Measured performances of coaxial-to-circular waveguide transitions

The reflection and transmission characteristics of coaxial-to-circular waveguide transitions are measured and investigated. Two identical transitions are directly connected so that they faced each other and evaluated using a vector network analyzer. The parameters of this transition are optimized in advance at the 5 GHz band using the method of moments. As a result, good agreement can be confirmed between the calculated and measured results. This transition targets not only the slot array antenna in circular waveguides but also the nondestructive inspection of wall thinning and cracks inside conductive pipes.