FROM EDN EUROPE: Network analyser performs multiport measurements to 8 GHz
By Graham Prophet -- EDN, February 3, 2005
In its ZVB Vector Network Analyser, Rohde & Schwarz has implemented a new architecture that simplifies operation from the user's point of view and leads to faster measurements (Picture). Each port on the four-port unit has an individual generator with a measurement and reference receiver; therefore, no need exists for electrical or mechanical switching between the four ports to achieve forward/reverse-path switching. This feature not only reduces measurement time, but also removes a source of inaccuracy. The four generators are locked to one source and constantly sampled to ensure leveling between the four paths. As well as permitting fast measurements on multiport and balanced devices, users can perform simpler measurements in parallel, reducing overall test time. A two-port version is also available.
As you would expect of a new-generation instrument, the ZVB follows current practice as a Windows-based unit, supporting fast data transfer. It also offers a variety of options for remote operation. Its basic specification includes dynamic range of more than 123 dB, maximum output power of 13 dBm, level sweep range of 50 dB, and IF bandwidths of 1 Hz to 500 kHz. Frequency coverage is from 300 kHz to either 4 or 8 GHz. At each of the four measurement ports, which come with N-type connectors, bias-T connections feed active components. There are also further rear-panel inputs to measure low-frequency voltages. The initial accuracy of the instrument is 1 dB, with greater precision possible through spot calibration.
Calibration is always a key specification area with network analysers. With the ZVB, Rohde & Schwarz has used an open-calibration file format, which can read ASCII-format calibration files from any manufacturer. An automatic calibration unit is available to match the analyser in both two- and four-port versions, and calibration within a measurement fixture is possible. The ZVB supports all common techniques for calibration. As well as providing a full range of VNA measurements, such as classical S-parameters plus measurements on multiport, balanced, active, and frequency-converting devices, the unit can work as a time-domain reflectometer, providing distance-to-fault measurements. Prices start at £20,000 for the 4-GHz version.—by Graham Prophet
Rohde & Schwarz, +49 89 41290, www.rohde-schwarz.com.
