Mesh parameters influence on transparent and active antennas performance at microwaves

Optically transparent and active square loop coplanar antennas operating in X-band are investigated in this letter. The frequency tunability is provided by a surface mounted beam-lead varactor with micrometric size, thereby no-visible to the naked eye. The influence of the metal mesh parameters on the sheet resistance (from 0.05 Ω/sq to 0.54 Ω/sq), the optical transparency (from 66% to 89%) and the microwave performance (return loss, resonance frequency, radiation pattern and gain) of such antennas is evaluated, compared with those of an opaque counterpart, and finally discussed. This study paves the way of their promising implementation on new surfaces, namely building and car windows for future wireless communications systems.