RF COMPONENTS USING OVER-MODED RECTANGULAR WAVEGUIDES FOR THE NEXT LINEAR COLLIDER MULTI-MODED DELAY Line RF DISTRIBUTION SYSTEM

We present the design and analysis for a set of smooth transitions from rectangular to circular waveguide that preserves their common reflection symmetries. The Smatrix of the transition connects modes of the same symmetry class, and for a sufficiently adiabatic transition preserves their TE (or TM) character. It is then also nonreflecting and, in the absence of degeneracy, its modal connections are one to one and order preserving. This property enables us to carry out all of the RF manipulations in the more easily handled over-moded rectangular waveguide.