Millimeter wave filters

• US 8,106,810 B2
• Filed: 11/03/2008
• Issued: 01/31/2012
• Est. Priority Date: 07/03/2008
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Holly, Sandor, Koumvakalis, Nicholas, Smith, Robert A.
• Primary Examiner(s): Brainard, Timothy A
• Application Number:
  US12/264,128
• Publication Number:
  US 20100001894A1
• Time in Patent Office: 1,184 Days
• Field of Search: 342/1, 342/5, 343/812
• US Class Current: 342/1
• CPC Class Codes: A61F 9/022 Use of special optical filters, e.g. multiple layers, filters for protection against laser light or light from nuclear explosions, screens with different filter properties on different parts of the screen; Rotating slit-discs optical filters per se G02B5/20
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective

Abstract

An electromagnetic radiation filter uses a plurality of dipole antennas to mitigate the transmission of electromagnetic radiation. The dipole antennas can form one or more arrays that scatter electromagnetic radiation. Examples of application include mitigating the reception of a difference frequency in non-linear radar, use in protective goggles, and use in a protective shield.

Claims

1. An electromagnetic radiation filter for filtering a difference frequency signal having a frequency Δ

f equaling a difference between a first scattering frequency f₁ and a second scattering frequency f₂, comprising;

a dielectric substrate defining a plane; and

a plurality of dipole antennas arranged in rows on the substrate, wherein each dipole is a one-half wavelength dipole at a frequency between the scattering frequencies f₁ and f₂, and wherein the dipoles in each row are spaced apart to form an end-fire array at the scattering frequencies such that electromagnetic radiation at the scattering frequencies perpendicularly incident to the substrate is scattered in the plane and wherein the difference frequency signal perpendicularly incident to the substrate passes though the substrate.

2. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are configured to scatter millimeter wave electromagnetic radiation.

3. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are substantially parallel with respect one another.

4. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in a two-dimensional array thereof.

5. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in two-dimensional arrays thereof with one two-dimensional array on each surface of the substrate.

6. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in a three-dimensional array thereof.

7. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in a three-dimensional array thereof, the three-dimensional array comprising a stack of two-dimensional arrays of dipole antennas.

8. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in a three-dimensional array thereof, the three-dimensional array comprising alternating layers of substrates and dipole antennas.

9. The electromagnetic radiation filter as recited in claim 1, wherein the dipole antennas are formed in a three-dimensional array thereof, the three-dimensional array comprising a plurality of layers of dipole antennas, the dipole antennas within each layer having substantially the same dimensions.

10. A method for filtering a difference frequency signal having a frequency Δ

f equaling a difference between a first scattering frequency f₁ and a second scattering frequency f₂, the method comprising;

providing a planar dielectric substrate defining a plane that includes a plurality of dipole antennas arranged in rows on the substrate, wherein each dipole is a one-half wavelength dipole at a frequency between the scattering frequencies f₁ and f₂ and wherein the dipoles in each row are spaced apart to form an end-fire array at the scattering frequencies such that electromagnetic radiation at the scattering frequencies perpendicularly incident to the substrate is scattered in the plane;

receiving electromagnetic radiation at the scattering frequencies perpendicularly to the substrate;

scattering the electromagnetic radiation at the scattering frequencies through the end-fire arrays in the plane defined by the substrate

receiving perpendicularly incident difference frequency electromagnetic radiation at the substrate; and

passing the incident difference frequency electromagnetic radiation through the substrate.

11. An antenna for non-linear radar system comprising:

a horn; and

a filter for inhibiting reception of electromagnetic radiation at a scattering frequency f₁ and a scattering frequency f₂ by the horn, the filter comprising a plurality of dipole antennas arranged in rows on a dielectric substrate defining a plane, wherein each dipole is a one-half wavelength dipole at a frequency between the scattering frequencies, a plurality of non-linear resonant circuits corresponding to the plurality of dipole antennas, and wherein the dipoles in each row are spaced apart to form an end-fire array at the scattering frequencies such that electromagnetic radiation at the scattering frequencies perpendicularly incident to the substrate is scattered in the plane and wherein electromagnetic radiation at a difference frequency equaling a difference between f₁ and f₂ perpendicularly incident to the substrate passes through the substrate;

wherein each of the dipole antennas comprises two antennas that are joined by a nonlinear resonant circuit.