A planar loop antenna for health monitoring device aimed at body-centric wireless communication applications

Recent wireless technologies in particular the RFID technology has been stimulating significant interest in several applications including in healthcare industries owing to their benefits to human being. The RFID offers a better identification system compared to a barcode scanning system due to its simple contact method to the receiver, its storage media, and good accuracy and reliability. In addition, body-centric wireless communications systems (BWCS) have received a great attention recently since their numerous applications including in combination with low rate wireless personal area (LR-WPAN)/Zigbee technology for medical data monitoring system. This paper presents a design of planar loop antenna for wearable health monitoring device aiming at BWCS applications. According to the calculated link budget, the antenna is set to operate at the center frequency 924 MHz, with the gain more than −35 dBi and wide beamwidth pattern in horizontal-plane. The antenna is put in the vicinity of the human body by about 2-mm from the human body surface. The antenna is numerically analyzed in the proximity to a three-layer phantom model, a voxel human body model and homogeneous muscle-equivalent model. As the result of simulation, the antenna performance shows 1.005 of VSWR, minimum gain by −22.18 dBi on axial-plane and −24.74 dBi on sagittal-plane (0≤El≤180°) at 924 MHz. The measurement is conducted to validate the simulation results by using a muscle-equivalent semi-solid phantom. The measured results tend to show good agreement with the simulation especially in terms of reflection coefficient and radiation pattern.