Introduction:
Near-field probes are classified asElectric field near-field probesrespond in singingMagnetic field near-field probesTwo kinds, want to understand the near-field probe probe is electric field or magnetic field, we first need to understand the working principle of the two kinds of near-field probe. Then you can choose the right near-field probe according to the test requirements, but also understand the near-field probe test is the electric field or magnetic field.
Principle of operation of the magnetic field near-field probe:
In order to reliably assess the quality of magnetic near-field probes, we need to focus on two important features:
Constant sensitivity over a wide frequency range:
Constant sensitivity of the near-field probe ensures that the spectrum of the magnetic field emitted by the device under test is correctly rendered; resonances and other irregularities in the near-field probe's frequency curve can falsify measurements and mislead developers. The near-field probe must have a consistent, almost constant frequency response in order for developers to find and implement convenient EMC measures for the device under test, which is a prerequisite for successful suppression of modular interference.
Powerful electric field rejection (magnetic field probe)
Magnetic field probes are designed to suppress the effects of electric fields (electric field suppression). The quality of the electric field suppression is critical for magnetic field probes.
For example, we measured the frequency response of two near-field probes of the same type on a microstrip line (2 mm wide, 50 ohm termination, 50 micron gap between near-field probe and microstrip line, 100 dBµV power supply). The microstrip line generates both electric and magnetic fields, so it is possible to test the frequency response of the probe along with its electric field rejection. The magnetic field probe is placed at the maximum and zero points of the magnetic field during testing.
Magnetic field probes have the ability to suppress electric fields
The shape of the magnetic field near-field probe:
The magnetic field near-field probe must be shaped like a ring because it has to receive the induced magnetic field lines and allow the magnetic inductance lines to pass through the probe before a voltage can be generated on the probe.
Magnetic field near-field probes must be looped
How do I correct the test data of a magnetic near-field probe?
When the near-field probe is obtained, the k-factor should be obtained from the factory data, and then the measured value using the spectrum analyzer should be added to this k-factor before the final test result of the magnetic near-field probe - the magnetic field strength.
Magnetic field near-field probe using k-factor correction test results
Principle of operation of the electric field near-field probe:
The electric field probe for measuring electric field uses inductive coupling to measure the electric field on the interference source, it only needs to design a loop-free antenna to obtain the magnitude of the electric field strength, the most important feature of the electric field near-field probe is that it does not have a loop to receive the magnetic field, and so it is also shielded from the magnetic field reception.
What is the difference between different models of electric field near-field probes?
EUTTEST agent sales many models of electric field near-field probe, when you understand the above working principle, only need to change the antenna size of the electric field probe, you can get different models of near-field probe, so we only need to be tested according to the size of the area to decide to choose how big the electric field near-field probe.
Summary:
When understanding the above introduction of the magnetic field near-field probe and electric field near-field probe working principle, near-field probe test is electric field or magnetic field just need to be determined according to the model of the probe, but we can not determine the source of interference emission is the electric field interference or magnetic field interference how to do? Then each kind of probe is measured once.
Using near-field probes is a common and easy task for hardware engineers, so contact EUTTEST as soon as possible to get theNear field probe+spectrum analyzerPerform EMC radiated emission localization and rectification commissioning bar.