VSWR measurement technique - lab procedure

VSWR

Anybody please let me know the laboraory process of determining VSWR??If you have any ebook or papers regarding he same plz pass i on o me at rahul.6sep@gmail.com

Regards,

Rahul

VSWR

Hello,

When you really want to measure VSWR, you have to follow the definition (ratio of maximum amplitude over minimum amplitude along a transmission line due to interference between reflected wave and forward wave).

For this procedure you need a transmission line where you can probe the line voltage. The line must be at least 0.5 lambda long (electrically). This is to make sure you have both a position of minimum and maximum amplitude.

Slotted lines and microstrip circuits are used in combination with diode detectors or other RF receiver (spectrum analyzer, measuring receiver). The disadvantage of the diode detector is that you have to apply a correction for the quadratic to linear transition in its DC_out versus RF-in characteristic.

Nowadays VSWR is mostly measured by determining the reflection coefficient (resistor bridge, directional coupler, network or scalar analyzer) and VSWR is calculated from the Refl. Coeff.

What method you use, depends on your budget, frequency, available instruments, knowledge and how many measurements you have to do.