Digital Uncoupling of Coupled Multi-Beam Arrays

Abstract

Antenna arrays consisting of up to thousands of elements are required in a plethora of applications, such as wireless communications, microwave imaging, radio astronomy, and radar. The electromagnetic fields surrounding the antenna elements are mutually coupled; this means that an excitation of a given element also causes voltages to be induced in the terminals of the neighboring elements. Such coupling causes deviation of the expected antenna array beam response unless mitigation of the mutually-coupled fields available within the beamforming scheme. Antenna mutual coupling also causes LNA noise coupling, which can severely degenerate the noise performance of an array receiver. The mutual coupling between elements can be quantified by measuring the scattering parameters across the array using a vector network analyzer. This paper proposes a low-complexity and real-time capable algorithm that will furnish the uncoupling of mutually coupled elements in the digital signal processing back-end using a fast inversion algorithm for tridiagonal toeplitz matrices.