Higher Order Modes in Coupled Helices (Correspondence)

The problem of electromagnetic wave propagation in a system consisting of the two infinitely long concentric sheath helices free space, shown in Fig. 1, may be approached as a boundary value problem. This has been done before for the case of the lowest mode, but the determinantal equation which gives the propagation constants the higher order modes has not been given before. This note describes the analysis which gives the propagation constants for all modes of propagation.