An experimental and theoretical investigation of beam waveguides at millimeter wavelengths

An experimental and theoretical investigation of wave propagation in a reflecting beam waveguide with two parallel concave reflectors is described. It is shown that the transverse field distribution, for conditions typical of practical applications at millimeter wavelengths, can be represented by that in conventional elliptic waveguides. A unique advantage of this approach is that it is applicable to both confocal and nonconfocal beam waveguides. Special numerical methods used in the theoretical analysis were described and the final results presented include the cutoff wavelengths, the field configurations, and the approximate attenuation constants of TE and TM modes. An experimental investigation was carried out an a beam-guide resonator with two parallel cylindrical reflectors in both confocal and nonconfocal configurations.