Modeling of a cylindrical wire antenna with flat end caps using a rigorousmoment method technique

With recent capabilities for accurately and efficiently modeling electrical ly thicker wire antennas, questions concerning the necessity of including e nd caps in the model have resurfaced. The finite charge on the ends, which can significantly affect the current distribution, as well as improve conve rgence and stability of the solution, has been characterized in the past by several approximate models. However, a more in-depth analysis of a wire an tenna with end caps is necessary for completely characterizing the end char ge density and understanding its effects on the near-field behavior and the current distribution of the wire. Such a treatment is especially important for moderately thick wires or resonant structures. A rigorous method of mo ments formulation is developed in this paper for the analysis of cylindrica l wire antennas with flat end caps. Circumferentially invariant axially dir ected trigonometric current basis functions are assumed on the cylindrical surface, and pulse charge density basis functions are assumed on the end ca ps. In addition, the formulation introduces a ring charge at the outer boun dary of the top and bottom end caps to account for the edge discontinuity. Exact analysis techniques are employed to obtain the solution to the electr ic field integral equation.