Radio frequency lens and method of suppressing side-lobes

• US 7,777,690 B2
• Filed: 03/30/2007
• Issued: 08/17/2010
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Winsor, Robert Scott
• Primary Examiner(s): MANCUSO, HUEDUNG XUAN CAO
• Application Number:
  US11/693,817
• Publication Number:
  US 20080238810A1
• Time in Patent Office: 1,236 Days
• Field of Search: 343/909, 343/754, 343/911.R, 359/321, 298/322
• US Class Current: 343/911.00R
• CPC Class Codes: H01Q 15/02 Refracting or diffracting devices, e.g. lens, prism
• CPC Class Codes: H01Q 15/08 formed of solid dielectric material
• CPC Class Codes: H01Q 15/10 comprising three-dimensional array of impedance discontinuities, e.g. holes in conductive surfaces or conductive discs forming artificial dielectric
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H01Q 19/06 using refracting or diffracting devices, e.g. lens radome H01Q1/42

Abstract

An RF lens according to the present invention embodiments collimates an RF beam by refracting the beam into a beam profile that is diffraction-limited. The lens is constructed of a lightweight mechanical arrangement of two or more materials, where the materials are arranged to form a photonic crystal structure (e.g., a series of holes defined within a parent material). The lens includes impedance matching layers, while an absorptive or apodizing mask is applied to the lens to create a specific energy profile across the lens. The impedance matching layers and apodizing mask similarly include a photonic crystal structure. The energy profile function across the lens aperture is continuous, while the derivatives of the energy distribution function are similarly continuous. This lens arrangement produces a substantial reduction in the amount of energy that is transmitted in the side-lobes of an RF system.

Claims

1. A beam manipulating device to manipulate a radio frequency (RF) beam comprising:

a refraction layer to refract an incident RF beam at a desired angle, wherein said refraction layer includes a first photonic crystal structure with a first parent material including a first dielectric constant varied across said first parent material to produce an electromagnetic field to refract said incident RF beam; and

at least one impedance matching layer to impedance match said refraction layer, wherein said at least one impedance matching layer includes a second photonic crystal structure with a second parent material including a second dielectric constant varied across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer and minimize surface reflections.

2. The device of claim 1, further including:

an absorbing mask layer to absorb extraneous energy and suppress emission of side-lobes from said incident RF beam.

3. The device of claim 2, wherein said device includes at least one of a lens and a prism.

4. The device of claim 1, wherein said first photonic crystal structure includes:

a first series of holes defined in said first parent material in a manner to vary said first dielectric constant across said first parent material to refract said incident RF beam at said desired angle.

5. The device of claim 2, wherein said device includes a pair of said impedance matching layers surrounding said refraction layer.

6. The device of claim 5, wherein said absorbing mask layer is attached to an impedance matching layer facing said incident RF beam.

7. A beam manipulating device to manipulate a radio frequency (RF) beam comprising:

a refraction layer to refract an incident RF beam at a desired angle, wherein said refraction layer includes a first photonic crystal structure that produces an electromagnetic field to refract said incident RF beam, wherein said first photonic crystal structure includes;

a first parent material including a first dielectric constant; and

a first series of holes defined in said first parent material in a manner to vary said dielectric constant across said first parent material to produce said electromagnetic field for refracting said incident RF beam at said desired angle; and

at least one impedance matching layer to impedance match said refraction layer, wherein at least one impedance matching layer includes a second photonic crystal structure including;

a second parent material including a second dielectric constant; and

a second series of holes defined in said second parent material in a manner to vary said dielectric constant across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer.

8. A beam manipulating device to manipulate a radio frequency (RF) beam comprising:

a refraction layer to refract an incident RF beam at a desired angle, wherein said refraction layer includes a first photonic crystal structure that produces an electromagnetic field to refract said incident RF beam;

at least one impedance matching layer to impedance match said refraction layer; and

an absorbing mask layer to absorb extraneous energy and suppress emission of side-lobes from said incident RF beam, wherein said absorbing mask layer includes a photonic crystal structure including;

a parent material including an absorbing property; and

a series of holes defined in said parent material in a manner to vary said absorbing property across said parent material to provide a desired absorption profile and reduce said side-lobes from said incident RF beam.

