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RFID: frequency and read range

Hallo,

RFID: i have a question regarding frequency and read range. In physics higher frequency means less range of the electromagnetic radiation (at equal power !).

Now, I read, that in RFID higher frequencies mean larger read ranges. I think RFID obeys the same physics rules... so why do RFID systems with higher frequencies have larger read ranges?

I know the difference between near- and far-field, so lets just regard far-field with >400MHz.

Are there other parameters important? Like environment, error-correction, reflection, sensibility of readers? Other factors?

Thanks CU Sven

Reply to
Sven Westenberg
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Hello Sven,

I am certainly no RFID expert but there is one other important factor: The antennas. Or antennae, as the Romans would have said. The little ferrite rods of 125kHz links are not all that efficient.

Regards, Joerg

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Reply to
Joerg

Designing interaction-devices utilizing RFid-technology I can tell you several things:

The various frequencies show different abilities in penetrating different materials. That is one aspect that is a distinctive factor in everydays useage.

The other one is the wavelength and the antenna: How much shorter is the wavelength of a 800MHz or a 13MHz in comparision to a 125KHz RFid? Now compare how much more optimized the Tag's antennas can be for the higher frequencies!

We have a 13MHz Tag having 4 separate antenna-coils, and the tag is just a quater of the size of the 125kHz tag which has only one antenna-coil. So whilst the 125'er looses a part of his reception-surface when you bend it slightly, the 13MHz Tag is still having an optimized antenna facing toward the reader.

That's most of the secret why the high-frequency-tags have better ranges than the lower frequency ones. You can even lower the readers antenna-signal, because you can have much more "receptive area" in comparision to a lower freq. tag in a 13 or 800MHz tag.

Funky, isn't it?

Sven Westenberg wrote:

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Sincerely

Ruediger
Reply to
Ruediger

Sven Westenberg schrieb:

Hallo,

und die Astronomen beobachten sehr weit entfernte Objekte =FCber den=20 gesamten Bereich des sichtbaren Lichts, ja mit Teleskopen auf Satelliten =

sogar im UV und R=F6ntgenbereich. Alles elektromagnetische Strahlung.

Bye

Reply to
Uwe Hercksen

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