A Digital Non-Foster VHF Radio Approach for Enabling Low-Power Internet of Things

Abstract

A digital non-Foster radio approach is proposed to mitigate Wheeler-Chu limits of electrically-small antennas, with significant potential to significantly reduce energy consumption in the VHF (very high frequency) band, where radio propagation losses below 200 MHz are 100 times less than losses above 2 GHz. Operation at lower frequency could greatly extend lifetimes of small low-power Internet-of-Things devices such as battery-powered sensors operating primarily as transmitters. Unfortunately, physical size constraints and the Wheeler-Chu limit have greatly hindered utilization of VHF bands for mobile devices, where even a 200 MHz half-wave dipole is an unwieldy 0.75 m. However, recent advances in non-Foster impedance matching methods have overcome these limits. In addition, recent digital non-Foster methods are shown to closely resemble digital radio architectures, suggesting that these newer digital non-Foster methods can be readily adopted in new digital radio designs. Therefore, a novel digital non-Foster radio architecture is proposed, where digital non-Foster methods enable small devices in energy-efficient VHF bands while overcoming Wheeler-Chu antenna-size limits.