Radiation from modulated surface wave structures - II

Approximate expressions are derived for the electromagnetic fields in a surface wave which propagates along a typical modulated structure - a rectangular slab of uniform thickness, mounted on a perfectly conducting surface, whose dielectric constant and/or permeability vary slowly in a sinusoidal manner along the direction of propagation. Radiation patterns are computed for such a structure of finite length set in an infinite ground plane. In contrast to the endfire pattern obtained from a homogeneous slab, it is possible to obtain a tilted beam from the modulated structure by proper control of the amplitude, wavelength and phase of the structure modulation.