Design and optimization of power-divider networks using the finite-difference time-domain method and circuit simulation tools

Power dividers are widely used RF-components, e.g. within phased array antennas. A stable phase and amplitude distribution is necessary for the generation of the desired antenna patterns. Several kinds of transmission lines with their special properties can be used for the power transfer. The design of a large power divider network requires an accurate knowledge of all incorporated structures (including edges, T-junctions, impedance transformers, etc). However, circuit models of discontinuities like edges or T-junctions are only available for a few kinds of transmission lines, e.g. microstrips or striplines. Other types of transmission lines may be more advantageous for reducing the losses and crosstalk, or increasing the mechanical and thermal stability. To model the discontinuities of such transmission lines it is necessary to analyze and optimize their characteristic properties and to extract equivalent circuit parameters. We describe the optimization of transmission line discontinuities by a combination of a 3D-FDTD algorithm with an optimization procedure. After the optimization of discontinuities for a minimal input reflection by changing the geometry, the optimal scattering parameters are extracted and included in a circuit model. In the next step, the entire structure is simulated by a SPICE-type circuit simulation software