Abstract

Wireless communications technology is one of the most rapidly growing fields. An antenna is a key element that makes wireless communications possible. One of the most popular antennas is the slot antenna which is widely used in many wireless systems. The characteristics of a slot antenna on a perfectly conducting elliptic cylinder coated by nonconfocal materials are investigated theoretically and experimentally. Fields interior and exterior to the slot antenna are found rigorously using the separation of variable technique. The analysis is carried out by expressing the fields in and around the cylinder in terms of Mathieu and modified Mathieu functions. The structure is fed with a line source or a plane wave. The unknown aperture fields on the slot are expressed in terms of Fourier series with unknown expansion coefficients. The expansion coefficients of the interior, aperture and exterior fields are found by enforcing the boundary conditions and employing the addition theorem and orthogonality properties of the Mathieu functions. The general formulations are expressed for the TM case. However, expressions of the eigenfunction expansions for the TE case are given, as well. Furthermore, efficient algorithms for calculating the Mathieu functions are developed using the software package MATLAB. The algorithm developed here for calculating the Mathieu function is compact, fast, and efficient, and compared well with other results in the literature. The exact analytical formulation is used to generate accurate numerical results and studying the effects of different geometrical and materials parameters. Numerical results of the antenna gain, aperture conductance, and aperture voltage (in a receiving mode) are presented and discussed for different design parameters and for both the TM and TE cases. For verification of accuracy and validation of formulations and software program, numerical results for special cases are generated and very good agreement between theory and available data is obtained. The antenna radiation patterns and directivities are computed for different design parameters. The accuracy of the solution is also attested by comparing with HFSS, a commercial CAD package, simulation results. Prototypes of non-coated and dielectric-coated elliptic slot antennas are designed, fabricated, and tested.