Reactively Loaded AOA Estimation Coexistent with a 16 x 16 MIMO Beam Steering Array

To achieve a channel capacity of over 10 Gbps for use in forthcoming connected car systems, a 16 × 16 multiple-input multiple-output (MIMO) antenna system has been developed, which is a version-up approach of our 4 × 4 MIMO circular phased array technology. The angle of arrival (AOA) estimation function must be embedded into the phased array so that the MIMO system is fully capable of accomplishing the beam steering functions. The most challenging issue is the mitigation of phase perturbation due to electromagnetic (EM) coupling between the AOA antenna and the surrounding MIMO subarray elements. In this paper, we present an AOA estimation antenna with reactive load impedances for reducing the EM-coupling. The results show that the estimated angle error is less than 0.5 degrees with an omnidirectional radiation pattern.