A Cole-Cole Diagram Representation of Microstrip Structure

Abstract

A method for analyzing the performance of a microstrip line using the concept of Cole-Cole diagram, is proposed. Analogous to dieletric relaxation considerations of Cole-Cole diagrams as applied to dieletric materials, a "reactive relaxation" concept is introduced to represent the frequency-dependent characteristics of a microstrip. Also, included in the algorithm are relevant considerations pertinent to the substrate dieletric and strip-line conductor losses. The dynamic permittivity of the microstrip structure (deduced via Cole-Cole diagram) leads to a convenient and modified Smith-chart representation that includes the frequency-dependent influence of the fringing field and the lossy characteristics of the line cohesively. The efficacy of the model is illustrated with an example concerning a microstrip patch antenna in ISM band. Relevant algorithms are useful in computer-aided designs (CADs).