9. In a beam manipulating device including a refraction layer and at least one impedance matching layer, a method of manipulating a radio frequency (RF) beam comprising:

(a) refracting an incident RF beam at a desired angle by producing an electromagnetic field via a first photonic crystal structure within said refraction layer, wherein said first photonic crystal structure includes a first parent material including a first dielectric constant varied across said first parent material to produce said electromagnetic field to refract said incident RF beam; and

(b) impedance matching said refraction layer via said at least one impedance matching layer, wherein said at least one impedance matching layer includes a second photonic crystal structure with a second parent material including a second dielectric constant varied across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer and minimize surface reflections.

10. The method of claim 9, wherein said beam manipulating device further includes an absorbing mask and said method further includes:

(c) absorbing extraneous energy and suppressing emission of side-lobes from said incident RF beam via said absorbing mask.

11. The method of claim 10, wherein said beam manipulating device includes at least one of a lens and a prism.

12. The method of claim 9, wherein step (a) further includes:

(a.1) defining a first series of holes within said first parent material in a manner to vary said first dielectric constant across said first parent material to refract said incident RF beam at said desired angle.

13. The method of claim 10, wherein said beam manipulating device includes a pair of said impedance matching layers, and step (b) further includes:

(b.1) surrounding said refraction layer with said pair of said impedance matching layers.

14. The method of claim 13, wherein step (c) further includes:

(c.1) attaching said absorbing mask to an impedance matching layer facing said incident RF beam.

15. In a beam manipulating device including a refraction layer and at least one impedance matching layer, a method of manipulating a radio frequency (RF) beam comprising:

(a) refracting an incident RF beam at a desired angle by producing an electromagnetic field via a first photonic crystal structure within said refraction layer, wherein said first photonic crystal structure includes a first parent material with a first dielectric constant, and step (a) further includes;

(a.1) defining a first series of holes within said first parent material in a manner to vary said dielectric constant across said first parent material to produce said electromagnetic field for refracting said incident RF beam at said desired angle; and

(b) impedance matching said refraction layer via at least one impedance matching layer, wherein at least one impedance matching layer includes a second photonic crystal structure including a second parent material with a second dielectric constant, and step (b) further includes;

(b.1) defining a second series of holes within said second parent material in a manner to vary said second dielectric constant across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer.

16. In a beam manipulating device including a refraction layer, at least one impedance matching layer and an absorbing mask, a method of manipulating a radio frequency (RF) beam comprising:

(a) refracting an incident RF beam at a desired angle by producing an electromagnetic field via a first photonic crystal structure within said refraction layer;

(b) impedance matching said refraction layer via at least one impedance matching layer; and

(c) absorbing extraneous energy and suppressing emission of side-lobes from said incident RF beam via said absorbing mask, wherein said absorbing mask includes a photonic crystal structure including a parent material with an absorbing property, and step (c) further includes;

(c.1) defining a series of holes within said parent material in a manner to vary said absorbing property across said parent material to provide a desired absorption profile and reduce said side-lobes from said incident RF beam.

17. A system for manipulating a radio frequency (RF) beam comprising:

a signal source providing an RF beam;

a beam manipulating device to refract said RF beam at a desired angle, wherein said beam manipulating device includes;

a refraction layer including a first photonic crystal structure with a first parent material including a first dielectric constant varied across said first parent material to produce an electromagnetic field to refract said RF beam; and

at least one impedance matching layer to impedance match said refraction layer, wherein said at least one impedance matching layer includes a second photonic crystal structure with a second parent material including a second dielectric constant varied across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer and minimize surface reflections.

18. The system of claim 17, wherein said beam manipulating device includes:

an absorbing mask layer to absorb extraneous energy and suppress emission of side-lobes from said RF beam.

19. The system of claim 18, wherein said first photonic crystal structure includes:

a first series of holes defined in said first parent material in a manner to vary said first dielectric constant across said first parent material to refract said RF beam at said desired angle.

