77-GHz Four-Element Phased-Array Radar Receiver Front End

A phased-array receiver module operating at 77 GHz is designed and manufactured to obtain beam-steering capability. The module has four patch antennas integrated with three active phase shifter (APS) chips on a single-layer Rogers 3003 printed circuit board PCB board. The W-band 1.65-mm
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novel APS chip is fabricated using 0.13-μm SiGe Heterojunction Bipolar Transistor (HBT) technology. The APS consumes 100-mW dc power and achieves a peak gain of 9 dB at W-band and covers 360°. The phase shifter chips and PCB are packaged using low-cost wire-bond interconnections with insertion loss less than 7.5 dB. A novel method that exploits Klopfenstein tapering is also designed to connect coplanar waveguide to microstrip line with minimum insertion loss around 77 GHz. The measured gains of the phased-array receiver and passive four-element antenna array are compared. The module and passive array achieve the maximum gains of 9.7 and 10.4 dBi at 77 GHz. The simulated and measured results present well agreement at the W-band frequency. The beam can be steered to ±30°.