| As with all wireless devices, satellite navigation receivers are subject to signal attenuation, interference, and multi-path reflections. Of these, multi-path is the most pernicious source of system degradation because its effects are subtle rather than obvious. Multi-path reflections result in position estimate biases on the order of the added signal propagation path length. The best way to mitigate multi-path distortion is to address it at the point of entry into the receiver system: at the antenna. In this work we show that an antenna with a received polarization pattern which is well matched to the signals transmitted from the satellite network is the best approach to multi-path mitigation. It is shown that an antenna which discriminates left from right handed polarization in radio signals, arriving from all angles, can not be realized with a strictly two dimensional structure. Helical antenna elements are simulated to achieve the best polarization discrimination. In addition, simple array configurations are evaluated to realize the best directional diversity in order to identify and remove sources of interference and multi-path. The importance of receiver orientation and attitude determination is discussed as an avenue of further research into system improvements. |
