In this paper, a general full wave, one and two dimensional, finite difference frequency domain method "1D and 2D FDFD" is presented to analyze different circular guiding structures, such as: coaxial lines, circular waveguides, cylindrical microstrip line and coupled microstrip lines. 1D-2FDFD, 1D-3FDFD and 2D-6FDFD equations are used to get the dispersion curves for these structures. The results which are obtained after solving these FDFD equations come through solving an eigen-value problem, where the obtained eigenvalues and eigen- vectors are used to produce the propagation constants, distribution of the fields and the characteristic impedance for these structures. The FDFD results are compared with those obtained through other analytical and numerical techniques.
