Rotman lens simulation using the finite element domain decomposition method

There has been an increased interest recently in the Rotman lens as a feed structure for phased array. These antennas/feed structures need to be easy to implement, be cost effective, provide for rapid beam scan across wide angles and be reliable in a sometimes harsh environment. The Rotman lens meets these requirements. Special purpose codes have been written to analyze a limited set of lens implementations and they are very efficient (Singhal, P.K. et al., 1998), but they are not general enough to analyze such electrically large devices in their many possible configurations. For a complete model with tight accuracy requirements, the number of unknowns would increase significantly and a different approach may be more effective. We believe that the domain decomposition method (DDM) may be such an approach. We discuss the basics of this procedure, how it is used to analyze a Rotman lens and conclude with a simplified lens example.