BROADBAND COMPOSITE DIPOLE ANTENNA ARRAYS FOR OPTICAL WAVE MIXING

• US 20080291108A1
• Filed: 05/24/2007
• Published: 11/27/2008
• Est. Priority Date: 05/24/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Holly, Sandor, Mack, William Daniel
• Granted Patent: US 7,796,092 B2
• Time in Patent Office: Days
• US Class Current: 343/814
• CPC Class Codes: H01Q 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them

Abstract

A broadband composite dipole array (CDA) includes an array of macro dipoles on a non-conducting substrate adapted to receive radiation at two frequencies. Each macro dipole is an array of micro dipoles adapted to receive radiation at substantially the mean of the two frequencies. The micro-dipoles are coupled to each other by a parallel resonant circuit including a nonlinear element, wherein the minimum impedance of the circuit is a substantially short circuit at the difference frequency f1-f2, and the circuit has a substantially open circuit impedance in the range of frequencies from f1 to f2. The micro dipoles resonate efficiently at both frequencies f1 and f2 with low-loss. The nonlinear element in the resonant circuit generates a signal at the difference frequency which is the resonant frequency of the macro dipole antenna. A composite of macro dipole antennas couple electromagnetically via a cluster of micro-dipole elements to broaden the bandwidth over a range of frequencies from f1 to f2 at which the macro dipole antenna resonates.

Claims

1. A composite macro dipole antenna array comprising:

at least one non-conducting substrate; and

a plurality of macro composite dipole antennas disposed on the substrate generally parallel to each other.

2. The antenna array of claim 1, wherein each macro composite dipole antenna further comprises:

a plurality of micro dipole antennas arranged in a linear column array in one dimension on the substrate surface; and

a plurality of reactive circuits including a nonlinear component disposed between each of the micro dipole antennas and electrically coupled to the micro dipoles.

3. The antenna array of claim 1, further comprising:

a plurality of micro dipole elements arranged on the substrate surface spaced apart from and parallel to each other and disposed between and parallel to one or more of the plurality of micro dipole antennas in the plurality of macro composite dipole antennas.

4. The macro composite dipole antenna array of claim 1, wherein the array of the plurality of macro composite dipole antennas disposed on the substrate parallel to each other is disposed in a plurality of rows on the substrate, thus forming a two dimensional composite array.

5. The macro composite dipole antenna array of claim 1, wherein the array is disposed on two or more substrates arranged relative to each other, thus forming a two or three dimensional macro composite dipole antenna array.

6. The macro composite dipole antenna array of claim 1, wherein the plurality of micro dipole antennas each have an effective length corresponding to a half wavelength at a frequency approximately at the midpoint frequency between two selected frequencies f1 and f2, and each micro dipole antenna is resonant substantially at the midpoint frequency.

7. The macro composite dipole antenna array of claim 6, wherein each macro composite dipole antennas has an effective length l corresponding to a half wavelength at the difference frequency Δ

f=f1−

f2, and wherein each macro composite dipole antenna is resonant at Δ

f.

8. The macro composite dipole antenna array of claim 7, wherein the reactive circuits behave substantially as a parallel resonant short circuits between each of the adjacent micro dipole antennas at the difference frequency Δ

f=f1−

f2.

9. The macro composite dipole antenna array of claim 8, wherein the nonlinear component in the reactive circuit nonlinearly couples radiation at the two frequencies f1 and f2 to generate the difference frequency Δ

f=f1−

f2.

10. The macro dipole composite antenna array of claim 9, wherein the reactive circuit is a quarter wave transmission line that is substantially parallel resonant at the frequencies f1 and f2.

11. The macro composite dipole antenna array of claim 10, wherein the nonlinear component in the reactive circuit is positioned in the reactive circuit at a location wherein the impedance of the nonlinear component is matched to the impedance of the quarter wave transmission line, thereby generating the difference frequency with maximum efficiency.

12. The macro composite dipole antenna array of claim 11, wherein the nonlinear component in the reactive circuit is a diode.

13. The macro composite dipole antenna array of claim 6, wherein the non-conducting substrate is characterized by a dielectric constant, the micro dipole antennas are conductive strips characterized by a thickness t normal to the surface of the substrate, and a width w in the plane of the substrate perpendicular to the length.

14. The macro composite dipole antenna array of claim 13, wherein the plurality of micro dipole elements are conductive strips characterized by a thickness t′

normal to the surface of the substrate, a length l′

, where l′

is equal to or less than l, and a width w′

in the plane of the substrate perpendicular to the length l′

.

15. The macro composite dipole antenna array of claim 14, wherein the micro dipole elements are spaced apart from each other by a spacer distance s on the surface of the substrate.

16. The macro composite dipole antenna array of claim 15, wherein the first dipole element and the last dipole element of each plurality of micro dipole elements are parallel and spaced apart from respective adjacent micro dipole antennas by a spacer distance s′

.

17. The macro composite dipole antenna array of claim 16, wherein, based at least on the substrate dielectric constant, conductor thicknesses t and t′

, lengths l and l′

, widths w and w′

, and spacer distances s and s′

, the micro dipole antennas and micro dipole elements couple electromagnetically to provide a multi-pole coupled bandwidth from frequencies f1 to f2 corresponding to the difference frequency Δ

f=f1−

f2.

18. A method of converting frequencies using a macro composite dipole antenna array, comprising:

transmitting a first electromagnetic beam at a first frequency;

transmitting a second electromagnetic beam at a second frequency offset from the first frequency by a third frequency which is a difference frequency;

receiving the first and second electromagnetic beams at the macro composite dipole antenna array; and

transmitting an electromagnetic beam at a third frequency from the macro composite dipole antenna array.

19. The method of claim 18, further comprising converting the first and second frequencies to the third frequency using a plurality of nonlinear circuit elements configured in the antenna array to generate the difference frequency.

20. A method of converting an image provided with electromagnetic radiation at one frequency to an image provided with electromagnetic radiation at another frequency comprising:

focusing a first image provided by a first beam of electromagnetic radiation at a first frequency on a macro composite dipole antenna array;

illuminating the macro composite dipole antenna array with a second beam of electromagnetic radiation at a second frequency;

generating in the macro composite dipole antenna array a third electromagnetic beam with a third frequency; and

imaging the third beam with an imaging device adapted to detect radiation at the third frequency.