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NVNA Port1 External Path Isolation Issue Causing Failure
Symptoms / Solutions:
In NVNA, after completing all NVNA calibration procedures, adding a tuner or pre-amplifier in the input side, with thru connected, a1 is not equal to b2.
In NVNA (for some older PNA-X models), the internal and external path of port 1 is not sufficiently isolated. So when the vector calibration is done via external path on port 1 (as your coupler is connected to the receiver jumper A), the source output via port 1 will affect the calibration. To prevent this, the source signal should not pass through the front port 1 output.
The setup and connection is shown below:
1. In NVNA, Response –> Port 1 Reference Mixer Switch… (Figure 1) –> External Path (Figure 2)
Figure 1
Figure 2
2. Stimulus –> Port Bypass Switches… (Figure 3) –> Port 1 Switch State Combiner Path (Figure 4)
Figure 3
Figure 4
3. To verify the path, Utility –> FW Visible (Figure 5), PNA Series Network Analyzer window will open.
Figure 5
In PNA Series Network Analyzer window, Trace/Chan –> Channel –> Hardware Setup –> Path Config… (Figure 6)
Figure 6
Verify Port 1 path is switched to Combiner Path and External (Figure 7)
Figure 7
Break the jumper (J10-J11) at the rear panel of PNA-X and connect port J11 to the external coupler at input side and repeat all NVNA calibrations.
Figure 8
The verification will now work correctly when adding a tuner or pre-amplifier into the setup after calibrations.
Keywords: NVNA, Calibration, X-parameter, Coupling, Isolation, Path
Last date modified: 31 March 2017
