A folded slot antenna with full ground plane for wearable waterproof wireless sensors

摘要

A 3D dual band slot antenna is presented for waterproof wearable wireless sensors. The size of the antenna is 52mm × 36mm × 12mm and the slot is etched on the internal walls of a waterproof plastic box which accommodates the sensor electronics. Numerical modeling of the structure against the body revealed a 10 dB impedance bandwidth of 12.3% at 2.45 GHz and 21% at 5.2 GHz respectively. The antenna features a full ground plane underneath which reduces the interaction between the human body and the radiator and so avoids the huge drop in antenna efficiency. The total efficiency of antenna is more than 90% in free space and reduces to 54% at 2.45 GHz and 70% at 5 GHz when located against the body.