Measuring impedance
To find the impedance, we should measure two values at least because
impedance is a complex quantity. Many modern impedance instruments
measure the real and the imaginary parts of an impedance vector and
then convert them into the desired parameters such as |Z|,
θ
, L, C, R, X, It is only necessary to connect the unknown component,
circuit, or material to the instrument. However, sometimes the
instrument will display an unexpected result (too high or too low). One
possible cause of this problem is incorrect measurement technique, or
the natural behavior of the unknown device. We will focus on the
traditional passive components and discuss their natural behavior in the
real world as compared to their idealistic behavior.
Parasitic
There are no pure L, C or R. All circuit components are neither pure
resistive nor pure reactive, they are a combination of these impedance
elements. The result all devices have parasites - unwanted inductance
in resistors, unwanted resistance in capacitors, unwanted capacitance
in inductors, etc. Of course, different materials and manufacturing
technologies produce varying amounts of parasites, affecting both a
component’s usefulness and the accuracy with which you can
determine its resistance, capacitance, or inductance. A real-world
component contains many parasites. With the combination of a
component’s primary element and parasites, a component will be like a
complex circuit.
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