Surveillance and identification system antennas
US5280286A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 12, 1992 |
| Grant date | Jan 18, 1994 |
| Priority date | — |
| Expiry date | Jun 12, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q21/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.