Small ultra wideband antenna having unidirectional radiation pattern

• US 20070257851A1
• Filed: 01/19/2006
• Published: 11/08/2007
• Est. Priority Date: 01/19/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yong-jin, Lee, Seong-soo, Kwon, Do-Hoon, Koshelev, Vladimir, Buyanov, Yuri, Balzovsky, Evgeny
• Granted Patent: US 7,589,686 B2
• Time in Patent Office: Days
• US Class Current: 343/726
• CPC Class Codes: H01Q 13/085 Slot-line radiating ends
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

A small ultra wideband (UWB) antenna designed to have a unidirectional radiation pattern is disclosed. The UWB antenna includes a substrate; a power feeding part, provided on an upper surface of the substrate, for receiving a supply of an external electromagnetic energy; a dipole radiator excited by the electromagnetic energy fed through the power feeding part and radiating electromagnetic waves in one and the other directions of the substrate; and an active loop radiator excited by the electromagnetic energy fed through the power feeding part, respectively enhancing and canceling the electromagnetic fields produced in one or the other directions of the substrate by the dipole radiator.

Claims

1. An ultra wideband (UWB) antenna comprising:

a substrate;

a power feeding part which is provided on a surface of the substrate and receives an external electromagnetic energy;

a dipole radiator which is excited by the electromagnetic energy fed through the power feeding part and radiates electromagnetic waves; and

a loop radiator which makes the electromagnetic waves radiated by the dipole radiator have a unidirectional radiation pattern by interfering the electromagnetic waves.

2. The UWB antenna as claimed in claim 1:

wherein the loop radiator comprises an active loop radiator excited by the electromagnetic energy fed through the power feeding part; and

wherein the active loop radiator is configured to guide the electromagnetic energy in the direction of the power feeding part, whereby an omnidirectional radiation pattern is formed around the UWB antenna.

3. The UWB antenna as claimed in claim 2, wherein the active loop radiator is configured to enhance and cancel the electromagnetic fields produced by the dipole radiator in one and the other directions of the substrate, respectively.

4. The UWB antenna as claimed in claim 2, further comprising at least one passive loop radiator:

wherein the at least one passive loop radiator is excited by the electromagnetic energy induced by the dipole radiator and the active loop radiator; and

wherein the at least one passive loop radiator radiates the electromagnetic energy in an omnidirectional pattern.

5. The UWB antenna as claimed in claim 4, wherein the at least one passive loop radiator is configured to enhance and cancel the electromagnetic fields produced by the dipole radiator in one and the other directions of the substrate, respectively.

6. The UWB antenna as claimed in claim 4, further comprising a delay part which is configured to match a phase of an electromagnetic field produced by the active loop radiator and the at least one passive loop radiators to a phase of an electromagnetic field produced by the dipole radiator.

7. The UWB antenna as claimed in claim 5, wherein the delay part is configured to connect the power feeding part with the dipole radiator, thereby delaying supply of the electromagnetic energy to the dipole radiator.

8. The UWB antenna as claimed in claim 4, wherein the active loop radiator, the dipole radiator and the at least one passive loop radiator are positioned on a same plane as the power feeding part on the surface of the substrate.

9. The UWB antenna as claimed in claim 8, wherein the active loop radiator, the dipole radiator and the at least one passive loop radiator are produced by patterning a single metal film deposited on the surface of the substrate.

10. The UWB antenna as claimed in claim 8, wherein the power feeding part comprises:

a signal terminal which is provided on the surface of the substrate and receives the electromagnetic energy; and

first and second ground terminals arranged on one and the other sides of the signal terminal, respectively, to form a coplanar waveguide structure on the surface of the substrate.

11. The UWB antenna as claimed in claim 10, wherein the active loop radiator has one end connected to the signal terminal and the other end connected to the first ground terminal.

12. The UWB antenna as claimed in claim 10, wherein the dipole radiator comprises:

a first pole arranged on the surface of the substrate to slope at a predetermined angle to one side of the substrate; and

a second pole arranged on the surface of the substrate to slope at a predetermined angle to the first pole.

13. The UWB antenna as claimed in claim 12, wherein the first pole is connected to the signal terminal and the second pole is connected to the second ground terminal.

14. The UWB antenna as claimed in claim 13:

wherein the dipole radiator further comprises a first slot line which excites the dipole radiator;

wherein one end of the first slot line is connected to the power feeding part and the other end of the first slot line forms an input part of the dipole radiator; and

wherein a space between the first pole and the second pole is gradually widened, starting from the input part.

15. The UWB antenna as claimed in claim 14, wherein the active loop radiator further comprises:

a second slot line which excites the active loop radiator; and

a loop connected to the second slot line and having remaining sides, except for a side connected to the second slot line, which are closed sides.

