Abstract: A method and apparatus for conducting DC current in the vicinity of a magnetometer without magnetic field interference thereto. The conductor in the area of the magnetometer is in the form of a plurality of twisted line pairs which are braided or otherwise intertwined to form a generally tubular-shaped construct which is preferably cylindrical. First and second equipotential surfaces are provided on each end of the construct with potential differences which are equal and opposite being applied between the first and second pair of surfaces, respectively. A first line of each twisted pair is connected between the first equipotential surfaces and the other line of each twisted pair is connected between the second equipotential surfaces, resulting in substantial equal and opposite DC currents flowing in the lines of each twisted pair. The magnetometer is positioned within the twisted pair construct, preferably near the center thereof.

Abstract: A beam is directed to an interfering source to obtain the best estimate of this signal. The beamformer output is fed into an inverse beamformer in such a way that the total delay experienced by a signal from any element of the array is the same as that of other elements in the array. Each output from the inverse beamformer is a spatially filtered replica of the signal received by the corresponding array element except for a fixed time delay constant for each element. The same delay is imparted in a second channel to each of the array outputs which are substituted from the corresponding inverse beamformer outputs. If the amplitude and delay of each signal to the subtracter are equal, the outputs from each of the subtracters will no longer contain signal components from the direction of the interfering signal.