Fragmented aperture antennas and broadband antenna ground planes

• US 6,323,809 B1
• Filed: 05/26/2000
• Issued: 11/27/2001
• Est. Priority Date: 05/28/1999
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Harms, Paul H., Smith, Glenn Stanley, Kesler, Morris Philip, Maloney, James Geoffrey
• Primary Examiner(s): Le, Hoanganh
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US09/579,560
• Time in Patent Office: 550 Days
• Field of Search: 343/700.MS, 343/846, 343/844, 343/853, 343/829, 343/770
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 15/14 Reflecting surfaces; Equivalent structures electromagnetic shields H01Q1/526
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/0442 with particular tuning means

Abstract

The present invention provides a fragmented aperture antenna. The antenna includes a planar layer having a plurality of conductive and substantially non-conductive areas. Each area has a periphery that extends along a grid of first and second sets of parallel lines so that each area comprises one or more contiguous elements defined by the parallel lines. The locations of the conducting materials in the fragmented aperture antenna are determined by a multi-stage optimization procedure that tailors the performance of the antenna to a particular application. The resulting configuration and arrangement of conductive and substantially non-conductive areas enable communication of electromagnetic energy wirelessly in a specific direction to the planar layer when an electrical connection is made to at least one of the conductive areas.

Claims

1. An antenna, comprising:

a planar layer having a plurality of first areas and a plurality of second areas, said first areas being more conductive than said second areas;

wherein each area has a periphery that extends along a grid of first and second sets of parallel lines so that each area comprises one or more contiguous elements defined by said lines; and

wherein said first and second areas are configured and arranged so that said planar layer can communicate electromagnetic energy wirelessly in a specific direction to said planar layer when an electrical connection is made to at least one of said first areas.

2. The antenna of claim 1, wherein said first and second sets of parallel lines are orthogonal, said elements are squares, and each said area is a square, rectangle, or geometric region having orthogonally diverging contiguous segments.

3. The antenna of claim 1, wherein said first areas comprise a conductive or semiconductive material and said second areas comprise a dielectric or semiconductive material.

4. The antenna of claim 1, further comprising a switch capable of electrically coupling at least two of said first areas.

5. The antenna of claim 4, wherein the switch is a micro-electromechanical switch.

6. The antenna of claim 4, wherein the switch is a PIN diode.

7. The antenna of claim 4, wherein the switch is a radio frequency (RF) transistor.

8. The antenna of claim 4, wherein the switch is a latch switch.

9. The antenna of claim 4, wherein the antenna can be configured to realize optimized patterns arranged to operate over specific bands of frequency and directions of radiation.

10. The antenna of claim 1, further comprising one or more other planar layers serving as a ground plane and situated substantially parallel to said planar layer that communicates said electromagnetic energy.

11. The antenna of claim 10, wherein one or more of said other planar layers comprises pluralities of said first and second areas.

12. The antenna of claim 10, further comprising a switch capable of electrically coupling at least two of said first areas of said other planar layers.

13. The antenna of claim 1, further comprising one or more other planar layers situated adjacent to and substantially in the same plane as said planar layer so that said layers together can operate as an antenna array.

14. The antenna of claim 13, wherein the size and spacing of the antenna array is selected to reduce grating lobes.

15. The antenna of claim 1, wherein said first and second areas of said planar layer are symmetric about each of two orthogonal lines situated in the plane of said planar layer.

16. A method for making an antenna, comprising the steps of:

defining a planar grid defined by first and second sets of parallel lines so that the grid comprises a plurality of elements defined by the lines; and

determining a first plurality of said elements that should be substantially conductive and a second plurality of said elements that should be substantially nonconductive so that a hypothetical antenna formed from said planar grid elements exhibits a desired frequency spectrum.

17. The method of claim 16, further comprising the steps of:

dividing said grid into a plurality of areas;

performing said determining step for one of said areas to derive a pattern of elements for said area; and

replicating said pattern in other areas.

18. The method of claim 16, further comprising the step of utilizing a genetic code to perform said determining step.

19. The method of claim 18, further comprising the step of simulating the electromagnetic characteristics of said, antenna with a genetic sequence program.

20. The method of claim 16, further comprising the step of defining an antenna comprising:

a planar layer having a plurality of substantially conductive areas and a plurality of substantially nonconductive areas;

wherein each area has a periphery that extends along said grid so that each area comprises one or more of said elements defined by said lines; and

wherein said areas are configured and arranged so that said planar layer can communicate electromagnetic energy wirelessly in a specific direction to said planar layer when an electrical connection is made to at least one of said conductive areas.

