Loop-type antenna

• US 7,123,210 B2
• Filed: 07/30/2002
• Issued: 10/17/2006
• Est. Priority Date: 07/30/2001
• Status: Expired due to Fees

• Current Assignee: Pygmalyon
• Original Assignee: Pygmalyon
• Inventors: Bernard, Tony, Martin, Jean-Marc
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): CABUCOS, MARIE G
• Application Number:
  US10/485,171
• Publication Number:
  US 20040257294A1
• Time in Patent Office: 1,540 Days
• Field of Search: 343/718, 343/726, 343/728, 343/732, 343/739, 343/741, 343/743, 343/744, 343/748, 343/842, 343/855, 343/866, 3405721-5728, 340/568.1
• US Class Current: 343/866
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G07C 1/24 Race time-recorders
• CPC Class Codes: G07C 1/26 Pigeon-timing or like equipment
• 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 7/005 with variable reactance for tuning the antenna

Abstract

The invention concerns an antenna for use as transmission/reception beacon (2), in a radio frequency identifying system, having a general upturned U configuration, located in a vertical plane, above the ground transversely to a passage (9), the vertical end portions (8b, 8c). The invention is applicable to a system for detecting, over a large width (L), the passage of people, animals or objects bearing electronic tags (7).

Claims

1. Loop antenna, used as a transmission/reception beacon in a radio frequency identification system, comprising:

a general configuration of an inverted “

U”

located in an essentially vertical plane, above a ground, transversal to a passage, in such a way as to form an open loop.

2. Loop antenna according to claim 1, wherein said antenna comprises a single wire, with a medial portion essentially horizontal, running above the ground, and with two terminal portions, which are essentially vertical and directed downward, one of them free and the other connected to a reader of a radio frequency identification system.

3. Loop antenna according to claim 2, wherein the vertical portion of the wire is connected to the reader implemented by way of an adapter circuit.

4. Loop antenna according to claim 3, wherein the adapter circuit comprises an impedance coil and a capacitor, all arranged inside a metallic housing, which is attached to a grille placed on the ground.

5. Loop antenna according to claim 4, wherein the two terminal portions of the wire are connected to the grille placed on the ground which runs across the entire width of the ground, said width defined by the antenna.

6. Loop antenna according to claim 3, wherein the adapter circuit comprises an impedance coil and a capacitor, all arranged in a metallic housing which is attached to a return cable which extends up to a vicinity of the free terminal portion.

7. Loop antenna according to claim 6, wherein the return cable overlaps the free terminal portion in order, together with said terminal portion, to comprise a capacitor.

8. Loop antenna according to claim 1, wherein said antenna comprises a principal wire, comprising an essentially horizontal portion and at least one essentially vertical portion connected to a reader of a radio frequency identification system, and at least one secondary wire, which includes a vertical portion opposite that of the principal wire, with the secondary wire being intertwined, without electrical contact, with the principal wire along a certain length, in order to form at least one capacitor.

9. Loop antenna according to claim 8, wherein said antenna is a three-dimensional antenna, comprising two or more loops in electrical series, located in essentially parallel vertical planes.

10. Loop antenna according to claim 1, wherein said antenna is used in a system which detects passage of persons, animals, or objects, each of which bears an electronic tag which enables their identification at a moment of said passage.