  A new operating regime of the Superconducting Quantum Interference Filter
(SQIF) is investigated. The voltage to magnetic field response function, V(H),
is determined by a Fraunhofer dependence of the critical current and magnetic
flux focusing effect in Josephson junctions (F-mode). For SQIF-arrays made of
high-Tc superconducting bicrystal Josephson junctions the F-mode plays a
predominant role in the voltage-field response V(H). The relatively large
superconducting loops of the SQIF are used for inductive coupling to the
external input circuit. It is shown that the output noise of a SQIF-array
measured with a cooled amplifier in the 1-2 GHz range is determined by the
slope of the V(H) characteristic. Power gain and saturation power were
evaluated using low frequency SQIF parameters. Finally, we consider the
influence of the spread in the parameters of Josephson junctions in the
SQIF-array on the V(H) characteristic of the whole structure.
