M-Shaped Dielectric Phase Shifter for Beam-Steerable Base-Station Antenna

摘要

We propose a simple and small phase shifter for a beam-steerable base-station antenna. This phase shifter has no metallic hetero-junction, 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 fo, the reflection coefficient = 0. In this phase shifter, the reflection coefficient becomes minimum at fo 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 0.27λ_0 ×0.12λ_0, where λ_0 is the free-space wavelength at f_0. The insertion loss is smaller than about 0.2 dB within a fractional bandwidth of 10%, and the phase shift can vary from 0 to about 80 degrees.