I work with an impedance analyzer, measuring impedance spectra of ionic conductors. I would like to know how the obtained data can be affected by input capacitance at higher frequencies (1kHz-1MHz). A person said that I cannot properly determine dielectric properties because the high input capacitance of the meter (on the order of 100 pF) does not allow measurement of solid samples that usually exhibit lower capacitance than the input capacitance. How can I see this input capacitance influence?

  • 2
    \$\begingroup\$ Could you give us a little bit of info about your impedance analyzer, and where your input capacitance figure is coming from? \$\endgroup\$
    – W5VO
    Nov 22, 2011 at 15:13

1 Answer 1


Actually the capacitors acts as an impedance which influences the circuit.
Impedance, the vector sum of reactance and resistance, describes the phase difference and the ratio
of amplitudes between sinusoidally varying voltage and sinusoidally varying current at a given frequency.
Fourier analysis allows any signal to be constructed from a spectrum of frequencies,
whence the circuit's reaction to the various frequencies may be found.
The reactance of a capacitor is given by: $$X_c=\frac{1}{2\pi{} f C}$$
$$f=frequency $$ $$C=Capacitance$$ As the frequency increases the reactance decreases.
like this capacitance influences the circuit.


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