TRL calibration for Free Space Measurements

[snkhan]

I want to perform TRL calibration for free space dielectric measurements.

Consider the two antennas that are 30cm apart. I am confused

i) THRU:: now do i need to set "zero length delay" in VNA calibration kit (i.e. default setting in VNA). Or i need to set delay corresponding to 30cm.

ii) REFLECT:: since the reflector will be place at the center (15cm), so the delay in VNA be equivalent to 15cm.


Kindly Help

 

[E Kafeman]

1. If needed, adjust electrical delay during calibration.
2. Most VNA's calculate S11 or S22 delay as sum of distance forward+back for the setup (2*15 cm).

 

[FvM]

I guess a dielectric measurement should be calibrated with dielectrica standards...

Primarly you have to find out if the setup is suitable for the intended purpose. I imagine some problems with antenna characteristics, near field effects, cable effect of unbalanced antenna ports. I don't believe that an electrical (cable bound) calibration will bring you far.