Measurements of Microstrip Effective Relative Permittivities

This paper presents normalized wide-bandwidth measurements of microstrip effective relative pemrittivities (epsilon/sub 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.