sub-millimetre wave components for steerable antennas with ... · sub-millimetre wave components...
TRANSCRIPT
Sub-millimetre wave components for steerableantennas with supporting MMIC design
R.Cahill, D.Linton, V. F. Fusco
Overview
• FSS structures• Reflectarray Antennas• Quasi-Optical Switches• V band QPSK MMIC• Conclusions
2
Objectives & Why Liquid Crystal ?
• Objective: Exploit the anisotropic property of Liquid Crystals to create phase shifters for mm & sub –mm wave beamsteering reflectarray antennas which is necessary for space observation objects.
• Why use liquid crystals >100GHz?- Thin tuneable LC film(<50µm) means:
* Low voltage electronic control ---- easy to be digitally controlled
* faster switching speed ---- which is important for some applications
* Device architecture and construction similar to optical LC displays---- fabrication
* Dielectric anisotropy increases & loss decreases with frequency
* Low weight, power consumption and cost
3
Frequency Selective Surface Technology
• Single And Dual Polarisation Beamsplitters At Frequencies Over The Range 100 - 470 GHz
• Single and Multilayer Periodic Structures Designed Using CST Microwave Studio
• Fabrication Uses Precision Micromachining Techniques With Submicron Accuracy
• Spectral Response Measured Using 100 -700 GHz VNA and QO Test Bench
Example of a Dual Polarisation (TE & TM, 45° Plane ) FSS; 316.5 -325.5 GHz/ 349.5 -358.5 GHz
300 310 320 330 340 350 360-40
-35
-30
-25
-20
-15
-10
-5
0
Tran
smis
sion
(dB)
Frequency (GHz)
TE Co meas. TE Co sim. TE X meas. TM Co meas. TM Co sim. TM X meas.
Dickie R, Cahill R, Gamble HS, Fusco VF, Huggard P, Moyna B, Oldfield M, Grant N and de Maagt P: ‘Polarisation Independent bandpass FSS’, IET Electron. Lett., 43, (19), 2007, pp. 1013 – 1015
4
Fabrication
• SOI Technology 10μm/2μm/525μm – Suitable for Rapid Prototyping
• Deep Reactive Ion Etching (etch rate 3.5 μm/min) – Patterning and Substrate Removal
• Sputter Coated 0.25μm Copper Seed Layer/1μm Electrodeposited Copper
Freestanding FSS
DRIE etched slots
SOI handle wafer
Substrate removed under mesh
30mm
5
Measurement setup
• Transmission Spectra Measured Using 100-540GHz Quasi-Optical Test Bench
- Reflective Focussing Optics Transforms Gaussian Beam –FSS Positioned at Beam Waist
- Dielectric Anisotropy Determined by Applying dc Bias
The DUTBiasingconnection
6
Frequency Selective Surface Technology
• Linear Polarised FSS Funded by Centre for Earth Observation Instrumentation (CEOI)
• Transmission in Band 440 – 456 GHz (0.25 dB) & Reflection in Bands 314 – 336 GHz (0.8 dB), 239 – 247 GHz (0.22 dB), 174 – 192 GHz (0.1 dB) , 113 – 123 GHz ) (<0.1 dB)
• Slot Length = 326 μm, Width = 20 μm, Thickness = 12 μm
-3 5
-3 0
-2 5
-2 0
-1 5
-1 0
-5
0
1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 4 5 0 5 0 0
F re q u e n c y (G H z )
Tran
smis
sion
(dB
)
C S T S 2 1 m e a s 1 1 3 - 1 2 3 m e a s 1 7 4 - 1 9 2 m e a s 2 3 9 -2 4 7m e a s 3 1 4 -3 3 6 m e a s 4 3 0 - 4 7 0
1 1 3 - 1 2 3
1 7 4 - 1 9 2
2 3 9 - 2 4 7
3 1 4 - 3 3 6
4 4 0 - 4 5 6
4 3 0 - 4 7 0
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
430 435 440 445 450 455 460 465 470Frequency (GHz)
CST_S21 meas
-5
-4
-3
-2
-1
0
100 150 200 250 300 350 400
Frequency (GHz)
Ref
lect
ion
(dB
)
CST S11 meas 113 - 123 meas 174 - 192meas 239 - 247 meas 314 - 336
113 - 123174 - 192
239 - 247
314 - 336
Spectral Transmission
Spectral Reflection
7
