Over-the-air radiated testing of millimeter-wave beam-steerable devices in a cost-effective measurement setup

With the severe spectrum congestion of sub-6 GHz cellular systems, large-scale antenna systems in the millimeter-wave (mmWave) bands can potentially meet the high data rate envisioned for fifth generation communications. Performance evaluation of antenna systems is an essential step in the product design and development stage. However, conventional cable conducted test methods are not applicable for mmWave devices. There is a strong need for over-the-air (OTA) radiated methods, where mmWave device performance can be evaluated in a reliable, repeatable, and feasible way in laboratory conditions. In this article, radiated testing methods are reviewed, with a focus on their principle and applicability for beam steerable mmWave devices. To explore the spatial sparsity of mmWave channel profiles, a cost-effective simplified 3D sectored multi-probe anechoic chamber system with an OTA antenna selection scheme is proposed. This setup is suitable for evaluation of beam-steerable devices, including both base station and user equipment devices. The requirements for the test system design are analyzed, including the measurement range, number of OTA antennas, number of active OTA antennas, and amount of channel emulator resource. Finally, several metrics to validate system performance are described for evaluation of mmWave devices.