Ultra-wideband 45° phase shifter based on multi-section broadside coupling structure

An ultra-wideband 45° phase shifter is presented in this letter. The phase shifter is designed using a multi-section broadside coupling structure that yields ultra-wideband bandpass response and constant phase shift. The measured reflection coefficient, insertion loss and phase variation are -12.5 dB, 0.67 dB, ±1.6° for the band from 2.85 to 10.70 GHz (112%), and -12.5 dB, 1 dB, ±5° for the band from 2.60 to 11.05 GHz (124%). This design outperforms the previously reported results about ultra-wideband 45° phase shift and is suitable for the ultra-wideband Butler matrices design.