Dual-Broadband Dual-Mode Wearable Antenna for On/Off-Body WBAN Communications

This paper proposes a dual-broadband dual-mode wearable antenna (DBDMA), designed for ON-body and OFF-body communication modes in wireless body area network (WBAN). The cavity mode theory is applied to the design of the DBDMA. The desired dual-broadband and dual-mode characteristics are then achieved by incorporating metallic vias and slots, combining the TM01 and TM02 modes of a circular patch with the TM01, TM10, and TM03 modes of a rectangular one. In addition, the antenna uses the stacked structure and coupled feeding mechanism to acquire dual-broadband and dual-mode characteristics in a single-port configuration. A prototype of the antenna is manufactured and tested. The obtained results demonstrate that the designed antenna has high electrical performance. The measured S11 bandwidths (S11 < -10 dB) are 23.07% and 26.61%, respectively. Moreover, the gain for horizontal omnidirectional radiation in the ON-body mode is -3.82 dBi, while that for directional radiation in the OFF-body mode is 5.07 dBi. The specific absorption rate (SAR) remains less than the international safety standards in the operating frequency bands, which ensures the safety of the antenna in wearable applications. The DBDMA provides an effective dual-mode multi-frequency broadband solution for WBAN communication, which makes it suitable for various wearable applications in medical and health monitoring.