Efficient current expansion modes for the triarm frequency-selective surface

An isolated symmetric triarm element is analyzed using the singularity expansion method (SEM). SEM poles, modes, and coupling coefficients yield considerable insight into the fundamental scattering characteristics of this element. It is shown that a simple sinusoidal approximation of the SEM current modes represents a highly efficient entire domain current expansion set when used in the usual Floquet moment method description of the triarm frequency-selective surface array.<>