Combination of generalized admittance matrices in the form of pole expansions

This paper describes a novel algorithm for the determination of the wide-ba nd mathematical model of a waveguide component, segmented into elementary b locks of known characteristics. Starting from the Y-matrices of the blocks, given in the form of pole expansions in the frequency domain, the algorith m yields the overall Y-matrix in the same form. Therefore, it can be applie d iteratively to find the pole expansion of the Y-matrix of larger and larg er waveguide structures. The algorithm is particularly useful if the Y-matr ix of the blocks are obtained by the boundary-integral-resonant-mode-expans ion (BI-RME) method, which yields the Y-parameters just in the desired form , Two examples show that the joint use of the BI-RME method and of the algo rithm described in this paper results in a very accurate and fast numerical code, well-suited for the wide-band modeling of complex waveguide structur es.