Theoretical Analysis Of Cross-Polarization Radiation Property Of Longitudinal Slots In Rectangular Waveguide

The cross-polarization radiation property is an important parameter that characterizes antenna performance. Since the cross-polarized interference signal cannot be effectively suppressed through ordinary antenna array design and signal processing techniques, the cross-polarization property of antennae has become one of the key factors that restrict the improvement in anti-jamming performance of antenna array and has been a hot topic in antenna array design and signal processing areas.With extremely low cross-polarization level, the waveguide longitudinal slot antennae have found numerous applications in suppressing cross-polarization interference. Since the slot parameters may vary through the manufacturing process, it is important to give accurate analysis on the impact of these parameter variations on the cross-polarization radiation property. So far, however, no specific research upon cross-polarization radiation property of waveguide longitudinal slots has been released to the author's knowledge. Since the cross-polarized radiation of a slot antenna is about two orders lower than the co-polarized one, the research on such a minor cannot be conducted via simulations by ordinary commercial electromagnetic software because the result is highly unreliable, and a specific mathematical model has to be built to solve the problem.This thesis employs the method of moments (MoM) to set up the mathematical model that can be applied to the investigation of far-field radiation properties of longitudinal slot antenna element and array in rectangular waveguide. The relevant equations are obtained by imposing the continuity of tangential H fields at the slot interface. By employing the relevant components of dyadic green's functions, the co- and cross-polarized equivalent magnetic current at the slot interface are included as the variable in the integration equation (IE). Then the model is built by solving the IE using MoM, and the far-field co- and cross-polarization radiation properties can be achieved after the slot fields are ascertained.Utilizing the above model, the co- and cross-polarization radiation properties of waveguide slot antenna in the normal direction are accurately characterized, while the impact of the antenna structure parameters as well as operating frequency on the radiation properties of longitudinal slot antenna element and array in rectangular waveguide are summarized which coincide well with the theoretical analysis results. The obtained model and trends provide an important guide rule for the design of slot antenna arrays. On the other hand, through the validation of the convergence of matrix elements, the correctness of analyze method and the liability of obtained mathematical model are further proved.