Antenna device and portable radio communication device

• US 6,947,000 B2
• Filed: 07/16/2001
• Issued: 09/20/2005
• Est. Priority Date: 07/14/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ito, Hiroki
• Primary Examiner(s): Matar, Ahmad F.
• Assistant Examiner(s): Nguyen, Quynh H.
• Application Number:
  US09/905,402
• Publication Number:
  US 20020061734A1
• Time in Patent Office: 1,527 Days
• Field of Search: 343/702, 379/451, 455/575.5
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 17/001 for modifying the directional characteristic of an aerial

Abstract

Providing an antenna device and a portable radio communication device whose conductive plate for use in reducing the amount of the electromagnetic waves to be absorbed into a human body can be reduced in size. The portable radio communication device 1 includes a circuit board (not shown) necessary for performing radio communication, shield case 2 as a ground conductor which shields the circuit board, a conductive plate 3, an antenna feeding portion 4, and an antenna 5. The circuit board, shield case 2, and conductive plate 3 are enclosed by a housing (not shown) made of nonconductive material. The conductive plate 3 has its one end along the longitudinal direction connected to the shield case 2 to form a short circuit via the conductor 7, and has its other end electrically opened from the shield case 2. The conductive plate 3 has two slits 8a, 8b near the conductor 7.

Claims

1. An antenna device having an antenna element and a ground conductor working as an antenna wherein the antenna element is fed via an antenna feeding portion, and a high-frequency current flows to the ground conductor via the antenna feeding portion, the antenna device comprising:

high-frequency current suppressing means formed of a conductive plate of a predetermined shape having one end along one direction connected to the ground conductor to form a short circuit and having an other end electrically opened from the ground conductor,

wherein the high-frequency current suppressing means has slits extending perpendicular to the one direction, and

wherein the slits make the effective length of the conductive plate ((2n+1)/4) times a wavelength of a radio communication frequency, n being a natural number including zero.

2. The antenna device as set forth in claim 1, wherein each of the slits is formed by cutting off a part of the conductive plate from a side to a center thereof.

3. The antenna device as set forth in claim 1, wherein the slits form an opening slit formed by cutting off a part of the conductive plate at a predetermined position thereof.

4. The antenna device as set forth in claim 1, wherein the high-frequency current suppressing means includes a first conductive plate corresponding to one radio communication frequency and a second conductive plate corresponding to an other radio communication frequency.

5. The antenna device as set forth in claim 4, wherein the first conductive plate has slits each formed by cutting off a part of the first conductive plate from a side to a center thereof.

6. The antenna device as set forth in claim 1, wherein the high-frequency current suppressing means is arranged to face a portion of the ground conductor wherein electromagnetic waves generated when the high-frequency current flows to the ground conductor and to be absorbed by a human body are maximum.

7. A portable radio communication device including an antenna device having an antenna element and a ground conductor working as an antenna wherein the antenna element is fed via an antenna feeding portion, and a high-frequency current flows to the ground conductor via the antenna feeding portion, wherein a circuit board for transmitting/receiving signals is shielded by the ground conductor, and the antenna device comprises:

high-frequency current suppressing means formed of a conductive plate of a predetermined shape having one end along one direction connected to the ground conductor to form a short circuit and having an other end electrically opened from the ground conductor, wherein the high-frequency current suppressing means has slits extending perpendicular to the one direction, and

wherein the slits make the effective length of the conductive plate ((2n+1)/4) times a wavelength of a radio communication frequency, n being a natural number including zero.

8. The portable radio communication device as set forth in claim 7, wherein each of the slits is formed by cutting off a part of the conductive plate from a side to a center thereof.

9. The portable radio communication device as set forth in claim 7, wherein the slits form an opening slit formed by cutting off a part of the conductive plate at a predetermined position thereof.

10. The portable radio communication device as set forth in claim 8, wherein the high-frequency current suppressing means includes a first conductive plate corresponding to one radio communication frequency and a second conductive plate corresponding to an other radio communication frequency.

11. The portable radio communication device as set forth in claim 10, wherein the first conductive plate has slits each formed by cutting off a part of the first conductive plate from a side to a center thereof.

12. The portable radio communication device as set forth in claim 7, wherein the high-frequency current suppressing means is arranged to face a portion of the ground conductor wherein electromagnetic waves generated when the high-frequency current flows to the ground conductor and to be absorbed by a human body are maximum.