Measurements of Microstrip Effective Relative Permittivities

This paper presents normalized wide-bandwidth measurements of microstrip effective relative pemrittivities (epsilon_eff) which were made on large-scale microstrip models. The experimental techniques are discussed, and the data are compared to the predictions of two recent closed-form design equations. These results agree favorably with the predictions of Kirschning aud Jansen´s model. In addition, suggestions concerning frequency limitations of microstrip use and comments on the reliability of CAD packages for microstrip circuits are made.