Support for the 85033 SMA calibration and verification kit 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 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.

Definitions of the SMA standards in the Kirkby Microwave 85033 calibration and verification kit

Standard label: 85033.
Type C0 C1 C2 C3 Offset length (mm) Offset loss (dB/sqrt(GHz))
Female short         12.41 0.0216
Female open 53.004 0.135167 0.095631 0.030937 11.93 0.0048
Male short         17.34 0.007
Male open 50.389 0.76136 -0.96822 0.068376 16.52 0.0067

Over the operating frequency range of this kit, the inductance of the short is negligable, so one should set L0=L1=L2=0

Older, non-Windows based VNAs

For older instruments, the method of entering the coefficients depends very much on the analyzer. You will need to consult the manual of the VNA, but you will require the definitions of the calibration kit listed above. If you need any help, please contact us.

Newer, Windows based VNAs

For a modern Windows based VNA, just download the file Kirkby Microwave 85033 SMA.calkit and read that into the VNA. 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.


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 appropiate calibration technique.

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