Tunable load MIMO with quantized loads

In this paper, we study the application of precoding schemes on practical electronically steerable parasitic array radiators (ESPARs), where quantized load impedances are considered for each antenna element. The presence of quantization in the loads results in a performance loss for practical ESPARs. To alleviate the performance loss, we propose to approximate the ideal current vector with convex optimization, where it is further shown that the optimality is achieved by optimizing the feeding voltages only. Specifically, we obtain the closed-form expression when single-fed ESPARs are assumed. Numerical results show that the proposed quantization-robust scheme can achieve a significant performance gain over ESPARs with quantized loads.