Method and apparatus for the automatic matching of a transmitter to an antenna

Claim 1

A method for automatically matching the final stage of a transmitter to an antenna comprising the steps of: detecting the anode a.c. voltage of a final stage tube of said final stage of said transmitter, rectifying said anode a.c. voltage and filtering out a modulation component from said rectified anode a.c. voltage; generating a d.c. voltage which is proportional to the square root of the output power to said antenna and thereafter filtering out the modulation component from said d.c. voltage; dividing said filtered, rectified, anode a.c. voltage by said filtered d.c. voltage so as to form a quotient signal which is proportional to the square root of the impedance of said final stage of said transmitter; subtracting said quotient signal from a reference signal characterizing the square root of the nominal value of said final stage impedance so as to generate a difference signal; and varying the value of a load coupling coil coupling said final stage to said antenna as a function of said difference signal when the power applied to said antenna is greater than a first predetermined minimum value and said anode voltage is greater than a second predetermined minimum value.

Claim 2

A method for automatically matching the final stage of a transmitter to an antenna comprising the steps of: detecting the anode a.c. voltage of a final stage tube of said final stage of said transmitter, rectifying said anode a.c. voltage and filtering out a modulation component from said rectified anode a.c. voltage; generating a d.c. voltage which is proportional to the square root of the output power to said antenna and thereafter filtering out the modulation component from said d.c. voltage; dividing said filtered, rectified, anode a.c. voltage by said filtered d.c. voltage so as to form a quotient signal which is proportional to the square root of the impedance of said final stage of said transmitter; subtracting said quotient signal from a reference signal characterizing the square root of the nominal value of said final stage impedance so as to generate a difference signal; and varying the value of a load coupling coil coupling said final stage to said antenna as a function of said difference signal when the power applied to said antenna is greater than a first predetermined minimum value and said anode voltage is greater than a second predetermined minimum value.

Claim 3

An apparatus for automatically matching the final stage of the transmitter to an antenna comprising: a load coupling coil coupling said final stage to said antenna; probe means for detecting and rectifying an anode a.c. voltage of a final stage tube of said final stage of said transmitter; a first low-pass filter for removing a modulation component from said detected, rectified anode a.c. voltage; directional coupling means for generating a d.c. voltage which is proportional to the square root of the output power to said antenna; second low-pass filter means for filtering said d.c. voltage; means for dividing the output of said first low-pass filter by the output of said second low-pass filter so as to form a quotient signal which is proportional to the square root of the impedance of said final stage of said transmitter; means for subtracting said quotient signal from a reference signal characterizing the square root of the nominal value of said final stage impedance so as to generate a difference signal; and means for varying the value of said load coupling coil as a function of said difference signal when the power applied to said antenna is greater than a first predetermined minimum value and said anode voltage is greater than a second predetermined minimum value.

Claim 4

An apparatus for automatically matching the final stage of the transmitter to an antenna comprising: a load coupling coil coupling said final stage to said antenna; probe means for detecting and rectifying an anode a.c. voltage of a final stage tube of said final stage of said transmitter; a first low-pass filter for removing a modulation component from said detected, rectified anode a.c. voltage; directional coupling means for generating a d.c. voltage which is proportional to the square root of the output power to said antenna; second low-pass filter means for filtering said d.c. voltage; means for dividing the output of said first low-pass filter by the output of said second low-pass filter so as to form a quotient signal which is proportional to the square root of the impedance of said final stage of said transmitter; means for subtracting said quotient signal from a reference signal characterizing the square root of the nominal value of said final stage impedance so as to generate a difference signal; and means for varying the value of said load coupling coil as a function of said difference signal when the power applied to said antenna is greater than a first predetermined minimum value and said anode voltage is greater than a second predetermined minimum value.