Circularly polarized antenna

• US 20070257844A1
• Filed: 07/24/2006
• Published: 11/08/2007
• Est. Priority Date: 05/04/2006
• Status: Active Grant

• Current Assignee: Megica Corporation (Chipbond Technology Corporation), Tatung Company, Tatung University
• Original Assignee: Tatung Company
• Inventors: Chang, The-Nan, Lin, Chun-Ming
• Granted Patent: US 7,382,320 B2
• Time in Patent Office: Days
• US Class Current: 343/700.MS
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 9/0428 radiating a circular polarised wave
• CPC Class Codes: H01Q 9/0457 electromagnetically coupled to the feed line

Abstract

The present invention relates to a circularly polarized antenna and, more particularly, to a compact circularly polarized antenna for transmitting and receiving a circularly polarized signal. The circularly polarized antenna comprises a substrate having an upper surface and a lower surface; a signal distributor; an antenna for transmitting and receiving the circularly polarized signal; and a plurality of support units. The upper surface of the substrate comprises a plurality of slots. One end of each slot overlaps with the respective ends of the other slots at a central region. The lower surface of the substrate comprises a coupling unit being electrically connected with the signal distributor, and the center of the coupling unit corresponds to the central region.

Claims

1. A circularly polarized antenna for transmitting and receiving a circularly polarized signal, comprising:

a substrate having an upper surface and a lower surface;

a signal distributor;

an antenna for transmitting and receiving the circularly polarized signal; and

a plurality of support units for supporting the antenna and maintaining a predetermined distance between the antenna and the upper surface of the substrate;

wherein the upper surface of the substrate comprises a plurality of slots, one end of each slot overlapping with the respective ends of the other slots at a central region;

the lower surface of the substrate comprising a coupling unit being electrically connected with the signal distributor, and the center of the coupling unit corresponds to the central region.

2. The circularly polarized antenna as claimed in claim 1, wherein the coupling unit comprises a coupling portion and a connecting portion, the connecting portion being electrically connected with the signal distributor and the coupling portion.

3. The circularly polarized antenna as claimed in claim 2, wherein the coupling portion is a coupling-ring portion with an opening.

4. The circularly polarized antenna as claimed in claim 1, wherein the substrate is an FR-4 microwave substrate.

5. The circularly polarized antenna as claimed in claim 1, wherein the signal distributor is a coaxial cable connector.

6. The circularly polarized antenna as claimed in claim 1, wherein the signal distributor is electrically connected with a coaxial cable.

7. The circularly polarized antenna as claimed in claim 1, wherein the quantity of the slots ranges from 4 to 36.

8. The circularly polarized antenna as claimed in claim 1, wherein each of the slots has the same width.

9. The circularly polarized antenna as claimed in claim 1, wherein the width of each of the slots is equal to the width of the coupling portion.

10. The circularly polarized antenna as claimed in claim 1, wherein each slots has a dumbbell-shaped end.

11. The circularly polarized antenna as claimed in claim 1, wherein the antenna is a copper plate.

12. The circularly polarized antenna as claimed in claim 1, wherein the substrate is a square-shaped plate.

13. The circularly polarized antenna as claimed in claim 1, wherein the antenna is a square-shaped plate.

14. The circularly polarized antenna as claimed in claim 1, wherein the antenna is a square-shaped plate with at least one corner being chamfered.

15. The circularly polarized antenna as claimed in claim 1, wherein the antenna is a polygon-shaped plate.

16. The circularly polarized antenna as claimed in claim 1, wherein the support unit is composed of an electrically insulating material.

17. The circularly polarized antenna as claimed in claim 1, wherein the frequency of the circularly polarized signal ranges from 900 MHz to 930 MHz.

18. The circularly polarized antenna as claimed in claim 1, wherein the frequency of the circularly polarized signal ranges from 400 MHz to 600 MHz.

19. The circularly polarized antenna as claimed in claim 1, wherein a side-length of the antenna ranges from the one-quarter to three-quarters of the wavelength of the circularly polarized signal.

20. The circularly polarized antenna as claimed in claim 1, wherein the predetermined distance between the antenna and the upper surface of the substrate is changed by adjusting the length of the supporting units.