An alternative expression for the curvature loss of a dielectric waveguide and its application to the rectangular dielectric channel

Abstract

An alternative expression for the radiative attenuation coefficient of a surface wave propagating along a curved dielectric waveguide of arbitrary cross section is derived, which contains integrals of the fields inside the guide rather than those outside, as in previous formulas. This is especially suitable for application to guides for which the exterior fields are not known accurately, but reasonable approximations exist for the internal fields. As an example the expression is applied to the case of a rectangular dielectric channel waveguide, and a comparison made with a previous result of Marcatili.