Wave propagation in chiral guides

Summary form only given. An original approach is proposed to the analysis of chiral waveguides. Two types of chiral waveguides are considered: a wire helix with arbitrary ratio of the helix diameter to the helix period and the wire diameter and a cylindrical metal waveguide with the walls corrugated along helical lines. A conventional analysis of wave propagation in helices is restricted to the case of sheath helices or helices made of infinitely thin wires. However, the wire diameter in real helices may be of the same order of magnitude as the helix diameter; it may even exceed the inner diameter of the helix. Under these conditions, one can hardly apply the model of sheath helices. We apply the summation theorem to the analysis of propagation of electromagnetic waves along helices. Our approach is based on the assumption that the cross section of the wire by a plane perpendicular to the helix axis is circular. In the general case, this is a rather strict restriction. However, when we deal with sufficiently stretched helices, which is the case when the pitch angle of the helix is greater or equal to 45 degrees, the assumption above seems to be fairly acceptable. Regarding the second type of chiral waveguides, namely, the cylindrical metal waveguides with helically corrugated walls, the method developed proves to provide an excellent model for the rigorous analysis of the wave propagation in these waveguides. For this purpose, one should make only slight modifications in analytic formulas and replace the geometrical parameters of the helix by the appropriate ones of the corrugated waveguide.