A compact arbitrary power division coupler with nonstandard phase-difference

Abstract

This paper presents a new coupler configuration which can be designed with both arbitrary power division and nonstandard phase difference at the output ports. The planar coupler ring is composed of four section microstrip lines and an open stub resulting in ease of fabrication. Its circuit parameters can be easily determined by the derived closed-form equations and the corresponding performance in terms of power division ratio, output phase difference, and the tunable parameters is mainly analyzed. Compared with the previous counterparts, its bandwidth and area have obvious superiority. For experimental verification, two prototypes, operating at 1 GHz, have been designed and implemented in microstrip process. One demonstrates a 45° phase difference with equal outputs and the other is designed for a 105° phase difference with 6.02 dB power division ratio. The design theory has been supported with good agreement between the simulated and measured responses.

Keywords:

• Nonstandard phase difference
• arbitrary power division
• ring coupler
• size reduction