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 0.27λ00.12λ0, where λ0 is the free-space wavelength at f0. 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.

This paper proposes serially arranged two parasitic elements above a fed dipole to obtain broad bandwidth in resonant frequency of a parasitic element. The above antenna can be used in triple-bands with one feed point. Its design method using FDTD is also presented. Next, application of the triple-bands antenna is proposed for 3-sector base station antenna. Its characteristics of return loss and radiation patterns are indicated. Calculated values are in good agreement with measured ones.