Superstrate (cover) dielectric or magnetic layers are often used to protect low profile conformal antennas, such as cavity backed antennas from environmental hazards. In loony cases these covers are naturally formed; e.g., ice layers during the flight or severe weather conditions. Whether the cover layer is naturally formed or imposed by design, it may affect the antenna basic performance characteristics, suds as gain, radiation resistance and efficiency. Moreover, the cover layers provide an additional degree of freedom for the antenna designer to optimize the overall antenna performance. The fundamental superstrate effect on printed antennas was first discussed in. In these papers, the superotrate effects on input impedance, gaits and efficiency are examined in detail only for electric current excitations. On the other hood, cavity barked slots are the dual problems where the excitation is an equivalent magnetic current. Cavity-harked slot/patch antennas with dielectric and magnetic overlays have also beets discussed by Biebl and Lee. Although these methods were rigorous, they were able to analyze only narrow slots residing in homogeneous rectangular cavities. On the other hand, in this paper, the hybrid FEM/MoM is been used to handle any aperture configuration backed by arbitrary shaped and filled (with general anicotropic material) cavities with multilayered dielectric/magnetic superstrates. In the cavity region the vector FEM is used to compote for the electric field, while the combination of Spectral/Spatial Domain MoM is used to compute the field in the exterior layered region. To demonstrate the accuracy of the method two cases will be analyzed and compared with other methods and measurements.
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