A two-Level GTD utilization in designing anechoic chambers for antenna measurements

Typical anechoic chambers for Far-Field (FF) antenna measurements comprise a rectangular metallic enclosure with internal surfaces covered by absorbing material - typically pyramidal, wedge or similar shapes. Conventional FF chambers also contain a source antenna as well as the positioning equipment necessary to rotate an antenna under test (AUT), and acquire far-field pattern data. The primary purpose of the chamber is to create a test zone surrounding the AUT, where the electric field is to be as uniform as possible, and multiple reflections are kept to a minimum. Clearly, the test zone performance depends on the chamber geometry, source antenna to AUT separation, and absorption properties as well as grades of absorbing material.