What is a null spot?
A null spot is an area in the reader field of view that actually has no radio frequency energy present. As a result, a tag remaining in that spot will not be read despite being in the readers field of view. This is essentially the reader’s blind spot. It is a phenomenon common to UHF systems and usually caused by multi-path reflections Radio wave arrive at that location via different paths. The varying path lengths can cause radio waves to arrive out of phase, thus, cancelling the energy.
