Multi-Way and Poly-Phase Differential Phase Shifters With Highly Reduced Footprint

Abstract

This paper introduces the conception, synthesis, and fabrication of a set of miniaturized five-way differential phase shifters that incorporate an integrated filtering capability. In order to achieve a highly reduced footprint in this design, the three-line coupled structure (TLCS) is applied as the phase-shifting element in each phase-shifting branch. The working principles of the TLCS have been subjected to in-depth scholarly investigation. Benefitting from the miniaturized size of the TLCS, the electric size of the phase-shifting element is about 0.005 λ_g², which exhibits a considerably smaller scale when juxtaposed with state-of-the-art solutions. To confirm the feasibility of the concept and synthesis strategy, a group of five-way poly-phase phase shifters has undergone design, fabrication, and measurement, and design guidelines are summarized accordingly. The measured results demonstrate that the achieved relative phase-shift values are 45° ± 1.7°, 90° ± 2.3°, 135° ± 3.2°, and 180° ± 4.1° across a 53% fractional bandwidth, accompanied by amplitude imbalances that do not exceed 0.15 dB across the various phase-shifting pathways.