Surface waves and anomalous wave radiation nulls on phased arrays of TEM waveguides with fences

This paper describes the behavior of an infinite array of parallel plane waveguides in a conducting ground plane with metallic fences perpendicular to the ground plane and spaced halfway between each pair of radiators. The study is mainly concerned with anomalous wave nulls and their relation to endfire surface-wave radiation, and in addition some data is presented to demonstrate the scan matching properties of the fence geometry. An interesting new development in open periodic structure theory is reported and is shown to apply to both surface waves and anomalous waves. Certain restrictions on the phase distributions of the aperture fields and fence currents are revealed and their origin outlined briefly. These restrictions are introduced to further emphasize relationships between surface and anomalous waves. In addition to these basic relationships, a numerical study of the scanning properties of waveguide-fence arrays is presented which has indicated that structures of this type can reduce impedance variation during scan and can be especially useful when it is desirable to scan very near to, or in the limited scan case, beyond the point at which a grating lobe moves into real space.