4
85130C Operating and Service Manual
Figure 2
Return Loss Setup
Return loss is measured by connecting a 50 ohm fixed load termination through a 12.5 cm airline to the
adapter, then attaching the adapter to port one of the test set (see
Figure 2
).
The effects of an imperfect load may be gated out using the network analyzer time domain option.
NOTE
Refer to your network analyzer’s Help system for specific instructions on using the functions
mentioned in the return loss test below.
1. Preset the analyzer.
2. Set a stimulus start frequency of the analyzer’s lowest frequency.
3. Set a stimulus stop frequency of 18 GHz.
4. Set an IF bandwidth of 100 Hz.
5. Perform, and then save, a 3.5 mm 1-port S
11
calibration.
6. With correction turned on, select the time domain mode.
7. Set a stimulus start time for the sweep to –0.05 nano-seconds.
8. Set a stimulus stop time for the sweep to 1.9 nano-seconds.
9. Select the gating function and gate-out everything but the adapter. See
Figure 3
.
10. Select the analyzer’s frequency domain mode.
11. Use the markers to read the return loss value.