A Metasurfaced Circularly-Polarized Antenna for Electronic Toll Collection System

In this paper, a metasurfaced circularly-polarized (CP) antenna with a double-layer structure is proposed for the electronic toll collection (ETC) system. The antenna composed of dual layer of printed circuit board (PCB) with an overall height of 6 mm. The top-layer (Layer 2) is a metasurface that made with 4×4 unit-cells of chamfered square patches. The driven patch is printed with a U-slot at the bottom layer (Layer 1). The addition of metasurface helps to achieve narrow beam width with a high gain. The simulation results demonstrate that the proposed metasurfaced CP antenna exhibits a mandated right-hand narrow beamwidth in the desired ETC frequency band, whereas its broadside gain is obtained greater than 6.5 dBic. In addition, both the achieved impedance bandwidth and axial ratio bandwidth are sufficient to cover the entire ETC band (5.75 GHz-5.9 GHz).