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I would like to build a confined enclosure(like a 50cm cube box) to limit and perform RFID scanning only within the box, not interfered by the RFID tags laying outside the box.

My intention is to be able to do a quick scan(stock take) on everything that is placed in the box, thus, the scanning distance of the RFID tags should cover the entire interior volumetric space of the box while the RFID reader will be placed in the box.

What is the material that I should use for the interior/exterior wall of the box? Any experience or advise in constructing such a box is also greatly appreciated too.

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    \$\begingroup\$ Google "Faraday cage". \$\endgroup\$ – The Photon Jul 22 at 14:35
  • \$\begingroup\$ Do you care that the enclosure may change the operating distances of the RFID tags inside the box? Do you care that the enclosure may alter/reshape the card reader's field? \$\endgroup\$ – Andy aka Jul 22 at 14:37
  • \$\begingroup\$ @Andy aka, as my intention is to be able to do a quick scan(stock take) on everything that is placed in the box, thus, maintaining or having the maximum possible scanning distance of the RFID tags within the box is needed. Logically, yes, the reader will be placed in the box too. \$\endgroup\$ – Jack Oat Jul 22 at 14:40
  • \$\begingroup\$ How big this box should be? \$\endgroup\$ – Eugene Sh. Jul 22 at 15:02
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    \$\begingroup\$ @JackOat point is that the low-frequency RFID isn't even actually "radio" in the strict sense: there's no propagating wave. Think of tag and reader as being the two sides of a transformer. Transformer efficiency drops off quickly with distance. \$\endgroup\$ – Marcus Müller Jul 22 at 19:14
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The easiest way to do this is with a conductive box with no holes (also known as apertures). You need a box that has a skin depth larger than the RFID signals. If using low frequency RFID which runs at 120–150 kHz, for aluminum or copper, you'll need at least 1mm of material for adequate blocking. If the RFID uses one of the faster bands, skin depth becomes less of a concern as 0.1mm would provide sufficient blocking above 1GHz.

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The simple answer is to try an experiment. You will need a cheap metal walled box, so steel should be a good choice. Ground the box, but the reader inside along with an RFID tag. See whether it reads the tag. If so, move it outside the box and try again.

While the thickness of steel is probably not too important at high frequencies this may be more problematic with low frequency RFID of tens or hundreds of kHz.

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Keep the tags and the reader away from the Faraday Cage walls, and you should have good results.

I suggest the tags be 5cm away from the walls.

You must experiment to learn what is reliable.

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  • \$\begingroup\$ May I ask what you mean by "away from the Faraday Cage walls"? My plan is to have the RFID tags and reader both placed within the box to do the scanning and not be interfered by the RFID tags placed outside the box. \$\endgroup\$ – Jack Oat Jul 22 at 15:28
  • \$\begingroup\$ Ok, thanks for th edit. I think I got what you meant - RFID tags and reader placed within the box to have 5cm 'padding' space from the walls. Will keep in mind and experiment. \$\endgroup\$ – Jack Oat Jul 23 at 4:00

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