Development of an analysis method and its simulation tool for microstrip-type microwave integrated circuit elements

A simulation tool for analyzing circuit characteristics of microstrip-type MIC (Microwave Integrated Circuit) passive elements is presented. The major part of this tool is the electromagnetic wave analysis based on the FD-TD (Finite-Difference Time-Domain) method combined with the mode expansion the ory. Although the element structures which can br treated in this tool are limited to only less than ten fundamental structures in tile present stage, its extension to the more versatile tool applicable to other various eleme nt types is rather straight forward and simple in principle. When using thi s tool, we first choose the element configuration to be calculated and give , oil a panel, necessary parameter values related to calculation range and mesh division scheme. Given these values, the first step calculation starts to obtain the characteristic impedance, cross sectional field distribution of the propagating mode, etc. of the basic microstrip line. Field distribu tions around the element configuration are calculated next with the mode fi eld oscillation being given. Through this process the field distributions o n a closed rectangular parallelepiped surface enclosing the element configu ration are stored in files, from which S parameter and radiated fields are calculated by invoking the reaction integral with propagation modes and rad iation modes, respectively. The results obtained in these three steps can b e expressed, at our discretion, as line drawings or two-dimensional density plots.