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
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.
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• 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!