Dual-Wideband Filtering Phase Shifter With Same Phase Differences, High Frequency Selectivity, and Wide Stopband

In this letter, a novel dual-wideband filtering phase shifter with the same constant phase difference within dual-band and high-frequency selectivity is presented. The proposed filtering phase shifter mainly consists of an asymmetric cross-shaped resonator (ACSR) and a short-ended coupled line. The ACSR includes a pair of parallel coupled line cascading short-ended stubs and open stubs. Meanwhile, by subtly choosing the electric length of the delay line, the same constant phase difference within the dual band can be obtained. For verification, a prototype is designed, fabricated, and measured. Measured results are found to coincide well with the simulated ones, exhibiting dual-wide passbands operating at 2.85 and 4.65 GHz with 3-dB FBW of 40% and 20.5%, respectively, the same in-band phase difference (90° ± 5.6° and 90° ± 4.5°), and sharp frequency selectivity.