A conveyor system processes items on which radio frequency identification tags are disposed and includes a frame and a conveyor that is disposed moveably 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 is 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. The antenna comprises a substrate and a plurality of patch elements having respective generally planar surfaces and that are disposed on the substrate in respecting positions that are sequential with respect to a direction transverse to the path of travel. The generally planar surfaces of the patch elements are generally coplanar. The antenna includes a feed network that applies respective signals to each patch element that drive electric current at the patch elements to radiate the radio frequency signals. The respective signals applied by the feed network to at least two patch elements define a predetermined phase shift with respect to each other. A radio frequency transmitter drives the antenna to emit the radio frequency signals.