Stacked-patch antenna with switchable propagating mode for UHF body-centric communications

The ability to electronically switch between off-body and on-body communications is a useful feature for wearable antenna applications. Therefore, we present a novel stacked-patch antenna with a switched propagation mode for body-centric communications at 2.45 GHz. Mounted 2 mm above a muscle-tissue phantom and in the on-body mode, the proposed single-port antenna had an efficiency of 62% and an impedance bandwidth of 70 MHz. The antenna performance increased in the off-body mode with an efficiency of 80% and an impedance bandwidth of 247 MHz. In terms of on-body coupling in anechoic conditions, peak |S21| path gains of -39.6 dB and -48.0 dB were obtained for the on-body and off-body configurations, respectively. These results clearly demonstrate the mode isolation obtained