Measurement and Performance of Textile Antenna Efficiency on a Human Body in a Reverberation Chamber

With the advent of on-body communication research in recent years, there is a growing need for antenna developments that satisfy a wide criteria (one being minimal efficiency degradation) in order to be integrated successfully onto human subjects; one promising development is the textile antenna. In this paper we investigate the efficiency performance of some newly designed small sized textile antennas on live human subjects using a reverberation chamber. First, we show that the material selection of these textile antennas can have a crucial effect on the on-body frequency detuning and efficiency levels, as via a comparison we determine that a lossier textile antenna in free space can actually outperform a higher free space efficient textile antenna when placed on-body. This has a profound impact on the material design choices for these small sized antennas. Second, we investigate the performance effects under bent conditions and finally we show that the overall performance of the textile antenna can be mitigated somewhat by variations in on-body distances from the human subject. It is revealed that in some cases a small 20 mm distance from the body is sufficient for the radiation efficiency to approach the free space levels. Theoretical, simulated and experimental evidence is presented to verify the conclusions.