Z-parameters are also known as " open-circuit impedance parameters " as they are calculated under open circuit conditions . i . e ., I x = 0, where x = 1, 2 refer to input and output currents flowing through the ports ( of a two-port network in this case ) respectively.
12.
So, Miller theorem expresses the fact that " "'connecting a second voltage source with proportional voltage V _ 2 = K { V _ 1 } in series with the input voltage source changes the effective voltage, the current and respectively, the circuit impedance seen from the side of the input source " " '.
13.
In this diagram, AC power is being transferred from the source, with phasor magnitude voltage | V _ \ mathrm { S } | ( peak voltage ) and fixed source impedance Z _ \ mathrm { S }, to a load with impedance Z _ \ mathrm { L }, resulting in a phasor magnitude current | I | . | I | is simply the source voltage divided by the total circuit impedance:
