Timo Arnall of the Touch project and Jack Schulze from BERG did some lovely explorations into the normally invisible fields of an RFID reader. They visualised the spatial qualities of the field with an RFID probe, that would flash an LED light when an RFID tag was read. They then captured the LED light with long exposure photography and stop framed it into an animation.
This is a really interesting follow-on from their Nearness project which focused on the invisible force fields between objects.
Read more about the project and how this exploration will inform how we could develop better spatial and gestural models of RFID in future on the Touch blog. You can even download their Field icon and start experimenting yourself.