Which waveguide antenna is more suited for one-dimensional scanning than scanning in two coordinates?

• A. Ridge guide array
• B. Patch array
• C. Waveguide slot array
• D. Diaphragm array

Answer: (C)

Beam steering with a single axis is easiest when the radiator aperture is effectively a line. A waveguide slot array inherently forms this kind linear aperture: slots cut along the waveguide radiate in a way that a progressive phase shift from slot to slot rotates the main beam in one plane (azimuth or elevation) while the other dimension stays fixed. That makes beam steering along one coordinate straightforward and efficient, with less complexity than trying to span two coordinates from a single-line aperture.

If you tried to do two-coordinate (2D) scanning with this type of structure, you’d need a more complex arrangement—adding a second independent set of phase controls or transitioning to a true two-dimensional slot lattice or another feeding approach—which increases hardware, loss, and cost. The other options either rely on planar or different geometries that are better suited to two-dimensional control, or they don’t naturally provide the simple one-dimensional sweep that a slot-array in a waveguide offers. So the waveguide slot array is the best fit when one-dimensional scanning is the goal.