International comparison GT-RF 78-1: high attenuation (60 dB, 100 dB) at 30 MHz in 50 Ω coaxial line

A worldwide comparison of national standard devices in which high attenuation values (up to 100 dB) at the frequency of 30 MHz have been compared is reported. Eleven national laboratories of metrology from the Netherlands, France, Italy, the United Kingdom, Sweden, Poland, Hungary, Australia, the People´s Republic of China, the USSR, and the Federal Republic of Germany participated. The transfer standards were two fixed attenuators with an attenuation of about 60 dB and 100 dB and one switchable attenuator with 100 dB. The maximum difference between any two results is 0.064 dB at an attenuation of 60 dB and 0.125 at 100 dB. For a considerable number of laboratories, the deviation between mean values was not larger than 0.001 dB for a 60-dB attenuation step, and not larger than 0.005 dB for a 100-dB attenuation step