Modulated Frequency Selective Surfaces for Wearable RFID and Sensor Applications

This paper presents a transponder based on a modulated frequency selective surface (FSS) as an alternative based on backscattering communication for wearable applications. The transponder is composed of an array of dipoles loaded with varactor diodes to modulate the backscatter response. The information is obtained by changing the cross section of the FSS. The detuning and the power loss of the transponder when in contact with the body are studied. Several FSSs with a different number of dipoles and placed on different surfaces are studied, as a proof of concept. In addition, a temperature sensor for on-body applications is proposed. The reader is also presented and experimental results are provided.