MIMO 2×2 reference antennas - Measurement analysis using the equivalent current technique

The reference antenna concept has been created to eliminate the uncertainties linked to the unknown antenna performances of the LTE 2×2 MIMO reference devices [1]. The wireless industry through the CTIA (The Wireless Association) and 3GPP (3G Partnership Project) standardization bodies has been using such antennas for characterizing the methodologies being proposed for the MIMO OTA tests [2]. The developments on the antenna concept and report on the measured performances at uniform incoming power distribution, figures and correlation between different labs have been presented in [3]. In this paper we present analysis of the measurements by using the equivalent radiating current technique (EQC). This technique is based on an integral equation formulation of the inverse source problem upon rigorous application of the equivalence principle [4]-[9]. The application of EQC enables to investigate the radiating details of the device and measurement setup. The aim of this paper is to show how the measurement set up can impacting the current distributions of the reference antennas and hence the performances.