MULTI-ARM CONFORMAL SLOT ANTENNA

• US 20130063321A1
• Filed: 08/27/2012
• Published: 03/14/2013
• Est. Priority Date: 08/26/2011
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Ruvinsky, Leonard, Lo, Zane, McKivergan, Patrick, Reed, Mark W.
• Granted Patent: US 9,270,028 B2
• Time in Patent Office: Days
• US Class Current: 343/771
• CPC Class Codes: H01Q 1/286 substantially flush mounted with the skin of the craft
• CPC Class Codes: H01Q 13/18 the slot being backed by, or formed in boundary wall of, a resonant cavity longitudinally slotted cylinder H01Q13/12 ; Open cavity antennas
• CPC Class Codes: H01Q 5/371 Branching current paths

Abstract

An octave bandwidth conformal cavity-backed slot antenna includes a ground plane with a number of different length slits that come together at the central feedpoint. The slit length varies from one-half a wavelength at the highest frequency at which the antenna is to operate for the short side to one wavelength at the highest frequency for the long side, with the proximal ends of the slits having a common feedpoint. Such slot antennas may be arrayed in a quad configuration. Because the trapezoidal envelope of the antenna induces the phase-center to shift with frequency, when two are arrayed with short sides adjacent, the spacing between them results in a phase center from one antenna to the next that is effectively within half a wavelength at all frequencies.

Claims

1. A wide bandwidth conformal cavity-backed slot antenna comprising:

a multi-arm slot antenna having a ground plane, a central feedpoint and a number of different length slits in said ground plane, said slits comprising the arms of said multi-arm antenna, said slits divided into at least short slits and long slits.

2. The antenna of claim 1, wherein the distal ends of said short slits and said long slits define a trapezoidal envelope.

3. The antenna of claim 2, wherein said trapezoidal envelope induces the phase-center of said multi-arm slot antenna to shift with frequency.

4. The antenna of claim 3, wherein the shortest distance between said short slits and said long slits is no more than one-quarter wavelength at the highest frequency at which said antenna is to operate.

5. The antenna of claim 3, wherein the sides of said trapezoidal envelope are at 45 degree angles with respect to the base thereof.

6. The antenna of claim 5, wherein the overall length of said long slits is twice that of the overall length of said short slits.

7. The antenna of claim 1, wherein said antenna includes three pairs of slits, each pair of slits electrically coupled together by a backbone slit such that each half of said antenna resembles a pitchfork.

8. The antenna of claim 7, wherein said backbones are in spaced adjacency, with the slits associated with one pair pointing in an opposite direction to those of the other pair.

9. The antenna of claim 8, and further including a slit serving as a feedpoint between said two opposed backbones.

10. The antenna of claim 1, and further including magnetic loading at the distal ends of said short slits and resistance loading at the distal ends of said long slits, thereby to improve the low frequency bandwidth of said antenna.

11. The antenna of claim 1, and further including an ultra wide band balun coupled to said central feedpoint.

12. The antenna of claim 1, wherein said slits are tapered outwardly from proximal end to distal end for improving the bandwidth of said antenna.

13. The antenna of claim 1, wherein the pattern of said slits resembles a pitchfork.

14. The antenna of claim 1, wherein the pattern of said slits resembles a spider pattern.

15. The antenna of claim 1, and further including a pair of said multi-arm slot antennas arrayed in back-to-back fashion, with said central feedpoint serving as a common feedpoint.

16. The antenna of claim 15, and further including a second pair of said multi-arm slot antennas arrayed back-to-back and oriented orthogonally to said first-mentioned back-to-back pair of antennas to form a quad array.

17. The antenna of claim 15, wherein said pair of multi-arm slot antennas are arrayed with a spacing therebetween that results in the phase-center associated with one back-to-back antenna being spaced from the phase-center associated with the other back-to-back antenna being within one-half a wavelength for all frequencies at which said antenna is to operate.

18. The antenna of claim 1, and further including four of said multi-armed slot antennas arrayed in a square configuration.

19. The antenna of claim 18, wherein said antennas in a square configuration are arrayed without exceeding a one-half wavelength array spacing for the phase-centers of said antennas.

20. An octave bandwidth conformal cavity-backed slot antenna comprising:

a number of different length slits in a ground plane with said slits having a common feedpoint.

21. The antenna of claim 20, wherein said slits have proximal and distal ends and wherein said slits are outwardly tapered from the proximal ends thereof to the distal ends thereof for purposes of improving the bandwidth of said cavity-backed slot antenna.

22. The antenna of claim 20, wherein said antenna is divided into two sides, each side having at least three slits going from the feedpoint thereof outwardly to the distal ends thereof, said sides connected by a feedpoint slit.

23. The antenna of claim 22, wherein the multiple slits for each side of said antenna are connected together through a central backbone slit such that each side of said antenna resembles a pitchfork.

24. The antenna of claim 22, wherein each side of said antenna includes a pair of in-line short slits, a pair of in-line medium size slits and a pair of in-line long slits.

25. The antenna of claim 24, wherein the overall length of said in-line short slits is equal to one-half wavelength at the highest frequency at which said antenna is to operate.

26. The antenna of claim 25, wherein the overall length of said in-line long slits is equal to one wavelength at the highest frequency at which said antenna is to operate.

27. The antenna of claim 20, wherein the tips of said slits define a trapezoidal envelope, with the sides of said trapezoidal forming a 45 degree angle at the base thereof.

28. The antenna of claim 20, wherein said cavity-backed slot antenna has short slits spaced from long slits and wherein the width of the antenna as measured by the shortest distance between said short slits and said long slits is no more than one-quarter wavelength at the highest frequency at which said antenna is to operate.