Broadband antenna for a transponder of a radio frequency identification system

• US 7,750,862 B2
• Filed: 11/08/2006
• Issued: 07/06/2010
• Est. Priority Date: 11/10/2005
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Hilgers, Achim
• Primary Examiner(s): Ho; Tan
• Application Number:
  US12/092,901
• Publication Number:
  US 20080266191A1
• Time in Patent Office: 1,336 Days
• Field of Search: 343/725, 343/726, 343/741, 343/793, 340/572.1, 340/572.7
• US Class Current: 343/726
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H01Q 5/00 Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements combinations of separate active antenna units operating in different wavebands and connected to a common feeder system H01Q21/30
• CPC Class Codes: H01Q 5/357 using a single feed point
• CPC Class Codes: H01Q 5/371 Branching current paths
• 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 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/28 Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines waveguide horns or mouths H01Q13/00; slot antennas H01Q13/00

Abstract

A broadband antenna structure (10) for a transponder of a radio frequency identification system comprises—a loop resonator (12) with a feedpoint (14) for connecting with an electronic circuit (16), and—a dipole resonator (18) electrically connected to the loop resonator (12) and comprising two electrically isolated legs (20, 22).

Claims

1. A broadband antenna for a transponder of a radio frequency identification system comprising:

a loop resonator with a feedpoint for connecting with an electronic circuit, and

a dipole resonator electrically connected to the loop resonator and comprising two electrically isolated legs,

wherein the loop resonator comprises two electrical lines, wherein;

one end of each line is provided for connecting with the electronic circuit,

the other end of each line is coupled to a respective one of the two electrically isolated legs of the dipole resonator, and

a coupling couples the other ends of the two lines.

2. An antenna as claimed in claim 1, wherein the coupling is an electrical connection forming a short circuit of the two lines.

3. An antenna as claimed in claim 1, wherein the coupling is a capacitive coupling structure.

4. An antenna as claimed in claim 1, wherein the coupling is formed by a capacitor.

5. An antenna as claimed in claim 1, wherein the dimensions and arrangement of the two electrical lines are selected such that the antenna shows at least two resonance bands in which the antenna is in a matched condition with the electronic circuit, wherein one of the two resonance bands lies in a first frequency range and the other one of the two resonance bands lies in a second frequency range different from the first frequency range.

6. An antenna as claimed in claim 1, wherein the lines are arranged in parallel.

7. An antenna as claimed in claim 6, wherein each of the lines has a predefined length and width, and both lines are arranged in a predefined distance, wherein the predefined length, width, and distance are selected such that the antenna shows at least two resonance bands in which the antenna is in a matched condition with the electronic circuit, wherein one of the two resonance bands lies in a first frequency range and the other one of the two resonance bands lies in a second frequency range different from the first frequency range.

8. An antenna as claimed in claim 7, wherein the coupling is an electrical connection with a predefined width.

9. An antenna as claimed in claim 1, wherein the two electrically isolated legs of the dipole resonator are arranged over a predefined length in parallel.

10. An antenna as claimed in claim 9, wherein both legs are arranged at the same predefined distance of the lines of the loop resonator.

12. An antenna as claimed in claim 9, wherein both legs diverge over a second predefined length after being arranged in parallel over a first predefined length and have a second predefined width.

13. An antenna as claimed in claim 1, wherein electrically conducting parts of the antenna are electrically conducting metallization deposited on or embedded into a substrate having a dielectric constant equal or larger than 1 and a permeability coefficient equal or larger than 1.

14. A transponder of a radio frequency identification system comprising an antenna as claimed in claim 1 and an electronic circuit to which the antenna is connected at its feedpoint.

11. An antenna as claimed in 9, wherein both legs have a first predefined width essentially equal to the width of the lines of the loop resonator at least for the predefined length for which they are arranged in parallel.

15. A broadband antenna for a transponder of a radio frequency identification system comprising:

a loop resonator with a feedpoint for connecting with an electronic circuit, and

a dipole resonator electrically connected to the loop resonator and comprising two electrically isolated legs,

wherein both legs diverge over a second predefined length after being arranged in parallel over a first predefined length and have a second predefined width.

16. An antenna as claimed in claim 15, wherein both legs are arranged at the same predefined distance of the lines of the loop resonator.

17. An antenna as claimed in 15, wherein both legs have a first predefined width essentially equal to the width of the lines of the loop resonator at least for the predefined length for which they are arranged in parallel.

18. A broadband antenna for a transponder of a radio frequency identification system comprising:

a loop resonator with a feedpoint for connecting with an electronic circuit, and

a dipole resonator electrically connected to the loop resonator and comprising two electrically isolated legs,

wherein electrically conducting parts of the antenna are electrically conducting metallization deposited on or embedded into a substrate having a dielectric constant equal

or larger than 1 and a permeability coefficient equal or larger than 1.