A hybrid GTD/FDTD technique for simulating the coupling between a large phased array and a reflector antenna operating in a shipboard environment

Hybrid methods that combine two or more numerical techniques to solve a complex problem are a natural choice in situations where no one method can handle the problem, accurately and efficiently, in its entirety. Antennas operating in a complex environment, such as the topside of a ship, represent an example of such problems that are very challenging indeed. The structure is obviously very large compared to the wavelengths of the operating radars and communication systems and, hence, ray methods are an obvious choice for analyzing the scattering characteristics of such an object. However, problems of radiation and scattering from phased array antennas with complex elements, or reflectors with complex feeds, are not amenable to attack via ray methods, and it becomes necessary, therefore, to seek alternative schemes that are not only tailored for these antenna problems, but also able to interface seamlessly with the ray codes that handle the topside scattering problem. We describe the hybridization of the conformal finite difference time domain (CFDTD) code with ray tracing, a code developed by the Naval Research Lab (NRL) via the use of an extensible markup language (XML) interface. We show how a large phased array, covered by a radome whose period is not commensurate with the array, is analyzed.