Abstract: A high sensitivity magnetic anomaly detector for geomagnetic exploration comprises a shorted coaxial transmission line having as central conductor an amorphous magnetic wire. A static magnetic field is applied along the transmission line. A transverse electromagnetic wave also propagates along the transmission line and excites a ferromagnetic resonance of the magnetic ions located within the depth of penetration of the circumferential microwave magnetic field into the magnetic wire. The microwave giant magnetoimpedance effect occurring in the magnetic wire changes the magnetic wire impedance as follows: the real part of the impedance peaks and the imaginary part passes through zero at a given frequency (the ferromagnetic resonance frequency). This frequency depends on the saturation magnetization of the magnetic wire and the strength of the static magnetic field.

Abstract: A high sensitivity magnetic anomaly detector for geomagnetic exploration comprises a shorted coaxial transmission line having as central conductor an amorphous magnetic wire. A static magnetic field is applied along the transmission line. A transverse electromagnetic wave also propagates along the transmission line and excites a ferromagnetic resonance of the magnetic ions located within the depth of penetration of the circumferential microwave magnetic field into the magnetic wire. The microwave giant magnetoimpedance effect occurring in the magnetic wire changes the magnetic wire impedance as follows: the real part of the impedance peaks and the imaginary part passes through zero at a given frequency (the ferromagnetic resonance frequency). This frequency depends on the saturation magnetization of the magnetic wire and the strength of the static magnetic field.

Abstract: A high sensitivity magnetic field sensor is described. The sensing element is a stress-sensitive, negative-magnetostriction, melt-extracted amorphous wire, in which a strong magneto-impendance effect develops when the wire is connected to conventional electronic circuitry, which can be an impedance-meter. An a.c. current is provided to the wire and its relative change in impedance is measured. Simultaneously, the wire is submitted to a longitudinal d.c. magnetic field, H. A saturating d.c. field pulse is also applied to this wire at the beginning of the operating cycle. Tensile stress is further generated in the wire by pulling one end of the wire with a given force. This stress can be fine-tuned for sensitivity and bias with the help of a suitable mechanism. All these elements are packaged in a rugged non-magnetic enclosure, which permits easy and reliable connection of the sensor to said conventional electronic circuitry.

Abstract: A high sensitivity magnetic field sensor is described. The sensing element is a stress-sensitive, negative-magnetostriction, melt-extracted amorphous wire, in which a strong magneto-impendance effect develops when the wire is connected to conventional electronic circuitry, which can be an impedance-meter. An a.c. current is provided to the wire and its relative change in impedance is measured. Simultaneously, the wire is submitted to a longitudinal d.c. magnetic field, H. A saturating d.c. field pulse is also applied to this wire at the beginning of the operating cycle. Tensile stress is further generated in the wire by pulling one end of the wire with a given force. This stress can be fine-tuned for sensitivity and bias with the help of a suitable mechanism. All these elements are packaged in a rugged non-magnetic enclosure, which permits easy and reliable connection of the sensor to said conventional electronic circuitry.