Rohde & Schwarz offers special waveguide calibration kits for test setups involving frequency converters.
Calibration Kit R&S ZV-WR10 is suited for the frequency converter R&S ZVA-Z110(E) (frequency range: 75 GHz to 110 GHz)
Calibration Kit R&S ZV-WR12 is suited for the frequency converter R&S ZVA-Z90E (frequency range: 60 GHz to 90 GHz)
Calibration Kit R&S ZV-WR15 is suited for the frequency converter R&S ZVA-Z75 (frequency range: 50 GHz to 75 GHz)
Calibration Kit R&S ZV-WR03 is suited for the frequency converter R&S ZVA-Z325 (frequency range: 220 GHz to 325 GHz)
The following sections describe the standards in the waveguide calibration kits and their use for system error corrections.
The waveguide calibration kit R&S ZV-WR10 allows to calibrate network analyzers for test setups involving frequency converters, in particular R&S ZVA-Z110 or R&S ZVA-Z110E.
The calibration kit contains the following standards:
A Short standard which also serves as a Reflect standard
A (Fixed) Match standard
A Shim that contains a short transmission line causing a λ/4 phase shift around the center frequency of the converters operating range and a 180 deg phase shift of the reflecting coefficient.
A Sliding Match standard (kit 1307.7100.11 only), providing more accurate results than the Fixed Match standard – at higher test effort.
The following table provides an overview of the available standards for rectangular waveguide calibration and the technical implementation using the calibration kit.
Standard Type
Technical implementation
Open
Not available in waveguide technology, replaced by "Offset Short"
Short
Contained in the calibration kit
Offset short
Short + Shim, both contained in the calibration kit
Match
Sliding match
Contained in the calibration kit 1307.7100.11, 1307.7500.31, and 1307.7700.11
Reflect
Short, contained in the calibration kit
Through
Direct through connection of the two waveguide flanges
Line1
Through connection of the two waveguide flanges with Shim in-between. In view of the bandwidth of the frequency converters, line 2 is not needed.
Attenuation
Not contained in the calibration kit
Symm. network
The standards in the calibration kit allow all one-port and two-port calibration types supported by the network analyzer except TNA.
The characteristic data of the standards are very stable and independent of the individual calibration kit. It is not required to deliver individual data with each kit and load the data into the analyzer. Instead the data is already stored in the network analyzer (software option R&S ZVA-K8 and a sufficiently new firmware version is required; refer to the What's New... section). It is possible to export the stored data to a file. Use the "Cal-Kits" dialog of the network analyzer for this purpose: "Channel" > "Calibration" > "Cal-Kits" > "Export Kit ..."
Performing a calibration using kit R&S ZV-WR10
The sliding match is a one-port standard consisting of a precision waveguide section with a movable, low-reflection load element (sliding load). This standard is used because no perfect match is available. However, a series of measurements at a given frequency with equal mismatch and varying phase yields reflection factors that are located on a circle in the Smith chart. The center of this circle corresponds to perfect match. The network analyzer determines and further corrects this match point following I. Kása's circle-fitting algorithm.
To obtain the reflection coefficient for a perfectly matched calibration standard, the sliding load must be measured at least at three positions which should be unequally spaced to avoid overlapping data points. Increasing the number of positions to 4 – 6 can improve the accuracy. It is recommended to use the positions listed below. Depending on your calibration kit, set the adjustable screw of the standard to the following positions:
R&S ZV-WR10: 0 mm, 0.35 mm, 0.8 mm, 1.4 mm, 2.1 mm, 4.2 mm
R&S ZV-WR12: 0 mm, 0.42 mm, 0.96 mm, 1.68 mm, 2.52 mm, 5.04 mm
R&S ZV-WR15: 0 mm, 0.52 mm, 1.2 mm, 2.1 mm, 3.15 mm, 6.3 mm
If you accidentally unscrew the knob completely, simply screw it on again.
The calibration kit R&S ZV-WR12 contains the same standard types as the calibration kit R&S ZV-WR10, however, the standards are optimized for the frequency range of the R&S ZVA-Z90E frequency converter (60 to 90 GHz). The calibration procedure for both kits is identical.
The calibration kit R&S ZV-WR15 contains the same standard types as the calibration kit R&S ZV-WR10, however, the standards are optimized for the frequency range of the R&S ZVA-Z75 frequency converter (50 to 75 GHz). The calibration procedure for both kits is identical.