Near-Field Evaluation of an Radiated-Two-Stage-Based Millimeter-Wave 5G New-Radio Multiple-Input-Multiple-Output Over-the-Air Test System

This paper presents a preliminary near-field evaluation of a radiated-two-stage (RTS)-based mm-wave 5G new-radio (NR) MIMO OTA test system. The aim is to verify whether the RTS method is applicable in the near-field for the frequency range 2 (FR2). In this paper, a software-defined-radio-based user equipment emulator has been developed, which contains a fully functioning baseband processing unit compliant with the 5G NR physical layer protocol. At the transmitting end, a base station emulator (BSE) from Anritsu has been incorporated with a channel emulator (CE). A controlling program to coordinate the different functional blocks in the testbed has also been developed. Some key factors which can significantly influence the performance of the RTS such as the antenna test functions (ATF) have been carefully studied through a measurement campaign in a fully anechoic chamber. Finally, the performance evaluation of the RTS method in the near field is presented through the preliminary measurement results.