Fast method for calculation of mutual coupling in planar microwave circuits on general multilayer substrates

Abstract

In this article a new fast method for the calculation of mutual coupling in planar microwave circuits is described. The circuit is divided into three component classes: lines, small discontinuities and larger, meshed, structures. Modules are proposed to calculate the intra-and inter class couplings. The first two models take full advantage of the specific properties of lines and small discontinuities to speed up calculations. For lines, this means using the traveling waves and for small discontinuities the radiation behavior is approximated by that of an elementary dipole. The third module is the regular method of moments (MoM), which has been altered in such a way that solving the integral equation matrix immediately yields the S-parameters on the lines that feed the structure. The new method uses far less unknowns and needs far less CPU time than the traditional MoM. The advantage over other circuit simulators such as Advanced Design System (ADS) and Microwave Design System (MDS) is that the new method includes the parasitical coupling effects in the entire circuit that are ignored in these commercial packages. These parasitical couplings can sometimes have a large effect upon the circuit.

Modeling of mutual coupling of arbitrary order in coupled circuits and array antennas

“…Based on our assumption, the parametric values in Figure 6a are the same as those in Figure 6b except for the unknown terms of the second-order mutual coupling. As Figure 6b does not include the effect of second-order mutual coupling, the equivalent circuit network of the second-order mutual coupling can simply be calculated from the difference of Y (2) and Y 0(2) through the standard network theorem. The self-admittance of second-order mutual coupling indicates the second-order mutual coupling effect on the self-admittance of each element.…”

“…The admittance matrix of this two-port network is designated as Y (2) . For extracting the equivalent circuit model of a second-order mutual coupling, we build up a cascaded equivalent circuit network with self-admittances of three elements and two first-order mutual coupling networks on the basis of the previous extraction results.…”

“…Equivalent source method has been used for calculating the mutual coupling between discontinuities in planar circuits [1][2][3]. When it comes to a large but finite-extent antenna array, there are two main methods for modeling mutual coupling, namely the spatial domain (element-byelement) method and the spectral domain (periodic cell) method [4].…”