Modal cutoff in coaxial transmission lines of conical and cylindrical geometries

We present numerical data on normalized cutoff wavelength versus cone half-angle for the first three higher-order TE/sub m1/ modes, as well as four other modes of interest, in conical coaxial transmission lines (the "co-conical" line). These are given as a function of the ratio of outer-to-inner cone half-angles (proportional to line impedance) for outer cone half-angles of 10 and 22.5 degrees. Results were compared to those for the coaxial transmission line of cylindrical geometry and found to be qualitatively similar.