20. The system of claim 17 further including:

a plurality of said beam manipulating devices each including a corresponding photonic crystal structure configured to refract said RF beam at a different angle and provide a different RF beam pattern, wherein said plurality of beam manipulating devices are interchangeable within said system to provide said differing beam patterns.

21. A system for manipulating a radio frequency (RF) beam comprising:

a signal source providing an RF beam;

a beam manipulating device to refract said RF beam at a desired angle, wherein said beam manipulating device includes a refraction layer including a first photonic crystal structure that produces an electromagnetic field to refract said RF beam, wherein said first photonic crystal structure includes;

a first parent material including a first dielectric constant; and

a first series of holes defined in said first parent material in a manner to vary said first dielectric constant across said first parent material to produce said electromagnetic field for refracting said RF beam at said desired angle;

at least one impedance matching layer to impedance match said refraction layer, wherein at least one impedance matching layer includes a second photonic crystal structure including;

a second parent material including a second dielectric constant; and

a second series of holes defined in said second parent material in a manner to vary said second dielectric constant across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer; and

an absorbing mask layer to absorb extraneous energy and suppress emission of side-lobes from said RF beam.

22. The system of claim 21, wherein said absorbing mask layer includes a third photonic crystal structure including:

a third parent material including an absorbing property; and

a third series of holes defined in said third parent material in a manner to vary said absorbing property across said third parent material to provide a desired absorption profile and reduce said side-lobes from said RF beam.

23. In a system for manipulating a radio frequency (RF) beam including a signal source and a beam manipulating device including a refraction layer and at least one impedance matching layer, a method of manipulating said RF beam comprising:

(a) providing an RF beam from said signal source; and

(b) refracting said RF beam at a desired angle by producing an electromagnetic field via a first photonic crystal structure within said refraction layer and impedance matching said refraction layer via said at least one impedance matching layer, wherein said first photonic crystal structure includes a first parent material including a first dielectric constant varied across said first parent material to produce said electromagnetic field to refract said RF beam, and wherein said at least one impedance matching layer includes a second photonic crystal structure with a second parent material including a second dielectric constant varied across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer and minimize surface reflections.

24. The method of claim 23, wherein said system further includes a plurality of said beam manipulating devices each including a corresponding photonic crystal structure configured to refract said RF beam at a different angle and provide a different RF beam pattern, and step (b) further includes:

(b.1) interchanging said beam manipulating devices within said system to provide said differing beam patterns.

25. In a system for manipulating a radio frequency (RF) beam including a signal source and a beam manipulating device, wherein said beam manipulating device includes a refraction layer including a first photonic crystal structure, at least one impedance matching layer and an absorbing mask, a method of manipulating said RF beam comprising:

(a) providing an RF beam from said signal source; and

(b) refracting said RF beam at a desired angle by producing an electromagnetic field via said first photonic crystal structure within said beam manipulating device, wherein step (b) further includes;

(b.1) refracting said RF beam via said refraction layer;

(b.2) impedance matching said refraction layer via said at least one impedance matching layer; and

(b.3) absorbing extraneous energy and suppressing emission of side-lobes from said RF beam via said absorbing mask.

26. The method of claim 25, wherein said first photonic crystal structure includes a first parent material with a first dielectric constant, and step (b.1) further includes:

(b.1.1) defining a first series of holes within said first parent material in a manner to vary said first dielectric constant across said first parent material to produce said electromagnetic field for refracting said RF beam at said desired angle.

27. The method of claim 26, wherein at least one impedance matching layer includes a second photonic crystal structure including a second parent material with a second dielectric constant, and step (b.2) further includes:

(b.2.1) defining a second series of holes within said second parent material in a manner to vary said second dielectric constant across said second parent material in proportion to said first dielectric constant of said first parent material to impedance match said refraction layer.

28. The method of claim 27, wherein said absorbing mask includes a third photonic crystal structure including a third parent material with an absorbing property, and step (b.3) further includes:

(b.3.1) defining a third series of holes within said third parent material in a manner to vary said absorbing property across said third parent material to provide a desired absorption profile and reduce said side-lobes from said RF beam.