Advances in the use of SQUIDs for RF attenuation measurement

The SQUID system for rf attenuation measurement has been advanced by a number of significant changes. A redesign of the L-band SQUID has resulted in a significantly simpler geometry which provides an adjustable coupling for precise matching to the electronics. The redesigned SQUID contains a permanently adjusted point contact in a replaceable cartridge. Attenuation measurement with this system relies heavily on proper signal processing in the room temperature components and a careful study of these conditions indicates a series of areas where error can be generated. These signal handling problems and appropriate solutions are discussed in detail.