Differential Microstrip Patch Antenna as

Feeder of a Hyper-Hemispherical Lens for

F-Band MIMO Radars

Dragos Dancila, Václav Valenta, Alina-Cristina Bunea, Dan Neculoiu,

Hermann Schumacher and Anders Rydberg

dragos.dancila@angstrom.uu.se

Uppsala University, Department of Engineering Sciences, Uppsala, Sweden

European Space Agency, The Netherlands

National Institute of R&D in Microtechnologies (IMT) and Politehnica University, Bucharest, Romania

Institute of Electron Devices and Circuits, Ulm University, Ulm, Germany

2

• Project context

• Key radar components

• Antenna design

– Differential feeding

– Matching network

– Compensated bondwire interconnects

– Radiation patterns with and without hemispherical lens

• Experimental measurements

Outline

3

NANOTEC (NANOstructured materials and RF-MEMS RFIC/MMIC

TEChnologies for highly adaptive and reliable RF systems)

• FP7-ICT-2010

• Three demonstrators with RF-MEMS to be developed

– Demo 1: RF-MEMS based low-cost X-band reflect array

– Demo 2: 94 GHz passive imaging for security screening

– Demo 3: F-band FMCW MIMO radar for hand-held screening

Project context: F-band MIMO radar

Micro Electro Mechanical Systems

Demo 1 Demo 2 Demo 3

project-nanotec.com/

4

Key frontend requirements

• Bandwidth (𝑆𝑝𝑎𝑡𝑖𝑎𝑙 𝑟𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 = c02 ∆𝑓 )

• Output power, conversion gain, output balance,

harmonic suppression, linear chirp etc.

Project context: F-band MIMO radar

104-152 GHz

Sparse array → Virtual array

Coherent chirp

distributionChirp generator

13-19 GHz

Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx

5

104-152 GHz

Coherent chirp

distributionChirp generator

13-19 GHz

Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx Tx/Rx

Key radar components

Technology

• IHP SG13S/G2

• HBTs with fT/fmax=300/500 GHz

Topic of this talk

Compensated bondwires

interconnect TR board (RO3003)

6

Antenna design:

Differential feeding

Limiting

amplifier

PA

LNA

3x Gilbert

cell

Limiting

amplifier

Active

unbal

PA3x Gilbert

cell

LO

Switch

Active

unbal

HV Generator

λ/4 transformer

MEMS SPDT

LO

TX

RX

IF

Compensated

bondwire interconnect

545 µm

745 µm

100 Ω line

Z-transformer

TX/RX IC

TR board (RO3003)

TR board (RO3003)

h = 127 µm, εr = 3 and tanδ = 0.0013

la wa

𝑤𝑎 =𝑐

2𝑓

2

𝜀𝑟 + 1

𝑙𝑎 =𝜆

2− 2Δ𝑙

Δ𝑙

ℎ= 0.412

𝜀eff + 0.3𝑤𝑎ℎ

+ 0.264

𝜀eff − 0.258𝑤𝑎ℎ

+ 0.8

𝜀eff =𝜀𝑟 + 1

2+𝜀𝑟 − 1

2

1

1 + 12ℎ𝑤𝑎

7

Antenna design:

Matching network

Limiting

amplifier

PA

LNA

3x Gilbert

cell

Limiting

amplifier

Active

unbal

PA3x Gilbert

cell

LO

Switch

Active

unbal

HV Generator

λ/4 transformer

MEMS SPDT

LO

TX

RX

IF

Compensated

bondwire interconnect

545 µm

745 µm

100 Ω line

Z-transformer

TX/RX IC

TR board (RO3003)

la wa

bandwidth (S11 < -10 dB)

125 - 137 GHz.

Z – QW

transformer

8

Antenna design: Compensated bondwire interconnects

0 20 40 60 80 100 120 140 160

-40

-30

-20

-10

0

150 m

175 m

uncompensated

Frequency (GHz)

Re

fle

ctio

n (

dB

)

-5

-4

-3

-2

-1

0

Tra

nsm

issio

n (d

B)

V. Valenta T. Spreng V. Ziegler D. Dancila A. Rydberg and

H. Schumacher, Design and Experimental Evaluation of

Compensated Bondwire Interconnects above 100 GHz,

International Journal of Microwave and Wireless

Technologies, 2014, DOI:10.1017/S1759078715000070

110 120 130 140 150

-70

-60

-50

-40

-30

-20

-30

-20

-10

0

110 120 130 140 150

Three different

TX ICs measured on-wafer

Simulation

IF p

ow

er

(dB

m)

Frequency (GHz)

LCL 1-1

LCL 2-1

LCL 2-2

/ Stub 1, Stub 2

LCL 1-1, LCL 2-1, LCL 2-2

Link budget

estimation

TX

po

we

r (d

Bm

)

Measurement results demonstrate that a

fractional bandwidth of 7.5% and an IL of

0.2 dB can be achieved for differential

interconnects as long as 800 µm.

9

Antenna design: Compensated bondwire interconnects

Limiting

amplifier

PA

LNA

3x Gilbert

cell

Limiting

amplifier

Active

unbal

PA3x Gilbert

cell

LO

Switch

Active

unbal

HV Generator

λ/4 transformer

MEMS SPDT

LO

TX

RX

IF

Compensated

bondwire interconnect

545 µm

745 µm

100 Ω line

Z-transformer

TX/RX IC

TR board (RO3003)

la wa

Compensated wire-bonding

allows bandwidth > 20 GHz !

L-C-L

0,2 0,5 1,0 2,0 5,0

-0,2j

0,2j

-0,5j

0,5j

-1,0j

1,0j

-2,0j

2,0j

-5,0j

5,0j

Antenna

Bondwire inductance

0.15 to 0.25 nH,

Cpad=15 fF

Impedance seen

by the antenna

bondwire

inductance

>0.25 nH leads

to a significant

mismatch

10

Antenna design: Radiation patterns with and without lens

diff. patch ant. +

hyper-hemispherical lens

3D printing of polyamide (εr=3.3)

optimized distance (d = 2.75 mm)

extension of 1.5 x R (R=10 mm)

overall gain 21.5 dBi

differential patch antenna

gain 8 dBi

Realized TR module

• low-cost packaging

solutions

• compensated

bondwire interconnect

• diel. lens (23 dBi)

Experimental results:

measurement setup

LO1: 13.75-17.5 GHz LO2: LO1+Δf

Δf = 1MHz (1kHz)

110-140 GHz wireless link

Spectrum analyzer /

PC Sound-card

LO1 LO2

IF spectrogram

Doppler measurements

GPIB ctrl

+ frequency responses

TR1 TR2

IF=8 MHz (8 kHz)

Experimental results:

measurement setup

13

TR1 TR2

IF

LO1 LO2

110-140 GHz wireless link

0.5 m

Two independent LO signals with offset of 1 MHz

were swept from 13.75 to 17.5 GHz (i.e. 110 to

140 GHz at the wireless interface) and fed to the

modules to create an IF tone exactly at 8 MHz.

14

• A differential microstrip patch antenna was wirebond

connected (800 μm long) using LCL compensation structures

to the TR modules realized in SiGe BiCMOS

• A 0.5 m wireless link between 120-140 GHz is demonstrated

• A 3D printed polyamide hyper-hemispherical lens

significatively improve the gain of the antenna. Experimental

results show a gain increase by 15 dB and an overall link

budget improvement by about 30 dB

Conclusions

Acknowledgement

• EU Funding (FP7 NANOTEC)

• IHP, SiR, Airbus

Thank you for attention!