Flexible Coupler Antenna Enhanced Wireless Communication: Modeling and Coupler Position Optimization

2026-06-07

AI Summary

This study addresses the high complexity and cost of conventional active array beamforming by proposing a low-power alternative based on a flexible coupler-based antenna architecture. The design enables mechanical beam steering through physical displacement of passive coupling elements alone, modulating induced currents without requiring any adjustment to active antennas. This approach pioneers purely passive element repositioning for beam control, substantially reducing both hardware cost and power consumption. Leveraging multi-port circuit theory, the authors develop line-of-sight and multipath channel models and employ a block coordinate conditional gradient algorithm to optimize coupler placement. Experimental results demonstrate that, despite significantly fewer active elements and RF chains, the proposed system achieves notably higher spectral efficiency compared to existing benchmark schemes.

Abstract

This paper proposes a novel flexible coupler antenna (FCA) that translates passive coupling elements around a fixed-position active antenna to reshape the induced currents on the passive elements for radiation. A new form of mechanical beamforming is achieved by moving only the passive coupling elements while keeping the active antenna stationary. The proposed design significantly reduces the antenna and radio-frequency (RF) chain costs of conventional active array beamforming with low mechanical control complexity and energy consumption. For the purpose of exposition, we consider a point-to-point communication system with one FCA at the transmitter and one fixed antenna at the receiver. Specifically, based on multi-port circuit theory, we establish both the line-of-sight (LoS) and multipath channel models and derive the mechanical beamforming weights of the passive couplers as functions of their positions. Then, we formulate a new problem to maximize the received signal-to-noise ratio (SNR) by optimizing the positions of passive couplers at the transmitter, subject to coupler movement and transmit power constraints. Solving the resulting problem is inherently difficult because coupled channel and mechanical beamforming create non-linearity in the objective function.To tackle this problem, we propose an efficient block-coordinate conditional gradient method to search for the best positions of all passive couplers by sequentially optimizing the position of each coupler with those of the other couplers fixed in an iterative manner.Simulation results demonstrate that the proposed system significantly outperforms benchmark schemes in terms of achievable rate, but with significantly reduced active antennas and RF chains.

Problem

• flexible coupler antenna
• mechanical beamforming
• position optimization
• SNR maximization
• wireless communication

Innovation

• flexible coupler antenna
• mechanical beamforming
• passive coupling elements
• block-coordinate conditional gradient
• multi-port circuit theory