Introduction to beamforming and beam-tracking technologies Ruey-Bing (Raybeam) Hwang Professor Phased-Array Technology Laboratory Institute of Communications Engineering ECE Department National Chiao Tung University https://sites.google.com/site/hrblab917/
Summary X-Band Phased-Array FMCW Radar System X-Band Direction-of-Arrival Estimator Hybrid digital/analog X-Band Beamforming System 2.4 GHz Transceiver and Hybrid Digital/Analog Beamforming system Mono-pulse Tracking System
Specification of the radar system X-band (centered @9410MHz, 50MHz bandwidth) Frequency-Modulated Continuous- Wave (FMCW) DoA (Direction-of-Arrival Estimation): Spatial Smooth MUSIC(Multiple Signal Classification) algorithm Hybrid digital/analog Beamforming (DDS for DBF and Phased LO for ABF)
Phased-Array FMCW Radar reflector Frequency R cft 2B R c 2B B Δf T Time receiver Detector (DAQ) MUSIC Algorithm transmitter Angle Estimation SNR 2 PG G sl t t r = ( p ) 3 4 4 RLkTB Ls = L + NF RF s
IF 5 IF 6 IF 7 IF 8 System Architecture of the FMCW radar system Transmitter Coupler BPF IF 1 IF 2 IF 3 IF 4 SSG 50 Power divider BPF Mixer IF 5 IF 6 IF 7 IF 8 IF 1 IF 2 IF 3 IF 4 BPF Receiver Coupler BPF Waveform Generator
BPF Multiplier IF 1 Mixer T connector Ant. Part 1 Power divider Power divider Power divider Phase shifter BPF Multiplier Phase shifter BPF Multiplier Phase shifter BPF Multiplier Phase shifter BPF Multiplier BPF BPF BPF BPF IF BPF 2 Mixer BPF IF 3 Mixer BPF IF 4 Mixer BPF IF 5 Mixer PA Phase calibration T connector 1 PA Phase calibration T connector 2 PA Phase calibration T connector 3 PA Phase calibration 4 T connector Ant. Ant. Ant. Ant. Part 2 Power divider Power divider Power divider Phase shifter BPF Multiplier Phase shifter BPF Multiplier Phase shifter BPF Multiplier Phase shifter BPF BPF BPF BPF IF 6 BPF Mixer IF 7 BPF Mixer IF 8 BPF Mixer BPF PA Phase calibration T connector 5 PA Phase calibration 6 T connector PA Phase calibration 7 T connector PA Phase calibration 8 Ant. Ant. Ant.
DoA-MUSIC (1) é ê ê ê ê ê ë x 1 x 2 x 8 ù ú ú ú= é a(q 1 ) a(q 2 ) a(q 3 ) ëê ú ú û steering vector é ê ùê ûú ê ë ê s 1 s 2 s 3 é ê ê a(q i ) = ê ê ëê é ù ê ú ê ú+ ê ú ê û ú ê ë 1 w 1 w 2 w 8 e jkd sinq i e j7kd sinq i ù ú ú ú ú ú û ù ú ú ú ú ûú
DoA-MUSIC (2) M: number of antenna D: number of target
DoA-MUSIC (3)
DoA-MUSIC (4) M=8,D=2 SNR=10dB Incident angle:-13degree,43degree
An Eight-Element Array DoA Estimator System block diagram Photo of the circuit module
Direction-of-Arrival (DoA) Estimation AOA estimation for two scatters (trihedrals) in an open site. We employ the trihedral because its RCS is less sensitive to the variation of the incident angle within certain range of the angular spectrum. It is obvious from the result shown in this figure that the two targets can be correctly identified through our DoA estimator in a complex outdoor environment. Traditional MUSIC Smoothed MUSIC
Estimated AoA with a moving target with the rate of two degrees per second. Measured data for modified MUSIC estimation algorithm were acquired from the eight-subarray X-Band array antenna. Yau-Hwa Tseng, Ing-Jiunn Su, and Ruey-Bing Hwang, "An X-band eight-subarray smart antenna system for direction of arrival estimation," Microwave and Optical Technology Letters, Vol. 56, No. 11, November, pp. 2582-2587, 2014.
Beamforming Performance ~ Phased LO Technique ΔΦ ΔΦ Simulation (CST Microwave Studio) Measurement R.-B. Hwang, and et. al., "A Frequency-Modulated Continuous Wave Phased Array Marine Radar System Based on Smart Antenna Technology," (Invited Paper) Forum for Electromagnetic Research Methods and Application Technologies (FERMAT), Vol. 5 (http://www.e-fermat.org/), 2014.
