Plane Wave Generator for Dynamic Quiet Zone Synthesis

Over-the-air (OTA) testing has become a dominant testing methodology for multiantenna systems. Apart from conducting radio frequency (RF) testing on the array under test (AUT), the industry also shows increasing interest in diagnosis and RF testing at the level of individual RF chains. This is typically achieved by sequentially switching on individual RF chains (i.e., with the “<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small>–<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small>” operation of the AUT) while the AUT is illuminated by a plane wave field. This letter proposes an in-situ OTA testing method for individual RF chains of the AUT, based on the plane wave generator (PWG) scheme. The basic idea is to generate a dynamic quiet zone, i.e., a plane wave field focused on the target AUT element, while the energy on the remaining AUT elements is significantly suppressed. The plane wave field focusing area can be sequentially moved to individual AUT elements by properly adjusting the excitation coefficients of PWG elements. The proposed approach can achieve in-situ testing of individual RF chains of AUTs with significantly improved measurement efficiency.