave Studio [8,9], the length of the resonating dipole has been fixed at 17.54 mm on each side.

The dimensions of the antenna element are shown in Figure 2. L1=L4=17.54 mm, L2=15.72 mm, L3=35.19 mm, L5=26 mm, L6=9.97 mm, W1=W3=W4=2 mm, W2=10.28 mm, W5=1.53 mm, S1=0.83 mm, S2=0.48 mm. The element consists of an angled dipole antenna fed by broadside-coupled balanced parallel strips. The angle of the dipole is 45. The wide ground plane acts as a reflector as well as helps in microstrip to parallel strip line transition. The overall dimensions of the element is 0.37 00.39 0 for 0=90 mm.

The element was simulated in CST Microwave Studio (used for all simulations in this work). The simulation and fabrication of the element has been carried out in two versions, namely, microstrip fed and probe fed [Figure 3]. This has been done keeping in mind that it may not be possible for a planar array to be fed by a microstrip feed.

Figure2:Layoutofangleddipoleantenna,(a)bottomlayer;(b) top layer.

Figure 3: Fabricated antenna element (top and bottomlayers), (a) microstrip fed; (b) probe fed.

Sanyal A, et al.: Planar Endfire Array in Sband for Airborne Applications

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Probe feed is the more practical option in such cases. Simulated and measured reflection coefficients for both cases are shown in Figure 4 and radiation patterns are in Figure 5.

2.2 Measurements

The return loss plot of the fabricated element [Figure 4] shows a 10 dB bandwidth of >1 GHz in the best case (measured), although this is not very realistic (loss and spurious radiation at the connector play a big role here). Realistic numbers, looking at simulated data for the probe feed, give a bandwidth from 3.2 to 3.7 GHz, with a best match at 3.3 GHz (l=90 mm). Subsequent pattern measurements were mostly done at 3.3 GHz. The far-field radiation pattern [Figure 5] of the fabricated element gives a worst-case f/b ratio of 8 dB, whereas the simulated f/b ratio is 10.7 dB. The deviation in the rear side is attributable to the effects due to the end connector of the fabricated element; it is more pronounced for the microstrip feed, as expected. In an array, the co-axial feed will be used; so, we have not attempted to improve the microstrip-fed antennas. It is seen that the element is quite reliable and its behavior can be accurately predicted by numerical simulation.

3. DEVELOPMENT OF 22 AND 44ARRAYS

3.1 DesignandSimulationofArrays

The design of arrays started from a consideration of the inter-element spacing in end-fire arrays. It is well known [7,10] that the spacing for a linear array should not exceed 0/2 if multiple main beams (grating lobes) are to be avoided. However, for a planar array (typically 10010 elements), the possibility of cancelling the spurious main beams caused by the 100-element array factor by the 10-element array factor exists in theory. Additionally, plenty of information on designing planar arrays exists [11], but in this case, it is not at all clear if any such design is practical, because the radiation from elements at the back travel through a host of printed antenna elements in front, and can be expected to undergo significant scattering.

So, first a 22 array and then a 4x4 array with element spacing of (3/4=67.5 mm in x) by (/2=45 mm in y) were developed. First considering the 22 array, the elements were excited with equal amplitude, but the phase of the rear elements were shifted by 90 degrees (progressive phase shift). The resulting far-field radiation pattern showed a single main lobe in the end-fire direction and a back lobe with an f/b ratio of 15 dB in simulation [Figure 6].

Furthermore, a 4x4 array was also designed and simulated. It is observed from the far-field radiation pattern that the f/b ratio improves to about 20 dB for equal amplitude excitation [Figure 7]. The pattern also

Figure4:SimulatedandmeasuredreflectioncoefficientofantennaelementindB(suffix1indicatesmicrostripfeedand2indicatesprobefeed).

Figure5:SimulatedandmeasuredEplanefarfieldradiationpatternofantennaelement(suffix1indicatesmicrostripfeedand2indicatesprobefeed).

Figure 6: 22arraywithuniformexcitation(simulated).


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Figure7:Simulated farfieldradiationpatternplotof44 array(uniformexcitation).

Figure8:Simulated farfieldradiationpatternplotof44 array(binomialexcitation).

