Automatic tuning AM transmitter

A method of matching an aerial impedance with a generator impedance of a low frequency radio transmitter, the method comprising the steps of:

• selecting a low frequency radio transmission frequency from a range of approximately 520 kilohertz to approximately 1700 kilohertz;
• measuring an aerial output voltage at the selected radio transmission frequency on a periodic basis;
• automatically incrementally increasing the magnitude of an aerial impedance on a periodic basis until the measured aerial output voltage has a magnitude that is less than a magnitude of a previously measured aerial output voltage;
• and
• decreasing the magnitude of the aerial impedance until the measured aerial output voltage is substantially equal to the previously measured aerial output voltage.

A method of matching an aerial impedance with a generator impedance of a low frequency radio transmitter, the method comprising the steps of:

• selecting a low frequency radio transmission frequency;
• measuring an aerial output voltage at the selected radio transmission frequency on a periodic basis;
• automatically incrementally increasing the inductance of an adjustable inductor coupled to the aerial by adjusting the inductance of a first coil when the selected radio transmission frequency is within a range of approximately 520 kilohertz to approximately 1000 kilohertz and adjusting the inductance of a second coil when the selected radio transmission frequency is within a range of approximately 1000 kilohertz to approximately 1700 kilohertz on a periodic basis until the measured aerial output voltage has a magnitude that is less than a magnitude of a previously measured aerial output voltage;
• and
• decreasing the magnitude of the aerial impedance until the measured aerial output voltage is substantially equal to the previously measured aerial output voltage.

A method of automatically adjusting aerial impedance to match generator impedance in a low frequency radio frequency transmitter, the method comprising the steps of:

• (a) selecting a low frequency radio transmission frequency from a range of frequencies from approximately 520 kilohertz to approximately 1700 kilohertz;
• (b) measuring an aerial output voltage at the selected radio transmission frequency;
• (c) generating and storing a reference aerial output voltage which is greater than the measured aerial output voltage;
• (d) increasing the aerial impedance based on the reference aerial output voltage;
• (e) measuring the aerial output voltage at the adjusted aerial impedance;
• (f) comparing the measured aerial output voltage at the adjusted aerial impedance to the reference aerial output voltage;
• (g) if the measured aerial output voltage is substantially equal to the reference aerial output voltage, storing the reference aerial output voltage as a previous reference aerial output voltage;
• (h) repeating steps (c) through (g) until the measured aerial output voltage is less than the reference aerial output voltage;
• and
• (i) adjusting the aerial impedance so that the measured aerial output voltage substantially equals the previous reference aerial output voltage.