A Monolithically Integrable Reconfigurable Antenna Based on Large-Area Electronics

Reconfigurable antennas introduce unique and dynamic system capabilities for wireless communication and sensing, by enabling controllable radiation pattern, frequency response, and polarization of electromagnetic (EM) waves. The antenna’s physical dimensions are critical to enhancing control of radiative characteristics, making it necessary to distribute RF control devices across a large-area aperture. Previous reconfigurable antennas have been limited in scale and performance by the need to assemble discrete active components. Large-area electronics (LAE) is a technology that can enable monolithic reconfigurable antennas, with flexible and large form factors. However, conventionally the speed of LAE, specifically of thin-film transistors (TFTs), has been restricted to 10–100 MHz. In this work, a reconfigurable antenna based on LAE RF TFTs is achieved through a combination of: 1) materials and device enhancements pushing fundamental TFT performance metrics to the giga-Hertz regime and 2) an architecture that employs the TFTs as passive switches, rather than active amplifiers, to enable aggressive biasing for high-frequency operation, yet within the breakdown limits. A 9 $\times $ 9 cm2 reconfigurable antenna consisting of an 11 $\times $ 11 array of metal patches as sub-radiators controlled by 208 TFT-based RF switches is demonstrated. Far-field and $S$ -parameter measurements show reconfigured beam steering by 90° and resonant-frequency tuning by 200 MHz.

I. Introduction

The Internet of Things (IoT) envisions a large number of widely and densely distributed sensing devices, which are typically accessed using low-power giga-Hertz radios [1], [2], [3]. As illustrated by the example of a smart warehouse in Fig. 1, the dense and spatial nature of the network requires several critical functionalities for wireless accessing, including direction finding, addressing, and transmission, as well as flexible spectrum allocation and polarization control. Such agility presents significant new opportunities and challenges for antennas, which serve as the interface between guided signals in the system and unguided electromagnetic (EM) waves to the distributed nodes. The constraints of traditional designs with fixed parameters motivate a new class of antennas, with designs where the key parameters, such as directionality, frequency response, and polarization, can be reconfigured. Fig. 1.

IoT systems envision antennas with dynamically tunable beam directionality and frequency.