Abstract
The paper discusses the application of the Characteristic Mode Analysis (CMA) to a number of problems arising in practical antenna applications, and identifies some challenging issues that have been encountered by in the process of applying the CMA to some real-world problems. These include, among others, excitation of the Characteristic modes on complex platforms; antenna placement on these platforms to achieve a desired radiation pattern, specified over a limited angular range; determining excitation coefficients of antennas to achieve interference suppression of unwanted signals. It then goes on to present some systematic approaches to addressing these problems by modifying the conventional Characteristic mode analysis in a suitable manner.