System and method for impedance matching an antenna to sub-bands in a communication band

• US 7,176,845 B2
• Filed: 07/26/2004
• Issued: 02/13/2007
• Est. Priority Date: 02/12/2002
• Status: Expired due to Term

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Wireless Corporation (Kyocera Corporation)
• Inventors: Fabrega-Sanchez, Jorge, Poilasne, Gregory, Toncich, Stanley S., Tran, Allen
• Primary Examiner(s): Wimer; Michael C.
• Application Number:
  US10/899,218
• Publication Number:
  US 20050007291A1
• Time in Patent Office: 932 Days
• Field of Search: 343/850, 343/860, 343/861, 455/575.7
• US Class Current: 343/861
• CPC Class Codes: G01R 27/2694 Measuring dielectric loss, e.g. loss angle, loss factor or power factor
• CPC Class Codes: H01G 7/06 having a dielectric selected for the variation of its permittivity with applied voltage, i.e. ferroelectric capacitors electrets H01G7/02
• CPC Class Codes: H01L 27/0808 Varactor diodes
• CPC Class Codes: H01P 1/203 Strip line filters
• CPC Class Codes: H01P 1/20336 Comb or interdigital filters
• CPC Class Codes: H01P 1/20363 Linear resonators
• CPC Class Codes: H01P 1/20381 Special shape resonators
• CPC Class Codes: H01P 1/2039 Galvanic coupling between Input/Output
• CPC Class Codes: H01P 1/2056 Comb filters or interdigital filters with metallised resonator holes in a dielectric block
• CPC Class Codes: H01P 1/213 combining or separating two or more different frequencies H01P1/215 takes precedence
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H01Q 1/00 Details of, or arrangements associated with, antennas arrangements for varying orientation of directional pattern H01Q3/00
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H01Q 13/06 Waveguide mouths horns H01Q13/02
• CPC Class Codes: H01Q 13/203 Leaky coaxial lines
• CPC Class Codes: H01Q 13/22 Longitudinal slot in boundary wall of waveguide or transmission line H01Q13/203 takes precedence
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0442 : with particular tuning means
• CPC Class Codes: H01Q 9/16 : with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/28 : Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines waveguide horns or mouths H01Q13/00; slot antennas H01Q13/00
• CPC Class Codes: H01Q 9/30 : with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/42 : with folded element, the folded parts being spaced apart a small fraction of the operating wavelength
• CPC Class Codes: H03B 5/04 : Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/1841 : the frequency-determining element being a strip line resonator H03B5/1805, H03B5/1817, H03B5/1864 and H03B5/1882 take precedence
• CPC Class Codes: H03B 5/362 : the amplifier being a single transistor H03B5/364 - H03B5/368 take precedence
• CPC Class Codes: H03F 1/56 : Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/294 : the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 : Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/191 : Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03H 7/38 : Impedance-matching networks
• CPC Class Codes: H03J 5/246 : using electronic means H03J5/244 takes precedence
• CPC Class Codes: H03L 1/022 : by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence
• CPC Class Codes: H03L 7/18 : using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H04B 1/0053 : with common antenna for more than one band
• CPC Class Codes: H04B 1/0458 : Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H
• CPC Class Codes: H04B 1/30 : for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A sub-band antenna matching method and an antenna matching system for selectively matching a communication bandwidth segment impedance have been provided. The method comprises: accepting a frequency-dependent impedance from an antenna; and, selectively supplying a conjugate impedance match for the antenna at a sub-band of a first communication band. In some aspects, the method selectively supplies a conjugate impedance match for the antenna at a sub-band of a second communication band. More specifically, the method comprises: tuning a first tuning circuit to a first frequency; simultaneously tuning a second tuning circuit to a second frequency to match the antenna at a low end of the first communication band. Likewise, the first tuning circuit is tuned to a third frequency and the second tuning circuit is tuned to a fourth frequency to match the antenna at a high end of the first communication band in response to the third and fourth frequencies.

Claims

1. An antenna matching system comprising:

an antenna having an interface port with a frequency-dependent impedance; and

a sub-band matching circuit including an output port connected to the antenna interface port, the sub-band matching circuit including;

a first tuning circuit selectively tunable to a first sub-band within a first communication band and selectively tunable to a second sub-band within a second communication band, the first tuning circuit comprising a first tunable ferroelectric (FE) capacitor having a first variable dielectric constant responsive to a first control voltage; and

,

a second tuning circuit selectively tunable to a third sub-band within the first communication band when the first tuning circuit is tuned to the first sub-band and selectively tunable to a fourth sub-band within the second communication band when the first tuning circuit is tuned to the second communication band, the second tuning circuit comprising a second tunable FE capacitor having a second variable dielectric constant responsive to a second control voltage;

wherein the first tuning circuit and the second tuning circuit supply a first conjugate impedance for receiving the first communication band on the antenna interface port and supply a second conjugate impedance for receiving the second communication band on the antenna interface port.

