Analysis of coaxial-to-circular waveguide transition

The coaxial-to-circular waveguide transition is analyzed using the Galerkin's method of moments. Because of the axisymmetric structure as well as the assumption of the TEM-mode incident wave, which is an axisymmetric mode, the scattered waves from the discontinuities in the coaxial and circular waveguides can be expressed as axisymmetric modes, and therefore, the analysis can be extremely simplified. The reflection characteristics are calculated as a function of frequency, and excellent agreement with the result presented in the reference literature is confirmed. This technique targets not only the nondestructive inspection of wall thinning and cracks inside conductive pipes but also the slot array antenna in circular waveguides.