16. The UWB antenna as claimed in claim 15, wherein the antenna is formed in a manner that a metal layer deposited on the surface of the substrate is patterned in a predetermined form, and the surface of the substrate that corresponds to an area between the first pole and the second pole, an area between the signal terminal and the first ground terminal, an area between the signal terminal and the second ground terminal, a loop area of the active loop radiator and a loop area of the at least one passive loop radiator is exposed.

17. The UWB antenna as claimed in claim 1, wherein the power feeding part comprises:

a signal terminal which is provided on the surface of the substrate and receives the electromagnetic energy; and

first and second ground terminals arranged on one and the other sides of the signal terminal, respectively, to form a coplanar waveguide structure on the surface of the substrate.

18. The UWB antenna as claimed in claim 17, further comprising at least one slot which intercepts current flowing backward to the first or second ground terminal.

19. The UWB antenna as claimed in claim 18, wherein the loop radiator comprises:

an active loop radiator which is excited by the electromagnetic energy fed through the signal terminal, and enhances and cancels the electromagnetic fields produced in one and other directions of the substrate from the dipole radiator, respectively; and

at least one passive loop radiator which is excited by the electromagnetic energy induced by the dipole radiator, and the active loop radiator and enhances the electromagnetic fields produced in one and other directions from the dipole radiator, respectively.

20. The UWB antenna as claimed in claim 19, wherein the at least one slot is positioned on a side of the active loop radiator which is formed on one side of the dipole radiator.

21. The UWB antenna as claimed in claim 20, further comprising another at least one slot which is positioned on a side of the at least one passive radiator which is formed on the other side of the dipole radiator.

22. The UWB antenna as claimed in claim 21, wherein:

the at least one slot on the side of the active loop radiator is formed on a same plane as the active loop radiator to constitute a coplanar structure; and

the other at least one slot on the side of the at least one passive loop radiator is formed on a same plane as the at least one passive loop radiator to constitute a coplanar structure.

23. The UWB antenna as claimed in claim 22, wherein an electrical length of one of the at least one slot and the other at least one slot is set in a range of 0.2 to 0.25 λ

min, where λ

min is a wavelength corresponding to a minimum frequency in an available frequency band.

24. The UWB antenna as claimed in claim 15, wherein the substrate is in the form of a rectangular flat board of which vertical sides are longer than its horizontal sides.

25. The UWB antenna as claimed in claim 24, wherein the power feeding part is positioned at an edge of the vertical side of the substrate, and the dipole radiator is arranged in a direction toward the side opposite to the vertical side where the power feeding part is positioned to radiate the electromagnetic waves in a same direction as a power feeding direction.

26. The UWB antenna as claimed in claim 24, wherein the power feeding part is positioned at an edge of the horizontal side of the substrate, and the dipole radiator is arranged in a direction toward the vertical side of the substrate to radiate the electromagnetic waves in a direction perpendicular to a power feeding direction.

27. The UWB antenna as claimed in claim 24, wherein the substrate is a rectangular flat board having a horizontal side of 0.2 λ

min and a vertical side of 0.3 λ

min if the minimum frequency in an available frequency band is fmin and the corresponding wavelength is λ

min.

28. The UWB antenna as claimed in claim 15, wherein a characteristic impedance of the second slot line is three or four times larger than a characteristic impedance of the first slot line.

29. The UWB antenna as claimed in claim 28, wherein a width of the second slot line is wider than a width of the first slot line to improve the characteristic impedance.

30. The UWB antenna as claimed in claim 28, wherein an area of the substrate, in which the second slot line is formed, is etched to increase a characteristic impedance of the second slot line.

31. The UWB antenna as claimed in claim 15, wherein an electric length difference between the first and second slot lines in the minimum frequency state is 0.15 λ

min if the minimum frequency in an available frequency band is fmin and the corresponding wavelength is λ

min.

32. The UWB antenna as claimed in claim 24, the at least one passive loop radiator is formed at a position on a horizontal side of the substrate, the position being 0.05 to 0.067 λ

min apart from a vertical side of the substrate where the power feeding part is located if the minimum frequency in an available frequency band is fmin and the corresponding wavelength is λ

min.

33. The UWB antenna as claimed in claim 8, wherein the active loop radiator and the at least one passive loop radiators are positioned on one and the other sides of the dipole radiator, respectively.

34. The UWB antenna as claimed in claim 12, wherein the first pole of the dipole radiator becomes a part of the active loop radiator.

35. The UWB antenna as claimed in claim 26, wherein the active loop radiator and the at least one passive loop radiators are positioned on one same side of the dipole radiator.

36. The UWB antenna as claimed in claim 26, wherein one end of the at least one passive loop radiator is connected to the first or the second ground terminal.