Open-Site Measurement: Case 1: 台積館 ( 825 m ) 225 m 鐵網 1.101 MHz ( 825 m ) 台積館 :target :radar location
Open-Site Measurement: Case 2: 天線塔 ( 1921 m ) 2.561 MHz ( 1921 m ) 天線塔 :target :radar location
Range Resolution Measurement 20Log(V rms ) -30-40 -50-60 -70-80 (789,-41.11) (792,-40.2) 800m 803m 20Log(V rms ) -20-30 -40-50 -60 (1989,-31.3) (1992,-31.08) 2000m 2003m -90-50 -60 740 760 780 800 820 840 Distance(m) (4986,-62.27) (4989,-62.14) 5000m 5003m -70 1940 1960 1980 2000 2020 2040-70 -75 Distance(m) (7987.5,-74.54) (7990.5,-75.97) 8000m 8003m 20Log(V rms ) -70-80 20Log(V rms ) -80-85 -90 4940 4960 4980 5000 5020 5040 Distance(m) -90 7960 7970 7980 7990 8000 8010 8020 Distance(m) 17
X-band FMCW Radar Antennas Gain (dbi) 25 20 15 10 5 0-5 -10-15 -20-25 -30-180 -120-60 0 60 120 180 Theta (degree) Measurement Simulation Gain (dbi) 25 20 15 10 5 0-5 -10-15 -20-25 -30-180 -120-60 0 60 120 180 Theta (degree) Measurement Simulation F.-Y. Kuo and R.-B.-Hwang, "High-Isolation X-band Marine Radar Antennas Design," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 5, May 2014
High Isolation T/R Antennas 75 70 h b Baffle TX Ant. Base s Baffle RX Ant. y z Isolation (db) 65 60 55 50 45 40 35 30 25 with Baffle (Measurement) with Baffle (Simulation) w/o Baffle (Measurement) w/o Baffle (Simulation) 9.2 9.3 9.4 9.5 9.6 Frequency (GHz)
A 2.4GHz IF Transceiver System block diagram of the transceiver module (centered at @2.4GHz with 250MHz bandwidth) To reduce the number of electronic components, and to achieve high degree of signal integrity, we employ the Direct- Conversion scheme as the circuit architecture Four-layer FR4 PCB
Phase Noise of STALO Phase noise: -80dBc/Hz @1MHz Phase noise: -110dBc/Hz @1MHz Phase noise: -140dBc/Hz @1MHz
Constellation and EVM Spectrum of I/O signal Nonlinearity of Amplifier Input power: -10 dbm Input power v.s. output power
EVM (%) Effect of IQ Imbalance on EVM EVM (%) 20 15 10 5 0 Phase Imbalance = 0 o Phase Imbalance = 10 o 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Amplitude Gain Imbalance Imbalance (db) (db) 10.00 8.750 7.500 6.250 5.000 3.750 2.500 1.250 0.000 1. 0 Gain Imbalance (db) The response of amplitude/phase imbalance v.s. EVM. 0. 8 0. 6 0. 4 0.2 0.0 0 2 4 6 8 0 2 10 Phase Imbalance (degree) 4 6 8 10 EVM (%) 23
RF Transceiver Module Design 24
Open-site Environment I Tx RF RF Rx I SMW200A Vector Signal Geneator Q LO LO Q FSW Signal and Spectrum Analyzer SSG-4000HP Synthesized Signal Generator SSG-4000HP Synthesized Signal Generator Setup of the open-site measurement and the environment.
