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short). SWR, a scalar, is defined as the ratio of the maximum RF envelope voltage to the minimum RF
envelope voltage at a given frequency. If the impedance is perfectly matched, SWR is equal to 1. For
open, short or lossless reactive circuits, SWR is infinite.
Reflection coefficient
Another method for reflecting measurement is the reflection coefficient (Γ), the reflection coefficient is the
ratio of the reflected voltage to the incident voltage, Γ includes the amplitude and phase information, and
the amplitude portion of Γ is called ρ, ρ has no unit, and the value ranges from 0 - 1. If the transmission
line is terminated with a characteristic impedance, all energy is transferred to the load, and no energy is
reflected, ρ=0. If the transmission line is terminated with an open device or a short device, all energy is
reflected, ρ=1.
Linear distortion:
It refers to the fact that the amplitude and linear phase shift cannot be maintained in the concerned
frequency band as the change of frequency.
Nonlinear distortion:
The circuit will generate new spectral components.
Phase measurement
As with amplitude measurements, phase measurements are also performed using S-parameters. The
phase measurement is a relative (ratio) measurement rather than an absolute measurement. The phase
of the incoming device signal (incident signal) is compared with the phase of the device response signal,
and the response signal can be either a reflected signal or a transmitted signal. Assuming that the
microwave analyzer has been accurately calibrated, the phase difference (i.e. phase shift) between the
two signals is a measure of the phase characteristics of the device to be tested.
Calibrate
Calibration uses an error model to eliminate one or more system errors. The microwave analyzer solves
error items in the error model by measuring high quality calibration standards such as open device, short
device, loads and through devices.
