Synthesis of radiation patterns for HF mobile communications using the method of characteristic modes

Mobile antenna systems have always presented engineers with a challenge. One particular problematic situation is when the antenna and structure on which it is mounted are comparable in size. Here induced current on the structure may dramatically alter the antenna characteristics. Much effort has therefore been applied, using the method of moments, in the development of modelling techniques for accurate analysis of the problem. An alternative approach is presented using the method of characteristic modes (CM). The technique allows a set of orthogonal functions to be defined from the moment method impedance matrix data to represent the current flow. This permits the antenna and associated structure to be considered as one. Pattern synthesis may hence be achieved by optimizing the modes of the total structure