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RFID Antenna placement for Smart Shelves/Lift&Learn

This technical note is a quick introduction to Nexmosphere RFID antenna placement and setup.

It is based on Nexmosphere's own Product Manual - XR Range RFID

Hiding the antennas

The antennas should be placed inside the shelf lid (except if the shelf lid is very thin).

In the pictures below, a hole has been carved in a translucent acrylic slab to allow the maximum proximity from the antenna to the RFID tag and to add a LED strip for extra effect.

This way the shelves light up upon picking the object.

Antenna Distances

Nexmosphere recommends a minimum distance between antennas, depending on the type and size. The Product Manual - XR Range RFID details the exact ranges.

In general:

  1. Ensure the distance between the tag and the antenna (A), including the shelf slab does not exceed the maximum recommended for the antenna. The ranges are about 28mm to 44mm depending on the antenna.

  2. Avoid metallic objects around or near the antennas. If the product is metallic or contains metal, place it on a plastic base and put the RFID tag below.

  3. The tags should be placed flat over the antenna, not exceeding an angle of 30ยบ between tag and antenna.

  4. If multiple antennas are used, a minimum clearance between them should be respected.

  5. Do not put the Driver (XR-DR1) box near the antenna.

  6. Do not roll the excess cable, if it cannot be kept in a straight line either make a zig-zag or 8 figure roll.

Example

Suppose we are building a 4-antenna shelf. We will base it upon the purchase list from before:

SKU Item Qty
XN-185 8x X-talk, USB 1
XR-DR1 XR antenna driver 4
XR-A60 RFID Antenna, rectangular, A6 148x105mm 4
XNR-S18 RFID tag, number 1-8 1

The selected antennas are A6 size (148x105) corresponding to the XR-A60 model.

We want to distribute them evenly under a 1 meter shelf:

We check the Product Manual - XR Range RFID details, which tells us that the Horizontal Clearance (B) for this model of antenna is of > 45mm, so we have to ensure that the antennas are separated by more than 45mm.

As the antennas are 148mm wide x 4 antennas = 592mm.

Of the 1m shelf, 408mm remain. If we leave 54mm each side, that\'s 308mm of space, divided between the 3 \"holes\" between antennas, we can leave 300mm/3 = 100mm between antennas.

The distances would be then:

Note that the cable from the antenna to each XR-DR1 might be very short (10cm) and cannot be extended. So if there\'s not enough distance we might need to place the XR-DR1 units under the shelf.

In this case it is important to keep a clearance between the units and the antennas so as they dont\' interfere each other:

Then it would be necessary to have the units under the shelf, near but not touching the antennas, and have the X-Talk cable go out to behind scenes, to the X-Talk controller (XN-185).

Note then the XR-DR1 box is about 610x400x160mm of size, so the slab has to have a deep enough hole for it to fit and hide.