Open-site Measurement Modulation type:qpsk Symbol rate:25 Msym/s EVM:4.35% SNR I/Q input power:5 dbm 2 1 EVM = 27.2 db Modulation type :16-QAM Symbol rate:25 Msym/s I/Q input power:5 dbm EVM :4.97% SNR 1 EVM 2 = 26.1 db Modulation type:64-qam Symbol rate:25 Msym/s I/Q input power:5 dbm EVM :5.07% SNR 1 EVM 2 = 25.9 db
Combining the switched-beam and beam-steering capabilities in a 2-D phased array system Yi-Che Tsai, Yin-Bing Chen, and Ruey-Bing Hwang,``Combining the switched-beam and beam-steering capabilities in a 2-D phased array system,'' Radio Science, Vol. 51, Issue 1. January, 2016, Pages 47-58, DOI: 10.1002/2015RS005764
Switched-beam patterns 90 90 90 0 90 90 0 0 90 90 0 90 90 0 90 0 0 0 0 0 0 90 0 90 90 0 90 90 0 0 90 90 0 90 90 90
Switched-Line Phase Shifter 45 Radial stub Path 2 Out Path 1 Radial stub 1.00mm DC 2 45 16.32mm Z 0 Z 0 6.79mm 16.62mm R3.0mm DC 1 2 1 DC 2 λ/4 transformer PIN diode In DC 1 10.20mm 0.40mm 7.45mm 16.20mm GND 0.40mm 13.20mm 14.25mm 6.60mm 1.50mm 26.50mm 29.50mm 1.50mm 9.70mm 5.45mm Path 1 Path 2 0.6 nh 0.6 nh 2.3 ohm Diode on 0.17 pf Diode off 3000 ohm
Switched-Line Phase Shifter ~ measured results 0 48 46 S-parameter / db -10-20 -30 Path #1_S11 Path #1_S21 Path #2_S11 Path #2_S21 Phase difference / degree 44 42 40 38 arg(path difference)_simulation arg(path difference)_measurement -40 2 2.2 2.4 2.6 2.8 3 Frequency / GHz 36 2 2.2 2.4 2.6 Frequency / GHz
Beam-steering using analog phase shifters y 330 Theta / degree 0 30 z 330 x Theta / degree 0 30 300 60 300 60 270 240 210-20 -15-10 -5 0 180 150 Simulation using CST 120 90 Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6 Pattern 7 270 240 XZ plane (Horizontal) 210-20 -15-10 -5 0 180 Measurement 150 120 90 Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6 Pattern 7
Desired mmwave MIMO System The base/mobile station contains several radio frequency (RF) channels each radiating a high-directivity beam, forming a MIMO channel. Seamless beam switching/steering in each RF channel is achieved by means of analog/digital beam-forming. DAC DAC DAC DAC DAC DAC Modulator Baseband PA Phased LO Baseband PA...... Phased LO Modulator Baseband PA...... RF Beamformer Phased LO RF Beamformer Modulator Baseband PA Phased LO Baseband PA Phased LO Modulator Baseband PA Phased LO... Array Antenna Array Antenna MIMO Channel Array Antenna Array Antenna Demodulator Baseband Phased LO Baseband...... Phased LO Demodulator Baseband Phased LO... Demodulator Baseband Phased LO Baseband...... Phased LO Demodulator Baseband Phased LO ADC ADC ADC ADC ADC ADC
A Time-Division Multiplexing Mono-pulse Antenna System for DVB-SH Application Stacked Patch Antenna Array Antenna A Antenna B Mode-former 0 π 0 DAQ & PC π Y Antenna C X Antenna D 0 π 0 π Switched-line Phase Shifter 4 Way Power Divider Ʃ ΔV ΔH TDM Y.-L. Tsai and R.-B. Hwang, "A Time-Division Multiplexing Mono-pulse Antenna System for DVB-SH Application," IEEE Transactions on Antennas and Propagation, Vol. 63, Issue 2, February, pp. 765-769, 2015
Mono-Pulse Principle x 1 n = G r,1 θ, φ exp +jk 0 r 1 x 2 n = G r,2 θ, φ exp +jk 0 r 2 r θ, φ r θ, φ S n + N 1 n S n + N 2 n = x 1 n x 2 n Σ x 1 n +x 2 n The distance between the two antennas is less than or equal to half wavelength for not to introduce the grating lobes. S n is the incident signal G r θ, φ is the antenna gain pattern N i n is the thermal noise on the receiver
Circuit and Antennas Layout Port 3 150.00 Port 2 150.00 102.00 4.50 4.50 150.00 101.50 4.50 4.50 4.50 150.00 14.70 6.88 150.00 32.00 2.00 R1.50 102.60 2.00 150.00 31.50 4.50 Z Y 101.50 Port 4 Port 5 32.60 31.50 X Port 1 Unit: mm Stacked Patch Antenna Array Antenna A Antenna B Top layer 1.50 6.00 Y Metal FR4 Bottom layer 1.60 Unit: mm Antenna C X Antenna D
Sum and Difference Patterns
S-curve
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References 黃瑞彬, 楊肅哲, 黃獻東 : 波束控制天線結構, 發明第 I 488362 號, 中華民國專利, 中華民國 104 年六月十一日 Ruey-Bing Hwang, Su-Che Yang and Hsien-Tung Huang, ``Beam Steering Antenna Structure, US Patent No.: US 9,166,288 B2, Oct. 20, 2015 黃瑞彬, 郭芳銚 : 天線結構, 發明第 I 530022 號, 中華民國專利, 中華民國 105 年四月十一日 黃瑞彬, 郭芳銚 : 單脈衝雷達的比較器及其信號產生方法, 發明第 I 4 95892 號, 中華民國專利, 中華民國 104 年八月十一日 Ruey-Bing Hwang, Fang-Yao Kuo, ``Comparator of Mono- Pulse Radar and Signal Generation Method Thereof, US Patent No.: US 9,134,400 B2, Sep. 15, 2015