Transparent microstrip patch antenna based on fluorine-doped tin oxide deposited by spray pyrolysis technique

Transparent microstrip antenna with fluorine-doped tin oxide (FTO or SnO₂:F) patch is studied here. The authors make use of spray pyrolysis technique to deposit FTO transparent patch on a Pyrex glass substrate. The deposited FTO patches show high optical transmittance (about 80-90%) and low electrical surface resistance (as low as 7 Ω/□). Two transparent microstrip patch antennas (with conventional conductor as ground plane), which are fed by proximity coupling at 2.5 and 5 GHz resonance frequencies, are fabricated and their radiation properties are presented and compared with copper patch antenna counterparts. In order to reduce the conductor loss of the antenna and ameliorate antenna efficiency, thick substrates should be used. The 2.5 GHz antenna shows low efficiency and significant loss in transparent layer but the 5 GHz one shows 3.63 dBi maximum gain and only ~0.83 dB degradation in comparison with the copper patch antenna.