A Batteryless Full-Duplex Radio Transceiver for Sensors

This work presents a radio frequency (RF) interface of a full-duplex radio transceiver capable of providing measurements of physical quantities by means of capacitive and inductive sensors incorporated into an oscillator, whose energy supply is harvested from electromagnetic waves sent by a remote central unit. To make this measurement system viable, it makes use of full-duplex communication. This system consists of a duplexer that allows the separation between transmission and reception; of a Colpitts oscillator, whose supply voltage is obtained from a rectifier. This oscillator works both as a measurement system and the RF transmitter, whose carrier frequency is modulated by a measurand providing by a relative humidity sensor. A prototype of this system operating around 27 MHz, simulation and measurement results are also presented.