Research on the influence mechanism of variable polarization signals on the adaptive nulling degrees of freedom of multi - element antennas for satellite navigation

To explore the influence mechanism of variable polarization signals on the degrees of freedom of adaptive nulling of multi-element satellite navigation antennas, this paper first establishes a steering vector model from dual-linear polarization signals to circularly polarized array antennas. Based on the idea of the eigen-subspace, the relationship between the eigenvalues of the autocorrelation matrix of the multi-element antenna and the ability to occupy the degrees of freedom for interference is given, and the influence of signal correlation and relative angle on the ability to occupy the degrees of freedom is investigated. Simulation results show that whether the two-component variable polarization signals are uncorrelated or correlated, a single incoming interference can occupy two spatial degrees of freedom of the circularly polarized array antenna, but the influence of D fixed-polarization signals cannot be equivalent to that of D/2 variable polarization signals. By setting up an experimental test environment, the consistency between the actual influence of variable polarization signals and the simulation analysis is further verified. Finally, the research points out that the inconsistency of cross-polarization between array elements and the time-varying polarization characteristics of variable polarization signals together lead to the conclusion that a single incoming variable polarization signal can occupy two degrees of freedom of the adaptive nulling antenna.