Figure 9: Dimensions of Wilkinson power divider.

lobes around 120 and 240 as expected, but these are small. It is further observed that if the amplitude is scaled binomially (in this case, 3:1 for inner and outer elements), the grating and side-lobes are minimized [Figure 8].

These results encourage us in developing such arrays with a 3/4 spacing, but as we will see next, the experimental results are not so encouraging.

3.2 FabricationandMeasurements

Prior to proceeding with fabrication, it was decided for simplicity of design that the antenna elements of the array will be fed through a power divider and phase-shifting network which will be embedded in the array. For power division, Wilkinson power dividers, as reported in [12], have been used with the layout shown in Figure 9. The dimensions of the power divider (in mm.) are given in Figure 9.

The 22 array was first simulated in CST Microwave Studio along with embedded power dividers on a 0.76 mm thick, er=2.2 substrate. The element separation in the radiating direction was kept at 3/4, whereas in the non-radiating direction, it was half wavelength. In addition to the power divider, required phase shifts have been provided by asymmetric positioning of the power divider. Since the antenna elements use double-sided structure, part of the structure containing the phase shifters are in microstrip, which changes to parallel strip prior to feeding the antenna elements [Figure 10]. The simulation results indicated an f/b ratio of 15 dB. On fabrication [Figure 11] and testing, the far-field radiation plot of the fabricated array gives an f/b ratio of 17.5 dB [Figure 12].

Proceeding further, a 44 array was similarly designed and simulated in CST Microwave Studio. This design is much more complicated due to the larger size of the array. The power dividers have been accommodated in a very small space and additional delay lines have


Figure 10: Design dimensions of 22 array with embedded powerdividers(a)toplayer;(b)bottomlayer.

Figure 11: Fabricated 22 array with embedded power dividers:(a)topand;(b)bottomlayers.

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Figure 12: Simulated and measured farfield radiationpatternof22 array with embedded power divider.

Figure 13: A 44endfirearray,(a)bottomlaver,showingvarious spacings; (b) top layer.

Figure 14: Fabricated 44endfirearray (topandbottomlayers).

Figure 15: Simulated and measured farfield radiationpatternof44endfirearraywithembeddedpowerdivider.

been incorporated to achieve phase shifts [Figure 13]. The f/b ratio of the simulated array is 27 dB. The array was fabricated on a similar substrate [Figure 14] and on testing, the f/b ratio was found to be 18 dB [Figure 15]. It is quite remarkable that despite the complicated power-dividing network seen in Figures 13 and 14 (these lines are also substantially parallel to the radiated electric field), the array works roughly as predicted by the simulations, and even shows the expected grating lobes around 110 in Figure 15. We can see the grating lobes are quite prominent now, and there is no alternative to using a spacing below /2. However, the correlation between simulated and measured results gives us confidence that in a practical case with probe feeds (and remote power division network), such arrays, and even larger ones will work quite successfully.

4. DEVELOPMENTOF32-ELEMENTARRAYS

As discussed earlier, an array with element spacing of 0.4=36 mm will avoid grating lobes. Furthermore, the array elements can be excited using Chebyshev polynomials [7,13] for good performance. We have simulated a number of arrays with excitation for Chebyshev pattern with 26 dB side-lobe level.

4.1 Simulations

A 44 array (excluding the power division network for this and other simulations in this section) with a spacing of 0.4 was simulated with Chebyshev amplitude excitation coefficients and progressive phase shift of 144. The resulting far-field radiation pattern gives an f/b ratio of 7.2 dB [Figure 16]. These results are quite poor, and are caused by the reduced spacing. However, the f/b ratio is found to improve considerably with larger arrays. A 4x8 array was simulated with a spacing of 0.4 and excited as above. The f/b ratio of this array is 25 dB [Figure 17]. There is a significant improvement in radiation pattern on addition of a row of dummy elements in the sides and rear following [14,15], excluding the radiating direction (these are matched terminated and not excited). This is shown in Figure 18. The improved performance basically stems from the fact that all excited elements radiate in roughly the same environment, as opposed to the very different environment seen by the elements at the edges if dummy elements are not used. For these relatively small arrays, the elements at the edges make us a significant fraction of radiators, and hence cannot be ignored.


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Figure16:Simulatedfarfieldplotof44 array excited with Chebyshevcoefficients.

