Portable radio apparatus

• US 7,180,452 B2
• Filed: 07/21/2004
• Issued: 02/20/2007
• Est. Priority Date: 07/28/2003
• Status: Expired due to Fees

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Saito, Tetsuya
• Primary Examiner(s): Le; Hoanganh
• Assistant Examiner(s): LE, TUNG X
• Application Number:
  US10/895,327
• Publication Number:
  US 20050024288A1
• Time in Patent Office: 944 Days
• Field of Search: 343/702, 343/906, 343/895, 343/900, 343/725, 343/727, 340/540, 340/572
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/244 extendable from a housing along a given path
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H03H 7/46 Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source for use in multiplex transmission systems H04J1/00
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A portable radio apparatus capable of providing an impedance match with an antenna and a simple matching circuit for all frequency components of a frequency band to be used. A portable radio apparatus includes a whip antenna, a matching circuit, a radio section changing switch, a first frequency band receiver, and a first frequency band transmitter. A parallel inductor causing a resonance with a frequency lower than a resonance frequency of the antenna is connected in parallel to the antenna for a two-resonance characteristic to thereby conduct a wide-band operation.

Claims

1. A portable radio apparatus, comprising:

an antenna for transmitting and receiving a radio signal;

a radio circuit for decoding the radio signal received via the antenna and encoding a signal to be transmitted as a radio signal via the antenna; and

a matching circuit for providing an impedance match between the antenna and the radio circuit;

wherein;

the matching circuit includes at least one inductive element connected in parallel to the antenna; and

said at least one of the inductive element has a Q factor more than a predetermined value, the Q factor being expressed as follows;

Q=ω

L/R

wherein R indicates a resistance component, L is an inductance component, and ω

designates an angular frequency of the radio signal.

2. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit; and

the first inductive element has a Q factor more than a Q factor of the second inductive element.

3. A portable radio apparatus in accordance with claim 2, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

4. A portable radio apparatus in accordance with claim 2, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

5. A portable radio apparatus in accordance with claim 2, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

6. A portable radio apparatus in accordance with claim 2, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

7. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit;

the first inductive element has a Q factor more than a Q factor of the second inductive element; and

the Q factor of the first inductive element takes a value, which sets radiation efficiency of the antenna to a value equal to or more than a predetermined value when the radio signal is transmitted.

8. A portable radio apparatus in accordance with claim 7, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

9. A portable radio apparatus in accordance with claim 7, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

10. A portable radio apparatus in accordance with claim 7, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

11. A portable radio apparatus in accordance with claim 7, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

12. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit;

the first inductive element has a Q factor more than a Q factor of the second inductive element; and

the Q factor of each of the first and second inductive elements takes a value, which sets radiation efficiency of the antenna to a value equal to or more than a predetermined value when the radio signal is transmitted.

13. A portable radio apparatus in accordance with claim 12, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

14. A portable radio apparatus in accordance with claim 12, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

15. A portable radio apparatus in accordance with claim 12, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

16. A portable radio apparatus in accordance with claim 12, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

17. A portable radio apparatus in accordance with claim 1, wherein the Q factor of each of the inductive elements is more than 40.

18. A portable radio apparatus in accordance with claim 17, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

19. A portable radio apparatus in accordance with claim 17, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

20. A portable radio apparatus in accordance with claim 17, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

21. A portable radio apparatus in accordance with claim 17, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

22. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit;

the first inductive element has a Q factor more than a Q factor of the second inductive element; and

the Q factor of each of the inductive elements is more than 40.

23. A portable radio apparatus in accordance with claim 22, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

24. A portable radio apparatus in accordance with claim 22, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

25. A portable radio apparatus in accordance with claim 22, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

26. A portable radio apparatus in accordance with claim 22, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

27. A portable radio apparatus in accordance with claim 22, wherein the matching circuit is a π

type circuit in which a first capacitive element is connected in parallel on the side of the antenna and a second capacitive element is connected in parallel on the side of the radio circuit.

28. A portable radio apparatus in accordance with claim 27, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

29. A portable radio apparatus in accordance with claim 27, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

30. A portable radio apparatus in accordance with claim 27, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

31. A portable radio apparatus in accordance with claim 27, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

32. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit;

the first inductive element has a Q factor more than a Q factor of the second inductive element;

the Q factor of the first inductive element takes a value, which sets radiation efficiency of the antenna to a value equal to or more than a predetermined value when the radio signal is transmitted; and

the Q factor of each of the inductive elements is more than 40.

33. A portable radio apparatus in accordance with claim 32, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

34. A portable radio apparatus in accordance with claim 32, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

35. A portable radio apparatus in accordance with claim 32, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

36. A portable radio apparatus in accordance with claim 32, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

37. A portable radio apparatus in accordance with claim 1, wherein:

the matching circuit is a π

type circuit in which a first inductive element is connected in parallel on the side of the antenna and a second inductive element is connected in parallel on the side of the radio circuit;

the first inductive element has a Q factor more than a Q factor of the second inductive element;

the Q factor of each of the first and second inductive elements takes a value, which sets radiation efficiency of the antenna to a value equal to or more than a predetermined value when the radio signal is transmitted; and

the Q factor of each of the inductive elements is more than 40.

38. A portable radio apparatus in accordance with claim 37, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

39. A portable radio apparatus in accordance with claim 37, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

40. A portable radio apparatus in accordance with claim 37, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

41. A portable radio apparatus in accordance with claim 37, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

42. A portable radio apparatus in accordance with claim 1, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands; and

the antenna has different two resonance frequencies in one of the frequency bands.

43. A portable radio apparatus in accordance with claim 1, wherein:

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands; and

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic.

44. A portable radio apparatus in accordance with claim 1, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

45. A portable radio apparatus in accordance with claim 1, further comprising:

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic;

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected; and

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.

46. A portable radio apparatus comprising:

an antenna for transmitting and receiving a radio signal;

a radio circuit for decoding the radio signal received via the antenna and encoding a signal to be transmitted as a radio signal via the antenna;

a matching circuit for providing an impedance match between the antenna and the radio circuit, the matching circuit including at least one capacitive element connected in parallel to the antenna;

a detector for detecting whether the antenna is in an expanded state in which the antenna is expanded; and

an expansion matching circuit impedance of which matches with the antenna in the expanded state in a particular frequency band when the expansion matching circuit is connected to the matching circuit;

wherein;

the radio circuit is a circuit for decoding and encoding the radio signal in a plurality of frequency bands;

the antenna has different two resonance frequencies in one of the frequency bands;

the antenna includes a straight section and a helical section, the helical section having a two-resonance characteristic; and

the expansion matching circuit is connected to the matching circuit when the antenna is in the expanded state and a particular one of the frequency bands is selected.

47. A portable radio apparatus in accordance with claim 46, wherein

impedance of the antenna in the expanded state matches that of the matching circuit in a frequency band for which the expansion matching circuit is not connected to the matching circuit.