Antenna arrangement in a metallic environment

• US 6,452,563 B1
• Filed: 06/11/2001
• Issued: 09/17/2002
• Est. Priority Date: 12/22/1998
• Status: Expired due to Fees

• Current Assignee: Gemalto SA (Thales SA)
• Original Assignee: Gemplus (Thales SA)
• Inventors: Porte, Philippe
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/857,979
• Time in Patent Office: 463 Days
• Field of Search: H01/Q.700, 343/866, 343/867, 343/741, 343/742, 343/767
• US Class Current: 343/866
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 7/04 Screened antennas H01Q7/02, H01Q7/06 take precedence

Abstract

The invention concerns an arrangement for an antenna (A) having the general shape of a loop, directly in the proximity of at least a metallic element (10). The invention is characterised in that each metallic element (10) comprises an orifice (18) arranged substantially opposite the surface defined by the antenna (A), and a slot (16) forming a gap width, arranged through the thickness of the metallic element (10), between the internal edge (21) delimiting the orifice (18) and the external edge (20) of said metallic element (10). The invention is applicable to scanners and radio frequency communication devices.

Claims

1. An arrangement comprising an external antenna (A) in the general form of a loop, at least one metallic element (10, 10′

) located in the vicinity of said antenna and having an aperture (18, 18′

) substantially opposite a surface delimited by the antenna and a slot (16, 16′

) forming an air gap through a thickness of the metallic element between an internal edge (21, 21′

) delimiting the aperture and an external edge (20, 20′

) of said metallic element, said metallic element having a space able to received a removable device (C) provided with an internal antenna (A′

) in the form of a loop, the external antenna being positioned directly in the vicinity of an external face (14, 14′

) of the metallic element.

2. The arrangement according to claim 1, wherein the antenna (A) extends substantially parallel to the metallic element (10, 10′

) of which it is directly in the vicinity.

3. The arrangement according to claim 1, wherein the surface delimited by the internal edge (21, 21′

) of the aperture (18, 18′

) is substantially equal to the surface of the antenna A.

4. The arrangement according to claim 1, characterised in that the internal edge(21, 21′

) of the aperture(18, 18′

) is substantially parallel to the contour of the antenna A.

5. The arrangement according to claim 1, characterised in that the internal edge 21, 21′

of the aperture (18, 18′

) coincides with a mid-axis P of the loop forming the external antenna (A).

6. The arrangement according to claim 1, wherein said metallic element comprises two metallic elements (10, 10′

) between which there is formed said space able to receive said removable device (C) provided with said internal antenna (A).

7. The arrangement according to claim 6, wherein the two metallic elements (10, 10′

) being joined together, and having respective apertures (18, 18′

) and slots (16, 16′

) that are associated so as to form a single air gap.

8. The arrangement according to claim 7, wherein the apertures (18, 18′

) of the two metallic elements (10, 10′

) are opposite each other.

9. The arrangement according to claim 7, characterised in that the slots (16, 16′

) of the two metallic elements (10, 10′

) are opposite each other.

10. The arrangement according to claim 7, characterised in that the two metallic elements (10, 10′

) have substantially identical shapes.

11. The arrangement according to claim 1, characterised in that the portion of the metallic element (10, 10′

) close to which the antenna (A) extends is flat.

12. The arrangement according to claim 6, wherein at least one of the metallic elements (10, 10′

) is a metallic plate.