Accurate Computation of Poles of a Lossless Multiport Network via Cepstrum Analysis

In this letter, we present a method to compute accurately the poles of a lossless N -port device for which the reflection and transmission(s) zeros are known. It does not require any particular symmetry of these roots and only assumes the poles are with a negative real part in the complex frequency domain. The basic concept is based on the cepstrum and allows to act on high-degree polynomials, thus being a viable option especially for the design of multiplexers.