ures 3 and 4 that the effective dielectric constant approaches Ž . the value q 1 r2 as the parameter pra increases when r 1 the eccentricity approaches 1.
Conclusions
Fast, simple, and accurate closed-form expressions have been derived for calculating the quasistatic line parameters of the Ž . elliptical coplanar waveguide CPW . We have clearly presented the effect of the elliptical curvature on the quasistatic characteristics of the line. Calculated results show that significant curvature effects are observed, especially for small values of the parameter pra . An increase of the angle 1
Ž
. q leads to an increase of the characteristic impedance 1 2 according to the case of a smaller angle. The quasistatic parameters approach those of a corresponding cylindrical CPW as the eccentricity goes to zero because the ellipses degenerate into circles as the focal distance goes to 1. Also, the present results have been compared with the results available in the literature for both the cylindrical CPW and the planar CPW. Furthermore, the present analytic expressions derived in this study can also be used for cylindrical CPW.