2. The system of claim 1 wherein the sub-band matching circuit selectively supplies the first conjugate impedance at a low end of the first communication band and at a high end of the first communication band.

3. The system of claim 1 wherein the sub-band matching circuit selectively supplies the second conjugate impedance at a low end of the second communication band and at a high end of the second communication band.

4. The system of claim 2 wherein the sub-band matching circuit selectively supplies the first conjugate impedance at the low end of the first communication band in response to tuning the first tuning circuit to a first frequency within the first communication band and tuning the second tuning circuit to a second frequency within the first communication band.

5. The system of claim 2 wherein the sub-band matching circuit selectively supplies the first conjugate impedance at the high end of the first communication band in response to tuning the first tuning circuit to a third frequency within the first communication band and tuning the second tuning circuit to a fourth frequency within the first communication band.

6. The system of claim 3 wherein the sub-band matching circuit selectively supplies the second conjugate impedance at the low end of the second communication band in response to tuning the first tuning circuit to a fifth frequency within the second communication band and tuning the second tuning circuit to a sixth frequency within the second communication band.

7. The system of claim 3 wherein the sub-band matching circuit selectively supplies the second conjugate impedance at the high end of the second communication band in response to tuning the first tuning circuit to a seventh frequency within the second communication band and tuning the second tuning circuit to an eighth frequency within the second communication band.

8. The system of claim 1 wherein the first control voltage and the second control voltage are in the range of zero to three volts dc.

9. The system of claim 1 wherein the first and second tunable ferroelectric capacitors are selected from the group including interdigital, gap, and overlay capacitors.

10. The system of claim 1 wherein the first tuning circuit includes:

a first inductor with a fixed inductance value;

the first tunable FE capacitor with a first selectable capacitance value; and

,

wherein the second tuning circuit includes;

a second inductor with a fixed inductance value;

the second tunable FE capacitor with a second selectable capacitance value.

11. The system of claim 10 wherein the first variable capacitor has a first terminal connected to the sub-band matching circuit output port;

wherein the first inductor is connected in shunt between a second terminal of the first tunable FE capacitor and a reference voltage;

wherein the second variable tunable FE capacitor has a first terminal connected to the first variable capacitor second terminal; and

,

wherein the second inductor is connected in series between a second terminal of the second tunable FE capacitor and a sub-band matching circuit input port.

12. The system of claim 11 wherein the first inductor has an inductance of 8 nano-Henrys (nH);

wherein the first tunable FE capacitor has a capacitance in the range between 2.35 and 3.1 picofarads (pF);

wherein the second inductor has an inductance of 2 nH; and

,

wherein the second tunable FE capacitor has a capacitance in the range between 1.85 and 3.5 pF.

13. The system of claim 12 wherein the first tuning circuit first frequency is responsive to a first tunable FE capacitor value of 2.35 pF, and the second tuning circuit second frequency is responsive to a second tunable FE capacitor value of 2.9 pF;

and,

wherein the first tuning circuit third frequency is responsive to the first tunable FE capacitor value of 2.6 pF, and the second tuning circuit fourth frequency is responsive to the second tunable FE capacitor value of 2.6 pF;

wherein the first tuning circuit fifth frequency is responsive to the first tunable FE capacitor value of 3.1 pF, and the second tuning circuit sixth frequency is responsive to the second tunable FE capacitor value of 1.85 pF; and

,

wherein the first tuning circuit seventh frequency is responsive to the first tunable FE capacitor value of 2.6 pF, and the second tuning circuit eighth frequency is responsive to the second tunable FE capacitor value of 3.5 pF.

14. The system of claim 1 wherein the sub-band matching circuit supplies the first conjugate impedance at the first communication band in the range between 824 and 894 megahertz (MHz) and at the second communication band in the range of 1850 and 1990 MHz.

15. The system of claim 1 wherein the sub-band matching circuit supplies the first conjugate impedance, with a retum loss of less than 2:

1, at the first communication band sub-band of approximately 45 megahertz (MHz) and at the second communication band sub-band of approximately 80 MHz.

16. The system of claim 1 wherein the sub-band matching circuit supplies the first conjugate impedance at a first plurality of sub-bands in the first communication band and supplies the second conjugate impedance at a second plurality of sub-bands in the second communication band.

17. The system of claim 1 wherein the dual-band matching circuit is a matching topology selected from the group including a tunable series element, a tunable shunt element, “

L”

, π

, “

F”

, and combinations of the above-mentioned topologies.

