Cross-polarization analysis of lossy microstrip resonators

With the increasing applications of microstrip patches in medium- and large-size aperture antenna arrangements, the use of Ludwig´s (1973) first definition becomes arguable. This paper focuses on a comparison between the first and third definition of cross polarization as applied to linearly polarized rectangular microstrip resonators. It is shown that, for a 45-degree skew angle, the third definition leads to higher cross-polarization values than the first one. The spectral domain immittance approach is used to fully predict and simulate the behaviour of the patch. In particular, with suitable modifications, the method is able to include the losses in the analysis and, therefore, provides accurate and reliable results for the complete set of radiation characteristics.