Dipole antenna array having dipole arms tilted at an acute angle
An antenna comprising a reflective surface; and an array of dipole antenna elements disposed adjacent to the reflective surface. Each antenna element has a pair of arms which together define a dipole axis, and the dipole axis is tilted at an acute angle with respect to the reflective surface. The pair of arms may be dipole arms, or may be Yagi director arms. In some embodiments the dipole axis is tilted at an acute angle with respect to a feed axis. In some embodiments the antenna element comprises a feed portion defining a feed axis; and the feed portion has a mounting portion which is tilted at an acute angle with respect to the feed axis.
1. An antenna comprising a reflective surface; and an array of dipole antenna elements disposed adjacent to the reflective surface, wherein each antenna element has a feed portion defining a feed axis and a pair of arms which together define a dipole axis, and wherein the dipole axis is tilted at an acute angle with respect to the reflective surface.
2. The antenna of claim 1 further comprising a feed network coupled to the array of antenna elements and adapted to selectively adjust a beam tilt of the antenna.
3. The antenna of claim 2 wherein the feed network includes one or more phase shifters adapted to selectively adjust a phase relationship between the antenna elements.
4. The antenna of claim 1 wherein the reflective surface comprises a continuous surface.
5. The antenna of claim 1 wherein the reflective surface is a single piece of material.
6. The antenna of claim 1 wherein the reflective surface is substantially planar.
7. The antenna of claim 1 wherein the reflective surface comprises a base of a tray, the tray further comprising a pair of side walls.
8. The antenna of claim 7 wherein the base and side walls of the tray is a single piece of conductive material.
9. The antenna of claim 1 wherein the dipole axis is tilted at an acute angle with respect to the feed axis.
10. The antenna of claim 1 wherein the feed axis is tilted at an acute angle with respect to the reflective surface.
11. The antenna of claim 1 wherein the feed portion includes a pedestal with a support surface which is tilted with respect to the reflective surface.
12. The antenna of claim 11 wherein the pedestal has a flange extending from the support surface, the flange being substantially parallel with the reflective surface.
13. The antenna of claim 1 wherein the pair of arms of each antenna element are disposed on a substrate, and the substrate is tilted at an acute angle with respect to the reflective surface.
14. The antenna of claim 1 wherein each antenna element comprises a dual polarized antenna element.
15. The antenna of claim 14 wherein the pair of arms of each dual polarized antenna element comprise first pair of dipole arms, wherein each dual polarized antenna element further comprises a second pair of arms comprising second pair of dipole arms, and wherein the feed axes corresponding to the first and second airs of arms define a central axis, each arm of the first and second pairs of arms having a first portion extending from the central axis of the dual polarized antenna element and a second portion extending out of a plane including the first portion and the central axis.
16. The antenna of claim 1 wherein the pair of arms of each antenna element are dipole arms.
17. The antenna of claim 1 wherein the pair of arms of each antenna element are Yagi director arms.
18. A base station comprising the antenna of claim 1 .
19. A wireless communication system comprising a plurality of base stations according to claim 18 , each antenna configured to communicate with a plurality of mobile devices in a respective cell.
20. A dipole antenna element comprising a feed portion defining a feed axis; and a pair of arms which together define a dipole axis, wherein the dipole axis is tilted at an acute angle with respect to the feed axis.
21. The antenna element of claim 20 wherein the pair of arms are disposed on a substrate, and the substrate is tilted at an acute angle with respect to the feed axis.
22. The antenna element of claim 20 wherein the pair of arms comprises a pair of Yagi director arms.
23. The antenna element of claim 22 wherein the feed portion comprises a pair of directly driven dipole aims, and the Yagi director arms are parasitically driven by the directly driven dipole arms.
24. The antenna element of claim 20 wherein the pair of arms comprise a pair of dipole arms.
25. A dipole antenna element comprising a feed portion defining a feed axis; and a dipole portion comprising a pair of arms, wherein the feed portion has a mounting portion which is tilted at an acute angle with respect to the feed axis.
26. The antenna element of claim 25 wherein the pair of arms together define a dipole axis, and wherein the mounting portion is tilted at an acute angle with respect to the dipole axis.
27. The antenna element of claim 25 wherein the feed portion comprises a substrate carrying a feed leg, and the mounting portion comprises an edge of the substrate.
28. The antenna element of claim 25 wherein the mounting portion comprises a flange.
29. The antenna element of claim 25 wherein the mounting portion engages the dipole portion.
30. A method of operating an antenna comprising an array of dipole antenna elements, each antenna element having a feed portion defining a feed axis and a pair of arms which together define a dipole axis, the method comprising energizing the antenna elements so as to transmit or receive radiation, and reflecting radiation to or from the antenna elements with a reflector disposed adjacent to the antenna elements which is tilted at an acute angle with respect to each dipole axis.