Measuring apparatus for weak electromagnetic signals from a sample at low frequencies, in addition to a method

US10551331B2 · kind B2 · utility

Assignee

• Forschungszentrum Jülich GmbH · DE

Inventors

• Stephan Appelt · Aachen, DE
• Martin Süfke · Aachen, DE
• Bernd Alexander Liebisch · Aachen, DE

Key dates

• Filing date: Sep 17, 2015
• Grant date: Feb 4, 2020
• Expiry date: Feb 11, 2037

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/60
• WIPO field: Measurement
• WIPO sector: Instruments

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. The quality of the filter coil and the quality of the capacitance exceed the quality of the pick-up coil, specifically at least by twice the amount. The measurement signal is then available at the two ends of the filter coil with a good signal-to-noise ratio.