Low-cost scalable UHF RFID reader antenna with no surface dead zones

Ultra High Frequency (UHF) Radio Frequency Identification (RFID) is an automatic identification technology which has already explored different ventures to replace barcode systems. Near-field (NF) identification is preferred in inventory containing liquids and metals, as well as point-of-sale applications where the challenge is to have an antenna that can scale to large sizes and has no blind spots on its surface. This paper presents a scalable NF antenna design that utilizes non-conventional but commercially available materials that makes the antenna inexpensive. The antenna architecture comprises of a rectangular spiral microstrip line with intentional impedance mismatches and a finite ground plane made from conductive tapes and sheets sandwiched by a non-conventional substrate material. Traditional patch and loop NF antennas suffer from size limitation, surface dead spots and have far-field (FF) component that introduces stray tag reads. The proposed antenna design has no surface blind spots, easily scalable and has potential for building an inexpensive tracking shelve with confined read zones that can detect both NF and FF tags. The light weight, chemical resistant, non-toxic, and self-extinguishing properties of the antenna can significantly expand the range of applications and deployment environments of UHF RFID.