Low profile, dual polarized/pattern antenna

• US 6,864,856 B2
• Filed: 06/10/2003
• Issued: 03/08/2005
• Est. Priority Date: 06/10/2002
• Status: Expired due to Fees

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Colburn, Joseph S., Lynch, Jonathan J.
• Primary Examiner(s): Nguyen, Hoang V.
• Application Number:
  US10/459,117
• Publication Number:
  US 20040027308A1
• Time in Patent Office: 637 Days
• Field of Search: 343/895, 343/700.MS, 343/850, 343/853, 343/846
• US Class Current: 343/895
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 9/27 Spiral antennas
• CPC Class Codes: H01Q 9/36 with top loading

Abstract

A spiral antenna system optimized to transmit and/or receive linearly polarized signals and circularly polarized signals. The antenna system includes a spiral antenna and a circuit for exciting the spiral antenna to transmit or receive linearly polarized and circularly polarized signals simultaneously.

Claims

1. A method of transmitting and/or receiving linearly polarized signals and circularly polarized signals within a frequency band, the method comprising:

providing a spiral antenna with a plurality of arms, where n equals the number of arms in said plurality of arms;

exciting said plurality of arms whereby adjacent arms have a phase shift of 720/n degrees between them for transmission and/or reception of circularly polarized signals;

supporting said spiral antenna at a distance above a ground plane; and

exciting a pair of conductors with respect to said ground plane and in phase with each other for transmission and/or reception of linearly polarized signals.

2. The method of claim 1 wherein a feed coaxial cable comprises said pair of conductors.

3. The method of claim 1 wherein said step of exciting said plurality of arms and said step of exciting a pair of conductors occurs independently or simultaneously.

4. The method of claim 1 wherein n equals 4.

5. The method of claim 1 further comprising the step of placing at least one resistor on at least one of said plurality of arms.

6. The method of claim 5 wherein the step of placing further comprises locating the at least one resistor at a distance of a quarter wavelength of a center frequency of said frequency band from an end of the at least one of said plurality of arms.

7. The method of claim 1 wherein the step of providing a spiral antenna with a plurality of arms includes disposing said spiral antenna with said plurality of arms on a planar surface.

8. The method of claim 1 wherein the step of providing a spiral antenna with a plurality of arms includes disposing said spiral antenna with said plurality of arms in a planar configuration.

9. The method of claim 7 wherein said linearly polarized signals are transmitted toward or received from a direction at or near a horizon and said circularly polarized signals are transmitted toward or received from a direction 30 to 70 degrees above the plane of said plurality of arms.

10. The method of claim 1 wherein said step of supporting further comprises the step of choosing said distance to optimize an elevation angle of peak radiation.

11. The method of claim 10 wherein said distance is at least 0.2λ

_c, wherein λ

_c is a wavelength at a geometric mean between a minimum and a maximum operating frequency of the spiral antenna.

12. An antenna system comprising:

a spiral antenna having a plurality of arms;

a ground plane located a distance from said spiral antenna; and

a feed network located on said ground plane, said feed network coupled with said spiral antenna, wherein said feed network excites said spiral antenna to generate linearly polarized signals and circularly polarized signals.

13. The antenna system of claim 12 wherein said spiral antenna has four arms.

14. The antenna system of claim 12 further comprising a coaxial cable coupled with said spiral antenna and said feed network.

15. The antenna system of claim 12 further comprising a plurality of resistors, each resistor disposed on one of said plurality of arms of said spiral antenna.

16. The antenna system of claim 12 wherein said distance optimizes an elevation angle of peak radiation.

17. The antenna system of claim 16 wherein said distance is at least 0.2λ

_c, wherein λ

_c is a wavelength at a geometric mean between a minimum and a maximum operating frequency of the spiral antenna.

18. The antenna system of claim 12 wherein said spiral antenna including the plurality of arms are disposed in a planar configuration.

19. A spiral antenna system operating within a band of interest, the antenna system comprising:

a spiral antenna having four arms;

a support for supporting said spiral antenna at a distance above a ground plane;

a microstrip circuit connected to said spiral antenna, said microstrip circuit exciting said spiral antenna;

a pair of conductors, having a first end and a second end, said first end coupled to said spiral antenna, said second end coupled to said microstrip circuit; and

wherein said spiral antenna system operates in both a top-loaded monopole mode and a second resonance spiral mode, where the top-loaded monopole mode is for receiving linearly polarized signals and the second resonance spiral mode is for receiving circularly polarized signals.

20. The spiral antenna system of claim 19 further comprising a plurality of resistors, at least one resistor of said plurality of resistors being disposed on one of said four arms of said spiral antenna.

21. The spiral antenna system of claim 20 wherein said at least one resistor is disposed on one of said four arms of said spiral antenna at a distance of a quarter wavelength of a center frequency of the band of interest from an end of one of said four arms.

22. The spiral antenna system of claim 19 wherein said support for supporting said spiral antenna is a polycarbonate cover.

23. The spiral antenna system of claim 19 wherein said distance is at least 0.2λ

_c, wherein λ

_c is a wavelength at a geometric mean between a minimum and a maximum operating frequency of the spiral antenna.

24. The spiral antenna system of claim 19 wherein said microstrip circuit comprises:

a first via and a second via for connecting said microstrip circuit to said spiral antenna;

a quarter wavelength transmission line with a first end and a second end, said first end coupled to said second via; and

a 90 degree hybrid coupler, having a first port, a second port, a third port and a fourth port, said first port of said 90 degree hybrid coupler coupled to said second end of said quarter wavelength transmission line, said second port of said 90 degree hybrid coupler coupled to said first via.

25. An antenna system operating within a band of interest, said antenna system comprising:

a spiral antenna having a plurality of arms;

a planar support substrate for supporting said spiral antenna at a distance above a ground plane, said distance optimizing an elevation angel of peak radiation;

a microstrip circuit connected to said spiral antenna, said microstrip circuit exciting said spiral antenna; and

a plurality of resistors, at least one resistor disposed on one of said plurality of arms of said spiral antenna.

26. The antenna system of claim 25 further comprising a pair of conductors, having a first end and a second end, said first end coupled to said spiral antenna, said second end coupled to said microstrip circuit.

27. The antenna system of claim 25 wherein said distance is at least 0.2λ

_c, wherein λ

_c is a wavelength at a geometric mean between a minimum and a maximum operating frequency of the spiral antenna.

28. The antenna system of claim 25 wherein said at least one resistor is disposed on one of said four arms of said spiral antenna at a distance of a quarter wavelength of a center frequency of the band of interest from an end of one of said four arms.

29. A method for providing a low profile antenna system comprising the steps of:

providing a spiral antenna, having at least one pair of arms;

supporting said spiral antenna at a distance above a ground plane, said distance optimizing an elevation angle of peak radiation;

connecting said spiral antenna to a feed cable, said feed cable having an outer conductor; and

exciting said outer conductor of said feed cable with respect to said ground to generate a monopole.

30. The method of claim 29 wherein said spiral antenna having at least two pairs of arms and further comprising the step of exciting said pairs of arms whereby adjacent arms have a 720/n degrees phase shift between them generating a second resonance spiral mode in said spiral.

31. The method of claim 29 wherein said distance is at least 0.2λ

_c, wherein λ

_c is a wavelength at a geometric mean between a minimum and a maximum operating frequency of the spiral antenna.