Figure 17: (a) Structure of 4x8 array with and without dummy elements (shown in black) and (b) Simulated far-field plot of 48 array without dummy elements excited withChebyshevcoefficients.

Figure18:Simulatedradiationpatternof48 array excited with Chebyshev coefficients on addition of dummyelements.

Figure 19: (a) Layout of 216elementarray (bottomandtop views) and (b) bottom view of 216 elements and additionaldummyelements(shownfilled).

To further explore the functioning of the non-uniform amplitude array, a 216 element array (which has a column of 16 elements in the end-fire direction (x) arranged in two rows as shown in Figure 19) was simulated and excited as above which gave an f/b ratio of 25 dB [Figure 20]. The Chebyshev case of Figure 21 is the most promising result among these larger arrays.


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Figure 21: Picture of 48 array (top view only).

Figure22:Pictureof1to32powersplitter.

Figure 23: Picture of a set of 8 strip-line delay lines (opened up to show the 2 substrates, which are screwed together duringoperation).

Figure24:Arrayreadyfortesting.

Figure25:Eplanepatternof48 array.

The side lobes in the radiating direction are minimal and of ~30 dB level. It is thus clear that the planar end-fire array is extendable to a large array size which makes it eligible for practical use in radars.

4.2 FabricationandTesting

The photograph of a 48 element array is shown in Figure 21. This is easy to fabricate, but for testing, to excite the 32 elements with the appropriate phase shifts is a difficult task without a dedicated facility for this purpose. Hence, only uniform excitation could be used.

The testing was achieved in the following way:A 1-to-32 corporate power splitter using Wilkinson power dividers was first made [Figure 22]. The specialty of the layout is that the outputs are all located exactly below the 32 feed points of the array.

The power splitter is placed below the array, with its ground facing the array, and the 32 outputs of the power splitter are connected to the antenna elements by strip-line delay lines (4 sets of delay lines, with 8 delay lines in each set as shown in Figure 23). Strip-line, being fully shielded, was preferred over the easier-to-fabricate microstrip to reduce interference with the radiated signals.

The complete setup is shown in Figure 24.


The measured E (x-y plane, f being the angular variable) and H (x-z plane, angle from +x going towards +z being the angular variable) radiation patterns at 3.33 GHz are shown in Figures 25 and 26, respectively. Simulated results here are for just the array, without any feeding network, since the whole structure was too big for our simulator.

________ Measured results

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As we can see, the H-plane pattern is fairly consistent with the simulation, while the E-plane pattern matches the simulation only in the main beam (and partially in the back lobe). This is expected since the major disturbance is caused by the strip-line ground planes for directions away from end-fire in the E-plane. The 3-dB beam-widths are approximately 20 for E-plane and 50 for H-plane, which gives a directivity of approximately 15 dB, which is very close to the simulated directivity of 15.5 dB. Note that these beam-widths can be substantially reduced by following a proper excitation for end-fire Chebyshev pattern [13] when independent transceivers are available for each element, as expected in actual airborne application.

The final confirmation that the structure works reasonably well is obtained from gain measurement. The measured gain (strictly speaking realized gain since this includes the effect of input mismatch) of this array is shown in Figure 27. This was obtained in the conventional way, by measuring transmitted power (fed to a 9 dB standard gain horn) and received power at the connector of our array with a spectrum analyzer (Agilent

Figure26:Hplanepatternof48 array.

Figure 27: Measured gain of the 48 array.

Figure 28: Measured |S21| for (a) power divider and (b) delay line.


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Figure29:Radiationpatternsoftheuniformlyexcited48 arraywithphasesforendfire,15offendfire,and30offendfire.

Figure30:RadiationpatternsoftheChebyshevexcited48arraywithphasesforendfire,15offendfire,and30offendfire.

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8564EC). The gain was also measured when half of the space between the array and the power divider was filled with absorbing material. This may be necessary in a real array, because a large ground plane (such as an aircraft body) below the array will probably severely

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disrupt the radiation in the end-fire direction (ideally a null direction considering the image radiator). For our small array, however, the effect of the image was not observed.

As we can see, we get an operating bandwidth of 3.13 to 3.55 GHz, with a gain >9 dB. The reason for selecting a figure of 9 dB is as follows:

We have seen that the directivity is 15 dB, but to get an idea of the antenna efficiency, we first measure the losses in the feed network with a network analyzer. Figure 28a shows the losses in the power divider (1 dB) and the Figure 28b shows the losses in the delay line (actually due to the connections at the ends of the delay line).

A simple SMA co-axial connector to microstrip line gives about 0.2 dB loss at this frequency; from this, we can conclude that the power splitter (which should ideally show |S21|=15 dB) gives a loss of 1.36 dB (=16.76 dB-15 dB-0.2dBx2). The delay line has a loss of 1.8 dB. One co-axial connector at the input gives 0.2 dB. This gives an overall loss of 3.36 dB. Since our best-case gain (without absorber) was about 10 dB, a directivity of 15.5 dB corresponds to 60% efficiency. For the worst-case gain, the efficiency becomes 48.5%. These are acceptable figures for a prototype antenna efficiency. For the case with absorber, around half of the power is further dissipated.

5. BEAM STEERING

It will naturally be desirable to steer the beam in the azimuthal plane (x-y) for radar applications. We see from simulation that this is possibly up to about 25 (this actually corresponds to the excitation phases set for 30), after which a spurious lobe (expected by symmetry) becomes quite high. Figure 29 shows the case for uniform excitation and Figure 30 shows the case for Chebyshev excitation.

6. CONCLUSION

Studies of planar end-fire arrays using a specially designed end-fire element in various configurations have been presented. It is concluded that a planar array with 0.4 element spacing in the end-fire direction with Chebyshev excitation and 0.5 spacing in the transverse direction is very suitable for airborne radar systems. The measured f/b ratio of 15 dB with uniform excitation and simulated f/b ratio of 25 dB with Chebyshev excitation give an indication that f/b

ratio better than 40 dB should be achievable for a 10010 array, which is expected in radars.

The presented designs are suitable for large arrays (typically 10010 for front and a similar one for back) with little weight penalty as they are fully planar, and have sufficient bandwidth for radar applications. They can be conveniently fed through co-axial connectors in the standard probe configuration.

Currently, larger arrays and their performance over a large ground plane appropriate for airborne antennas is being investigated.

REFERENCES

1. R Hendrix, Aerospace system improvements enabled by modern phased array radar. IEEE Radar Conference, 2008. (RADAR 08). Rome, 2630 pp. 16, May 2008.

2. R A Alhalabi, and G M Rebeiz, High efficiency angleddipole antennas for millimeterwave phased array applications, IEEE Transactions on Antennas and Propagation, Vol. 56, No. 10, pp. 313642, October 2008.

3. Y Qian, W R Deal, N Kaneda, and T Itoh A uniplanar quasiYagi antenna with wide bandwidth and low mutual coupling characteristics. Proc. IEEE APS International Symposium, Vol. 2, pp. 9247, 1999.

4. H K Kan, R B Waterhouse, A M Abbosh, and M E Bialkowski, Simple Broadband Planar CPWFed Quasiyagi Antenna, IEEE, Antennas and wireless propagation Letters, Vol. 6, pp. 1820, 2007.

5. W R Deal, N Kaneda, J Sor, Y Qian, and T Itoh, A new quasiYagi antenna for planar active antenna arrays, IEEE Transactions on Microwave Theory and Techniques, Vol. 48, pp. 9108, Jun 2000.

6. B Edward, and Rees, A broadband printed dipole with integrated balun, Microwave Journal, May 1987

7. C A Balanis, Antenna Theory Analysis and Design, Second edition, John Wiley and Sons Inc., New Jersey, 2005.

8. CST Microwave Design Studio (software), www.cst.de.

9. T Weiland, M Timm, and I Munteanu, A practical guide to 3D simulation, IEEE Microwave magazine, Dec 2008.

10. Microstrip Antenna Design Handbook, P.Bhartia, Inder Bahl, R.Garg, A.Ittipiboon; Artech House, 2001.

11. L A Greda, A Walstra, M Heckler, and A Dreher, A simulation tool for design and analysis of planar antenna arrays, IEEE Antennas and Propagation Society International Symposium, 2008. APS 2008, pp. 14, July 2008.

12. N Misran, M Tariqul Islam, and KJ Ng, A feed network for a novel EH shaped microstrip patch antenna array, Journal of Applied Sciences 8(10), pp. 19826, 2008.

