Coupled sectorial loop antenna for ultra-wideband applications

• US 20060055619A1
• Filed: 08/22/2005
• Published: 03/16/2006
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: EMAG Technologies, Inc.
• Original Assignee: EMAG Technologies, Inc.
• Inventors: Sarabandi, Kamal, Behdad, Nader
• Granted Patent: US 7,268,741 B2
• Time in Patent Office: Days
• US Class Current: 343/866
• CPC Class Codes: H01Q 5/28 Arrangements for establishing polarisation or beam width over two or more different wavebands
• CPC Class Codes: H01Q 5/357 using a single feed point
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A single-element antenna system that provides a wide bandwidth and consistent polarization over the frequency range to which the antenna is impedance matched. In one embodiment, the wideband antenna system includes two parallel coupled sectorial loop antennas (CSLA) that are coupled along an axis of symmetry. In another embodiment, half of the coupled sectorial loop antenna is electrically coupled to a ground plane, where the antenna includes one pie-slice shaped sector and two arches. In alternate embodiments, sections of the sector can be removed to reduce the weight of the antenna system.

Claims

1. An antenna structure comprising:

a first sectorial loop antenna including two sectors and an arch therebetween; and

a second sectorial loop antenna including two sectors and an arch therebetween, wherein the first loop antenna and the second loop antenna are coupled to define a coupled sectorial loop antenna fed by a single feed, and wherein one sector of the first sectorial loop antenna and one sector of the second sectorial loop antenna combine to form a pie-slice shaped first sector of the coupled sectorial loop antenna and the other sector of the first sectorial loop antenna and the other sector of the second sectorial loop antenna combine to form a pie-shaped second sector of the coupled sectorial loop antenna.

2. The antenna structure according to claim 1 wherein the coupled sectorial loop antenna is fed at the points of the first sector and the second sector of the coupled sectorial loop antenna.

3. The antenna structure according to claim 1 wherein an input impedance of the feed is a function of R_in, R_out and α

of the first and second sectorial loop antenna, where R_in is the inner radius of the arches, R_out is the outer radius of the arches and α

is the arc angle in degrees of the sectors of the first and second coupled sectorial loop antennas.

4. The antenna structure according to claim 1 wherein the arch angle of the first and second sectors of the coupled sectorial loop antenna is 120°

.

5. A sectorial loop antenna comprising:

a first pie-slice shaped sector having a point;

a second pie-slice shaped sector having a point;

an arch electrically coupled to ends of the first and second pie-slice shaped sectors opposite to their points; and

a feed electrically coupled to the points of the pie-slice shaped sectors.

6. The sectorial loop antenna according to claim 5 wherein the first and second pie-slice shaped sectors and the arch define a semi-circle.

7. The antenna according to claim 5 wherein the first and second sectors have an arch angle in the range of 20°

-80°

.

8. A sectorial loop antenna comprising:

a ground plane;

a pie-slice shaped sector having a point positioned adjacent to the ground plane;

a first arch coupled to the ground plane and one side of the sector opposite to the point;

a second arch coupled to the ground plane and an opposite side of the sector opposite to the point; and

a feed electrically coupled to the point of the sector and electrically isolated from the ground plane.

9. The antenna according to claim 8 wherein the sector has an arc angle of about 120°

.

10. The antenna according to claim 8 wherein an input impedance of the feed is a function of R_in, R_out and α

of the sector, where R_in is the inner radius of the arches, R_out is the outer radius of the arches and α

is the arc angle in degrees of half of the sector.

11. The antenna according to claim 10 wherein R_in=27.8 mm, R_out=28 mm and α

=60°

.

12. The antenna according to claim 10 wherein the thickness of the first and second arches is about 0.4 mm.

13. The antenna according to claim 8 wherein the first arch, the second arch and the sector define an elliptical configuration.

14. The antenna according to claim 8 wherein the first arch, the second arch and the sector define a circular configuration.

15. The antenna according to claim 8 wherein the coupled sectorial loop antenna has an 8.5:

1 impedance bandwidth.

16. The antenna according to claim 8 wherein the feed includes a coaxial connector, wherein an inner conductor of the coaxial connector is coupled to the point of the sector and an outer conductor of the coaxial connector is coupled to the ground plane.

