Array Gain for Pinching-Antenna Systems (PASS)

TL;DR

This paper characterizes the array gain of pinching-antenna systems (PASS), deriving bounds, analyzing asymptotic behavior, and optimizing antenna number and spacing to significantly improve array gain over conventional systems.

Contribution

It introduces a closed-form upper bound on array gain for PASS, analyzes asymptotic behavior, and proposes an optimization method for antenna placement considering mutual coupling.

Findings

PASS can achieve higher array gain than conventional antennas.

Optimal number of antennas maximizes array gain.

Optimal inter-antenna spacing enhances array performance.

Abstract

Pinching antennas is a novel flexible-antenna technology, which can be realized by employing small dielectric particles on a waveguide. The aim of this letter is to characterize the array gain achieved by pinching-antenna systems (PASS). A closed-form upper bound on the array gain is derived by fixing the inter-antenna spacing. Asymptotic analyses of this bound are conducted by considering an infinitely large number of antennas, demonstrating the existence of an optimal number of antennas that maximizes the array gain. To approach this bound, an antenna position refinement method is introduced. The relationship between the array gain and inter-antenna spacing is further explored by incorporating the effect of mutual coupling. It is proven that there also exists an optimal inter-antenna spacing that maximizes the array gain. Numerical results demonstrate that by optimizing the number of antennas and inter-antenna spacing, PASS can achieve a significantly larger array gain than conventional-antenna systems.