5-11
Optimizing Measurement Results
Increasing Sweep Speed
Sweep Speed-Related Errors
IF delay occurs during swept measurements when the signal from the analyzer source is
delayed in reaching the analyzer receiver because of an electrically long device. The
receiver has a narrow IF band pass filter that tracks the receiver frequency because the
receiver is sweeping. The delayed signal will be attenuated because the center of the
internal IF filter has moved.
For most measurements, swept list mode will be the optimum choice. If there is any doubt
about the effect of IF delay, perform the following test:
1. Set up the measurement using the swept list mode, as in the previous procedure.
2. Make the measurement and save the data trace to memory:
and
3. Then switch to stepped list mode:
• If there is no difference between the measurements in either list mode, then use the
swept list mode.
• If the memory trace indicates that there is more attenuation in swept list mode, it
may be due to IF delay. You can usually remedy this problem by increasing the sweep
time.
NOTE IF bandwidths of 30 to 10 Hz cause the sweep (or that segment of the sweep)
to always be stepped, thus eliminating IF delay.
To Decrease the Frequency Span
The hardware of the network analyzer sweeps the frequency range in separate bands,
where switching from band to band takes time. Modify the frequency span to eliminate as
many band switches as possible while maintaining measurement integrity. Refer to the
following table to identify the analyzer's band switch points:
Table5-3 Band Switch Points
Band Frequency Span Band Frequency Span
1 50 MHz to 110 MHz 8 2.55 GHz to 4.71 GHz
2 110 MHz to 230 MHz 9 4.71 GHz to 8.256 GHz
3 230 MHz to 470 MHz 10 8.256 GHz to 13.562 GHz
4 470 MHz to 698 MHz 11 (8720ET/ES
and 8722ET/ES) 13.562 GHz to 20.05 GHz
5 698 MHz to 1.17 GHz 12 (8722ET/ES) 20.05 GHz to 25.0 GHz
6 1.17 GHz to 1.878 GHz 13 (8722ET/ES) 25.0 GHz to 40.0 GHz
7 1.878 GHz to 2.55 GHz
Display
DATA → MEMORY
DISPLAY: DATA
MEMORY
Sweep Setup
SWEEP TYPE MENU
EDIT LIST
LIST TYPE: [STEPPED]
DONE