ATTENUATION OF MICROWAVE FILTERS FOR SINGLE-ELECTRON TUNNELING EXPERIMENTS

Two types of microwave filters, metallic powder fitters and a tilter u sing a resistive coaxial cable, were tested. Attenuation of the metall ic powder filters using copper or stainless steel (SUS304L) was measur ed at 300 K, 77 K, and 4.2 K, and it was found that SUS304L powder of nominal 30 mu m grain size gives best result as the microwave filter f or single electron tunneling (SET) experiments, Attenuation of a coaxi al filter, or Thermocoax with SMA connectors attached at both ends is larger at low temperatures than that at room temperatures, and the tem perature dependence of the attenuation does not agree with Zorin's mod el, The filter arrangement in our cryostat designed for SET experiment s, is also reported.