FYI, other than using a very long USB extension cable with your dongle and adding electromagnetic shielding to your other devices/appliances (like your Raspberry Pi enclosure), another tip is to add electromagnetic shielding to all the parts of the dongle circuit board that is not the PBC trace antenna.
This type of electromagnetic shielding can done by first wrapping it in one layer of some kind of isolating film or tape around it and then wrapping a layer of conductive metallic tape on top of that.
Just make sure to not cover the antenna and as well as electrically grounding the conductive metallic tape to the USB jacketing (which act as a point of the electrical ground) checking it makes contact.
Rather than using just any tape lying around a better solution would probably be a good idea try using either heat-shrink tubing or kapton-tape as the isolation layer (both types are widely available online).
https://en.wikipedia.org/wiki/Heat-shrink_tubing
https://en.wikipedia.org/wiki/Kapton
Also, rather than using any metallic tape, suggested consider buying conductive copper tape (checking that the adhesive/glue on the metallic tape really is a “conductive” variant as “non-conductive” variant also exist, as then it should be easy to ground that conductive tape by just wrapping part of the USB mantel/jacketing as the point of the electrical ground). Tip is to just search for “conductive metal tape”.
https://en.wikipedia.org/wiki/Electrically_conductive_adhesive
https://en.wikipedia.org/wiki/Copper_tape
…once I get around to this myself I probably do it overkill style; i.e.:
- First wrap a layer of Kapton-tape (no need to touch USB mantel, and making sure not to cover the PCB trace antenna on the board),
- Then wrap a layer of conductive metallic tape, (that needs to touch USB mantel/jacketing, and making sure not to cover the PCB trace antenna on the board).
- Lastly heat-shrink tubing over everything (here you could probably choose if you also want to cover PCB trace antenna or not).
Again, be sure to touch USB to ground copper-tape but not to cover the tip of the dongle/stick circuit board which has PCB trace antenna!
Reference:
https://en.wikipedia.org/wiki/Electromagnetic_shielding
PS: If you are using a Raspberry Pi or other single-board-computer with wired Ethernet and you do not need to use its WiFi or Bluetooth then you can also add a layer of electromagnetic shielding to its enclosure as well (or just buy a metal case for it).