Comment on "On the Design of Dielectric Loaded Waveguides" [Letters]

In the above paper, the authors show that, by loading a rectangular waveguide with an E-plane dielectric slab, its theoretical power-handling capacity can be significantly increased. Their conclusion may come as a surprise to experimenters designing high-power E-plane devices such as ferrite isolators or phase shifters. It is a well-known fact that such structures tend to exhibit breakdown at power levels well below those of the empty waveguide.