Equivalent Mode Representation as the Basis for the Analysis and Synthesis of Symmetric Microwave Networks

Abstract

Symmetrical reactive bipolar networks, which include microwave filters, constitute the most commonly used class of passive electrical circuits in practice. This chapter develops analytical models of these circuits in relation to their implementation on the basis of multi-wire systems of coupled microstrip lines. Such systems are characterized by the inequality of the residue mode phase velocities, which is due to the inhomogeneity of the substrate-air medium. The substitution networks for this type of symmetric network are defined as an equivalent mode representation, which forms the basis for the analysis and synthesis of high-selective filters. The operating principle of these filters is built upon the inequality effect of residue modes phase velocities. The relationship between the amplitude-frequency response and the group delay time of symmetric networks of both minimum phase and non-minimum phase types has been revealed.

Keywords: Dielectric substrate, Electromagnetic waves, Frequency response, High-selective filter, Microwave network, Microstrip line, Microwave range, Phase velocity, Symmetrical structures.