A Dual-Band, Polarization-Reconfigurable Transparent Antenna for Ground-to-Air V2X Communications

This article proposes a dual-band, polarization-reconfigurable glass-mounted transparent antenna for vehicle-to-everything (V2X) communications. The antenna is etched on a polyester (PET) with a thickness of 0.1 mm using indium-doped tin oxide (ITO) transparent conductive film with a thickness of 0.125 mm, achieving an overall light transmittance of 84.2%. The antenna structure includes two circular monopole patches and a frame surrounding the monopole patches. The circular monopole patches are coupled and fed by T-type feedlines. Four diode switches are soldered onto the ITO surface using conductive silver paste to control the polarization of the antenna. The biasing of the diodes switches the antenna in three different polarization states: linear polarization (LP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). Simulations and measurements of the antenna were conducted on a vehicular glass. The overall size of the antenna is 96.7 x 68.9 mm², with a total thickness of 0.225 mm, an LP matching bandwidth of 2.3–6.5 GHz, and a circular polarization bandwidth of 5.4–6.4 GHz (15%) in the 2.5- and 5.8-GHz dual-frequency operation. Finally, the ground-to-air communication link is studied using the transmission coefficient between the glass-mounted (proposed) antenna and an uncrewed aerial vehicle (UAV) operating with different attitudes. The results indicate link improvements due to the polarization reconfigurability offered by the proposed antenna.