Cavity resonator... Need Urgent Help !!

[rafalizou]

If a cavity resonator is excited by a signal of frequency greater than the natural resonant frequency of the resonator

what will be the frequency of the signal coupled/reflected back.
(assuming there is no coupled/reflected signal, if the input signal has frequency equal to the natural resonant frequency of the resonator )

Thanks !!

 

[jiripolivka]

As any resonator is a passive device, the only frequency on a connected line will be the signal frequency.
Only signal amplitude will vary, in dependence of the type and level of coupling the line to the resonator.

 

[rafalizou]

As any resonator is a passive device, the only frequency on a connected line will be the signal frequency.
Only signal amplitude will vary, in dependence of the type and level of coupling the line to the resonator.

Dear Sir,
Thanks for the reply. I want to determine the expression for the output signal if the cavity is excited by a signal (having frequency equal to the natural resonant frequency of the cavity [fc] ) frequency modulated by a signal of lower frequency (fm).

ie. wether the output signal will have a frequency equal to that of the base signal fc or that of the frequency modulated signal.
and also the dependance of the amplitude on the modulating signal ie. fm.

Your help is highly appreciated !!

 

[jiripolivka]

You can use an equivalent circuit for your resonator which is a parallel L-C resonant circuit.
Such resonant circuit should also include a loss resistor , e.g. in series with the L which determines the Q of the resonant circuit. And Q determines the "line width" of the resonant circuit.
Then if you send a frequency-modulated signal through such circuit, then the response will be limiting the FM spectrum of your signal.

All details can be found in a basic textbook of RF electronics.