Higher ORDER MODE ANALYSIS USING FINITE DIFFERENCE Coaxial waveguides and the determination of their cutoff frequencies have been discussed by Marcuvitz . This involves finding zeros of a function that involve products of Bessel functions of 1 st kind and 2 nd kind for TM modes and products of derivatives of Bessel functions of 1 st kind and 2 nd kind for TE modes. These zeros pertain to a certain order and need a number of iterations to be performed to obtain a set of cutoff wavenumbers. Finite difference methods in the conventional form have been applied t0 a variety of cross sections. However, the same technique involving the formation of rectangular meshes to a circular coaxial waveguide does not seem to be appealing in context with the selection of truncation boundaries and appropriate adjacent node points for the region between the inner and outer conductors. The increase in the number of spurious modes generated and the decrease in accuracy are al...