Low-Complexity MRC for ESPAR Based on the Polynomial Expansion of the Admittance Matrix

The electronically steerable parasitic array radiator (ESPAR) has been acknowledged as an inexpensive multiple antenna architecture. Nonetheless, due to the non-linear behavior on the loads used in its control, its related computational complexity can be prohibitive for practical implementations. The current paper deals with such an issue by proposing an approximation of its model via a truncated polynomial expansion of the inverse impedance matrix. The proposed approximation allows to reframe the problem of reactance optimization for beamforming, referred to as analog maximum ratio combining (A-MRC) in previous work. The method proposed in this paper provides a means to obtain a computationally efficient solution to the problem of reactance optimization and it avoids the need of an iterative-based approach. Therefore, resulting in a major computational complexity reduction with respect to related work in the literature.