Optically Transparent Patch Antennas Using Saltwater for WLAN Applications

This paper presents the design, fabrication, and measurement of a novel transparent patch antenna using saltwater with high-optical-transparency applications for wireless local area networks (WLANs) at 2.4–2.5 GHz. The most important reason for using saltwater for transparent antenna applications is its superior average optical transparency (OTav >90%) compared to other typical transparent electrodes, such as indium tin oxide (ITO; OTav >80%) or metal-mesh film (MMF; OTav >60%). This study designs three types of antennas: an antenna with a conductive part made of copper sheet (CS) for both the radiator and ground plane (case 1) to compare the performance with two types of proposed transparent antennas that use saltwater as the conductive parts; an antenna with saltwater for the radiator and MMF for the ground plane (case 2); and an antenna with saltwater for both the radiator and ground plane (case 3). The case 1, case 2, and case 3 antennas have peak gains of 6.87, 4.4, and 1.91 dB, respectively, and have corresponding radiation efficiencies of 93.5%, 62%, and 34%. To the best of our knowledge, this is the first demonstration of a transparent patch antenna using saltwater.