Simple, low-noise uhf SQUID magnetometer

Abstract
We describe the development of a simple, rugged, low‐noise SQUID magnetometer, biased in the uhf range, and constructed around the extensively used two‐hole SQUID ring. This design is novel, both in the manner in which rf is coupled to the SQUID ring, and in the ability of the magnetometer system to couple strongly to an external signal or a flux transformer cell.