Transparent Antennas for Wireless Systems Based on Patterned Indium Tin Oxide and Flexible Glass

Efficient antennas were achieved at 2.4 GHz and 5.8 GHz in which a transparent conductor, ITO, was deposited on only one side of the glass through sputtering. Antenna structures including grid, loop, and split ring monopoles were also designed and tested. An ITO layer of 650 nm was needed to consistently maintain a sheet resistance of 10 ohms/square or less to reduce antenna losses. A 100 nm aluminum doped silicon dioxide layer was deposited to buffer the ITO from the flexible glass to ensure high conductivity, and photolithography was used to define the antennas followed by an annealing process to improve the ITO conductivity and transparency. A packaging technique using 3D printed frames, Corning® GPPO connectors, and conducting epoxies yielded good antenna performance in terms of radiation efficiency and mismatch loss. Good agreement between simulations and measurements for packaged devices was obtained. Examples of antenna packaging, measurement results, and performance are presented.