Correction of Over-the-Air Transmit and Receive Wireless Device Performance Errors Due to Displaced Antenna Positions in the Measurement Coordinate System

Over-the-air (OTA) performance evaluation for wireless devices require electromagnetic field measurements in the far-field (FF). This is typically achieved by using one or multiple test probes to scan a sphere encompassing the device under test (DUT), which can be either set to transmit (Tx) or receive (Rx). Measurement data are usually collected in magnitude-only and near-field to FF transformations cannot be straightforwardly applied in a majority of test cases. In the case of large DUT, the active antenna in the device may not be located at the center of the measurement coordinate system, due to mechanical positioner or anechoic chamber constraints. Such an offset is known to introduce significant errors on assessed radiated quantities, which are mostly due to variations in the path length and the angular position of the apparent phase center of the Tx/Rx structure, with respect to the probe boresight direction. This article proposes a novel solution to this problem and introduces an algorithm to compensate errors from known antenna displacements within the coordinate system. This compensation applies to both OTA Tx and Rx cases. The accuracy of the identified solution is demonstrated through simulated and experimental results, using setups operating at 5G NR millimeter-wave frequencies.