Analyzing Phased Arrays with Basis Functions Associated with Characteristic Modes

The properties of the aggregate basis function associated with characteristic modes (CMBFs) are discussed. The behavior of CMBFs is compared with that of the synthetic basis functions (SBFs). Analysis shows that CMBFs are efficient basis functions for expanding surface currents induced by incident fields but not much efficient for expanding currents by feeding sources. For one element in a phased antenna arrays, it is reasonable to separate its current into two parts: one part caused by the feeding source, and one part caused by mutual couplings. The first part is proportional to the current on the element when it works alone, and the second part can be expanded efficiently with CMBFs/SBFs. Numerical examples demonstrate that the number of unknowns can be significantly reduced with the proposed method.