Electromagnetically coupled small broadband monopole antenna

• US 20050116867A1
• Filed: 09/08/2004
• Published: 06/02/2005
• Est. Priority Date: 09/08/2003
• Status: Active Grant

• Current Assignee: Ajou University Industry Cooperation Foundation, Samsung Electronics Co. Ltd.
• Original Assignee: Daewoo Educational Foundation, Samsung Electronics Co. Ltd.
• Inventors: Lee, Seong-Soo, Kim, Young-Il, Park, Ikmo, Jung, Jong-Ho, Moon, Young-Min
• Granted Patent: US 7,215,288 B2
• Time in Patent Office: Days
• US Class Current: 343/725
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0457 electromagnetically coupled to the feed line
• CPC Class Codes: H01Q 9/27 Spiral antennas
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/36 with top loading
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

A small broadband monopole antenna including a shorted patch and a probe with a strip line that are electromagnetically coupled with each other. The probe with a strip line has a length of about λ/4, where λ is a wavelength. The strip line may be one of a spiral type, a folded type and a helix type. A resonance frequency of the antenna can be adjusted by varying the inductance and the capacitance of the resonance circuits. In addition, a double-band antenna or a single-band antenna having a broad bandwidth can be designed in accordance with application purpose of the antenna.

Claims

1. A monopole antenna, comprising:

a probe having one of a strip line and a wire of a predetermined length; and

a shorted patch,

wherein the shorted patch is electromagnetically coupled to the probe.

2. The monopole antenna as claimed in claim 1, wherein the predetermined length has a value between 0.24λ

₀ and 0.26λ

₀, where λ

₀ is a wavelength in free space.

3. The monopole antenna as claimed in claim 1, wherein the one of the strip line and the wire has a shape selected from a group of a spiral shape, a helix shape, and a folded shape that is made by folding a straight strip line or wire.

4. The monopole antenna as claimed in claim 1, wherein the shorted patch operates as a monopole antenna with a capacitive component when the probe operates as a monopole antenna with an inductive component such that the capacitive component of the shorted patch is compensated by an inductive component of the probe, thereby providing a low resonance frequency.

5. The monopole antenna as claimed in claim 1, wherein the antenna provides a wide single-bandwidth when a resonance frequency of the probe and a resonance frequency of the shorted patch are adjacent with each other.

6. The monopole antenna as claimed in claim 1, wherein the antenna provides a dual-band when a resonance frequency of the probe and a resonance frequency of the shorted patch are different from each other.

7. The monopole antenna as claimed in claim 1, wherein the antenna has an omni-directional radiation pattern.

8. The monopole antenna as claimed in claim 1, wherein the strip line is a rectangular spiral strip line, being probe-fed by a coaxial line at a predetermined height from a ground plane, and a sum of a length of the rectangular spiral strip line and a probe height from the ground plane has a value between 0.24λ

₀ and 0.26λ

₀, where λ

₀ is a wavelength in free space, and wherein the shorted patch is a rectangular plate, occupying an area wider than the rectangular spiral strip line, and the center of the shorted patch is connected to the ground plane via a shorting pin.

9. The monopole antenna as claimed in claim 8, further comprising a dielectric substrate disposed between the shorted patch and the strip line.

10. The monopole antenna as claimed in claim 8, further comprising a predetermined number of shorting pins by which reactance of the antenna can be adjusted.

11. The monopole antenna as claimed in claim 10, wherein the shorting pins are arranged in a predetermined shape in the shorted patch.

12. The monopole antenna as claimed in claim 11, wherein the bandwidth of the antenna is adjusted by adjusting an electromagnetic coupling force by changing a distance between the shorting pins and the probe.

13. The monopole antenna as claimed in claim 12, wherein the distance between the shorting pins and the probe equals a distance between the probe and a gravity center of the shorting pins.

14. The monopole antenna as claimed in claim 11, wherein the resonance frequency of the antenna is adjusted by changing an alignment interval between the shorting pins.

15. The monopole antenna as claimed in claim 11, wherein the bandwidth of the antenna is adjusted by changing an alignment interval between the shorting pins.

16. The monopole antenna as claimed in claim 11, wherein the resonance frequency of the antenna is adjusted by changing the number of the shorting pins.

17. The monopole antenna as claimed in claim 11, wherein the bandwidth of the antenna is adjusted by changing the number of the shorting pins.

18. The monopole antenna as claimed in claim 1, wherein the strip line is a circular spiral strip line, being probe-fed by a coaxial line at a predetermined height from a ground plane, and a sum of a length of the circular spiral strip line and a probe height from the ground plane has a value between 0.24λ

₀ and 0.26λ

₀, where λ

₀ is a wavelength in free space, and wherein the shorted patch is a rectangular patch, occupying an area wider than the circular spiral strip line, and the center of the shorted patch is connected to the ground plane via a shorting pin.

19. The monopole antenna as claimed in claim 18, further comprising a dielectric substrate disposed between the shorted patch and the strip line.

20. The monopole antenna as claimed in claim 18, further comprising a predetermined number of shorting pins by which reactance of the antenna can be adjusted.

21. The monopole antenna as claimed in claim 20, wherein the shorting pins are arranged in a predetermined shape in the shorted patch.

22. The monopole antenna as claimed in claim 21, wherein the bandwidth of the antenna is adjusted by adjusting an electromagnetic coupling force by changing a distance between the shorting pins and the probe.

23. The monopole antenna as claimed in claim 22, wherein the distance between the shorting pins and the probe equals a distance between the probe and a gravity center of the shorting pins.

24. The monopole antenna as claimed in claim 21, wherein the resonance frequency of the antenna is adjusted by changing an alignment interval between the shorting pins.

25. The monopole antenna as claimed in claim 21, wherein the bandwidth of the antenna is adjusted by changing an alignment interval between the shorting pins.

26. The monopole antenna as claimed in claim 21, wherein the resonance frequency of the antenna is adjusted by changing the number of the shorting pins.

27. The monopole antenna as claimed in claim 21, wherein the bandwidth of the antenna is adjusted by changing the number of the shorting pins.

28. The monopole antenna as claimed in claim 1, wherein the strip line is a folded strip line having an upper strip line and a lower strip line that are connected to have a space by a strip line, being fed by a probe at a predetermined height from a ground plane, and a sum of a length of the folded spiral strip line and a probe height from the ground plane having a value between 0.24λ

₀ and 0.26λ

₀, where λ

₀ is a wavelength in free space.

29. The monopole antenna as claimed in claim 28, further comprising a dielectric substrate disposed between the shorted patch and the strip line.