Dual-Band Circularly-Polarized Transparent GNSS Antenna for Vehicular Applications

A dual-band circularly-polarized transparent antenna for Global Navigation Satellite System (GNSS) is proposed. The antenna is designed with resonance frequencies centered at 1176 MHz and 1582 MHz, targeting the simultaneous coverage of the L5 and L1 bands. Aiming at integration into the glass sun-roof of a vehicle, the antenna is designed using an unperturbed single-substrate layer, i.e., without any via or probe feed. A fine metal mesh based on printed copper is used to achieve around 90% transparency while maintaining satisfactory antenna gain and radiation efficiency within both operation bands. The phenomenon of frequency shifting observed when converting a solid metal-layer antenna to a metal-mesh antenna is thoroughly analyzed and investigated, to assist in speeding up the antenna optimization. The proposed design is fabricated and measured to validate the design concepts.