A Wideband Schiffman Phase Shifter Based on SISL Platform

A class of substrate integrated suspended line (SISL) platform-based broadband Schiffman phase shifter is newly proposed. By loading the open-circuited stubs as compensation capacitors, the problem of unequal phase velocity of odd-mode and even-mode existing in parallel coupled-line is solved, which significantly improved the phase shifter's return loss. According to the simulation results, the return loss is better than 27 dB over the operating frequency band, and it reaches 48 dB at the optimal point. A 90° phase shift is basically achieved near the center frequency, and the measured phase imbalance is within ± 5° from 3.27 GHz to 4.72 GHz.