A Low-Profile Fully-Fabric High Isolation Dual-Port MIMO Antenna For UWB Wearable Applications

Abstract

A compact, 2-port Multiple-Input-Multiple-Output (MIMO) antenna that is entirely made of textile is proposed for Ultra-Wide-Band (UWB) wearable applications. The conductive parts of the MIMO antenna are made of ShieldIt with a conductivity of 1.8 × 105 S/m and thickness of 0.17 mm. The MIMO antenna is mounted on a 1.5 mm thick Felt substrate. The designed MIMO antenna has a compact size of 30 mm × 45 mm and operates over the UWB frequency band ranging from 3.1 GHz to 10.6 GHz. It displayed an average radiation efficiency of 85.5% and a peak gain of 5 dBi within the UWB spectrum. To reduce the mutual coupling between the antenna elements, two approaches are applied. Orienting one radiator by 180° with respect to the other and adding a parasitic structure in-between the 2 radiators led to achieving a high isolation amongst the antennas. This is inspected through analyzing the achieved outcomes of S21 < −25 dB, very low Envelope Correlation Coefficient (ECC) < 0.001, high Diversity Gain (DG) > 9.995 dB, and low Channel Capacity Loss (CCL) < 0.2bits/s/Hz throughout the UWB spectrum. Furthermore, the Specific Absorption Rate (SAR) is lower than 1.6 W/kg, averaged over 1g of tissue, at various frequencies. Finally, the MIMO antenna was manually fabricated, where the tested outcomes matched with the simulated ones. Compared to the published work, the proposed antenna has a compact size, high radiation efficiency, has a bendable platform and achieves very competitive MIMO parameter. Therefore, the proposed MIMO antenna can be highly suggested for UWB wearable applications.