A system for deriving an electrical representation of an angle, which system includes two coils arranged to have their axes perpendicular to one another and connected to receive alternating excitation voltages which are identical except that the voltage to one coil is shifted in phase by 90.degree. relative to the voltage to the other coil, whereby there is produced a magnetic field which rotates in the plane defined by the coil axes, and a positioning member located in the field and mounted for rotation about an axis perpendicular to the coil axes, the angle to be detected being between one of the coil axes and a reference axis fixed relative to the positioning member and extending perpendicular to the axis of rotation thereof. The positioning member includes a high magnetic permeability rod oriented at an angle to the axis of rotation of the positioning member and the system includes a stationary third coil surrounding the positioning member and oriented so that its axis is parallel to the axis of the positioning member. The rotating magnetic field produced by the two coils is distorted by the rod so that a portion of the field flux passes through the region enclosed by the third coil in a direction normal to the plane of the third coil, and induces in the third coil a voltage whose phase relative to the phase of the voltage in one of the two coils corresponds to the angle between the reference axis and the axis of that one coil.

In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

An angular position sensor comprising a generator coil driven by an oscillator to provide an alternating magnetic field which is symmetrical about an axis, an annular rotor of electrically-conductive or magnetic material such that it distorts the magnetic field around it and arranged so that it is asymmetrical about its axis of rotation and lies outside the equatorial plane of the magnetic field and two sensing coils disposed within the magnetic field. As the rotor 16 rotates about its axis the emfs induced in the sensing coils vary in dependence upon the angular position of the rotor relative to the axis of the undistorted magnetic field.

A first stationary part or component possesses a first conductor arrangement which is coupled in a contactless manner with a second conductor arrangement located upon a second part or component. The second conductor arrangement contains two essentially rotationally symmetrical parts which build-up a toroidal electrical and/or magnetic field. The first conductor arrangement is arranged in the field of the second conductor arrangement. To fabricate the conductor arrangements there can be used existing technology for manufacturing printed-circuit boards. The inventive apparatus can be advantageously used, for instance, in radar installations, vehicles having a rotatable upper portion, such as a turret, turbines, generators and theodolites. The dual conductor arrangement of the inventive apparatus provides a functionally better de-coupling and therefore reduced cross-talk.