Extremely Low-Profile Antenna for Attachable Bio-Sensors

In this paper, an extremely low-profile patch-type slot antenna for on-body wireless bio-sensor is presented in the medical body area network (MBAN) band. By locating the proposed antenna at the top of the sensor as a sensor cover layer, it is able to maintain compact and flexible sensor structure as well as to enhance its radiation efficiency. The proposed antenna consists of a rectangular loop for balanced feeding and patch with slots for radiating element, and it is designed on flexible printed circuit board (FPCB). To further improve the performance of the antenna with extremely low-profile sensor, air substrate is employed to satisfy the bandwidth, gain, and efficiency requirements. The proposed antenna is measured on a human phantom model with permittivity and conductivity close to those of a human body. From the measured results, it is found that the 3-dB bandwidth of the antenna is sufficient to cover the entire MBAN band (2.36-2.39 GHz) and has a relatively reasonable peak gain of -04 dBi on the human body model.