Electrically tuned resonance circuit using piezo and magnetostrictive materials

• US 20060154617A1
• Filed: 01/11/2005
• Published: 07/13/2006
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Clingman, Dan J., Calkins, Frederick T.
• Granted Patent: US 7,426,373 B2
• Time in Patent Office: Days
• US Class Current: 455/78
• 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: H03J 3/16 Tuning without displacement of reactive element, e.g. by varying permeability
• CPC Class Codes: H03J 3/22 of single resonant circuit by varying inductance and capacitance simultaneously
• 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

Abstract

An impedance tuning system, especially for a cellular telephone system. The system can be used to match the impedance of an antenna element with that of an output stage of a transmitter driving the antenna element. The system includes a piezo capacitor in parallel with the magnetostrictive inductor to form an LC circuit. A voltage controller applies a voltage bias signal to the piezo capacitor and a current controller applies a current bias signal to the inductor. A primary controller monitors the frequency of the output signal from the transmitter and controls the voltage and current controllers as needed to alter the impedance of the system as needed to match the impedance of the antenna element with that of the output stage of the transmitter. In an alternative form an ultrasonic sensor is provided.

Claims

1. A tuning apparatus for tuning an impedance of an antenna coupled to an electromagnetic wave transmitter, the apparatus comprising:

a piezoelectric capacitor;

a magnetostrictive inductor coupled in parallel with the piezoelectric capacitor to form a resonance circuit, said resonance circuit being in electrical communication with said antenna;

a biasing circuit for biasing each of said piezoelectric capacitor and said magnetostrictive inductor to thus alter a resonant frequency of said resonance circuit; and

a controller for controlling said biasing circuit in accordance with a frequency of said transmitter to match said impedance of said antenna to said impedance of said transmitter.

2. The apparatus of claim 1, wherein said biasing circuit includes a voltage controller for applying a voltage bias signal to said piezoelectric capacitor.

3. The apparatus of claim 1, wherein said biasing circuit includes a current controller for applying a current bias signal to said magnetostrictive inductor.

4. The apparatus of claim 1, wherein said controller is responsive to an output of said transmitter.

5. An electrically tunable antenna, comprising:

an antenna element;

an electromagnetic wave energy transmitter for generating electromagnetic wave signals applied to said antenna element;

a piezoelectric material forming a piezoelectric capacitor;

an inductor including a magnetostrictive material, the inductor disposed in parallel and in electrical communication with said piezoelectric capacitor to form an electrically variable resonance circuit, the resonance circuit being electrically coupled to said antenna to control an impedance of said antenna;

a voltage supply for providing a bias voltage to said piezoelectric capacitor to alter a capacitance of said piezoelectric capacitor;

a current supply for providing a bias current to said magnetostrictive material to alter an inductance of said inductor; and

a controller responsive to said transmitter for controlling said voltage supply and said current supply to control said resonance circuit to match an impedance of said antenna element to an impedance of said transmitter.

6. The electrically tunable antenna of claim 5, wherein said controller is responsive to a frequency of said signals being output from said electromagnetic wave energy transmitter.

7. The electrically tunable antenna of claim 5, wherein said current supply comprises a current controller.

8. The electrically tunable antenna of claim 5, wherein said voltage supply comprises a voltage controller.

9. The electrically tunable antenna of claim 5, further comprising a pair of direct current blocking capacitors disposed in series with said piezoelectric capacitor on opposite sides of said piezoelectric capacitor.

10. The electrically tunable antenna of claim 5, wherein said magnetostrictive material comprises an alloy including terbium, dysprosium and iron.

11. The electrically tunable antenna of claim 5, wherein said magnetostrictive material comprises at least one alloy including mixtures of at least two of terbium, dysprosium, gallium and iron.

12. The electrically tunable antenna of claim 5, wherein said inductor comprises a first coil and a second coil wrapped around said magnetostrictive material, with said first coil being coupled in parallel across said piezoelectric capacitor and said second coil being coupled in parallel with said current supply.

13. A cellular telephone, comprising:

an antenna element;

a transmitter for generating electromagnetic wave signals applied to an input of said antenna element;

a non-linear piezoelectric capacitor;

a magnetostrictive inductor forming an inductor, the inductor being disposed in parallel with said piezoelectric capacitor, and in electrical communication with said input of said antenna element, to form an electrically controllable resonance circuit;

a voltage source for providing a bias voltage to said piezoelectric capacitor to alter a capacitance of said piezoelectric capacitor;

a current source for providing a bias current to said magnetostrictive inductor to alter an inductance of said magnetostrictive inductor; and

a controller responsive to a frequency of said signals from said transmitter, for independently controlling an output of said voltage source and an output of said current source to control said resonance circuit, in real time, so that an impedance of said antenna element matches an output impedance of said transmitter.

14. The electrically tunable antenna of claim 13, wherein said magnetostrictive inductor comprises a core, and wherein the core includes an alloy including mixtures of at least two of terbium, dysprosium, gallium and iron.

15. An electrically tunable resonance circuit for altering an impedance of an electrical component, said circuit comprising:

a piezoelectric capacitor;

a magnetostrictive inductor coupled in parallel to said capacitor to form a resonance circuit, said resonance circuit being in electrical communication with said electrical component;

a biasing system for providing a biasing voltage to said piezoelectric capacitor and a biasing current to said magnetostrictive inductor; and

a controller for controlling said biasing voltage and said biasing current, in accordance with a frequency of a signal being applied to said electrical component, to selectively alter said impedance of said electrical component.

16. The circuit of claim 15, wherein said controller controls said biasing voltage and said biasing current in real time to enable real time adjustment of said impedance of said electrical component.

17. The circuit of claim 15, wherein said controller controls said biasing system, in real time, to match an external electrical component generating said signal.

18. A method for tuning an antenna, comprising

using a piezoelectric capacitor and a magnetostrictive inductor to form an impedance matching circuit;

biasing at least one of said piezoelectric capacitor and said magnetostrictive inductor to alter an impedance of said impedance matching circuit in accordance with a frequency of a signal being applied to said antenna, to thus controllably alter an impedance of said antenna to match an impedance of a component generating said signal.

19. The method of claim 18, further comprising:

monitoring said frequency of said signal in real time and adjusting said impedance of said impedance matching circuit in real time as needed to continuously match said impedance of said antenna with said component generating said signal.

20. The method of claim 19, further comprising using a controller to monitor said frequency of said signal and to control biasing of said piezoelectric capacitor and said magnetostrictive inductor.

21. A sensor for detecting a frequency of a vibration signal being applied to a structure, the sensor comprising:

a magnetostrictive inductor;

a piezoelectric wafer coupled to the structure to experience a vibration signal affecting the structure, the magnetostrictive inductor being coupled in parallel to the piezoelectric wafer to form an LC circuit;

a biasing system for applying biasing signals to each of said magnetostrictive inductor and said piezoelectric wafer;

a user control for controlling said biasing system for enabling said LC circuit to be tuned to different frequencies, said LC circuit generating an output signal when said piezoelectric wafer experiences a vibration signal and generates a signal to said LC circuit that tunes said LC circuit to a resonant frequency.

22. The sensor of claim 21, further comprising an amplifier for amplifying an output from the LC circuit.

23. The sensor of claim 21, wherein said magnetostrictive inductor comprises at least one alloy including mixtures of at least two of terbium, dysprosium, gallium and iron.

24. The sensor of claim 22, further comprising a data logging device responsive to the amplifier for providing an indication to a user when said resonant frequency is detected.