NVNA Port1 External Path Isolation Issue Causing Failure

June 12, 2024


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