FRACTAL DIPOLE ANTENNA

• US 20060170604A1
• Filed: 02/01/2005
• Published: 08/03/2006
• Est. Priority Date: 02/01/2005
• Status: Active Grant

• Current Assignee: ELTA Systems Limited (Government of Israel)
• Original Assignee: ELTA Systems Limited (Government of Israel)
• Inventors: Almog, Benyamin, Habib, Laurent
• Granted Patent: US 7,113,141 B2
• Time in Patent Office: Days
• US Class Current: 343/795
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• 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

Abstract

A dipole fractal antenna and a method of manufacturing thereof are described. The antenna includes a pair of oppositely directed radiating arms coupled to a feeding terminal and extended therefrom along a central axis in a common plane. At least a portion of each radiating arm has a fractal geometric shape. The antenna also includes at least one pair of electrical shunts configured for connecting at least two points selected within the fractal portion of one radiating arm correspondingly to two points selected within the fractal portion of another radiating arm. The dipole fractal antenna further may comprise a balun arranged at the feeding terminal and configured for coupling the pair of oppositely directed radiating arms to a coaxial cable to provide a balanced feed.

Claims

1. A dipole antenna comprising:

a pair of oppositely directed radiating arms coupled to a feeding terminal and extended therefrom along a central axis, at least a portion of each radiating arm having a fractal geometric shape; and

at least one pair of electrical shunts configured for connecting at least two points selected within the fractal portion of one radiating arm correspondingly to two points selected within the fractal portion of another radiating arm.

2. The dipole antenna of claim 1 configured and operable to provide decrease of return losses for the frequency bands provided for another antenna having the same structure as said antenna, but without said at least one pair of electrical shunts.

3. The dipole antenna of claim 1 further comprising a balun arranged at the feeding terminal and configured for coupling said pair of oppositely directed radiating arms to a coaxial cable to provide a balanced feed.

4. The dipole antenna of claim 3 configured and operable to provide one broad frequency band in the frequency band where a plurality of the frequency bands is observed for another antenna having the same structure as said antenna, but without said balun.

5. The dipole antenna of claim 1 wherein said at least two points are selected on opposite edges of the fractal portions of each radiating arm relative to the central axis.

6. The dipole antenna of claim 1 further comprising a substrate made of a nonconductive material, wherein said two radiating arms are formed as a layer of conductive material overlying a surface of said substrate.

7. The dipole antenna of claim 6 wherein said two radiating arms are arranged on one side of said substrate.

8. The dipole antenna of claim 6 wherein one radiating arm of said two radiating arms is arranged on one side of said substrate and another radiating arm of said two radiating arms is arranged on another side of said substrate.

9. The dipole antenna of claim 1 wherein said fractal geometric shape is a Sierpinski gasket.

10. The dipole antenna of claim 9 wherein said feeding terminal is coupled to the apex of each triangular Sierpinski gasket portion.

11. The dipole antenna of claim 9 wherein said at least two points are selected at vertices at the base of each triangular Sierpinski gasket portion.

12. The dipole antenna of claim 9 wherein an iteration ratio of self-similarity of said fractal geometric shape is higher than 2.

13. The dipole antenna of claim 3 wherein an impedance of said radiating arms is matched to the impedance of the coaxial cable.

14. The dipole antenna of claim 3 wherein said balun comprises a first layer of conductive material and a second layer of conductive material arranged on first and second sides of a nonconductive substrate, correspondingly;

each of said first and second layers includes a narrow strip and a wide strip, said narrow and wide strips have proximal and distal ends with respect to the radiating arms, each narrow strip is coupled to a feedpoint of the corresponding radiating arm at its proximal end and to the corresponding wide strip of the same conductive layer via a bridging strip at their distal ends;

said narrow strip of the first layer is positioned beneath the wide strip of the second layer and said narrow strip of the second layer is positioned over the wide strip of the first layer.

16. An electronic device comprising the antenna of claim 1.

17. The electronic device of claim 16 further comprising a balun arranged at the feeding terminal and configured for coupling said pair of oppositely directed radiating arms to a coaxial cable to provide a balanced feed.

18. The electronic device of claim 16 being selected from the group that includes communication devices, jamming stations, radars, and telemetry systems.

19. The electronic device of claim 16 wherein said dipole antenna being configured to operate within the frequency range of about 20 MHz to 40 GHz.

15. A dipole antenna comprising:

a pair of oppositely directed radiating arms coupled to a feeding terminal and extended therefrom along a central axis, at least a portion of each radiating arm having a fractal geometric shape;

at least one pair of electrical shunts configured for connecting at least two points selected within the fractal portion of one radiating arm correspondingly to two points selected within the fractal portion of another radiating arm; and

a balun arranged at the feeding terminal and configured for coupling said pair of oppositely directed radiating arms to a coaxial cable to provide a balanced feed.

20. A method of fabricating a dipole antenna comprising:

forming a pair of oppositely directed radiating arms coupled to and extended from a feeding terminal along a central axis, at least a portion of each radiating arm having a fractal geometric shape; and

forming at least one pair of electrical shunts configured for connecting at least two points selected within the fractal portion of one radiating arm correspondingly to two points selected within the fractal portion of another radiating arm.

21. The method of claim 20 further comprising forming a balun arranged at the feeding terminal and configured for coupling said dipole antenna to a coaxial cable to provide a balanced feed.

22. The method of claim 20 wherein said forming of the pair of radiating arms includes cutting the radiating arms from a solid sheet of conductive material.

23. The method of claim 20 further comprising providing a nonconductive substrate of a predetermined form, and wherein the pair of radiating arms is formed as a layer of electrically conductive material overlaying a surface of said nonconductive substrate.

24. The method of claim 20 wherein said forming of the two electrical shunts includes forming strips of electrically conductive material on the surface of said nonconductive substrate for connecting said at least two points.

25. The method of claim 21 wherein said forming of the balun comprises:

providing a nonconductive substrate of a predetermined form;

providing a first layer of conductive material and a second layer of conductive material on first and second sides of said nonconductive substrate, correspondingly;

each of said first and second layers includes a narrow strip and a wide strip, said narrow and wide strips have proximal and distal ends with respect to the radiating arms, each narrow strip is coupled to a feedpoint of the corresponding radiating arm at its proximal end and to the corresponding wide strip of the same conductive layer via a bridging strip at their distal ends;

said wide strips are coupled to each other at their proximal ends;

said narrow strip of the first layer is positioned beneath the wide strip of the second layer and said narrow strip of the second layer is positioned over the wide strip of the first layer.