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

Abstract

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 under test (AUT) with the AUT mechanically rotating in a far-field 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 far-field 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 paper proposes a novel near-field multi-beam 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 firstly validated by electromagnetic simulations with CST Studio Suite. Besides, a practical system prototype has been built and experimentally validated where the near-field reconstructed multi-beam patterns are shown to match well with the far-field target patterns in terms of beam direction, beam gain, and pattern similarity percentage.