Abstract: The invention concerns a maser having an electromagnetic resonant circuit comprising a pick-up coil, a capacitance and a filter coil, an active medium of organic or maser-capable molecules in the pick-up coil as well as a population inversion device for generating a population inversion in the active medium.

Abstract: The problem addressed by the invention is that of providing a coil having advantageous properties for an oscillating circuit, in particular for a measuring device for electromagnetic signals. This problem is solved in that the coil comprises an electric conductor, the ends of which form the two terminals of the coil. Wound sections of the electric conductor are twisted together, that is to say wound helically around one another. The electric conductor is in principle surrounded by insulation, for example made of plastic or varnish. As a result of the twisting, increases in spacing between adjacent conductor sections within the windings are achieved. This results in an improved quality of the coil.

Abstract: The invention relates to a measuring apparatus for detecting weak electromagnetic signals from a sample at low frequencies, specifically in the frequency range of 1 kHz-10 MHz, in particular, and to a measuring method. The problem addressed by the invention is that of providing an apparatus which can be used to detect weak electromagnetic signals from a sample, in particular in the frequency range of 1 kHz-40 MHz, with a good signal-to-noise ratio. For the solution, the measuring apparatus comprises an electromagnetic resonant circuit having a pick-up coil of low quality, a preferably tunable capacitance and a filter coil; the filter coil and the capacitance have a high quality of at least 100, advantageously at least 200, particularly preferably at least 500. Alternatively or additionally, the quality of the resonant circuit is at least 100, advantageously at least 200, particularly preferably at least 500.

Abstract: The invention concerns a maser having an electromagnetic resonant circuit comprising a pick-up coil, a capacitance and a filter coil, an active medium of organic or maser-capable molecules in the pick-up coil as well as a population inversion device for generating a population inversion in the active medium.

Abstract: The invention relates to a measuring apparatus for detecting weak electromagnetic signals from a sample at low frequencies, specifically in the frequency range of 1 kHz-10 MHz, in particular, and to a measuring method. The problem addressed by the invention is that of providing an apparatus which can be used to detect weak electromagnetic signals from a sample, in particular in the frequency range of 1 kHz-40 MHz, with a good signal-to-noise ratio. For the solution, the measuring apparatus comprises an electromagnetic resonant circuit having a pick-up coil of low quality, a preferably tunable capacitance and a filter coil; the filter coil and the capacitance have a high quality of at least 100, advantageously at least 200, particularly preferably at least 500. Alternatively or additionally, the quality of the resonant circuit is at least 100, advantageously at least 200, particularly preferably at least 500.

Abstract: The problem addressed by the invention is that of providing a coil having advantageous properties for an oscillating circuit, in particular for a measuring device for electromagnetic signals. This problem is solved in that the coil comprises an electric conductor, the ends of which form the two terminals of the coil. Wound sections of the electric conductor are twisted together, that is to say wound helically around one another. The electric conductor is in principle surrounded by insulation, for example made of plastic or varnish. As a result of the twisting, increases in spacing between adjacent conductor sections within the windings are achieved. This results in an improved quality of the coil.