A hybrid technique for combining the moment method treatment of wire antennas with the GTD for curved surfaces

This hybrid technique is a method for solving electromagnetic problems in which an antenna is located near a conducting body. The technique accomplishes this by casting the antenna structure in a moment method (MM) format, then modifying that format to account for the effects of the conducting body via the geometrical theory of diffraction (GTD). The technique extends the moment method to handle problems that cannot be solved by GTD or the moment method alone. Wire antennas are analyzed to find their input impedance when they are located near perfectly conducting circular cylinders, although the methods used are not restricted to circular cylinders. Three orthogonal orientations are identified, and antennas to match them are analyzed. For each case, the hybrid solution is checked with one of three independent solutions: an MM-eigenfunction solution, image theory, or experimental measurement. In almost all cases, excellent agreement is obtained due in large part to the fact that the moment method near fields are, for the first time, cast into a ray optical form.