Measurement of Transmit and Receive Characteristics of Electrically Large Active Antennas in Spherical Near Field Systems

The measurement of active devices or Active Antenna Systems (AAS) necessitates the assessment of transmitter and receiver characteristics, such as radiated power, sensitivity, and occasionally data throughput. The AAS transmit and receive properties can be fully characterized by evaluating two spatial power quantities. Equivalent Isotropic Radiated Power (EIRP) when the AAS operates as a transmitter, and Equivalent Isotropic Sensitivity (EIS) when it functions as a receiver. This testing often requires an Over-the-Air (OTA) measurement setup and is relatively simple to perform when the measurement distance is sufficient for both the probe and AAS to be in the far field. For physically and electrically large AAS's, this assumption can be hard to satisfy. This paper explores techniques for assessing spatial-directional transmitted and received power-related performance metrics of active devices using spherical near field measurement techniques. This approach can be complemented by phase recovery techniques to enable accurate NFFF transformation. The presented method is validated by experiments on a suitable validation mockup.