Method and system for radiating RF power from a trailing wire antenna
First Claim
1. A method of applying the output of a transmitter power amplifier means to a trailing wire antenna of an airborne RF transmitter system to effect optimum message transmission during extension and retraction toward and from the optimum length of the antenna, comprisingvarying the inductance of the antenna coupler in response to the antenna change of length to provide a high-resistance load having minimal reactance to the power amplifier means, andvarying the value of the power output of the power amplifier means as a function of the voltage amplitude sensed at the feed end of the antenna and the voltage and current sensed at opposite sides of the coupler.
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Accused Products
Abstract
A trailing wire antenna coupling and control method for providing maximum voltage limited power output from power amplifiers of a high power low frequency RF transmitter system while varying the inductance of the coupling circuit to present a high resistance load having practically zero reactance to the power amplifiers, all during extension and retraction of the antenna toward and from its optimum length, as well as at the optimum length.
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Citations
7 Claims
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1. A method of applying the output of a transmitter power amplifier means to a trailing wire antenna of an airborne RF transmitter system to effect optimum message transmission during extension and retraction toward and from the optimum length of the antenna, comprising
varying the inductance of the antenna coupler in response to the antenna change of length to provide a high-resistance load having minimal reactance to the power amplifier means, and varying the value of the power output of the power amplifier means as a function of the voltage amplitude sensed at the feed end of the antenna and the voltage and current sensed at opposite sides of the coupler.
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5. An airborne RF communication system having a transmitter and trailing wire antenna capable of being extended to and retracted from an optimum length, said system comprising a power amplifier means connected to the transmitter operable to output selected voltage increments from a predetermined minimum to maximum, a coupling circuit connecting the output of the amplifier means to the antenna,
said coupling circuit including a first and second inductance in series with the output of the amplifier means and the antenna wire, a capacitance connected between the first and second inductance and ground segregating the coupling circuit into a first and second impedance mesh, a first voltage sensor positioned to sense the voltage to ground between the amplifier means output and the first inductance, a second voltage sensor positioned to sense the voltage to ground between the first and second inductances, a third voltage sensor positioned to sense the voltage to ground between the second inductance and antenna wire at its feed end; -
a first current sensor positioned to sense the current between the amplifier means output on the first inductance, a second current sensor means positioned to sense the current between the second inductance and the feed end of the antenna wire, means to detect values corresponding to the transmitter output frequency, the first inductance, the capacitance, and the quality factors of the inductance and capacitance; first sampling means to sample the voltage of the second and third voltage sensors and the second current sensor; first determining means governed by the detected values and sampled values of the first sampling means to determine the reactance of the antenna and the sum of the reactances of the second mesh impedance, second detecting means to determine the reactance of the second inductance in accordance with the determined values of the first determining means, third determining means governed by the values sampled by the first sampling means to determine the value of the second inductance, fourth determining means governed by the reactance of inductance determined by the second means and the value of second inductance determined by the third means to determine the desired change in second inductance, means to vary the second inductance in accordance with the desired change. - View Dependent Claims (6)
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7. A coupling circuit and control system for a trailing wire antenna of an RF transmitter for providing maximum voltage limited power output while the antenna is not at its optimum length, comprising
a power amplifier means connected to the output of the transmitter, a coupling circuit having a first and second inductance in series with the amplifier means output and the trailing wire antenna at its feed end, a capacitance means electrically connected to the circuit between the first and second inductances and ground to provide first and second impedance meshes, first voltage and current sensors to sense amplitude and phase of the voltage and current between the power amplifier means output and the first inductance, second voltage and current sensors to sense amplitude and phase of the voltage and current between the second inductance and the antenna at its feed end, a third voltage sensor to sense the amplitude and phase of the voltage to ground between the first and second inductances, means responsive to signals from the second voltage and current sensors and the third voltage sensor to first vary the second inductance of the circuit to correspond to a predetermined value, means responsive to signals from the first voltage and current sensors to further vary the second inductance to reduce phase error toward zero, and means responsive to a signal from the third voltage sensor subsequent the first variation of the second inductance to selectively increase or decrease the power amplifier output.
Specification