E-textile microstrip patch antennas for GPS

Body-worn microstrip patch antennas made from e-textile (Electro-Textile) materials were designed, built, and tested for the 1575 MHz (L1) and 1227 MHz (L2) Global Positioning System (GPS) frequencies. E-textiles, including fabrics and foam sheets, are flexible, lightweight, wearable, conformal, and the materials are low cost compared to conventional antenna materials. A variety of materials were tested to determine suitability for e-textile antennas. Gain was measured and found to be a few dB lower than for patch antennas built with conventional copper-clad materials, largely due to higher ohmic losses in the conductive fabrics. Gain was also measured on a human body “phantom” which is a plastic shell filled with fluids formulated to replicate the electromagnetic properties of the body. Use of wearable antennas removes the antenna from the receiver which reduces the size and weight of the receiver, and also allows larger antennas to be used. This effort also helps prepare for possible future applications of multiple wearable antennas such as interference mitigation, anti-spoof, indoor position detection, multiple-input-multiple-output (MIMO) communications, and body-worn antennas for health monitoring or covert communications.