Circuit to test the working of at least one antenna

• US 6,437,577 B1
• Filed: 05/22/2000
• Issued: 08/20/2002
• Est. Priority Date: 05/22/1999
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Wagner, Thomas, Fritzmann, Martin
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US09/575,440
• Time in Patent Office: 820 Days
• Field of Search: 343/703, 324/503, 324/523, 324/501, 324/521, 324/527, 324/529, 73/530.1
• US Class Current: 324/523
• CPC Class Codes: H01Q 1/32 Adaptation for use in or on road or rail vehicles
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

A circuit to test the working of antennas for a radio telephone. The antennas each have a radiator with one end that open rises up into the space. The test currents flow through antenna wires to the antennas independent of a signal current (I_RF). A secondary path with an impedance that is parallel to the RF path is connected to each radiator to return the separate test currents. A voltage evaluator monitors the operating state of the antennas by comparing the test voltages induced by the test currents at the antenna connections with a reference value and generates corresponding indication signals that provide information on the operating state of the antennas.

Claims

1. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current,

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator, and

wherein there are resistors connected in series in the secondary path with feed cables whose lengths are shorter than one-tenth of the transmission wavelength so that the feed cables do not significantly affect the high-frequency characteristics of the radiator.

2. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current;

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator, and

wherein the secondary path with the impedance is located in the interior of the body of the antenna.

3. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current,

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator, and

wherein the test current is either a DC current or an AC current with a wavelength that is many times longer than the transmission wavelength of the signal current.

4. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current,

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator, and

wherein by several antenna connections, which are each connectable to the antenna wire, for antennas are alternately connected to a transceiver by an antenna selection switch and contain secondary paths with separate test currents flowing through them.

5. A circuit according to claim 4, wherein during stand-by mode of the radio telephone, a control circuit periodically switches an antenna selection switch from a primary antenna to a secondary antenna for a short time via a control input to test the working of the secondary antenna.

6. A circuit according to claim 4, wherein there is a separate voltage evaluator present for the test voltage of each antenna connection.

7. A circuit according to claim 4, wherein decoupling resistors R_K1 and R_K2 combine the test voltages of the antenna connections so that a voltage evaluator analyzes the combined input voltage from both antenna connections, and in that one decoupling resistor is larger than the other to allow the voltage evaluator to unambiguously associate a fault with the corresponding antenna connection.

8. A circuit according to claim 7, wherein the voltage evaluator detects a number of different typical input voltages corresponding to the number of possible combinations of faults on the antenna connections by comparison with stored ranges of values and outputs these as a data signal, and

wherein a control circuit generates and outputs correspondingly detailed error messages for the data signal output.

9. A circuit according to claim 4, wherein the secondary paths have resistors with different resistance values depending on the type of the antenna so that the control circuit of the radio telephone can differentiate between the antennas connected to a plurality of antenna connections, which are each connectable to the antenna wire, according to their type and automatically detect which antenna is connected to which antenna connection using the corresponding voltage evaluator.

10. A circuit according to claim 9, wherein after detecting which antenna is connected to which antenna connection, the control circuit, switches an antenna selection switch to that position in which the antenna connection of the transceiver is connected internally to a preferred antenna.

11. A circuit according to claim 9, wherein after detecting which antenna is connected to which antenna connection, the control circuit generates an error message for a display and/or correspondingly configures the input/output data for the antenna connections.

12. A circuit according to claim 9, wherein values for series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

13. A circuit according to claim 4, wherein each secondary path contains at least one ohmic resistor and a voltage evaluator on the antenna connection compares the value of the test voltage induced by the test current to a reference value to test the working of the corresponding antenna.

14. A circuit according to claim 13, wherein during stand-by mode of the radio telephone, a control circuit periodically switches the antenna selection switch from a primary antenna to a secondary antenna for a short time via a control input to test the working of the secondary antenna.

15. A circuit according to claim 13, wherein there is a separate voltage evaluator present for the test voltage of each antenna connection.

16. A circuit according to claim 13, wherein the secondary paths have resistors with different resistance values depending on the type of the antenna so that the control circuit of the radio telephone can differentiate between the antennas connected to the antenna connections according to their type and automatically detect which antenna is connected to which antenna connection using the corresponding voltage evaluator.

17. A circuit according to claim 16, wherein after detecting which antenna is connected to which antenna connection, the control circuit, switches the antenna selection switch to that position in which the antenna connection of the transceiver is connected internally to a preferred antenna.

18. A circuit according to claim 16, wherein after detecting which antenna is connected to which antenna connection, the control circuit generates an error message for a display and/or correspondingly configures the input/output data for the antenna connections.

19. A circuit according to claim 16, wherein the values for the series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

20. A circuit according to claim 13, wherein decoupling resistors R_K1 and R_K2 combine the test voltages of the antenna connections so that a voltage evaluator analyzes the combined input voltage from both antenna connections, and

wherein one decoupling resistor is larger than the other to allow the voltage evaluator to unambiguously associate a fault with the corresponding antenna connection.

