Reflection Phase Shifter Topology With 180° Tuning Range Using Impedance Transforming Coupler and Series Resonant Load for K-Band Phased Arrays

A reflection phase shifter topology that simultaneously provides a large continuous phase tuning range and low insertion loss is presented for application in emerging low Earth orbit (LEO) satellite communications (SATCOMs) systems. An impedance-transforming coupler and a series-resonant load are used in the proposed circuit structure to achieve 180° phase tuning range while maintaining an insertion loss below 2-dB. To validate the design concept, two prototypes operating from 19.5 to 20.5 GHz are fabricated and tested. The first prototype uses stepped impedance loads to create an effective inductance in the series-resonant load. This prototype achieves a tunable phase tuning range of 183° with ±0.9° phase imbalance and an insertion loss below 1.6-dB with 0.3-dB variation across the entire operating band assuming a 15-dB return loss as the reference. To enhance scalability, short-circuit stubs are used in the second prototype to replace the stepped impedance loads to make the phase shifter less vulnerable to fabrication tolerances at the cost of a slight degradation in the performance. The simplicity of the proposed design, the low insertion loss, and the flatness of the phase and amplitude across the band and tunable phase conditions are the main features of the presented devices compared with other relevant designs.