9. Other types of metal guides

9.1 Ribbed guides

There are two types of ridged waveguide: single-ribbed (figure 17 a) and double-ribbed (figure 17 b). In the cross-section of the waveguide, the discontinuity caused by the rib results in a capacitive load which, compared with the equivalent rectangular waveguide of dimensions a and b, has the effect of lowering the cut-off frequency of the fundamental mode TE ₁₀ and leaving that of the first higher-order mode...