VSWR Meter measurement
1. Move the probe along the slotted line to get maximum deflection in
VSWR meter.
2. Adjust the VSWR meter gain control knob or variable attenuator
until the meter indicates 1.0
on normal VSWR scale.
3. Keep all the control knob as it is move the probe to next minimum
position.
4. Read the VSWR on scale.
Can anybody explain, why we are using first three steps instead
of measuring direct VSWR reading from VSWR meter ?
[img]
../imgqa/eboard/Antenna/rf-fcb2sect04b.jpg[/img]
The method you are describing utilizes the VSWR meter as a part of the detector and slot-line system to evaluate the standing wave in a waveguide.
This is done in three steps as described. The VSWR is therefore the RATIO of the standing wave MAXIMUM to MINIMUM, normalized to ONE.
The scale on the VSWR meter is calibrated so you can read the RATIO.
You should also read detector positions along the line= this serves to measure the wave length IN WAVEGUIDE (except of air coaxial lines, it differs from the wavelength in air).
I would recommend you to read some basics from a textbook to undestand.
the metod described by you is traditional method. currently vswr meter can give direct reading due to automation.
the circuit has two detectors, highly directional coupler and selection switch with controller and indicator.