Composite antenna for electronic article surveillance systems
US5061941A · kind A · utility
99Cited by
5References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 1, 1990 |
| Grant date | Oct 29, 1991 |
| Priority date | — |
| Expiry date | Feb 1, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q7/04
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A composite antenna system for an article surveillance system, in which a plurality of differently-phased loop antennas are supplied with different currents to provide desired positioning of peaks and nulls in the near-field strength, and to produce near-zero far-field strength, as desired. In one preferred form, a smaller loop is placed near the floor and a larger loop placed above it, with the lower loop supplied with a correspondingly higher-intensity of current to provide an enhanced near-field strength near the floor, while still maintaining far-field cancellation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.