Compact AFSIW Antenna With Integrated Digitally Controlled Impedance Tuner for Smart Surfaces

Abstract

For unobtrusive smart-surface integration, an air-filled substrate-integrated waveguide (AFSIW) antenna for the [5.15-5.85]GHz band is co-designed with a tunable matching network and a cavity-integrated biasing circuit. It features a reconfigurable matching network to mitigate impedance mismatch due to objects in its reactive near field. A digitally controlled biasing circuit with switched-mode power supply is seamlessly integrated inside the air-filled antenna cavity to accurately control the matching network through a serial interface. The proposed impedance-tunable antenna covers an impedance bandwidth from 4.64 GHz to 6.09 GHz with a peak gain of 4.51 dBi at its center frequency. Measurements show that the cavity-integrated circuitry has negligible influence on the antenna performance, yielding novel integration potential. The impedance-tunable antenna is tested in a smart surface desktop integration scenario where it corrects detuning by objects placed on top, improving the wireless link for IEEE 802.11ac bands.