Extraordinary dependences of dispersion characteristics of lossy SiC cylindrical waveguide on the radius

Here we for the first time present the dependencies of the dispersion characteristics of the main mode propagating in a lossy cylindrical waveguide on its radius. The waveguide is made of absorbing microwave silicon carbide (SiC) material. The dispersion characteristics of ceramic SiC waveguide were investigated by the partial area method. The complex roots of the dispersion equation are found by the Muller method. The calculations were fulfilled at the waveguide radii equal to 0.5, 1.0, 1.5, 1.9, 2, 2.1, 2.9, 3, 3.1 mm when the temperatures are 1850°C and 1900°C. We discovered that the dependencies of complex longitudinal propagation constant have an unusual protrusion at some waveguide radii at very higher temperatures. The area of anomaly dispersion shifts to the lower frequencies when the radius increases.