Modelling cross-polarisation patterns of axially-symmetrical monopulse antennas for cross-polarisation jamming analysis

Abstract

Most radar systems do not consider the situation where the return is dominated by the polarisation orthogonal to the polarisation transmitted by the radar. A cross-polarisation jammer exploits this limitation by transmitting a signal with this orthogonal polarisation to cause an angular error. Mathematical models of crosspolarisation monopulse patterns are derived, and their results are shown to be similar to those of five simulated monopulse antennas and one measured monopulse antenna. The polarisation accuracy of the jammer is shown to play a crucial role, with the jammer needing high polarisation accuracy. The induced angular error increases slowly when the jammer-to-signal ratio (JSR) is between 0 dB and 20 dB and increases faster when the JSR is greater than 20 dB.