Low-cost dual polarized GPS antenna for effective signal acquisition in multipath environment

There has been increasing demand for precise positioning from Global Positioning System (GPS) satellites, particularly in fading environments that are challenging for the autonomous and semi-autonomous vehicle. GPS signals are right hand circularly polarized (RHCP) however, in dense multipath environments the polarization of a GPS signal may change to become left hand circularly polarized (LHCP). Conventional GPS receivers use RHCP antenna, which reject LHCP signals, and parallel searching acquisition methods that are not sensitive to the resulting weak signals. In vehicular communications, urban environments is a source multipath and weak signals that can lead to GPS lock loss, but obtaining consistent positioning information in urban environments is crucial for vehicular communication. In this paper, we propose a very low-cost dual polarization patch antenna for LHCP GPS signals, but due to the weak signal strength from reflected signals we also propose a modified serial searching acquisition method using a software-based GPS receiver. The experimental results show that using this method we were able to acquire additional satellites that could be used to compensate for the loss of RHCP signals in multipath environments.