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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

Currently no Rohde & Schwarz VNA has the necessary data in the firmware for use with the Kirkby Microwave calibration and verification kits. Therefore these must be entered as a user-defined calibration kit. This is not a difficult process, but it needs to be done correctly for the calibration of the VNA to be valid. The data given below can be used with all Rohde & Schwarz analyzers, both old and new. The more modern instruments can take data not only in the format traditionally used by Rohde & Schwarz, but also in the format used by HP/Agilent/Keysight. We provide data in the traditional Rohde & Schwarz format, as that is more widely supported by Rohde & Schwarz VNAs.

Older, non-Windows based VNAs

Microwave will be able to offer assistance, but you will need access to the manual on the instrument too. Kirkby Micrwave can supplied the coefficients in the format required by your VNA, but we are unable to provide files that can be read by the VNA. If you need any help, please contact us.

Newer, Windows based VNAs

For a modern Windows based VNA, the coefficients are saved into a file with the extension .calkit, an example of which is Kirkby_Microwave_85033_SMA.calkit. That can be created from the VNA using the coefficients supplied by Kirkby Microwave, or if you wish, just ask us to create the file, as Rohde & Schwarz supplied us an emulator, so we could create files for the modern VNAs. The process is described below. In this example, it is assumed that the calibration kit devices 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.

Press PRESET

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 best, although the Thru Open Short Match (TOSM) is shown. It corrects for the following error types:

TOSM 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. This is well suited for the TOSM (Through - Open - Short - Match) calibration. If an adapter is needed to make the through connection, then a UOSM (Unknown through - Open - Short - Match) calibration is required. 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.

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