Transparent Wideband Circularly Polarized GNSS Antenna for Vehicular Applications

In this paper, a single-layer one-sided wideband coplanar waveguide (CPW)-fed transparent circularly polarized (CP) rectangular slot antenna with tilted beam is proposed. The antenna is designed on a glass substrate with a mesh grid in the conductive layer in order to increase the transparency. Since most of the vehicles’ windshields are inclined for about 30 degrees, the beam of the antenna is designed to be tilted for about 30 degrees in elevation. For measurement verification, an inclined stage is fabricated to resemble the inclined surfaces (such as the windshields). The 10-dB impedance bandwidth of the antenna is 40.8% (1.13 - 1.71 GHz) with a 3-dB axial ratio bandwidth of 47.4% (1.06 - 1.72 GHz) and a 3-dB gain bandwidth of about 54% (1.02 - 1.78 GHz) with a maximum right handed circular polarization (RHCP) gain of 5.3 dBic. Also, the transparency of the antenna is about 95%. Therefore, the antenna is a good candidate for vehicular applications such as location tracking, using global navigation satellite system (GNSS) and specifically global positioning systems (GPS). Furthermore, a small-size transparent reflector is designed to be used below the proposed antenna in order to increase the front to back ratio (FBR).