Multi-band antenna system

• US 20050156796A1
• Filed: 01/20/2004
• Published: 07/21/2005
• Est. Priority Date: 01/20/2004
• Status: Active Grant

• Current Assignee: NETGEAR, Inc.
• Original Assignee: Sierra Wireless Incorporated
• Inventors: Nysen, Paul A.
• Granted Patent: US 7,053,843 B2
• Time in Patent Office: Days
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/2275 associated to expansion card or bus, e.g. in PCMCIA, PC cards, Wireless USB
• 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 5/335 at the feed, e.g. for impedance matching
• CPC Class Codes: H01Q 9/20 Two collinear substantially straight active elements; Substantially straight single active elements H01Q9/28 takes precedence

Abstract

A multi-band antenna system for a portable communications device (e.g. a PC Card wireless modem) is disclosed. The multi-band antenna system comprises a dipole antenna, a reactive circuit, and transmission means coupled between the reactive circuit and the dipole antenna. For signals having frequencies within a first frequency band (e.g. the CDMA 0.86 GHz band), the reactive circuit operates as a trap, i.e. as a substantially high impedance, which enables a radiation impedance of a monopole formed by the presence of the trap to be coupled directly into the feed system (e.g. a diplexer) of the antenna system. The dipole antenna is configured and dimensioned to receive signals within a second frequency band (e.g. the PCS 1.92 GHz band). Second frequency band signals received by the dipole antenna are conducted through the signal conductor of the transmission means to the feed system substantially unimpeded by the reactive circuit. The multi-band antenna system may further include a diversity antenna, which may be configured so that it is polarized orthogonal the to dipole antenna.

Claims

1. A multi-band antenna system, comprising:

a dipole antenna;

transmission means having a first end coupled to the dipole antenna; and

a reactive circuit coupled between a second end of the transmission means and a PC Card wireless modem,

wherein the reactive circuit is configured to operate as a trap for received signals having frequencies within a first frequency band.

2. The multi-band antenna system of claim 1 wherein the dipole is configured to receive signals having frequencies within a second frequency band.

3. The multi-band antenna system of claim 2 wherein the first frequency band corresponds to the CDMA 0.86 GHz band and the second frequency band corresponds to the PCS 1.92 GHz band.

4. The multi-band antenna system of claim 1 wherein a ground plane of a printed circuit board of the PC Card wireless modem and/or a conductive housing of the PC Card wireless modem functions as a counterpoise for the antenna apparatus.

5. The multi-band antenna system of claim 4 wherein combined lengths of a pole of the dipole antenna and a portion of the transmission means operate as a monopole antenna for received signals having frequencies within the first frequency band.

6. The multi-band antenna system of claim 1, further comprising a matching circuit coupled between first and second poles of the dipole antenna.

7. The multi-band antenna system of claim 6 wherein said matching circuit is further configured to operate as a balun.

8. The multi-band antenna system of claim 6 wherein the matching circuit, the dipole, and a portion of the transmission means are formed on a first printed circuit board.

9. The multi-band antenna system of claim 1 wherein the reactive circuit is formed on a printed circuit board.

10. The multi-band antenna system of claim 8 wherein the reactive circuit is formed on a second printed circuit board.

11. The multi-band antenna system of claim 1, further comprising a diversity dipole.

12. The multi-band antenna system of claim 9, further comprising a diversity dipole.

13. The multi-band antenna system of claim 12 wherein the diversity dipole is formed on the printed circuit board.

14. The multi-band antenna system of claim 10, further comprising a diversity dipole.

15. The multi-band antenna system of claim 14 wherein the diversity dipole is formed on the second printed circuit board.

16. A multi-band antenna system for a portable communications device, comprising:

a dipole antenna;

transmission means having a first end coupled to the dipole antenna; and

a reactive circuit coupled between a second end of the transmission means and the portable communications device,

wherein the reactive circuit is configured to operate as a trap for received signals having frequencies within a first frequency band.

17. The multi-band antenna system of claim 16 wherein combined lengths of a pole of the dipole antenna, and a portion of the transmission means form a whip antenna capable of receiving signals having frequencies within the first frequency band.

18. The multi-band antenna system of claim 16 wherein the dipole antenna is configured to receive signals having frequencies within a second frequency band.

19. The multi-band antenna system of claim 18 wherein the first frequency band corresponds to the CDMA 0.86 GHz band and the second frequency band corresponds to the PCS 1.92 GHz band.

20. The multi-band antenna system of claim 16 wherein the portable communications device comprises a PC Card wireless modem.

21. The multi-band antenna system of claim 20 wherein a ground plane of a printed circuit board of the PC Card wireless modem and/or a conductive housing of the PC Card wireless modem functions as a counterpoise for the antenna apparatus.

22. The multi-band antenna system of claim 16, further comprising a matching circuit coupled between first and second poles of the dipole antenna.

23. The multi-band antenna system of claim 22 wherein said matching circuit is further configured to operate as a balun.

24. The multi-band antenna system of claim 22 wherein the matching circuit, the dipole, and a portion of the transmission means are formed on a first printed circuit board.

25. The multi-band antenna system of claim 16 wherein the reactive circuit is formed on a printed circuit board.

26. The multi-band antenna system of claim 24 wherein the reactive circuit is formed on a second printed circuit board.

27. The multi-band antenna system of claim 16, further comprising a diversity dipole.

28. The multi-band antenna system of claim 25, further comprising a diversity dipole.

29. The multi-band antenna system of claim 28 wherein the diversity dipole is formed on the printed circuit board.

30. The multi-band antenna system of claim 26, further comprising a diversity dipole.

31. The multi-band antenna system of claim 30 wherein the diversity dipole is formed on the second printed circuit board.