Multi-loop antenna system for contactless applications

• US 9,293,825 B2
• Filed: 03/15/2013
• Issued: 03/22/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Verifone, Inc. (Verifone Systems, Inc.)
• Original Assignee: Verifone, Inc. (Verifone Systems, Inc.)
• Inventors: Rivera, Marinel Salaver
• Primary Examiner(s): Levi, Dameon E
• Assistant Examiner(s): Hu, Jennifer F
• Application Number:
  US13/837,365
• Publication Number:
  US 20140266966A1
• Time in Patent Office: 1,103 Days
• Field of Search: 343/741, 343/742, 343/743, 343/744, 343/867
• US Class Current: 1/1
• 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: H01Q 1/2216 used in interrogator/reader equipment
• 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 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H01Q 5/314 using frequency dependent circuits or components, e.g. trap circuits or capacitors
• CPC Class Codes: H01Q 5/50 Feeding or matching arrangements for broad-band or multi-band operation
• 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

An antenna system suitable for use with contactless transaction devices, the antenna system including a reader, a primary loop antenna having a first end and a second end, each one of the first and second ends being coupled to the reader and at least one secondary loop antenna galvanically connected to the primary loop antenna at a single connection point and positioned with respect to the primary loop antenna so as to make capacitive coupling therebetween negligible.

Claims

1. An antenna system suitable for use with contactless transaction devices, said antenna system comprising:

a reader;

a primary loop antenna having a first end and a second end, each one of said first and second ends being coupled to said reader such that there is a current return path between said primary loop antenna and said reader whereby said primary loop antenna presents an inductive load to said reader; and

at least one secondary loop antenna galvanically connected to said primary loop antenna at a single connection point,

said at least one secondary loop antenna being coupled to said reader at only a single one of its ends, such that establishment of a current path return between said secondary loop antenna and said reader is prevented, whereby said at least one secondary loop antenna does not present an inductive load to said reader, and

said connection point between said secondary loop antenna and said primary loop antenna additionally serving as a connection point between said single end of said secondary loop antenna and said reader,

wherein said secondary loop is closed on itself to form a closed loop.

2. An antenna system according to claim 1, wherein said at least one secondary loop antenna comprises a single secondary loop antenna.

3. An antenna system according to claim 1, wherein said first and second ends of said primary loop antenna are connected to a matching circuit, said matching circuit being operative to match an impedance of said primary loop antenna to an impedance of said reader.

4. An antenna system according to claim 1, wherein said primary loop antenna comprises three turns.

5. An antenna system according to claim 4, wherein said secondary loop antenna comprises three turns.

6. An antenna system according to claim 1, wherein said primary loop antenna has a resonant frequency of 13.56 MHz.

7. An antenna system according to claim 6, wherein said secondary loop antenna has a resonant frequency in a range of 12-20 MHz.

8. An antenna system according to claim 7, wherein said resonant frequency of said primary loop antenna is offset from said resonant frequency of said secondary loop antenna by at least 400 kHz.

9. An antenna system according to claim 1, wherein said secondary loop antenna comprises a capacitor for tuning said secondary loop antenna.

10. An antenna system according to claim 1, wherein said primary loop antenna is separated from said secondary loop antenna by a distance of at least 1.5 mm.

11. An antenna system according to claim 1, wherein said secondary loop antenna is located within and enclosed by said primary loop antenna.

12. An antenna system according to claim 1, wherein said primary loop antenna and said secondary loop antenna are formed on a printed circuit board.

13. An antenna system according to claim 12, wherein said primary loop antenna is formed on an upper surface of said printed circuit board and said secondary loop antenna is formed on a lower surface of said printed circuit board.

14. An antenna system according to claim 12, wherein said primary loop antenna and said secondary loop antenna are formed on a common surface of said printed circuit board.

15. An antenna system according to claim 1, wherein said primary loop antenna is coupled to said reader by way of a coaxial cable.

16. An antenna system according to claim 1, wherein said contactless transaction device comprises a near field communication device.

17. An antenna system according to claim 1, wherein said contactless transaction device comprises a contactless credit card.