Patent ID: 7592915

Claim:
A conveyor system for processing items on which radio frequency identification tags are disposed, said system comprising: a frame; a conveyor that is disposed movably on the frame and that conveys items through a path of travel, each item having at least one respective radio frequency identification tag disposed thereon; an antenna disposed on the frame with respect to the path of travel so that the antenna radiates radio frequency signals into a first area through which the items pass, wherein the antenna comprises a substrate and a plurality of patch elements having respective generally planar surfaces and that are disposed on the substrate in respective positions that are sequential with respect to a direction transverse to the path of travel, wherein the generally planar surfaces of the patch elements are generally coplanar, wherein the antenna includes a feed network that applies respective signals to each said patch element that drive electric current at the patch elements to radiate the radio frequency signals, wherein the antenna is disposed with respect to the conveyor and the path of travel so that respective said radio frequency identification tags on said items are detected by a near field component of the radio frequency signal radiated by one of the patch elements without interference from the other patch elements, and wherein the respective signals applied by the feed network to at least two said patch elements define a predetermined phase shift with respect to each other that is fixed so that respective electric current patterns on the at least two patch elements are out of phase with each other; and a radio frequency transmitter that drives the antenna to emit the radio frequency signals into the first area.