Monotonic multi-section tapers for over-moded circular waveguides

The results of a detailed analysis of the propagation of circular electric modes, H0n, is extended, approximated and eventually adapted to the design of monotonic multi-section conical tapers. The formulae and graphs obtained are directly applicable to the calculation of mode conversion loss encountered when two colinear waveguides are connected together by means of a multi-section taper, and the conversion loss is related to the wavelength and the geometry of the structure. The design procedure is illustrated in detail by several numerical examples. It is thereby clearly demonstrated that, for a given mode conversion loss and bandwidth, a considerable reduction in the overall taper length is possible if a multi-section taper of suitable proportions is used in preference to a simple linear taper.