UHF RFID transponder

Abstract

The invention relates to a UHF RFID transponder with an antenna and an RFID chip, wherein the antenna has a first dipole structure, a first inductive loop and an infeed point, and the first dipole, the inductive loop and the RFID chip are electrically connected to the infeed point. The purpose of the invention is to create an RFID transponder that can be tuned with reduced influence from the geometric tolerances involved in the production of the antenna. As a result, these RFID transponders are intended to be particularly suitable for attaching to glass panes, as the impedance of the antenna can be tuned to the impedance of the RFID chip with less influence from the thickness or material composition of the glass. This task is achieved in that the antenna (2) has a second inductive loop (8) and that this second inductive loop (8) is electrically connected to the infeed point (3) and connected in parallel to the first inductive loop (7).

Claims

1. A UHF RFID transponder with an antenna and an RFID chip, wherein the antenna has a first dipole structure, a second dipole structure, a first inductive loop, a second inductive loop and an infeed point, wherein the first dipole structure and the second dipole structure are folded dipoles, and wherein the first dipole structure, the second dipole structure, the first inductive loop, the second inductive loop and the RFID chip are electrically connected to the infeed point, wherein the second inductive loop is connected in parallel to the first inductive loop, wherein the dipole structures designed as folded dipoles, each featuring a slit that is parallel to one long side of the antenna, and each slit having curved ends, and wherein the curved ends of the first dipole structure and the curved ends of the second dipole structure are turned towards each other.

2. The UHF RFID transponder of claim 1, wherein the second inductive loop is arranged as a mirror image of the first inductive loop in a mirror plane, wherein the mirror plane intersects the infeed point and is parallel to a dipole axis of the first dipole structure.

3. The UHF RFID transponder of claim 1, wherein the first and second inductive loops are arranged in a common plane.

4. The UHF RFID transponder of claim 1, wherein the second dipole structure is arranged as a mirror image of the first dipole structure in a mirror plane, wherein the mirror plane intersects the infeed point and is parallel to a dipole axis of the first dipole structure.

5. The UHF RFID transponder of claim 1, wherein the antenna is produced using a subtractive process on a substrate with a metallic coating or using an additive process on a substrate.

6. The UHF RFID transponder of claim 1, wherein the UHF RFID transponder features a hologram.

7. The UHF RFID transponder according to of claim 6, wherein the hologram is made of plastic.

Description

(1) Embodiments of the invention are explained by means of drawings below. These show:

(2) FIG. 1a Overhead view of UHF RFID transponder to which the invention relates

(3) FIG. 1b Spatial depiction of UHF RFID transponder in accordance with FIG. 1a

(4) FIG. 2a Overhead view of a further embodiment of a UHF RFID transponder to which the invention relates

(5) FIG. 2b Spatial depiction of UHF RFID transponder in accordance with FIG. 2a

(6) FIG. 1a and FIG. 1b show the UHF RFID transponder 1 to which the invention relates, with FIG. 1a showing this from an overhead view and FIG. 1b showing a spatial depiction. The UHF RFID transponder 1 features an antenna 2 with an infeed point 3, and the feeding point 3 is connected to an RFID chip. The RFID chip is not shown, however.

(7) The antenna 2 consists of a first dipole structure 4 with a dipole axis 5, a second dipole structure 6, a first inductive loop 7 and a second inductive loop 8, and the dipole structures 4 and 6 and inductive loops 7 and 8 are each electrically connected to the infeed point 3. The second inductive loop 8 is arranged as a mirror image of the first inductive loop 7 reflected in a mirror plane 9, which intersects the infeed point 3 and is parallel to the dipole axis 5. In addition, the first and second inductive loops 7 and 8 are in a common plane and the infeed point is arranged between the two loops 7 and 8. In a space-saving version, the loops have a rectangular shape, whereby the loops can be formed from a rectangular recess in a metallic layer.

(8) The second dipole structure 6 is arranged as a mirror image of the first dipole structure 4 in the mirror plane 9. Both dipole structures 4 and 6 are designed as folded dipoles with slits. These slits feature curved ends 10 and 11, wherein the curved ends 10 of the first dipole structure 4 and the curved ends 11 of the second dipole structure 6 point towards each other. In principle, however, slits without curved ends 10 and 11 or curved ends 10 and 11 oriented differently to the illustration are also conceivable.

(9) The antenna 2 was formed from a plastic film with a metallic coating using a subtractive process; however, the formation of the antenna 2 is not limited to this process. The antenna 2 could also be produced by vapour deposition of a metal on a plastic film substrate 12 with the use of shadow masks, for example. The use of a plastic film is also not essential. For example, paper can also be used as a substrate 12. Another option for manufacturing the antenna 2 is by stamping it from a metal film. The metal film, plastic film or paper substrate can be equipped with an adhesive film, which means that the UHF RFID transponder 1 can be attached to a motor-vehicle windscreen, for example.

(10) FIG. 2a shows a further embodiment of the UHF RFID transponder 1 relating to the invention from an overhead view. FIG. 2b shows the UHF RFID transponder 1 from FIG. 2a in a spatial depiction. The antenna 2 of the UHF RFID transponder 1 is designed with only one dipole structure. As already shown in the embodiment in accordance with FIG. 1b, the second inductive loop 8 is arranged as a mirror image of the first inductive loop 7 reflected in a mirror plane 9, which intersects the infeed point 3 and is parallel to the dipole axis 5. Both loops 7 and 8 are in one plane (substrate plane). The infeed point 3 is located between the two loops 7 and 8.

(11) In the figures, the black areas show the metallic areas of the antenna 2 of the UHF RFID transponder 1.

(12) To increase securityagainst product counterfeiting, for examplethe UHF RFID transponder can be equipped with a hologram. This hologram can be attached to the antenna or to an area close to the antenna, for example. This type of hologram can be made of plastic, for example.

LEGEND

(13) 1 UHF RFID transponder

(14) 2 Antenna

(15) 3 Infeed point

(16) 4 Dipole structure

(17) 5 Dipole axis

(18) 6 Dipole structure

(19) 7 Inductive loop

(20) 8 Inductive loop

(21) 9 Mirror plane

(22) 10 End

(23) 11 End

(24) 12 Substrate