Modeling of the Ring-Hybrid Dipole Antenna and Mutual Coupling in a Small Antenna Array

摘要

This thesis project modeled a microstrip ring-hybrid dipole that is capable of simultaneously producing a sum pattern and difference pattern using the method of moments (MoM) based on the Rao-Wilton-Glisson (RWG) edge elements. The ring- hybrid dipole is simply a ring-hybrid coupler driving a dipole antenna. A two-feed point dipole model was developed and its antenna parameters were found to be a good representation of the ring-hybrid dipole actual values. In the feed network modeling, the matrix solution combined the MoM equations on the antenna surfaces and a magic-tee scattering matrix by applying Kirchhoff's voltage and current laws at the terminals of the antenna, Once the excitation is specified, the complete system of equations was solved to yield the MoM current expansion coefficients and the signals in the feed network. The effect of mutual coupling in an array of three ring-hybrid dipoles was examined by extending the model, In the receive mode, the direction and polarization of the incidence plane wave were varied, The phases for both the sum port and difference port outputs were observed to change smoothly, except during situations of cross polarization and zero phase difference, The array model will ton% the foundation for the design and analysis of a mutual coupling compensation network.