Design of a Compact Ka-Band Reflection-Type Vector Modulator Phase Shifter

This letter presents a new compact reflection-type vector modulator phase shifter (RTVMPS) for the Ka-band. Unlike conventional passive VMPSs, which use two reflection-type biphase variable attenuators (RTBVAs) in a transmission-mode vector-sum configuration, the proposed VMPS is implemented entirely in the reflection mode, reducing the number of components needed. The phase shifter was designed and fabricated on a printed circuit board (PCB). Measurement results show 360° of phase shift range, 13.5 dB of insertion loss at 28.75 GHz, and a return loss higher than 10 dB between 27 and 30 GHz. The phase and gain errors are less than 2° and 0.3 dB, respectively. The effective area occupied by the phase shifter is
$10.0\times5.5$
mm2. To our knowledge, this is the most compact design of a VMPS implemented on a PCB in the Ka-band.