In a trough waveguide loaded by equispaced posts on its center fin the phase velocity of the dominant mode can have a phase velocity greater or less than that in frees pace. The radiation from this periodic struct¬ure can be controlled by lowering the sidewall of the trough waveguide until the tops of the posts protrude above it. At any phase velocity close to that of free space, radiation patterns are end fire, with polarization parallel to the center fin.
展开▼
