Low-cost nonplanar microstrip-line ferrite phase shifter utilizing circular polarization

A low-cost microwave ferrite phase shifter is proposed in this paper. The phase shifter is comprised of three parallel nonplanar microstrip lines separated from a ground plane by a substrate containing a ferrite rod/slab. The amount of phase shift between the input and output ports is determined by the strength of the magnetic bias field applied to the ferrite. A three-way power divider was designed to feed the microstrip lines with different magnitudes and phases. By combining the effects of the nonplanar geometry and the phase offsets introduced by the feed network, circularly polarized waves can be produced in the ferrite. These waves strongly interact with the biased ferrite resulting in a large phase shift over a short distance-90/spl deg//cm based on current simulation results. This device will be best suited for use in high-gain phased-array radar systems.

I. Introduction

MICROWAVE ferrite phase shifters are primarily used in phased-array antenna systems to electronically steer the antenna beam by providing a different phase shift to each radiating element of the array. Because a typical phased-array antenna system consists of thousands of radiating elements, consequently, thousands of phase shifters are also needed. Therefore, low-cost, compact phase shifters are required that can provide the full 360° range of phase shift.