Phase Agile Reflectarray Antennas Based on Liquid Crystals
• Phase Shifters are Created By Exploiting the Dielectric Anisotropy Property Of Liquid Crystals
• Parallel Plate Topology Is Suitable for Reflectarray Antenna Design
• Reconfigurable Radiation Patterns Are Generated By Applying A Small Bias Voltage
• Sum and Difference Radiation Pattern Switching Demonstrated At 10 GHz
• Beam Steering Antenna Measured At 94 GHz
-40
-35
-30
-25
-20
-15
-10
-5
0
-90 -70 -50 -30 -10 10 30 50 70 90Angle (deg)
Pow
er (d
B)
10.3 GHz - difference pattern
10.3 GHz - sum pattern
Alignment layer Electrode
mm wave E field ε⊥
No Biasing Field
⊥−=Δ εεε //eff
mm wave E field∼
With Biasing Field
V ε//
Hu W, Ismail MY, Cahill R, Encinar JA, Fusco V F, Gamble H S, Linton D, Dickie R, Grant N and Rea S P: ‘Liquid crystal based reflectarray antenna with electronically switchable monopulse patterns’, IET Electron. Lett., 43, (14), 2007, pp. 744 -745
9
Electronically Reconfigurable Quasi – Optical Switches
• A Tunable Bandpass FSS Is Created By Inserting A Thin Layer Of Liquid Crystals Between Two Screens
• Dynamically Switching The Transmitted Signal Between ‘ON’ and ‘ OFF’ States Has Been Demonstrated At 145 GHz
• This Structure Can Be Used To Determine The Permittivity, Dielectric Anisotropy And Loss Tangent Of Tunable Liquid State Materials
Dynamic transmission range
Biasingconnection
Y
XZ
Hu W, Dickie R, Cahill R, Gamble H S, Ismail MY, Fusco V F, Linton D, Rea S P and Grant N: ‘ D-Band Tunable Frequency Selective Surface Based on Liquid Crystals’, Proc. IEEE Microwave and Wireless Components Letters, 17, (9), September 2007, pp. 667- 700
10
Summary
Broadband millimetre wave QPSK Modulator
• Frequency span, 35GHz~65 GHz
• The phase errors are ±15°
• The amplitude errors are ±1dB
• The insertion loss is 9 ±1.5 dB
• The input return loss is below -10 dB
• The output return loss is below -10 dB
• The input 1 dB compression power is 18 dBm
• The DC power consumption is below 60mW
11
V band QPSK Modulator MMIC
• MMIC broadband QPSK modulator
• 0.15 um pHEMT technology
• the chip size is 2.7mm*1mm
12
35.0G 40.0G 45.0G 50.0G 55.0G 60.0G 65.0G-60
-30
0
30
60
90
120
150
180
210
240
270
300
(phase(S(43))-phase(S(21)))_Simu (phase(S(65))-phase(S(21)))_Simu (phase(S(87))-phase(S(21)))_Simu (phase(S(43))-phase(S(21)))_Meas (phase(S(65))-phase(S(21)))_Meas (phase(S(87))-phase(S(21)))_Meas
Pha
se(d
egre
e)
Freq(Hz)
The QPSK four states simulated and measured phase performances vs. Carrier frequency for QPSK
modulator
14
35.0G 40.0G 45.0G 50.0G 55.0G 60.0G 65.0G-15
-14
-13
-12
-11
-10
-9
-8
-7In
serti
on L
oss(
dB)
Freq(Hz)
dB(S(2,1)) dB(S(4,3)) dB(S(6,5)) dB(S(8,7))
The QPSK four states insertion loss vs. Carrier frequency for QPSK modulator
15
40 45 50 55 6035 65
-25
-20
-15
-10
-5
-30
0
freq , G Hz
dB(S
(1,1
))dB
(S(3
,3))
dB(S
(5,5
))dB
(S(7
,7))
The QPSK four states input return loss vs. Carrier frequency for QPSK modulator
16
40 45 50 55 6035 65
-25
-20
-15
-10
-5
-30
0
freq, GHz
dB(S
(2,2
))dB
(S(4
,4))
dB(S
(6,6
))dB
(S(8
,8))
The QPSK four states output return loss vs. Carrier frequency for QPSK modulator
17
Conclusions
• 450 GHz Bandpass FSS filter with an insertion loss of 0.2 dB
• Sum and difference LC Radiation Pattern demonstrated at 10 GHz
• Beam Steering LC planar array demonstrated at 94 GHz
• Quasi-optical switch demonstrated at 145 GHz
• Broadband millimetre wave QPSK MMIC modulator demonstrated 35 – 65 GHz
18