2013 Volume E96.B Issue 8 Pages 2095-2101
We propose a simple and small phase shifter for a beam-steerable base-station antenna. This phase shifter has no metallic heterojunction, and the phase shift is controlled by moving an M-shaped dielectric plate between the strip conductor and the ground plane of a strip line. We derive a design equation from the condition that at the center frequency f0, the reflection coefficient =0. In this phase shifter, the reflection coefficient becomes minimum at f0 regardless of the movement distance, r, of the dielectric plate, and the relationship between the phase shift and r is linear. These characteristics are verified by performing simulations and measurements. The size of the M-shaped dielectric phase shifter is 0.27λ0×0.12λ0, where λ0 is the free-space wavelength at f0. The insertion loss is smaller than about 0.2dB within a fractional bandwidth of 10%, and the phase shift can vary from 0 to about 80 degrees.
