The DUT is connected to the Analyzer ports. The Analyzer emits a test signal (stimulus) out of a source port. Simultaneously, all ports of the Analyzer are receivers. The frequency of the test signal changes in the specified range discretely from point to point. At each frequency point, the Analyzer simultaneously measures the magnitude and phase of the signal transmitted through and reflected from the DUT. These are compared with the magnitude and phase of the incident test signal. The Analyzer calculates the S-parameters of the DUT at each frequency point based on this comparison (See figure below).
S-parameter Terms
The S-parameter is a relation between the complex magnitudes of two waves:
Providing the , except = 0, where denote the DUT port number.
For a two-port DUT, the full scattering matrix is measured:
The construction feature of TR Analyzer is that Port 1 is a source port and receiver, and Port 2 is only a receiver (See Principles of Operation) . Thus, the Analyzer can only measure S11 and S21 simultaneously with one DUT connection.
To measure S11 and S21 parameters, connect Port 1 to the input of the DUT, and Port 2 to the output of the DUT. The incident and reflected waves will be measured by Port 1. The transmitted wave will be measured by Port 2.
To measure S12 and S22 parameters, reconnect the DUT. Connect Port 1 to the output of the DUT, and Port 2 to the input of the DUT. The incident and reflected waves will be measured by Port 2. The transmitted wave will be measured by Port 1.
This way, using two connections of the DUT, you can measure full scattered matrix of a two-port DUT.
