Abstract: The SQUID magnetometer for a device for the single-channel or multi-channel measurement of very weak magnetic fields caused by at least one field source to be detected contains at least two super-conducting gradiometer loops which, with two Josephson tunnel elements form a d-c SQUID. This magnetometer should have high sensitivity with good interference suppression. At least one detection loop and at least one compensation loop are located as the gradiometer loops as well as the Josephson tunnel elements together with superconducting connecting conductors between these parts one behind the other on a three-dimensional surface of a carrier and the mutual distance between the detection loop and the compensation loop is chosen sufficiently large that the magnetic flux, also picked up by the compensation loop of the field source to be detected, amounts to at most 20% of the magnetic flux picked up by the detection loop.

Abstract: A SQUID magnetometer is disclosed which can be fabricated by thin-film technology and used for apparatus for measuring weak magnetic fields. It contains a d-c SQUID with a SQUID loop surrounding the effective area of a coupling hole as well as a superconducting flux transformer with a gradiometer coil and a coupling coil surrounding the coupling hole thereby to achieve an effective inductive coupling of a measuring signal into the SQUID. To this end, the invention provides a separate superconducting surface (3a) with the coupling hole (4), to which the coupling coil (8) and or the SQUID loop (12) is/are assigned. The coupling coil (8) surrounds the SQUID loop (12) while maintaining a sufficient distance (e) for d-c decoupling.

Abstract: For manufacturing a gradiometer having a three-dimensional structure for a device for measuring magnetic fields with field intensities down to below 10.sup.-10 T, the superconducting gradiometer coils are arranged on a support body and are coupled by means of superconducting connecting lines and a coupling coil to a superconducting quantum interference element (SQUID) which is located on a substrate body of its own. These gradiometers should be capable of being linked to the respectively assigned SQUID in a simple manner. For this purpose, the gradiometer coils and at least the associated connecting lines are applied onto a common three-dimensional support body in at least one coating operation which is either preceded by a lithographic process for the fixation of the position of the corresponding conductor runs, or is followed by an etching process.