21. A circuit according to claim 20, wherein the voltage evaluator detects a number of different typical input voltages corresponding to the number of possible combinations of faults on the antenna connections by comparison with stored ranges of values and outputs these as a data signal, and

wherein a control circuit generates and outputs correspondingly detailed error messages for the data signal output.

22. A circuit according to claim 20, wherein resistors R_Vl and R_V2 are placed in series with the source resistors R_S1 and R_S2, respectively, and

wherein the voltage evaluator is connected to the connection points of that series circuit via decoupling resistors R_K1 and R_K2.

23. A circuit according to claim 22, wherein the values for the series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

24. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current,

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator, and wherein each secondary path contains at least one ohmic resistor and a voltage evaluator, on an antenna connection, which is connectable to the antenna wire, that compares the value of the test voltage induced by the test current to a reference value to test the working of the corresponding antenna.

25. A circuit according to claim 24, wherein during stand-by mode of the radio telephone, a control circuit periodically switches the antenna selection switch from a primary antenna to a secondary antenna for a short time via a control input to test the working of the secondary antenna.

26. A circuit according to claim 24, wherein there is a separate voltage evaluator present for the test voltage of each antenna connection.

27. A circuit according to claim 24, wherein the secondary paths have resistors with different resistance values depending on the type of the antenna so that the control circuit of the radio telephone can differentiate between the antennas connected to the antenna connections according to their type and automatically detect which antenna is connected to which antenna connection using the corresponding voltage evaluator.

28. A circuit according to claim 27, wherein after detecting which antenna is connected to which antenna connection, the control circuit, switches the antenna selection switch to that position in which the antenna connection of the transceiver is connected internally to a preferred antenna.

29. A circuit according to claim 27, wherein after detecting which antenna is connected to which antenna connection, the control circuit generates an error message for a display and/or correspondingly configures the input/output data for the antenna connections.

30. A circuit according to claim 27, wherein the values for the series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

31. A circuit according to claim 24, wherein decoupling resistors R_K1 and R_K2 combine the test voltages of the antenna connections so that a voltage evaluator analyzes the combined input voltage from both antenna connections, and

wherein one decoupling resistor is larger than the other to allow the voltage evaluator to unambiguously associate a fault with the corresponding antenna connection.

32. A circuit according to claim 31, wherein the voltage evaluator detects a number of different typical input voltages corresponding to the number of possible combinations of faults on the antenna connections by comparison with stored ranges of values and outputs these as a data signal, and

wherein a control circuit generates and outputs correspondingly detailed error messages for the data signal output.

33. A circuit according to claim 31, wherein resistors R_V1 and R_V2 are placed in series with the source resistors R_S1 and R_S2, respectively, and

wherein the voltage evaluator is connected to the connection points of that series circuit via decoupling resistors R_K1 and R_K2.

34. A circuit according to claim 33, wherein the values for the series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

35. A circuit for testing the working of at least one antenna for a radio telephone having a control circuit, said circuit comprising:

a test current that is sent in an RF path via an antenna to the antenna by a voltage source independent of an RF signal current flowing on said RF path via said antenna wire, and

a measuring device, connected between said antenna wire and a common return, to monitor the continuity of the test current,

wherein each antenna has a radiator with one end that open rises up into the space,

wherein a secondary path parallel to the RF path containing an impedance is connected to each radiator and to the common return to return separate test currents,

wherein the monitoring of the test current is performed by a voltage evaluator,

wherein resistors R_V1 and R_V2 are placed in series with source resistors R_S1 and R_S2, respectively, and

wherein the voltage evaluator is connected to connection points of that series circuit via decoupling resistors R_K1 and R_K2.

36. A circuit according to claim 35, wherein the values for the series resistors are selected so that for both antenna connections the sum of the values of the corresponding resistor in the secondary path and the resistor connected in series to it are the same in order to unambiguously identify the case in which the antennas are connected incorrectly and are swapped.

37. A test circuit for testing the working of an antenna of a radio telephone, antenna having a radiator with one end that open rises upon into space, said test circuit comprising:

a secondary path associated with said antenna that is connected in parallel with a RF path of said antenna,

a voltage source which feeds a separate test current independently from an RF signal currently flowing on said RF path via an antenna wire which is connected to said antenna,

wherein said secondary path comprises;

an impedance inseparably connected with said radiator of said antenna and a common return to return said test current, said impedance being connected in a manner so that removal or breaking off of said radiator will cause said secondary path with said impedance to be disconnected, and

a voltage evaluator connected between the antenna wire and the common return to monitor the continuity of said test current.

38. A test circuit according to claim 37, wherein said impedance in said secondary path is connected to said radiator via a connection wire, the length of which is shorter than one-tenth of the transmission wavelength.

39. The test circuit according to claim 37, wherein said impedance in said secondary path is many times higher than a radiation resistance of the antenna.