The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 18, 1994
Filed:
Jun. 12, 1992
John D Williamson, Los Gatos, CA (US);
Smart Tag Systems, Inc., Akron, OH (US);
Abstract
An antenna system (20) in transponder article surveillance and identification system (10) employs a separate interrogating transmitting antenna (31) and interrogating receiving antenna (41) both of which are circularly polarized in opposite hand senses whereby very little of a transmitted electromagnetic interrogation signal is coupled to the interrogation receiving antenna (41) and reflections from nearby surfaces are transparent, significantly improving system performance. Interrogating transmitting antenna (31) and interrogating receiving antenna (41) are cavity-backed, crossed-dipole-fed antennas producing a substantially hemispherical radiation pattern. Transponder (11) is mounted together with a dipole antenna (50) on a tag (13) carried on each article to be identified. Dipole antenna (50) includes two substantially paddle-shaped radiating members (52,53) formed upon a substrate (54), each paddle-shaped radiating member (52, 53) having an end centrally disposed on substrate (54) terminating at an angle whereby the impedance of dipole antenna (50) substantially matches the impedance of the transponder (12) in electrical connection therewith.