Miniaturized EBG-backed textile microstrip patch antenna for Bluetooth wearable sensor applications

In this paper, textile microstrip patch antennas are designed and fabricated to operate at 2.45 GHz. One particular prototype has a multi-layer design since it is miniaturized by using an Electromagnetic Bandgap substrate operating in its slow-wave region. To design the patch antenna and EBG structure the dielectric properties of a fleece substrate is measured by utilizing ring resonator characterization method. Subsequently, the in-house fabricated textile patch antennas are employed in a wireless Bluetooth Low Energy (BLE) system for identification and monitoring human vital signs. Using TI's Bluetooth transceiver dongle with a personal laptop computer, and TI CC2540EM and SmartRF05EB boards as a transceiver tag, a communication distance of 17.69m was measured for a mere tag identification. This range is twice of what was obtained with a commercial dipole-type wire antenna. As well, when a vital sign sensor is added to BLE system with textile microstrip patch antenna successful remote measurement of human pulse rate was observed.