25 SNA5000A Vector Network Analyzer User Manual
2
Basic measurement
This chapter introduces in detail each function button on the front panel of SNA5000A series
vector network analyzers and the following menu functions.
2.1 Measurement parameters
2.1.1
S parameters
S parameters are used to describe the degree of a transmitted or reflected signal through
an impedance discontinuity. S parameters are relative measurements, defined as the ratio of
two complex voltages. They contain the amplitude and phase information of the relevant
signals. For the 2-port vector network analyzer, there are 4 S parameters (S11, S21, S12, S22).
The specific meaning of each S parameter can be described by the following items:
Sxy x,y
∈
(1,2):
x:
The response port is also known as the receiving port of the vector network
analyzer. The transmitted signal enters the port after passing through the DUT.
y:
The excitation port is also known as the transmitting port of the vector network
analyzer. The output signal of this port is provided to the DUT.
Here is a list of common S parameter measurements:
Reflection parameters
Transmission parameters
•
Return loss
•
SWR
•
Reflection coefficient
•
Input impedance
•
S11, S22
•
Insertion loss
•
Transmission coefficient
•
Gain/loss insertion
•
group delay
•
Linear phase shift
•
electrical delay
•
S21, S12
2.1.2
Balanced S parameters
Balanced S parameters are also relative. They are used to measure the S parameters of
differential ports such as those found on baluns and transformers. They are also defined as
the ratio of complex voltages, which contain the amplitude and phase information of relevant
signals. The topology and logical port mappings for the differential devices to be tested need
to be created or edited before the test. "Logical ports" are used to describe the test ports of the
physical vector network analyzer that have been remapped to the new port.
1.
Map any two physical ports of the vector network analyzer to a balanced logical port.
Summary of Contents for SNA5000A Series
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