Beam Squinting Effects in Super Wideband Communication Systems

TL;DR

This paper investigates beam squint effects in super wideband systems with high mutual coupling, revealing how strong coupling reduces squint and extends bandwidth through a circuit-theoretic modeling approach.

Contribution

It introduces a circuit-theoretic framework to model mutual coupling effects in super wideband arrays and derives closed-form SNR expressions for beamforming performance.

Findings

Strong mutual coupling reduces beam squint in super wideband arrays.

Derived closed-form expressions for average SNR with beamforming.

Tightly coupled arrays exhibit nonlinear frequency dependence in true time delays.

Abstract

Beam squint, the frequency-dependent shift of the main beam, poses a major challenge for wideband antenna arrays. This paper focuses on the beam squint effects in super wideband (SW) systems, where high mutual coupling (MC) effects are present. These high MC effects complicate beamforming (BF) by creating frequency-dependent phase relationships that invalidate conventional approaches. To accurately model MC effects, this paper uses a circuit-theoretic framework for tightly coupled SW uniform linear arrays (ULAs). We derive closed-form expressions for the average received signal-to-noise ratio (SNR) with BF in conventional half-wavelength spaced, weakly coupled arrays and validate them. Extending our analysis to tightly coupled SW arrays, we demonstrate that, in contrast to conventional weakly coupled arrays, the effective true time delays exhibit a nonlinear dependence on frequency due to coupling-induced phase shifts. A comparative analysis reveals that strong MC in SW arrays significantly reduces squint in phase-controlled BF, extending the usable bandwidth considerably.