An L-slot Compact Antenna for Medical, Wearable Device and IoT Applications

A compact size of $25.83 \times 21.7\ \text{mm}^{2}$ L-slot-based compact microstrip patch antenna has been proposed for a wearable device, medical and Internet of Things (IoT) applications. A top patch with one L-form slot, two strip shape slots, and three edge cuts consists of the proposed antenna. The designed antenna radiates at 2.4, 3.9, and 5.7 GHz, covering the 2.4/5.7 GHz ISM (Industrial Scientific Medical) band, WLAN (Wireless Local Area Network) band. The proposed antenna return loss is less than −10 dB across all radiating frequencies, and results show overall good efficiency and gain over the operating band. An extensive Specific Absorption Rate (SAR) simulation has been carried out by using the human head 3D model to evaluate SAR (W/kg) level. The results are promising, below the United States and European Union maximum SAR (W/kg) rating and safe to use for medical and wearable applications. The proposed multi- band wearable antenna has been fabricated using the LPKF protomat machine and tested by a Vector Network Analyzer (VNA). The antenna measurement results showed good agreement with the simulation results and are ready for practical implementation.