Modal propagation in ideal soft and hard waveguides

This paper presents an investigation on the modal wave propagation in circular and rectangular waveguides with perfectly soft and hard boundary conditions on the walls. For the case of soft rectangular waveguides, the solution cannot be derived in analytical form, thus requiring a numerical analysis. A knowledge of the field distribution associated with perfectly hard or soft waveguide modes, through a schematization of the reality, may help the design of corrugated horns or quasi-TEM waveguides, and to find new uses for soft and hard surfaces.