Reverse sweep / backward sweep

Question

For my measurements I need a frequency sweep from higher to lower frequencies.

How can I do this?

Answer

To do this you need the K4 option.

The K4 option allows you to create an arbitrary frequency conversion.

Example:

If you want to make an S11 from 8 GHz to 300 kHz you have to make the following settings:

  • Preset
  • Change to S11
  • Start frequency = 300 kHz, stop frequency = 8 GHz
  • In the Port Configuration, change the source frequency to '-1 * fb +8.0003 GHz'.
    8.0003 GHz is the sum of the start frequency and the stop frequency
  • Accept this setting

The VNA will now sweep from 8 GHz to 300 kHz.

A reverse sweep created this way is a workaround and not part of the specifications and final production testing. Because the settling times are different to those in standard frequency sweeps, spurs or other effects may occur.

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