Four-Port Reference MIMO Antenna for OTA Application

Reference antennas with different correlation coefficients for 4 × 4 multiple-input multiple-output (MIMO) systems are investigated in this paper. Two types of reference antennas are designed, i.e., bad reference antenna with high correlations (HC) and good reference antenna with low correlations (LC). The correlations are controlled by changing the orientation of the elements of the reference antenna. By using the reference antennas with known performances, the unknown antenna effects can be eliminated, which is vital for experimental verification of over-the-air (OTA) testing solutions. Moreover, in order to have a good matching and isolation between the antenna elements, impedance matching method and decoupling scheme are applied during the design process of the reference antennas.