Towards Compact and Frequency-Tunable Antenna Solutions for MIMO Transmission with a Single RF Chain

TL;DR

This paper introduces a compact, frequency-tunable antenna for beam-space MIMO that simplifies hardware and enables dynamic reconfiguration, facilitating efficient multi-signal transmission with a single RF chain in small wireless devices.

Contribution

The work presents a novel single-radiator antenna design with load reconfiguration for beam-space MIMO, eliminating external matching circuits and supporting a 1:2 tuning range.

Findings

Prototype demonstrates effective single-RF multiplexing at fixed frequency.

Simulation and measurement results show excellent agreement.

Reconfigurable loads enable beam-space multiplexing over a 1:2 frequency range.

Abstract

Recently, a technique called beam-space MIMO has been demonstrated as an effective approach for transmitting multiple signals while using a single RF-chain. In this work, we present novel design considerations and a compact antenna solution to stimulate the deployment of beam-space MIMO in future wireless applications. Targeting integration in small wireless devices, the novel antenna is made of a single integrated radiator rather than an array of physically-separated dipoles. It also drastically simplifies the implementation of variable loads and DC bias circuits for BPSK modulated signals, and does not require any external reconfigurable matching circuit. Finally, we show that this antenna system could be reconfigured by dynamic adjustment of terminating loads to preserve its beam-space multiplexing capabilities over a 1:2 tuning range, thereby promoting the convergence of MIMO and dynamic spectrum allocation via reduced-complexity hardware. A prototype achieving single-RF-chain multiplexing at a fixed frequency is designed and measured, showing excellent agreement between simulations and measurements.