18. A wireless communications device with a bandwidth segment antenna matching system, the device comprising:

a transceiver having a wireless communications port to communicate information in a first communication band;

an antenna having an interface port with a frequency-dependent impedance; and

a sub-band matching circuit including an input port connected to the transceiver wireless communications port and an output port connected to the antenna interface port, the sub-band matching circuit including;

a first tuning circuit selectively tunable to a first bandwidth segment within the first communication band and selectively tunable to a second bandwidth segment within the first communication band, the first tuning circuit comprising a first tunable ferroelectric (FE) capacitor having a first variable dielectric constant responsive to a first control voltage; and

,

a second tuning circuit selectively tunable to a third bandwidth segment within the first communication band when the first tuning circuit is tuned to the first bandwidth segment and selectively tunable to a fourth segment within the first communication band when the first tuning circuit is tuned to the second bandwidth segment, the second tuning circuit comprising a second tunable FE capacitor having a second variable dielectric constant responsive to a second control voltage;

wherein the first tuning circuit and the second tuning circuit supply a first conjugate impedance for receiving a first set of frequencies in the first and third bandwidth segments and supply a second conjugate impedance for receiving a second set of frequencies in the second and fourth bandwidth segments.

19. The device of claim 18 wherein the sub-band matching circuit selectively supplies the first conjugate impedance at a low end of the first communication band and at a high end of the first communication band.

20. The device of claim 18 wherein the first control voltage and the second control voltage is in the range of zero to three volts dc.

21. The device of claim 18 wherein the first and second tunable ferroelectric capacitors are selected from the group including interdigital, gap, and overlay capacitors.

22. The device of claim 18 wherein the first tuning circuit includes:

a first inductor with a fixed inductance value; and

the first tunable FE capacitor with a first selectable capacitance value; and

,

wherein the second tuning circuit includes;

a second inductor with a fixed inductance value; and

the second tunable FE capacitor with a second selectable capacitance value.

23. The device of claim 22 wherein the first variable capacitor has a first terminal connected to the sub-band matching circuit output port;

wherein the first inductor is connected in shunt between a second terminal of the first tunable FE capacitor and a reference voltage;

wherein the second variable capacitor has a first terminal connected to the first tunable FE capacitor second terminal; and

,

wherein the second inductor is connected in series between a second terminal of the second tunable FE capacitor and a sub-band matching circuit input port.

24. The device of claim 23 wherein the first inductor has an inductance of 8 nano-Henrys (nH);

wherein the first tunable FE capacitor has a capacitance in the range between 2.35 and 3.1 picofarads (pF);

wherein the second inductor has an inductance of 2 nH; and

,

wherein the second tunable FE capacitor has a capacitance in the range between 1.85 and 3.5 pF.

25. A method for sub-band impedance matching an antenna, the method comprising:

tuning a first tuning circuit to a first sub-band within a first communication band when receiving communications in the first communication band, comprising the step of;

applying a first control voltage using a first voltage source to a first tunable ferroelectric (FE) capacitor having a first variable dielectric constant;

tuning the first tuning circuit to a second sub-band within a second communication band when receiving communications in the second communication band, comprising the step of;

applying a second control voltage using the first voltage source to the first tunable FE capacitor;

simultaneously tuning a second tuning circuit to a third sub-band within the first communication band when receiving communications in the first communication band, comprising the step of;

applying a third control voltage using a second voltage source to a second tunable ferroelectric (FE) capacitor having a second variable dielectric constant;

simultaneously tuning the second tuning circuit to a fourth sub-band within the second communication band when receiving communications in the second communication band, comprising the step of;

applying a fourth control voltage using the second voltage source to the second tunable FE capacitor;

wherein the first tuning circuit and the second tuning circuit supply a first conjugate impedance for receiving the first communication band on the antenna and supply a second conjugate impedance for receiving the second communication band on the antenna.

26. The method of claim 25 wherein the first conjugate impedance matches the antenna at a low end of the first communication band.

27. The method of claim 25 wherein the first conjugate impedance matches the antenna at a high end of the first communication band.

28. The method of claim 25 wherein the first voltage source and the second voltage source supply voltages in the range between zero and 3 volts dc.

29. The method of claim 25 wherein the first tuning circuit comprises a first inductor with a first fixed inductance value;

and,

wherein the second tuning circuit comprises a second inductor with a second fixed inductance value.

30. The method of claim 29 wherein the first tunable FE capacitor has a first selectable capacitance in the range between 2.35 and 3.1 picofarads (pF), is connected to the first inductor with the first fixed inductance value of 8 nano-Henrys (nH);

and,

wherein the second tunable FE capacitor has a second selectable capacitance in the range between 1.85 and 3.5 pF, and is connected to the second inductor with the second fixed inductance value of 2 nH.

31. The method of claim 25 wherein the first communication band is in the range of 824 to 894 MHz;

and,

wherein the second communication band is in the range of 1850 to 1990 MHz.

32. The method of claim 25 wherein the first sub-band is a plurality of first sub-bands in the first communication band;

and,

wherein the second sub-band is a plurality of second sub-bands in the second communication band.