Method to measure the Stokes parameters of GPS signals

As Global Positioning System (GPS) signals travel to the ground, they are affected by the medium through which they propagate. Consequently, measurements of signal amplitude and phase are used in a variety of remote sensing applications. A limitation of current receiver systems is that they do not measure polarization. While GPS signals are transmitted with right-hand circular polarization, the same cannot necessarily be said for the signal reaching the antenna, and this difference will contain further information about the propagation path. This paper describes a method for combining two GPS receivers into a device that is capable of measuring the Stokes parameters of the signal. A mathematical procedure for converting the receiver data into the Stokes parameters is derived, and the results of proof-of-concept experiments are presented.