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Support for Kirkby Microwave calibration and verification kits with a Rohde & Schwarz VNA

Kirkby Microwave 85033 with Rohde & Schwarz ZNB8 VNA

The calibration standards are indivdually measured prior to dispatch of our kits. Therefore the coefficients must be entered as a user-defined calibration kit. This is not a difficult process. We supply data in the following three formats:

  1. A human readable text file, which can be used to set up all Rohde & Schwarz analyzers, both old and new. Here is an example .txt file for an SMA calibration kit. It has all the data, in the format traditionally used by Rohde & Schwarz.
  2. A .prn file, that many Rohde & Schwarz VNAs can read. Here's an example .prn file, which many Rohde & Schwarz VNAs can read.
  3. A .calkit file, that many Rohde & Schwarz VNAs can read. Here's an example .calkit file. The .calkit files are supplied free of charge if you request one. We don't supply these with every kit, as only a small fraction of our customers will want the file and we have no totally automated way of creating the files. (We open the .prn file on a Rohde & Schwarz VNA, then save it as a .calkit file.)

How to enter the coefficients

The way the coefficients are entered depends on the VNAs:

Older, non-Windows based VNAs

A text file, easily read by a human (e.g. 85033_SN_0409_for_Rohde_and_Schwarz.txt) has all the information needed. You will need to consult the manual for your VNA to determine how to enter the coefficients. If you need any help, please contact us.

Newer, Windows based VNAs

For a modern Windows based VNA, the coefficients can be read from a .prn file (always supplied on the USB stick) or a .calkit file (optionally created if needed). The process desribed below use a .calkit file, but it is probably easiest to use a .prn file, as they are supplied on every USB stick since late August 2018. For this example, it is assumed that the calibration kit definitions are on a USB stick as drive E:\ in a subdirectory Rohde-and-Schwarz.

Step 1 - Preset the analyzer to get it into a known state.

Press the "PRESET" key to get the Rohde & Schwarz into a known state.


Step 2 - Press CAL on the analyzer

Press Cal

Step 3 - Press Cal Devices on the analyzer

Press Cal

Step 4 - Import the calibration kit by pressing "Import Cal kit..".

Import the SMA calibration kit

Step 5 - Select the calibration kit to import.

In this example, there are two calibration kits which may be imported. The Kirkby Microwave 85033 is the 7 GHz type-N kit - although this is also available with lower costs loads, which limit the frequency range to 6 GHz. The coefficients of the two kits are the same. The other kit we see, the Kirkby Microwave 85033 is an SMA calibration kit. Loading the coefficients for the wrong calibration kit will result in calibration errors, so it's important to load the correct kit.

Calibration presetting

Step 6 - Start the calibration.

As you can see, the Rohde & Schwarz analyzer supports many calibration types. The best type depends on the DUT and the accuracy required, but the USOM type is generally best for use with our calibration kits. This corrects for:

UOSM calibration

Step 6 - Select the sex of the test ports

The calibration kit definition of the Kirkby Microwave 85033 calibration kit assumes a zero length thru. This means during calibration, one port is assumed to be male, and the other female. If you have two male cables, which is quite common, the UOSM (Unknown through - Open - Short - Match) calibration is certainly the best choice, as no knowledge about the adapter is needed. The VNA determines the properties of the thru. UOSM, also known as "unknown thru" is a powerful calibration technique. The analyzer will automatically default to USOM if the connectors at the ports will not mate. There are excellent help menus in the modern Rohde & Schwarz analyzers, so it should be easy to determine an appropriate calibration technique.

Kirkby Microwave Ltd is registered in England and Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT.