Antenna
US5859621A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 21, 1997 |
| Grant date | Jan 12, 1999 |
| Priority date | — |
| Expiry date | Feb 21, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q11/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An antenna for use at frequencies of 200 MHz and upwards has a cylindrical ceramic core with a relative dielectric constant of at least 5, and pairs of helical elements extending from a feed point at one end of the core to the rim of a conductive sleeve adjacent the other end of the core, the sleeve acting as a trap for isolating from ground currents circulating in the helical elements. To yield helical elements of different lengths, the sleeve rim follows a locus which deviates from a plane perpendicular to the core axis in that it describes a zig-zag path. The helical elements form simple helices with approximately balanced radiation resistances.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.