In this article we propose an efficient method for analysis of microstrip Rotman lens using two-dimensional finite difference time domain (2D-FDTD). Both the dielectric and conductor losses are modeled in this method in order to achieve results which are in good agreement with 3D simulation. Using 2D analysis, the required simulation time is reduced considerably, which in turn, enables us to use the proposed analysis method in an optimization procedure. Based on this optimization procedure, we present an improved design of a microstrip Rotman lens in which both the efficiency and also the gain of isotropic antenna array are increased. In this design, the Rotmanl ens has 5 beam ports and 16 array ports and operates in Ku frequency band.

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