A NEW APPROACH FOR ANALYSIS OF RESONANT STRUCTURES BASED ON THE SPATIAL FINITE-DIFFERENCE AND TEMPORAL DIFFERENTIAL FORMULATION

This paper presents a new procedure for analyzing resonant structures using the spatial finite-difference and temporal differential formulat ion. Unlike the conventional finite-difference time-domain methods, th e finite-difference are only enforced in the spatial domain for Maxwel l's equations, The time-domain differentials of Maxwell's equations ar e kept, resulting in a system of first-order differential equations, I n consequence, a resonant structure problem can be formulated in the e igenvalue problem form and resonant modes are obtained by solving the corresponding eigenvalue problem directly, It is shown that the coeffi cients of the matrix for the eigenvalue problem can be simply obtained from the finite-difference time-domain formulation. As a result, an e fficient alternative way of using the finite-difference time-domain ap proach to solve the resonant structure problems is presented. The algo rithm is applied to metallic waveguide structures and the numerical re sults agree well with those from other techniques.