17. A coupled sectorial loop antenna comprising:

a ground plane;

a first pie-slice shaped sector and a second pie-slice shaped sector each having a point positioned adjacent to the ground plane and defining a pie-slice shaped open portion therebetween;

a first arch electrically coupled to the ground plane and an end of the first sector opposite to the point of the first sector;

a second arch electrically coupled to the ground plane and an end of the second sector opposite to the point of the second sector; and

a feed electrically coupled to both points of the first and second sectors and electrically isolated from the ground plane.

18. The antenna according to claim 17 wherein the open portion is between −

30° and

+30°

relative to a radius that bisects the open portion.

19. The antenna according to claim 17 wherein the first and second sectors have an arc angle of 30°

.

20. The antenna according to claim 17 wherein a portion of the first and second sectors is removed.

21. The antenna according to claim 20 wherein the removed portions of the sectors are between 40°

and 50°

of the first sector and −

40° and

−

50°

of the second sector relative to a radius that bisects the open portion.

22. The antenna according to claim 17 wherein an input impedance of the feed is a function of R_in, R_out and α

of the first and second sectors, where R_in is the inner radius of the arches, R_out is the outer radius of the arches and α

is an arc angle in degrees.

23. The antenna according to claim 22 wherein R_in=27.8 mm, R_out=28 mm and α

=60°

.

24. The antenna according to claim 17 wherein the thickness of the arches is about 0.4 mm.

25. The antenna according to claim 17 wherein the first arch, the second arch and the sector define an elliptical configuration.

26. The antenna according to claim 17 wherein the first arch, the second arch and the sector define a circular configuration.

27. The antenna according to claim 17 wherein the coupled sectorial loop antenna has an 8.5:

1 impedance bandwidth.

28. The antenna according to claim 17 wherein the feed includes a coaxial connector, wherein an inner conductor of the coaxial connector is coupled to the point of the sectors and an outer conductor of the coaxial connector is coupled to the ground plane.

29. An antenna structure comprising:

a ground plane;

a feed; and

an antenna, said antenna including a substrate mounted to the ground plane, a first electrical trace printed on the substrate and electrically coupled to the feed, a second electrical trace printed on the substrate and electrically coupled to the ground plane, a third electrical trace printed on the substrate and electrically coupled to the ground plane and a fourth electrical trace electrically coupled to the first, second and third electrical traces.

30. The antenna structure according to claim 29 wherein the feed is a coaxial feed having a center conductor electrically coupled to the first trace and an outer conductor electrically coupled to the ground plane.

31. The antenna structure according to claim 29 wherein the first, second, third and fourth electrical traces define an E-shape.

32. An antenna structure comprising:

a ground plane;

a feed; and

an antenna, said antenna including a substrate mounted to the ground plane, a first antenna trace printed on a first side of the substrate and a second antenna trace printed on a second side of the substrate, said first trace including a first end electrically coupled to the feed and a second end electrically coupled to the ground plane and said second trace including a first end electrically coupled to the feed and a second end electrically coupled to the ground plane.

33. The antenna structure according to claim 32 wherein the first ends of the first and second traces overlap on opposite sides of the substrate proximate the feed.

34. The antenna structure according to claim 32 further comprising a first inductor electrically coupled to the first trace proximate the second end of the first trace and a second inductor electrically coupled to the second end of the second trace proximate the second end of the second trace.

35. The antenna structure according to claim 34 wherein the inductors are lumped inductors or distributive inductors.

36. The antenna structure according to claim 32 wherein the feed is a coaxial feed having a center conductor electrically coupled to the traces and an outer conductor electrically coupled to the ground plane.

37. A coupled sectorial loop slot antenna comprising:

a substrate;

a metallized ground plane deposited on one side of the substrate, said metallized ground plane including a first removed portion defining a separated pie-slice shaped sector of the plane electrically isolated from the remaining portion of the metallized ground plane and a second removed portion defining a second pie-slice shaped sector electrically isolated from the remaining portion of the metallized ground plane; and

a feed electrically coupled to points of the two pie-shaped sectors.