21. The method of claim 20, further comprising the step of evaluating an effect on said frequency spectrum of one or more other planar layers serving as a ground plane and situated substantially parallel to said planar layer that communicates said electromagnetic energy.

22. The method of claim 21, further comprising the step of evaluating an effect on said frequency spectrum of a switch capable of electrically coupling at least two elements of said other planar layers.

23. The method of claim 20, further comprising the step of evaluating an effect on said frequency spectrum of one or more other planar layers situated adjacent to and substantially in the same plane as said planar layer so that said layers together serve as an antenna array.

24. The method of claim 16, further comprising the steps of:

representing said elements of said grid with a set of bit values;

mapping a geometric shape having an area greater than one of said elements across said grid;

defining said bit values based upon said mapping; and

performing said determining step based upon said bit values.

25. The method of claim 16, wherein said first and second sets of parallel lines are orthogonal and said elements are squares.

26. The method of claim 16, further comprising the step of defining areas with said elements, each said area being a square, rectangle, or geometric region having orthogonally diverging contiguous segments.

27. The method of claim 16, further comprising the step of evaluating an effect on said frequency spectrum of a switch capable of electrically coupling at least two of said conductive elements.

28. The method of claim 16, wherein said conductive and nonconductive elements are symmetric about each of two orthogonal lines situated in the plane of said grid.

29. The antenna of claim 16, wherein the substantially conductive element is conductive ink containing silver particles arranged on a substrate.

30. The antenna of claim 16, wherein the substantially conductive element is resistive ink containing carbon particles arranged on a substrate.

31. The antenna of claim 16, wherein the planar grid is flexible so that it can be molded to conform to the shape of three dimensional objects.

32. An antenna made by the process of:

arranging a plurality of conducting strips in an optimized sequence according to desired performance quality for said antenna; and

modifying conductor configuration at one or more randomly selected locations on said antenna until said antenna acquires said desired performance quality.

33. The antenna of claim 32, wherein a conductor is removed if said location contains a conductor, wherein a conductor is inserted if no conductor is contained in said location.

34. A two-stage process to synthesize a design of a fragmented aperture antenna in three dimensions using a computer, the process comprising the steps of:

loading a computer with a genetic algorithm model and an electromagnetic code, the genetic algorithm model being a preselected set of permutations of alternative geometric configuration possibilities for a fragmented aperture antenna within a three-dimensional volume and wherein the electromagnetic code is a correlation model that correlates fragmented aperture antenna prospectives from genetic antenna configurations;

specifying to the computer a desired set of electromagnetic antenna element properties;

directing the computer to identify a first set of fragmented aperture antenna designs from the fragmented aperture antenna prospectives by testing the preselected set of permutations proposed by the genetic algorithm using in three dimensions the electromagnetic code;

directing the computer to identify a final set of fragmented aperture antenna designs from the first set of fragmented aperture antenna designs by testing the first set of fragmented aperture antenna designs by the genetic algorithm using in three dimensions the electromagnetic code;

selecting a fragmented aperture antenna design from the final set of fragmented aperture antenna designs; and

wherein the fragmented aperture antenna is quadrantly symmetrical with a centrally located transmission feed line.

35. A process to synthesize a design of a printed fragmented aperture antenna in three dimensions using a computer, said process comprising the following steps:

loading an algorithm comprising a space of possible solutions represented by some representational scheme which, by some iterative process, will converge to an optimal solution, to be used in conjunction with an electromagnetic code onto a computer;

specifying a desired set of electromagnetic properties for the fragmented aperture antenna element to be designed;

defining size, geometry and/or features of said fragmented aperture antenna;

specifying a sample population size to be randomly or otherwise selected from among all possible fragmented aperture antenna configurations based upon said size, geometry, and/or features of said fragmented aperture antenna;

computing electromagnetic properties of a plurality of conducting and non-conducting elements in each fragmented aperture antenna configuration in three dimensions in the sample population using the electromagnetic code and rank solutions in order of performance, wherein the fragmented aperture antenna comprises a centrally located transmission feed;

modifying the population by a method that brings the population incrementally closer to an optimum solution;

repeating this iterative process a specified number of generations or until the population fitness reaches equilibrium which is considered an optimal solution.