Near field probe
A near field probe is used for the contactless detection of the electric or magnetic fields in the near field of electric or electronic circuits or assemblies in the context of EMC measurements for electromagnetic compatibility . The detection of the magnetic and electrical near-field components is used to be able to detect the interference emissions from electrical devices during development and to minimize them in order to avoid undesired mutual influences of electrical devices.
General
The electronic circuits or assemblies, which are usually implemented on printed circuit boards , cause the currents flowing in the conductor tracks and the voltages applied in the vicinity to cause magnetic and electric fields. In particular with high-frequency currents and voltages, radiation occurs with the appropriate spatial geometry of the conductor routing - this fact is deliberately exploited in antennas , but is undesirable in the context of minimizing interference with electromagnetic compatibility.
These fields can be qualitatively recorded in terms of their strength and spatial extent without contact using near-field probes; different designs and different construction variants for the separate detection of the magnetic and electrical field components are common for the respective application. For the measurement, the probes are brought in close proximity to the area to be examined, such as a conductor track. For measuring signal acquisition, near-field probes have a shielded electrical connection that allows the respective field components to be displayed and evaluated in the time domain on an oscilloscope or in the spectral domain on a spectrum analyzer .
In contrast to the more complex EMC conformity measurements in absorber chambers , near-field probes can be used more easily as part of the development of electronic circuits in the laboratory and during development and allow the early detection and assessment of the effects of possible sources of interference.
literature
- Adolf J. Schwab, Wolfgang Kürner: Electromagnetic Compatibility . 6th edition. Springer, 2011, ISBN 978-3-642-16610-5 .
Individual evidence
- ↑ H. Weisser: Elimination of interference emissions in HF circuits with EMC near-field probes . 14th volume, no. 6 . Microwave Magazine, 1988, p. 527-529 .