Integrated-Antenna Over-the-Air Testing for Millimeter-Wave Applications: An Overview of Systems and Uncertainty [Measurements Corner]

Recent wireless communication systems, including the 5G communication New Radio (NR) operating in the millimeter-wave (mm-wave) bands, demand performance measurements using an over-the-air (OTA) test instead of using the traditional conducted methods. This article provides an overview of various OTA measurement systems that measure the integrated antenna inside a 5G-and-beyond mm-wave device, including the direct far-field (DFF), indirect FF (IFF), near-field (NF), and midfield measurements. By considering several significant parameters, including minimum measurement distance required, metrics that can be measured, and complexity of the electrical and mechanical components of the system, suitable OTA measurement methods for integrated antennas can be selected. Furthermore, factors contributing to the measurement uncertainty of OTA systems based on the technical report (TR) of the 3rd Generation Partnership Project (3GPP) are summarized and discussed. By analyzing the significant parameters of each OTA system and contributors of the measurement uncertainty, the reader can determine the OTA method that is most suitable to measure the integrated antennas for mm-wave communications.