Optically transparent frequency-agile antenna for X-band applications

The performance of an optically transparent and frequency-agile antenna operating from 8.8 to 9.8 GHz is reported. The transparent square-loop coplanar antenna is made of a mesh silver film printed onto a glass substrate. A high level of transparency (T > 80%) and low sheet resistance (Rs <; 0.2 Ω/sq) are achieved from such a material. Antenna tunability is provided by a surface mounted beam-lead varactor which is invisible to the naked eye. The microwave performance of such an antenna is reported, discussed and compared with that of a reference counterpart made of a continuous silver layer (and thus totally opaque). The optically transparent frequency-agile antenna exhibits gain values ranging from 1 to 3.5 dBi with 10.8% of frequency tunability.