Back to results
US 4,825,222 AGranted
Omnidirectional antenna with hollow point source feed
AssigneeBritish Telecommunications plc
InventorMiles E. Butcher
Life of this patent
Estimating the term…
Abstract
An omnidirectional antenna comprises a ring-shaped subreflector surrounding an omnidirectional feed and a ring-shaped main reflector for redirecting radiation from the subsidiary reflector to the target zone. The feed has a focal ring and a hollow centre to accommodate supports, feeders etc which facilitates stacking of antennas.
Claims15
An antenna comprising:
- an omnidirectional primary feed means for radiating signals in directions substantially transversely of an axis, said feed means including a ring-shaped ground plane disposed about said axis;
- a ring-shaped secondary reflector disposed about said axis, and
- a ring-shaped main reflector means positioned about the said axis, said secondary reflector so positioned relative to said main reflector means as to reflect radio signals onto the surface of said main reflector means, said main reflector means for redirecting said reflected signals in directions substantially transversely of the said axis,
- wherein the feed means and the secondary reflector have ring foci substantially coincident with one another, and the feed means is hollow and comprises a plurality of substantially point source radiator elements disposed about said ring-shaped ground plane.
1 more element
An omnidirectional RF antenna comprising:
- an annular conductive ground plane surface;
- omnidirectional radiator means including plural radiator elements spaced from and disposed along a first annulus about said ground plane surface, said radiator means for radiating RF energy substantially omnidirectionally outwardly from said ground plane surface;
- annular secondary reflector means disposed substantially concentrically with and about said first annulus and said ground plane surface for redirecting signals radiated by said radiator elements, said secondary reflector means redirecting said radiated signals in directions approximately coplanar with said ground plane surface;
- and
- annular primary reflector means for reflecting said redirected signals outwardly from said ground plane surface in a radiation pattern that is substantially omnidirectional in at least one plane.
2 more elements
Dependencies are inferred from the claim text.