A Huygens Source Quasi-End-Fire Button Antenna

Obtaining end-fire patterns is a serious challenge to antenna design in wearable applications, especially for unobtrusive antenna configurations integrated in clothing accessories such as buttons. Herein we propose a button antenna to serve Wireless Body Area Networks (WBAN) and apply the principle of Huygens source to produce the desired end-fire patterns. To this end, the antenna ground plane is exploited to construct a magnetic current loop which is a radiation component of the realized Huygens source. Experimental validation of a prototype suggests that this button antenna is capable of partially covering the Unlicensed National Information Infrastructure (U-NII) band. Moreover, a good agreement between pattern simulation and measurement validates the expected quasi-end-fire patterns in free-space and in on-phantom scenarios.