HP 8712ES - Measuring S-Parameters

ES User’s Guide 3-9
Making Measurements
Measuring Devices with Your Network Analyzer
Measuring S-Parameters
Figure 3-4 Measuring S-Parameters
Refer to Figure 3-4 for the following discussion of S-parameters.
S-parameters are used to completely describe the electrical behavior of a
linear two-port device that operates at high frequencies. An N-port
device has N
2
S-parameters. So, a two-port device has four S-parameters.
The numbering convention for S-parameters is that the first number
following the “S” is the port where energy emerges, and the second
number is the port where energy enters. So, S
21
is a measure of power
coming out port 2 as a result of applying an RF stimulus to port 1. When
the numbers are the same (e.g., S
11
), it indicates a reflection
measurement.