Multilayer Flexible Substrate Antenna for Smart Wearable Electronics

This paper focuses on designing a wideband flexible antenna for smart wearable electronics, operating in the 2.45 GHz ISM band. A novel multi-layer substrate technique is used to design a micro-strip rectangular patch antenna of height 4 mm with flexible substrate materials. Teflon and foam having dielectric constant (εr) values of 2.1 and 1.07, respectively, are two flexible materials used in this work. The multi-layering technique is used in three different configurations, viz., single-layer, double-layer, and three-layer substrates using Teflon and foam with varying thicknesses. The antennas designed in all three configurations are simulated using ANSYS HFSS electromagnetic simulation software, and a comparative analysis is tabulated. It is established from the simulated results that the bandwidth increases with each successive dielectric layer, keeping antenna height constant. Therefore, a three-layered substrate antenna having thicknesses of 0.5 mm, 1.25 mm, and 2.25 mm at the first, second, and third layers, respectively, has achieved the highest bandwidth and is selected for fabrication and testing. The Anritsu MS46322A 20 GHz Vector Network Analyzer is further used to test the fabricated antenna, and the measured results are then compared with the simulated ones. The three-layered fabricated antenna resonates at 2.45 GHz and measures the bandwidth of 104 MHz at -14.37 dB.