Results comparison of microwave lowpass filters three- and one-dimensional modeling

Abstract

In the research and design of microwave devices it is a standard three-dimensional electromagnetic modeling. Three-dimensional modeling greatly enhances the possibilities, but due to the complexity of the model, the connection between construction and its characteristics is largely implicit. As the result the synthesis of construction based on the visibility of the said connection is complicated or even becomes impossible. In this paper it is examined the using of simple one-dimensional model for microstrip lowpass filters by comparing the results of three- and one- dimensional modeling. The results of three- and one-dimensional modeling of the lowpass filters based on traditional microstrip technology and microstrip three-dimensional electromagnetocrystalline inhomogeneities are compared. Two designs of filters are examined: filters based on high and low impedance sections of microstrip line and with capacitive stub. One-dimensional model is a heterogeneous transmission line with equivalent parameters. One-dimensional model allows obtaining analytical expressions for the transmission characteristics of such filters. Three-dimensional modeling is performed in the program package CST Microwave Studio. Calculated transmission characteristics are presented. Features of stubs characteristics are analyzed. The proposed one-dimensional model can be used as a model of the first approximation. One-dimensional model allows separate filter elements (even such complicated as three-dimensional electromagnetocrystalline) characterized by equivalent wave impedance and relative dielectric constant. It is interesting to investigate the possibility of one-dimensional model using for filters with other transmission characteristics.