High-Tc rf SQUIDs with Large Flux Focusing

The high-Tc rf SQUID (superconducting quantum interference device) sensor, in which the rf SQUID was placed face to face with superconductor flux concentrator/dielectric resonator, was designed and fabricated. The SQUID sensor was made up of a SQUID washer (with an area of 9.6 mm2 and an inductance of 150 pH) and a flux focusing/dielectric resonator (with an area of 100 mm2 and an resonant frequency varied from 430 to 650 MHz). The author conducted a test to prove that with a white flux noise spectral density of SΦ 1/2=3×10-5Φ0/ Hz1/2 and field sensitivity of BN100 fT/Hz1/2, this flux focusing/dielectric resonator-type rf SQUID sensor can work stably where electromagnetic interference is smaller.