Attach an RFID electronic tag to the surface of a metal device and bring the reader close - the reading distance is rapidly reduced, and it may even be completely unrecognizable. This is not because the label is broken, but because the metal has' eaten 'the signal.

13.56MHz is the standard operating frequency for high-frequency RFID and NFC, with a wavelength of approximately 22.1m, much larger than the distance between the reader antenna and the electronic tag. Therefore, the electromagnetic field between the antenna and the tag can be treated as an alternating magnetic field. When this alternating magnetic field encounters a metal surface, according to Faraday's law of electromagnetic induction, eddy currents will be generated in the metal. The direction of eddy currents is opposite to the original magnetic field of the antenna, forming a counteracting reverse magnetic field that severely weakens or even completely cancels out the effective signal of the antenna. The result is a shortened read-write distance and communication failure.

2、 Focused magnetic flux and low magnetic loss: a pair of parameters that require precise balance

The core function of 13.56MHz high-frequency electronic tag absorbing materials is determined by two key parameters: the real part of magnetic permeability (μ ') and the imaginary part of magnetic permeability (μ'), as well as the loss tangent tan δ (=μ '/μ') defined by the ratio of the two.

The Way of Balance:μ 'determines' how much magnetic flux can be bundled', and tan δ determines' whether the bundled signal is interference or useful '. The ideal 13.56MHz absorbing wave plate needs to have a sufficiently high μ 'to resist metals and a sufficiently low tan δ to avoid loss of useful signals. Generally, when the magnetic permeability of absorbing materials is above 10MHz, μ 'rapidly decays and μ' rapidly increases. Therefore, 13.56MHz is the critical frequency point for high-frequency anti metal applications.

3、 Two application directions of absorbing materials

There are two completely different application directions for absorbing materials in the field of electromagnetic compatibility, and understanding this difference is a prerequisite for selecting the right one:

4、 Ferrite vs nanocrystals: material system selection

5、 Key Performance: What Engineers Should Pay Attention to

6、 Typical application scenarios

7、 Selection considerations: from thickness to magnetic permeability

8、 Conclusion

The essence of the absorbing material for 13.56MHz high-frequency electronic tags is to use high magnetic permeability materials to "build a path around the metal" for the magnetic field lines of RFID/NFC. It does not change the communication protocol or amplify signal power - it only changes the spatial distribution of magnetic field lines, allowing the magnetic field that should have been "short circuited" by the metal to return to the effective area of the antenna.

Understanding the working logic of absorbing materials - focusing magnetic flux instead of amplifying signals, low magnetic loss instead of high loss - is the key to upgrading this thin film with a thickness of less than 0.1mm from an "accessory" to an "engineering solution". In scenarios such as metal surface tags, smartphone NFC, and industrial asset management, the 13.56MHz high-frequency electronic tag absorbing material provides the final piece of the puzzle for near-field communication to move from "ideal laboratory conditions" to the "real engineering world".