A note on the radiation characteristics and forced surface wave phenomena in triangular-grid circular waveguide phased arrays

Forced surface wave resonances are shown to occur in dielectric-free 45-degree triangular-grid circular waveguide phased arrays. Similar surface wave phenomena were observed in an identical grid array of rectangular waveguides in the
H
-plane of scan. In the circular waveguide array, however, the resonance is observed in the
E
-plane and is shown to be an isolated point. This isolation is further illustrated by observing certain vector symmetries in the radiation patterns.