Large Effective Area High T-C Rf Squid

We have designed and fabricated a new type of high T-c if SQUID sensor. A high T-c coplanar superconducting resonator and a large area high T-c superconducting film concentrator have been used simultaneously. With a large effective area and low white flux noise, we have achieved a flux noise of 2.1 x 10(-5) phi(0)/ rootHz and a magnetic field sensitivity of 34fT/ rootHz in white noise range, respectively, using an effective area of 1.27 mm(2) concentrator on a 15 mm x 15 mm substrate. This design can be easily applied to higher frequency high T-c rf SQUID system.