I've been working on some RFID stuff lately and I'm wondering if someone could help me understand how the beam direction works?
I'm having problems with my RFID reader picking up signals from tags that are behind it. From what I understand, the beam that powers the passive tags should be a cone and therefore it shouldn't be able to reach tags that are behind the reader, but this is being done by both of my RFID readers (the readers are Chafon UHF high performance integrated reader, model CF-RU5309). I did some more digging into my RFID reader and it's apparently omnidirectional but I'm not sure if this is possible. Does this mean it can read any tag within a circular area around it?
I've tried to put up some aluminum shielding on the wall behind where the reader is installed but that doesn't seem to have done much other than stopping tags that were really far back behind it from being read, while close ones can still be read. The shielding is a 3ft square placed at the center of the reader, with another rectangle of aluminum shielding that covers up to 2 ft above where the tags sit behind the reader. The tags being read are xerafy microX ii and are set up so that there's two tags on a large aluminum piece of metal. I've included a quick sketch of my setup and a link to the products I'm using. The tags being read are about 3 feet off the ground while the reader is about 10 feet above ground.
The antenna is claimed to be a 9dbi circular antenna. Not sure if this means it can't be omnidirectional but I'm pretty sure that I found online that the reader is stated to be omnidirectional.