A Proposed rat-race coupler design with a ferromagnetic core

Abstract

Microwave couplers are the most often used passive devices in microwave circuitry. The primary function is to divide (or combine) a radio frequency signal into (from) two distinct signals by a phase difference and specific ratio. A decrease in the size of a dis- tributed coupler would prove helpful with the demand for smaller electronic devices. A Rat-Race Coupler is a microwave coupler made from microstrips shaped like a ring/circle. In the case of a conventional four-port Rat-race coupler, each port is positioned one-quarter wavelength (λ ) apart around the top half of the ring. The bottom half of the ring measures three-quarter wavelengths (λ ). It has three branches that are 90 ◦ phase-shifted from each other and one branch that provides a 270 ◦ phase shift. The central idea of this work is concerned with effects after the addition of a ferro- magnetic material core inside the ring of Rat-race Coupler. After adding the ferromagnetic core, we see some phase shifting and non-reciprocal circuit effects. We propose two types of Rat-race couplers design in this work; the conventional one and also the reduced electri- cal length Rat-race coupler.