METHODS AND APPARATUS FOR REDUCING RADIO FREQUENCY INTERFERENCE FOR COLLOCATED ANTENNAS

• US 20070257856A1
• Filed: 03/30/2007
• Published: 11/08/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Peterson, Lewis
• Granted Patent: US 7,612,731 B2
• Time in Patent Office: Days
• US Class Current: 343/840
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 15/0026 said selective devices having a stacked geometry or having multiple layers

Abstract

Methods and apparatus for a plate to prevent energy from a first antenna from interfering with a collocated second antenna. In one embodiment, the plate includes first and second conductive layers to shadow the second antenna and thereby block energy from reaching the second antenna. A resonant quarter wavelength spacing of the plates forces energy broadside minimizing the spillover the edge caused by diffraction. Multiple conductive layers having increasing radii can block diffracted energy from spilling over and around the plate. The multiple plates of increasing radii affect a waterfall-like spill wherein energy is lost in each level.

Claims

1. An apparatus, comprising:

a first conductive layer;

a dielectric layer proximate the first conductive layer; and

a second conductive layer substantially parallel to the first conductive layer and proximate the dielectric layer so that the first and second conductive layers sandwich the dielectric layer to create a resonant cavity for reducing radio frequency interference between a collocated first antenna and a second antenna operating in a first frequency band.

2. The apparatus according to claim 1, wherein the first and second layers are parallel to within a tenth of a wavelength within the frequency band.

3. The apparatus according to claim 1, wherein the first conductive layer has a surface area that is sufficient to shadow the first antenna from the second antenna.

4. The apparatus according to claim 1, wherein the first and second conductive layers are disposed in parallel with a distance between the first and second conductive layers being one-quarter of a wavelength of an operating frequency of the first antenna within the first frequency band.

5. The apparatus according to claim 4, wherein a thickness of the dielectric layer is selected to take into account attenuation of velocity of wave propagation to achieve the one-quarter wavelength.

6. The apparatus according to claim 1 wherein the dielectric layer includes a foam material.

7. The apparatus according to claim 1, further including a third conductive layer generally parallel to the second conductive layer.

8. The apparatus according to claim 7, wherein a distance between adjacent one of the first, second, and third conductive layers is one-quarter wavelength of the operating frequency within the first frequency band.

9. The apparatus according to claim 1 wherein the first and second conductive layers are concentric circular disks.

10. The apparatus according to claim 1, wherein the first plate optically shadows the second antenna.

11. The apparatus according to claim 1, further including a third conductive layer and a fourth conductive layer and a further dielectric layer so that the third and fourth conductive layers sandwich the further conductive layer to create a further resonant cavity for reducing radio interference by the second antenna from the first antenna, wherein the first and second conductive layers operate to reduce radio interference by the first antenna of the second antenna.

12. An antenna installation system, comprising:

a first antenna;

a second antenna collocated with the first antenna; and

a plate optically shadowing the second antenna from the first antenna, wherein the plate comprises;

a first conductive layer;

a dielectric layer proximate the first conductive layer; and

a second conductive layer substantially parallel to the first conductive layer and proximate the dielectric layer so that the first and second conductive layers sandwich the dielectric layer to create a resonant cavity for reducing radio frequency interference between a collocated first antenna and a second antenna operating in a first frequency band.

13. The system according to claim 12, wherein the first and second conductive layers are disposed in parallel with a distance between the first and second conductive layers being one-quarter of a wavelength of an operating frequency of the first antenna within the first frequency band.

14. The system according to claim 12, further including a third conductive layer generally parallel to the second conductive layer.

15. The system according to claim 12, wherein the first and second conductive layers are concentric circular disks.

16. A method, comprising:

providing a first conductive layer;

providing a dielectric layer proximate the first conductive layer;

providing a second conductive layer substantially parallel to the first conductive layer and proximate the dielectric layer so that the first and second conductive layers sandwich the dielectric layer to create a resonant cavity for reducing radio frequency interference between a collocated first antenna and a second antenna operating in a first frequency band.

17. The method according to claim 16, wherein the first and second conductive layers are disposed in parallel with a distance between the first and second conductive layers being one-quarter of a wavelength of an operating frequency of the first antenna within the first frequency band.

18. The method according to claim 16, wherein the dielectric layer includes a foam material.

19. The method according to claim 16, wherein the first and second conductive layers are concentric circular disks.

20. The method according to claim 16, wherein the plate optically shadows the second antenna.