Circular Section Metal Wall Cut-Off Wave guide Accurate Calculation when used as a Standard Attenuator

In this paper, the mathematical analysis is carried out from many angles, so that the theoretical calculation problem of the circular metal wall cut-off wave guide used as a premary attenuation standard is completely solved, and the Chinese national standard of the attenuation quantity is established. The benchmark was completed by the Chinese National Institute of Metrology (NIM) with an accuracy of 5×10-5; Reach the international advanced level. The calculation accuracy provided in this paper is 10-6~10-7. This is a good example of a project combining theory and practice.