Development and Validation of Testing System for Automated Millimeter-Wave Phased Array Multibeam Near-Field Measurement

To ensure millimeter-wave (mmWave) radio system performance, multiple beam-steered radiation patterns of phased arrays are required to be measured in conventional antenna measurement ranges. This is typically done by sequentially measuring the radiation pattern of phased array antenna under test (AUT) with the AUT mechanically rotating in a far-field (FF) setup for each steered beam in a beam-lock mode. However, the conventional pattern measurement procedure for mmWave phased arrays with multiple beams is time-consuming and costly due to the repetitive mechanical rotation and the use of FF anechoic chamber. The problem becomes even more pronounced for mmWave phased arrays with large-scale antenna configuration due to many more beam states and more directive beam patterns. To address this issue, this article proposes a novel near-field (NF) multibeam measurement system for mmWave phased arrays, which offers unique advantages in terms of short measurement time, support for full automation, no need for mechanical rotation, compact measurement setup, and low system cost. For the pattern with its beam steered to any given direction can be reconstructed based on the AUT element patterns retrieved from a few sparse measurement samples. In this work, the principle and effectiveness of the proposed measurement system have been first validated by electromagnetic (EM) simulations with Computer Simulation Technology (CST) Studio Suite. Besides, a practical system prototype has been built and experimentally validated where the NF reconstructed (“NF reco.”) multibeam patterns are shown to match well with the FF target (“FF targ.”) patterns in terms of beam direction, beam gain, and pattern similarity percentage.