Compact Single-Unit Two-Bit Reflection-Type Phase Shifters with Large Phase Shift Range

Multi-bit phase shifters are typically implemented by cascading multiple phase-shifting units, therefore incurring large dimensions and higher insertion losses. This paper presents highly compact single-unit two-bit reflection-type phase shifters (SUTBRTPSs), with large phase shifts range and lower insertion loss by using only one 3-dB hybrid coupler, unlike traditional multi-bit reflection type phase shifters. To achieve this, two identical dual-voltage controlled reactance blocks (DVCRBs) are loaded to the 3-dB hybrid directional coupler at through and coupled ports, and 04 states of phase shifts are obtained between the input and isolated ports. Each DVCRB consists of 03 open circuited transmission lines and switching p-i-n diodes and provides half of the required susceptance to achieve the desired phase shifts. Design theory is presented in detail, and for validation and demonstration, two typical SUTBRTPSs (0 degrees /45 degrees /90 degrees /135 degrees and 0 degrees /22.5 degrees /180 degrees /202.5 degrees) are designed, fabricated and measured. Being implemented in a single-unit structure, the proposed method yields highly compact dimensions of 0.44 ?g x 0.46 ?g and 0.54 ?g x 0.46 ?g, respectively. The simulation and measurements results are in good agreement and indicate maximum insertion losses of 1.7 and 2.1 dB with a return loss better than 20 dB and phase error of less than 1.5 degrees.