Mobile antenna circuit with variable line length
First Claim
1. A mobile antenna circuit for resonant transmitting from an RF signal source comprising:
- an antenna having a base and at least first and second conductive sections, one of said first and second sections being extendable and retractable to lengthen and shorten said antenna;
a motor operatively connected to said first antenna section for extending and retracting said antenna in response to control signals thereto;
impedance matching circuit means coupling said RF signal source to the base of said antenna for matching the impedance thereof at a specified frequency;
control means connected to said motor to produce said control signals for extending and retracting said first antenna section so as to resonantly tune said antenna at said specified frequency;
a phase angle detector connected between said RF signal source and said impedance matching circuit means for developing a voltage differential proportional to the phase shift between RF line voltage and RF line current, said voltage differential being fed to said control means for producing said control signals to extend and retract said first antenna section to automatically tune said antenna at said specified frequency; and
feed line selection means connected between said phase angle detector and said antenna base by which a specified length of feed line may be placed in series with said impedance matching circuit and in combination therewith create a phase shift between said RF line voltage and RF line current equal to one-quarter or any multiple of one-quarter wave length of feed line for said specified frequency.
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Abstract
A mobile antenna circuit for resonant transmitting from an RF signal source may comprise: an antenna having a base and at least first and second conductive sections one of which is extendable and retractable to lengthen and shorten the antenna; a motor operatively connected to one of the conductive sections for extending and retracting the antenna in response to control signals thereto; an impedance matching circuit coupling the RF signal source to the base of the antenna for matching impedance thereof at a specified frequency; and control components connected to the motor to produce control signals for extending and retracting the antenna section so as to resonantly tune the antenna at a specified frequency. The circuit may include a phase angle detector connected between the RF signal source and the impedance matching circuit for developing a voltage differential being fed to the control components for producing the control signals for extending and retracting the antenna section.
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Citations
12 Claims
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1. A mobile antenna circuit for resonant transmitting from an RF signal source comprising:
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an antenna having a base and at least first and second conductive sections, one of said first and second sections being extendable and retractable to lengthen and shorten said antenna; a motor operatively connected to said first antenna section for extending and retracting said antenna in response to control signals thereto; impedance matching circuit means coupling said RF signal source to the base of said antenna for matching the impedance thereof at a specified frequency; control means connected to said motor to produce said control signals for extending and retracting said first antenna section so as to resonantly tune said antenna at said specified frequency; a phase angle detector connected between said RF signal source and said impedance matching circuit means for developing a voltage differential proportional to the phase shift between RF line voltage and RF line current, said voltage differential being fed to said control means for producing said control signals to extend and retract said first antenna section to automatically tune said antenna at said specified frequency; and feed line selection means connected between said phase angle detector and said antenna base by which a specified length of feed line may be placed in series with said impedance matching circuit and in combination therewith create a phase shift between said RF line voltage and RF line current equal to one-quarter or any multiple of one-quarter wave length of feed line for said specified frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification