Antenna coupling reduction apparatus and method

• US 20050014540A1
• Filed: 04/23/2004
• Published: 01/20/2005
• Est. Priority Date: 04/25/2003
• Status: Abandoned Application

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Shim, Joo-Heon
• Application Number:
  US10/831,512
• Publication Number:
  US 20050014540A1
• Time in Patent Office: Days
• US Class Current: 455/575.700
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers
• CPC Class Codes: H04B 1/48 in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence
• CPC Class Codes: H04B 7/0805 with single receiver and antenna switching H04B7/0822 takes precedence

Abstract

The present invention provides an antenna coupling preventing system and method capable of minimizing coupling between a GPS antenna and a CDMA antenna. The system comprises first and second antennas for receiving first and second RF signals of first and second frequencies, respectively; a mobile switch for measuring performance characteristics of the second antenna; and a switch circuit connected between the second antenna and the mobile switch for controlling flow of the first RF signal to the second antenna.

Claims

1. A signal coupling prevention system for a mobile communication terminal having a GPS function, comprising:

first and second antennas for receiving first and second RF signals of first and second frequencies, respectively;

a mobile switch for measuring performance characteristics of the second antenna; and

a switch circuit connected between the second antenna and the mobile switch for controlling flow of the first RF signal to the second antenna.

2. The apparatus of claim 1, wherein when the terminal is in a first mode, the switch circuit changes an input impedance of the second antenna to a first level to cut off flow of the first RF signal.

3. The apparatus of claim 1, wherein when the terminal is in a second mode, the switch circuit changes the input impedance of the second antenna to a second level to allow the second RF signal to flow to a diplexer.

4. The apparatus of claim 1, wherein the second signal comprises a DCN (Digital Cellular Network) signal and a PCS (Personal Communication Service) signal.

5. The apparatus of claim 1, wherein the switch circuit comprises:

a choke coil for transmitting a control signal to a diode;

a conducting means connected between the second antenna and a load for controlling flow of the second RF signal received by the second antenna according to the control signal; and

a transmission line for transmitting the second RF signal which has passed the conducting means, to the diplexer.

6. The apparatus of claim 5, wherein the conducting means comprises a pin diode.

7. The apparatus of claim 5, wherein the control signal is provided by a mobile station modem (MSM).

8. The apparatus of claim 5, wherein the control signal is provided at a first level in the GPS mode.

9. The apparatus of claim 5, wherein the control signal is provided at a second level in the CDMA mode.

10. The apparatus of claim 5, wherein the conducting means increases impedance of the second antenna to cut off inflow of the RF signal.

11. A signal coupling prevention system for a mobile communication terminal having separated GPS antenna and CDMA antenna for receiving respective GPS and CDMA signals, wherein a switch circuit for controlling an input impedance of the CDMA antenna is connected between the CDMA antenna and a mobile switch to cut off a first RF signal received by the CDMA antenna in a GPS operation mode and to allow passing of a second RF signal received by the CDMA antenna in a CDMA operation mode.

12. The apparatus of claim 11, wherein the first RF signal comprises a GPS signal and the second RF signal comprises a CDMA signal.

13. The apparatus of claim 11, wherein the switch circuit comprises:

a choke coil for transmitting a control signal for controlling input impedance of the CDMA antenna to a diode;

a conducting mechanism connected between the CDMA antenna and a load for cutting off or allowing the second RF signal to pass according to the control signal; and

a transmission line for connecting the conducting mechanism to a diplexer.

14. The apparatus of claim 13, wherein the conducting mechanism comprises a pin diode.

15. The apparatus of claim 13, wherein the conducting mechanism comprises a MOS transistor.

16. The apparatus of claim 13, wherein the control signal is provided from a mobile station modem (MSM) and has a low level in the GPS mode and a high level in the CDMA mode.

17. An antenna coupling preventing apparatus for a mobile communication terminal having a GPS antenna and a CDMA antenna to receive a GPS signal and a CDMA signal, wherein an input impedance of the CDMA antenna is maintained high in a GPS operation mode to cut off inflow of a GPS signal, and the input impedance of the CDMA antenna is maintained low in a CDMA operation mode to receive a CDMA signal.

18. An antenna coupling preventing apparatus comprising:

first and second antennas for receiving first and second RF signals respectively, having first and second frequencies; and

a switch circuit connected to the first antenna for cutting off inflow of the second RF signal, received by the second antenna, to the first antenna.

19. The apparatus of claim 18, wherein the first antenna receives a GPS (Global Positioning System) signal and the second antenna receives a CDMA (Code Division Multiple Access) signal.

20. The apparatus of claim 18, wherein the switch circuit is connected between the first antenna and a mobile switch measuring performance of wired characteristics of the first antenna.

21. The apparatus of claim 18, wherein the switch circuit maintains a first impedance in order to cut off inflow of the first signal to the second antenna.

22. The apparatus of claim 21, wherein the first impedance is a high impedance.

23. The apparatus of claim 18, wherein if the CDMA signal is received by the first antenna, the switch circuit maintains a second input impedance to prevent coupling with a GPS signal received by the second antenna.

24. The apparatus of claim 23, wherein the CDMA signal comprises at least of one of a PCS (Personal Communication Service) signal and a DCN (Digital Cellular Network) signal.

25. The apparatus of claim 18, wherein the switch circuit comprises:

a choke coil for transmitting a control signal controlling the input impedance of at least one of the first and second antennas;

a conducting mechanism connected to the first antenna and a load to control flow of the first RF signal received by the first antenna according to the control signal; and

a transmission line for transmitting the first RF signal to a diplexer.

26. The apparatus of claim 25, wherein the conducting mechanism comprises a pin diode.

27. The apparatus of claim 25, wherein the conducting mechanism comprises a MOS transistor.

28. The apparatus of claim 25, wherein the control signal is provided by a mobile station modem (MSM).

29. The apparatus of claim 25, wherein the control signal has a low level in the GPS mode.

30. The apparatus of claim 25, wherein the control signal has a high level in the CDMA mode.

31. A method for reducing coupling between a first antenna and a second antenna of a mobile terminal, wherein the first antenna is configured to receive a first signal and a second antenna is configured to receive a second signal, the method comprising:

setting a first impedance for the first antenna to prevent flow of the second signal in the first antenna;

when the mobile terminal is in a second reception mode; and

setting a second impendence for the first antenna to allow flow of the first signal in the first antenna, when the mobile terminal is in a first reception mode.

32. The method of claim 31, wherein the first signal comprises a CDMA signal.

33. The method of claim 31, wherein the second signal comprises a GPS signal.

34. The method of claim 31, wherein the first reception mode is a CDMA reception mode.

35. The method of claim 31, wherein the second reception mode is a GPS reception mode.

36. The method of claim 31, wherein the first impedance is a high value.

37. The method of claim 31, wherein the second impedance is a low value.

38. The method of claim 31, wherein a control signal provided by a modem defines whether the mobile terminal is in at least one of the first and second reception modes.

39. The method of claim 37, wherein a switch mechanism controls the flow of the first and second signals in the first and second antennas based on the control signal'"'"'s value.

40. The method of claim 31, wherein the first signal comprises a digital cellular network (DCN) signal.

41. The method of claim 31, wherein the first signal comprises a personal communication service (PCS) signal.