Broadband microwave attenuation measurement standard in the frequency range from 10 MHz to 26.5 GHz

A broadband microwave attenuation measurement standard using audio frequency substitution method is described in this paper. The broadband standard includes a single channel and a dual channel system. The single channel system is used to perform accurate attenuation measurement from 10 MHz to 2 GHz. From 2 GHz to 26.5 GHz, the dual channel system is used to reduce the receiver noise and improve the measurement accuracy. Attenuation up to 110 dB can be measured by this standard. The measurement uncertainty of the standard is also analyzed. The expanded measurement uncertainties of a 0.01 dB ~ 110 dB variable attenuator are estimated to be 0.0028 dB ~ 0.028 dB from 10 MHz to 26.5 GHz.