We have developed a novel coplanar resonator serving as a tank circuit for radio frequency washer superconducting quantum interference devices (SQUIDs). Two coplanar lines surrounded the circular flux concentrator washer, 13.4 mm in diameter. The SQUID, 3.5 mm in diameter, was coupled to the concentrator in the flip-chip configuration. All parts were fabricated from single-layer epitaxialYBa2Cu3O7films onLaAlO3substrates. In this layout, the resonant frequency could be set between 600 and 850 MHz. With SQUID loops of100×100 &mgr;m2(SQUID) inductanceLs=150 pHor10×500 &mgr;m2(Ls=260 pH),we determined at 77 K white flux noise levelsS&fgr;1/2of1.0×10−5and1.5×10−5&fgr;0/Hz,respectively. Both figures corresponded to the field resolution of about30 fT/Hz.©1997 American Institute of Physics.