Optical Alignment of the Spherical Antenna Measurement System

摘要

Precise range and positioner alignment are required for the accurate measurementof the radiation characteristics of microwave antennas using a spherical antenna measurement range. This report presents a custom designed system and novel techniques developed at DREO, based on optical instrumentation, to conveniently measure and monitor both the range alignment and the orthogonality and intersection of the multi-positioner spherical system axes. This system is an indoor spherical test range located in an anechoic chamber. The alignment hardware consists of several levels, an electronic theodolite with built-in autocollimation capability, and a unique target mirror assembly with the target viewable from both sides. A hand-held programmable calculator is also used to calculate angular positions and distances. Numerous techniques and procedures developed for optical alignment are described in detail. The user is guided through each step required for a precise optical alignment.