Agilent Technologies N5241A, Service Manual

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Service Guide N5242-90001 5-3
PNA Series Microwave Network Analyzers Theory of Operation
N5241A/42A Network Analyzer System Operation
Network Analyzer System Operation
The PNA network analyzer generates two (2-port models) or four (4-port models)
phase-locked incident signals and an LO signal from the internal synthesized source. By
means of signal separation, the incident signals are divided into reference signals and test
signals.
The reference signals are applied to the receiver group, while the test signals are applied
to the device under test (DUT) and then to the receiver group. The LO signal is applied
directly to the receiver group where it is mixed with the test and reference signals to
produce IF signals for each of the eight receivers (A
–
D, R1
–
R4) for 4-port models or four
receivers (A, B, R1, R2) for 2-port models. These IF signals are downconverted and then
sampled and digitally processed.
If configured with the optional 2nd source, the 2-port models provide two auxiliary source
outputs, SRC 2 OUT 1 and SRC 2 OUT 2.
Figure 5-1 is a simplified block diagram of the 4-port network analyzer system and Figure
5-2 is a simplified block diagram of the 2-port network analyzer system.
Figure 5-1 4-Port System Simplified Block Diagram