VERY SIMPLE AND ACCURATE COMPUTER-AIDED-DESIGN (CAD) MODELS DEVELOPED BY GENETIC PROGRAMMING FOR THE QUASI-STATIC ANALYSIS OF UNSHIELDED SUSPENDED AND INVERTED MICROSTRIP LINES

Abstract

Very simple computer-aided-design (CAD) models are introduced to determine the characteristic parameters such as effective permittivities and characteristic impedances of unshielded suspended and inverted microstrip lines. CAD models are determined with the use of the genetic programming (GP). The results of CAD models are compared with the results of quasi-static analysis, experimental works available in the literature and a commercial electromagnetic simulator. The comparison results clearly show that CAD models proposed in this work are in very good agreement with the simulation, theoretical and experimental results for the suspended and inverted microstrip lines. The design parameter ranges in this work are 2 ≤ εr2 ≤ 20, 0.5 ≤ w/b ≤ 10, 0.1 ≤ a/b ≤ 1.5, and the respective characteristic impedances of unshielded suspended and inverted microstrip lines are 28Ω ≤ Z0 ≤ 185Ω, and 24 Ω ≤ Z0 ≤ 159 Ω, respectively. It is observed that the accuracies of CAD models proposed in this paper are good enough for the most practical cases.