A Coupler With Wide Power Division Ratio Tuning Range and Flexible Coupling Direction
Huy Nam Chu, Tzyh‐Ghuang Ma
Abstract
We propose a new tunable coupler with flexible coupling direction and a wide power division ratio (PDR) tuning range. The structure consists of two 90° hybrid couplers with two reconfigurable synthesized transmission lines (RSTLs) inserted in between. The RSTL is designed to operate either in the passband as an analog phase shifter or in the transition region and stopband as a mismatched circuit with tunable reflection/transmission coefficients. By properly controlling the electrical responses of RSTLs, the PDR tuning range can be greatly extended in both forward- and backward-wave coupling operations. The proposed coupler was designed and tested at 2.4 GHz. Our design, among one of few couplers exhibiting switchable coupling paths, yields the widest measured PDR tuning range in both operations while still keeping comparable performance with previous works.