Wide bandwidth automatic tuning circuit
First Claim
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1. An automatic tuning circuit for matching an antenna to a radio receiver, the automatic tuning circuit comprising:
- a tunable non-Foster circuit coupling the receiver and the antenna; and
sensing and feedback circuits sensing the combined reactance of the tunable non-Foster circuit and the antenna and for tuning the tunable non-Foster circuit to automatically minimize the combined reactance of the tunable non-Foster circuit and the antenna without making the combined reactance of the tunable non-Foster circuit and the antenna equal to zero so that an absolute value of the reactance of the tunable non-Foster circuit is maintained at a slightly smaller value than an absolute value of the reactance of the antenna to maintain stability of the tunable non-Foster circuit.
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Abstract
An automatic tuning circuit for matching an antenna to a radio receiver. The automatic tuning circuit includes a tunable non-Foster circuit for coupling the receiver and the antenna; and sensing and feedback circuits for sensing the combined capacitance of the tunable non-Foster circuit and the antenna and for tuning the tunable non-Foster circuit to automatically minimize the combined capacitance of the tunable non-Foster circuit and the antenna.
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Citations
45 Claims
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1. An automatic tuning circuit for matching an antenna to a radio receiver, the automatic tuning circuit comprising:
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a tunable non-Foster circuit coupling the receiver and the antenna; and sensing and feedback circuits sensing the combined reactance of the tunable non-Foster circuit and the antenna and for tuning the tunable non-Foster circuit to automatically minimize the combined reactance of the tunable non-Foster circuit and the antenna without making the combined reactance of the tunable non-Foster circuit and the antenna equal to zero so that an absolute value of the reactance of the tunable non-Foster circuit is maintained at a slightly smaller value than an absolute value of the reactance of the antenna to maintain stability of the tunable non-Foster circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A tuning circuit for matching an antenna to a variable frequency oscillator, the automatic tuning circuit comprising:
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a tunable non-Foster circuit coupling the variable frequency oscillator and the antenna; and sensing and feedback circuits for sensing the combined reactance of the tunable non-Foster circuit and the antenna and for tuning the tunable non-Foster circuit to minimize the combined reactance of the tunable non-Foster circuit and the antenna without making the combined reactance equal to zero and such that the combined reactance of the tunable non-Foster circuit is less than the reactance of the antenna and of the same sign. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A tunable non-Foster circuit comprising:
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a conventional non-Foster circuit having an output where a negative capacitance is realized; and a variable capacitor coupled in parallel with the output of the conventional non-Foster circuit where the negative capacitance is realized, the variable capacitor having a capacitance less than the absolute value of the negative capacitance realized by the conventional non-Foster circuit, so that a variable negative capacitance is realized across the output of the conventional non-Foster circuit by varying the variable capacitor.
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18. A method of matching an antenna to a radio receiver, the method comprising:
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coupling a tunable non-Foster circuit between the receiver and the antenna, the tunable non-Foster circuit and the antenna having a combined reactance; sensing the combined reactance of the tunable non-Foster circuit and the antenna in a sensing circuit; and tuning the tunable non-Foster circuit to minimize the combined reactance of the tunable non-Foster circuit and the antenna as sensed by the sensing circuit without making the combined reactance of the tunable non-Foster circuit and the antenna equal to zero so that an absolute value of the reactance of the tunable non-Foster circuit is maintained at a slightly smaller value than an absolute value of the reactance of the antenna to maintain stability of the tunable non-Foster circuit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 30)
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25. A method of matching an antenna to a variable frequency oscillator, the method comprising:
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coupling the variable frequency oscillator to the antenna via a tunable non-Foster circuit which emulates a variable negative capacitor; and sensing the combined reactance of the tunable non-Foster circuit and the antenna; and tuning the tunable non-Foster circuit to minimize the combined reactance of the tunable non-Foster circuit and the antenna without making the combined reactance of the tunable non-Foster circuit and the antenna equal to zero so that an absolute value of the reactance of the tunable non-Foster circuit is maintained at a slightly smaller value than an absolute value of the reactance of the antenna to improve stability of the tunable non-Foster circuit. - View Dependent Claims (26, 27, 28, 29, 31)
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32. A method of automatically matching an antenna to a radio receiver, the method comprising:
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coupling a tunable non-Foster circuit between the receiver and the antenna; sensing the combined reactance of the tunable non-Foster circuit and the antenna; tuning the tunable non-Foster circuit to reduce the combined reactance of the tunable non-Foster circuit as sensed during said sensing step without attaining a zero value thereof; repeating said sensing and tuning steps until said combined reactance of the tunable non-Foster circuit and the antenna attain a small, non-zero, value thereof. - View Dependent Claims (33, 34, 35, 36, 37)
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38. An automatic tuning circuit for matching an electrically small antenna having a capacitive reactance to a radio receiver, the automatic tuning circuit comprising:
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a tunable non-Foster circuit coupling the receiver and the antenna, the tunable non-Foster circuit generating a negative capacitance; and sensing and feedback circuits sensing the combined capacitance of the tunable non-Foster circuit and the antenna and for tuning the tunable non-Foster circuit to automatically reduce the combined capacitance of the tunable non-Foster circuit and the antenna to a near zero value without making the combined capacitance equal to zero so that an absolute value of the capacitance of the antenna is slightly larger than an absolute value of the negative capacitance of the tunable non-Foster circuit. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45)
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Specification