Making Waveguide Measurements |
The FieldFox is capable of making accurate measurements using waveguide media. Waveguide can be thought of as a bandpass filter. Waveguide is intended to pass frequencies for which it is designed and reject frequencies outside of the band. This web site includes a table of valid frequency ranges for types of waveguide: http://en.wikipedia.org/wiki/Waveguide_(electromagnetism)
The following are tips for making good waveguide measurements in NA mode and CAT mode.
When using Time Domain Transform (Option 010), set transform mode to Band Pass. Do NOT use Low Pass Step or Low Pass Impulse. These modes will attempt to set the stimulus frequencies outside the valid frequency range of the waveguide.
Waveguide is limited to narrow frequency ranges of operation. When making DTF measurements in waveguide:
Set Frequency Mode to [BandPass]. Do not use [Lowpass] for DTF waveguide measurements.
Set DTF Min Start Frequency to the lower limit of the waveguide frequency band (also known as the cutoff frequency) Example: For X-band waveguide, set the Start Frequency to 8.2 GHz.
Set DTF Max Stop frequency to the upper limit of the waveguide frequency band. For X-band waveguide, set the Stop Frequency to 12.4 GHz.
Perform a narrowband user calibration with the correct waveguide calibration kit.
Calibrations must be performed within the valid frequency range for the waveguide being used. For example, X-band waveguide frequency limits are 8.2 GHz to 12.4 GHz. The FieldFox does NOT allow waveguide calibration outside the valid frequency range.
After calibration, the FieldFox will turn correction OFF if the start or stop frequency is set outside the range of the waveguide cal. A message reports calibration is turned OFF when that happens.