Multi-band L/sub 5/-capable GPS antenna with reduced backlobes

We present a novel multiband antenna design for GPS applications at three different frequencies (L/sub 1/-1575.42MHz, L/sub 2/-1227.60MHz, and L/sub 5/-1176.45MHz). The future GPS system will introduces an L/sub 5/ capability, allowing the possibility of extended services using the new GPS signal. The designed antenna employs the aperture-coupled stacked patch configuration and achieves improved performance in terms of bandwidths, axial ratios, cross-polarization rejection levels and multipath rejection characteristics. To mitigate the multipath interference, a novel structure (vertical choke ring) using multiple metallic disks with center cylinders of different diameters was introduced. The use of the vertical choke ring helps achieve very low backlobes, without the need to increase the diameter of the ground plane, by suppressing the surface waves and the edge diffractions. The designed antenna has been fabricated and tested. The measured performance of the designed antenna is presented in the paper.