Antenna apparatus

• US 6,784,850 B2
• Filed: 03/14/2002
• Issued: 08/31/2004
• Est. Priority Date: 06/27/2001
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Iitsuka, Yasushi, Haga, Toshiyuki, Morooka, Tasuku, Iwasaki, Hisao
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US10/096,654
• Publication Number:
  US 20030016185A1
• Time in Patent Office: 901 Days
• Field of Search: 343/895
• 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, each antenna element including a straight portion extending parallel to the axis of the helical antenna section; 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)°

;

said straight portion having a lenath corresponding to about one-fourth of the height of the helical antenna section.

2. An antenna apparatus according to claim 1, wherein said straight portion is formed at a location corresponding to ½

to ¾

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

3. An antenna apparatus according to claim 1, wherein when a reception wavelength is λ

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

to 0.35 λ

;

wherein the number of turns of each antenna element is about 1; and

wherein each antenna element of the helical antenna section has a pitch angle of about 22°

.

4. An antenna apparatus according to claim 1, wherein when a reception wavelength is λ

, the length of each antenna element is 3/4 λ

.

5. An antenna apparatus according to claim 1, wherein said helical antenna section is attached to a surface of the base plate, on which the radio frequency signal supplier is provided.

6. An antenna apparatus according to claim 1, 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

.

7. An antenna apparatus according to claim 1, further comprising a low noise amplifier which amplifies a received signal sent from the helical antenna section via the radio frequency signal supplier.

8. An antenna apparatus according to claim 1, further comprising a radome covering at least said helical antenna section.

9. An antenna apparatus according to claim 1, further comprising fixing means for fixing the antenna apparatus to a movable body.