13. D G Babas, and J N Sahalos, On the design of Chebyshev Endfire Arrays subject to a performance index, Electrical Engineering, Springer, Vol. 90, no. 2, Dec 2007.

14. S Edelberg, and A Oliner, Mutual coupling effects in large antenna arrays: Part 1Slot arrays, IRE Transactions on Antennas and Propagatio, Vol. 8, no. 3, pp. 28697, May 1960.

15. Y C Beng. Effects of mutual coupling in small dipole array antennas, Ph.D. Thesis, Naval Postgraduate School, Monterey, California, Mar. 2002.


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DOI: 10.4103/03772063.94080; Paper No JR 386_10; Copyright 2012 by the IETE

AUTHORSAbhijit Sanyal completed M.Tech from I.I.T.Delhi in 2009, and is presently serving in the Indian Navy.

E-mail: [email protected]

Ananjan Basu was born Aug 12, 1969. He received the B.Tech degree in electrical engineering and M.Tech degree in communication and radar engineering from the Indian Institute of Technology Delhi (I.I.T.DeIhi), in 1991 and 1993 respectively, and the PhD. degree in electrical engineering from University of California at Los Angeles (UCLA), in 1998. He has been with the

Centre for Applied Research in Electronics, I.I.T.DeIhi as an Assistant Professor (20002005) and Associate Professor (since 2005). His specialization is in microwave and millimetrewave component design and characterization.


Shiban Kishen Koul received the B.E. degree in Electrical Engineering from the Regional Engineering College, Srinagar in 1977, and the M.Tech and PhD degrees in Microwave Engineering from the Indian Institute of Technology, Delhi, India. He is a Professor at the Centre for Applied Research in Electronics, Indian Institute of Technology Delhi where he is involved in teaching and

research activities. His research interests include: RF MEMS, Device modeling, Millimeter wave IC design and Reconfigurable microwave circuits including antennas. He is the Chairman of M/S Astra Microwave Pvt. Ltd, a major private company involved in the Development of RF and Microwave systems in India. He is author/coauthor of 192 Research Papers and 7 stateofthe art books. He has successfully completed 25 major sponsored projects, 50 consultancy projects and 30 Technology Development Projects. He holds 7 patents and 4 copyrights.

Dr. Koul is a Fellow of the IEEE, USA, Fellow of the Indian National Academy of Engineering (INAE) India and Fellow of the Institution of Electronics and Telecommunication Engineers (IETE) India, He has received Gold Medal

by the Institution of Electrical and Electronics Engineers Calcutta (1977); S.K.Mitra Research Award (1986) from the IETE for the best research paper; Indian National Science Academy (INSA) Young Scientist Award (1986); International Union of Radio Science (URSI) Young Scientist Award (1987); the top Invention Award (1991) of the National Research Development Council for his contributions to the indigenous development of ferrite phase shifter technology; VASVIK Award (1994) for the development of Ka band components and phase shifters; Ram Lal Wadhwa Gold Medal (1995) from the Institution of Electronics and Communication Engineers (IETE); Academic Excellence award (1998) from Indian Government for his pioneering contributions to phase control modules for Rajendra Radar, Shri Om Prakash Bhasin Award (2009) in the field of Electronics and Information Technology, and teaching excellence award from IIT Delhi in 2012.

Dr. Koul is a distinguished IEEE Microwave Theory and Techniques Lecturer for the year 2012-2014.


Mahesh Abegaonkar received his Ph.D. in Physics from the Department of Physics, University of Pune in 2002. He served as PostDoctoral Researcher and Assistant Professor with Kyungpook National University, Daegu, South Korea, from 20022004.He is an Assistant Professor at C.A.R.E. I.I.T.Delhi since 2005. His research interests include multiband, wideband, reconfigurable

and UWB antennas and filters. He is a recipient of the Young Engineer Award 2008 of the Indian National Academy of Engineering


Suma Varughese serves as Scientist in the Centre for Airborne Systems D.R.D.O. Govt. of India.


P. B. Venkatesh Rao serves as Scientist in the Centre for Airborne Systems, D.R.D.O. Govt. of India.



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A Planar End-fire Array in S-band for Airborne Applications