Ridge Waveguide Interpretation A ridge waveguide can be viewed, in first order, as which kind of modified waveguide?

Introduction / Context:
Ridge waveguides introduce one or more conductive ridges into a rectangular waveguide. This structural change alters the field distribution and cutoff frequency, enabling broader bandwidth or smaller cross-sections for a given operating band.

Given Data / Assumptions:

• Air-filled metallic waveguide with one or two ridges attached to the broad wall(s).
• Dominant mode under consideration (usually TE10).
• Losses are not the main focus here; the qualitative loading effect is.

Concept / Approach:

The ridges effectively increase the electric-field concentration between the ridge tips and the opposing wall. This action increases the effective capacitance between the broad walls, lowering the dominant-mode cutoff frequency. Describing the structure as “capacitively loaded” captures this first-order effect on the modal dispersion.

Step-by-Step Solution:

Verification / Alternative check:

Cutoff formulas and mode charts for ridge guides show reduced cutoff compared to smooth guides of the same external dimensions, confirming the capacitive-loading viewpoint.

Why Other Options Are Wrong:

Inductive loading (A) would require inserts that increase magnetic path rather than electric-field concentration; (C) refers to dielectric loading, a different technique; (D) and (E) are irrelevant to standard microwave guides.

Common Pitfalls:

Equating “lower cutoff” with lower loss; ridge guides usually have higher conductor loss near ridge edges.

Final Answer:

capacitively loaded guide