Introduction to Calibration
Calibration is of critical importance for making accurate measurements from your VNWA.
Without calibration the VNWA will indicate random values.
While Calibrating, a Short circuit SMA connector, a Open circuit SMA connector and finally a 50R SMA load are connected to the VNWA TX Port in turn.
During Calibration we step the TX port frequency (S11) over the Frequency band of interest. This way the VNWA builds up calibration table for each frequency for the following measurement points:
- Low end of the measurement scale (short = 0 Ohm)
- High end of measurement scale (open – infinity)
- Mid scale point on the measurement scale of 50R Resistive load - normalizing value of S-parameter measurements.
Next, connecting the TX port to the the RX port via a Thru Cable and performing a Thru Calibration sets the transmission loss between these two ports to 0dB and allows accurate insertion loss measurements.
Video Tutorial by Kurt Poulson OZ7OU: First time VNWA Calibration (duration 16 mins)
Note: SDR-Kits is taking all reasonable steps when measuring and recording the actual value of the Load Resistor. Calibration Kits should only be used however for "Indication Purposes not for final testing"
SDR-Kits supplies a choice of low cost and premium calibration kits as described below.
Low Cost Calibration Kits with Amphenol Connex parts
3 pcs Male SOL Calibration Kit Amphenol Parts or 4 pcs Plug (Male) Calibration Kit
This is a low cost Calibration Kit but good results are obtainable up to 1 GHz...1.3 GHz.
The value of the Amphenol SMA load supplied is always exactly 50 Ohm and therefore set as the default value in the Calibration Kit - Simple SOLT Model settings Tab.
The Amphenol kits are supplied with a data sheet courtesy of Kurt Poulsen OZ7OU
Note: 4pcs Calibration Kit only available as part of VNWA 3 / 3EC Presentation Case
Premium 12 GHz Calibration Kits
This is a premium product which is specified up to 12.4 GHz.
Female SMA SOL 4 pcs Calibration Kit of 12 GHz Parts in wooden box by SDR-Kits
-1 pc 50 Ohm 1 Watt Jack (female) Load
actual value of the 12 GHz load supplied is measured and recorded
by SDR-Kits on label inside box
-1 pc 0 0hm Short Jack (female)
-1 pc SMA Jack - Jack (Female-Female) Open connector & Adapter
-1 pc SMA Plug - Plug (Male-Male Open) connector & Adapter
Male SMA SOL 4 pcs Calibration Kit of 12GHz Parts in wooden box by SDR-Kits
-1 pc 50 Ohm 0.5 Watt Plug (Male) Load
actual value of the 12 GHz load supplied is measured and recorded by SDR-Kits on label inside box
-1 pc 0 0hm Short Plug (Male)
- 1 pc SMA Plug - Plug (Male-Male Open) connector & Adapter
-1 pc SMA Plug (Male) Open Connector - Dustcap
The value of the 50R Load is laser trimmed during manufacture to the specified S11 return loss over the extended frequency range. Therefore the value of the Load resistor is no longer 50 Ohms. The actual value of the 12 GHz Load is measured by SDR-Kits and the value is supplied to the Customer with the Calibration kit. When using the 12 GHz Calibration parts VNWA users must therefore enter this value in the Calibration Kit - Simple SOLT Model settings Tab.
The SDR-Kits Premium 12GHz Calibration kits are supplied with a datasheet courtesy of Kurt Poulsen OZ7OU
Download Information on how the new improved Calibration Standards were measured by Kurt Poulsen OZ7OU