Antenna apparatus

• US 20030016185A1
• Filed: 03/14/2002
• Published: 01/23/2003
• Est. Priority Date: 06/27/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Iwasaki, Hisao, Haga, Toshiyuki, Iiduka, Yasushi, Morooka, Tasuku
• Granted Patent: US 6,784,850 B2
• Time in Patent Office: Days
• US Class Current: 343/895
• CPC Class Codes: H01Q 1/3275 mounted on a horizontal surface of the vehicle, e.g. on roof, hood, trunk
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 11/08 Helical antennas

Abstract

Power is supplied to antenna elements of a helical antenna section, which are arranged at an angular distance of 90° therebetween, with a phase difference of 90°. When a reception wavelength is λ, the height of the helical antenna section is 0.6 λ to 0.75 λ, the number of turns, T, of each antenna element is about 1, and the pitch angle α of each antenna element is 50° to 60°. A straight portion with a length corresponding to ¼ of the height of the antenna section is formed at a location corresponding to ½ to ¾ of the height of the antenna section, the height of the antenna section is about 0.3 λ to 0.35 λ, the number of turns, T, is about 1, and the pitch angle α is about 22°.

Claims

1. An antenna apparatus comprising:

a base plate having one surface provided with a ground conductor;

a helical antenna section attached to the base plate and provided with an n-number of antenna elements helically formed at an angular distance of (360/n)°

therebetween; and

a radio frequency signal supplier which is provided on the other surface of the base plate and supplies power to the n-number of antenna elements of the helical antenna with a phase difference of (360/n)°

.

2. An antenna apparatus according to claim 1, wherein said helical antenna section comprises a four-wire helical antenna having four antenna elements arranged at an angular distance of 90°

therebetween, and

said radio frequency signal supplier supplies power to the four antenna elements of the helical antenna section with a phase difference of 90°

.

3. An antenna apparatus according to claim 2, wherein when a reception wavelength is λ

, the height of the helical antenna section is 0.6 λ

to 0.75 λ

.

4. An antenna apparatus according to claim 2, wherein the number of turns of each antenna element is about 1.

5. An antenna apparatus according to claim 2, wherein each antenna element of the helical antenna section has a pitch angle of about 50°

to 60°

.

6. An antenna apparatus according to claim 1, wherein said helical antenna section comprises a four-wire helical antenna having four antenna elements arranged at an angular distance of 90°

therebetween,

each of the antenna elements includes a straight portion extending parallel to the axis of the helical antenna, and

said radio frequency signal supplier supplies power to the four antenna elements of the helical antenna section with a phase difference of 90°

.

7. An antenna apparatus according to claim 6, wherein said straight portion is formed with a length corresponding to about ¼

of the height of the helical antenna section at a location corresponding to ½

to ¾

of the height of the helical antenna section from the ground conductor.

8. An antenna apparatus according to claim 7, wherein when a reception wavelength is λ

, the height of the helical antenna section is about 0.3 λ

to 0.35 λ

.

9. An antenna apparatus according to claim 7, wherein the number of turns of each antenna element is about 1.

10. An antenna apparatus according to claim 7, wherein each antenna element of the helical antenna section has a pitch angle of about 22°

.

11. An antenna apparatus according to any one of claims 1 to 10, wherein when a reception wavelength is λ

, the length of each antenna element is ¾

λ

.

12. An antenna apparatus according to any one of claims 1 to 10, wherein said helical antenna section is attached to a surface of the base plate, on which the radio frequency signal supplier is provided.

13. An antenna apparatus according to any one of claims 1 to 10, wherein when a reception wavelength is λ

, said ground conductor has a substantially circular shape with a diameter of 0.5 λ

to 1.0 λ

.

14. An antenna apparatus according to any one of claims 1 to 10, further comprising a low noise amplifier which amplifies a received signal sent from the helical antenna section via the radio frequency signal supplier.

15. An antenna apparatus according to any one of claims 1 to 10, further comprising a radome covering at least said helical antenna section.

16. An antenna apparatus according to any one of claims 1 to 10, further comprising fixing means for fixing the antenna apparatus to a movable body.