Method and device for tuning a HF source, in particular for tuning a microwave source of an electron spin resonance spectrometer

A method for tuning a microwave bridge of an electron spin resonance spectrometer including

• a first microwave source generating a first microwave signal of a first microwave frequency,
• a second microwave source being adjustable in frequency in generating a second microwave signal of a second microwave frequency, said second microwave source having a frequency modulation input,
• a sweep generator for generating an audio frequency sweep signal and an audio frequency modulation signal, said sweep generator in communication with said frequency modulation input,
• a mixer,
• a microwave resonator, and
• display means having Y and X inputs for displaying a tuning signal,
• the method comprising the steps of:
• modulating said second microwave frequency at a rate of said audio frequency modulation signal to generate a modulated second microwave signal;
• mixing said first microwave signal with said modulated second microwave signal to generate a mixed microwave signal;
• absorbing said mixed microwave signal;
• reflecting a tuning signal corresponding to the power of said mixed microwave signal absorbed by said microwave resonator as a function of time;
• using said tuning signal as an input to said Y-input and using said audio frequency sweep signal as an input to said X-input of said display means for displaying a mode curve with at least one dip therein, said dip having a depth value within said mode curve;
• and
• adjusting said second microwave frequency of said second microwave source to a maximum value of said depth value.

An apparatus for tuning a circuit including

• a first HF source (61) generating a first HF signal of a first HF frequency (f.sub.O),
• a second HF source (65) being adjustable in frequency and generating a second HF signal of a second HF frequency (f.sub.M), said second HF source having a frequency modulation input,
• a sweep generator for generating an audio frequency sweep signal (U.sub.S) and an audio frequency modulation signal (U.sub.M), said sweep generator being in communication with said frequency modulation input,
• a narrow-band HF component (62), and
• display means (67) having Y and X inputs for displaying a tuning signal,
• the apparatus further comprising:
• means for modulating said second HF frequency at a rate of said audio frequency modulation signal to generate a modulated second HF signal by connecting said sweep generator to said frequency modulation input of said second HF source;
• means for mixing said first HF signal with said modulated second HF signal within said mixer to generate a mixed HF signal (S);
• means for feeding said mixed HF signal to said narrow-band HF component;
• means for detecting a tuning signal corresponding to the power of said mixed HF signal absorbed by said narrow-band HF component as a function of time;
• means for feeding said tuning signal to said Y-input and feeding said audio frequency sweep signal to said X-input of said display means for displaying a mode curve with at least one dip therein, said dip having a depth value within said mode curve;
• and
• means for adjusting said second HF frequency of said second HF source to a maximum value of said depth value.

An apparatus for tuning a microwave bridge of an electron spin resonance spectrometer including

• a first microwave source generating a first microwave signal of a first microwave frequency,
• a second microwave source being adjustable in frequency and generating a second microwave signal of a second microwave frequency, said second microwave source having a frequency modulation input,
• a sweep generator for generating an audio frequency sweep signal and an audio frequency modulation signal, said sweep generator in communication with said frequency modulation input,
• a microwave resonator, and
• display means having Y and X inputs for displaying a tuning signal,
• the apparatus comprising:
• means for modulating said second microwave frequency at a rate of said audio frequency modulation signal to generate a modulated second microwave signal;
• means for mixing said first microwave signal with said modulated second microwave signal to generate a mixed microwave signal;
• a microwave resonator for absorbing said mixed microwave signal, and for reflecting a tuning signal corresponding to the power of said mixed microwave signal absorbed by said microwave resonator as a function of time;
• display means, receiving said tuning signal to said Y-input and receiving said audio frequency sweep signal to said X-input, said display means for displaying a mode curve with at least one dip therein, said dip having a depth value within said mode curve;
• and
• means for adjusting said second microwave frequency of said second microwave source to a maximum value of said depth value.

A method for tuning HF circuit, comprising the steps of:

• generating an audio frequency sweep signal (U.sub.S) and an audio frequency modulation signal (U.sub.M);
• generating a first HF signal having a first HF frequency (f.sub.O);
• generating a second HF signal having a second HF frequency (f.sub.M);
• modulating said second HF frequency at a rate of said audio frequency modulation signal to generate a modulated second HF signal;
• mixing said first HF signal with said modulated second HF signal to generate a mixed HF signal (S);
• absorbing said mixed HF signal;
• generating a tuning signal corresponding to the amount of power, associated with said mixed HF signal, absorbed as a function of time;
• using said audio frequency sweep signal and said tuning signal to display a mode curve having at least one dip therein, said dip having a depth value within said mode curve;
• and
• adjusting said second HF frequency of said second HF source to a maximum value of said depth value.

An apparatus for tuning an HF circuit, comprising:

• a sweep generator for outputting an audio frequency sweep signal and an audio frequency modulation signal;
• a first HF source for outputting a first HF signal of a first HF frequency;
• a second HF source responsive to said audio frequency modulation signal and operative to modulate a second HF frequency, of an internally generated second HF signal, at a rate of said audio frequency modulation signal thereby outputting a modulated second HF signal;
• a mixer for mixing said first HF signal with said modulated second HF signal, and operative to generate a mixed HF signal;
• a narrow-band HF component responsive to said mixed HF signal, and operative to absorb a portion of said mixed HF signal and to reflect another portion of said mixed HF signal as a tuning signal, such that said tuning signal corresponds to the power of said mixed HF signal absorbed by said narrow-band HF component as a function of time;
• display means having Y and X inputs for receiving said tuning signal at said Y-input and receiving said audio frequency sweep signal at said X-input, said display means for displaying a mode curve with at least one dip therein having a depth value within said mode curve;
• and
• means for adjusting said second HF frequency of said second HF source to generate a maximum value of said depth value.