A Ka Band Coaxial Three-Reflector Zoom Antenna Based on the Principle of Optical Zoom

This paper presents a novel approach to design zoomable antenna at 30 GHz by using three reflectors and a TE₁₁ mode circular waveguide feed. The main reflector and the feed is designed to remain in a fixed position, and a pair of moveable subreflectors are used as zoom components to control the Half-Power Beamwidth (HPBW). By rearranging the location of two subreflectors based on the principle of optical zoom, the HPBW can be broadened by about 2.8 times. The GRASP simulation results verify the feasibility of the design.

I. Introduction

Zoom antenna is a kind of antenna that can broaden the beamwidth of radiation pattern, and it can find its applications in the design of satellite antenna. It could compensate the changes of coverage region when the satellite travelling in elliptical orbits, that is making the radiation beam spot diameter on the ground independent of the antenna altitude. Previous studies have achieved dynamic control of the beamwidth by several methods using array or reflector antenna.