Having spent several years in a university high-frequency laboratory and later working as a sales engineer at Rohde & Schwarz, I can help you find the best solutions for a wide range of high-frequency and microwave measurement problems, including the selection of suitable instruments and the development and manufacturing of various test fixtures, cabling, interfaces, and controllers for automated measurement systems.
In addition to the integration of radio-electronic test and measurement systems for industry, research, and science, I offer training for companies that are not focused on radio electronics but still need to perform some radio measurements.
Coverage measurement of aeronautical ground radio stations was a topic I dealt with extensively. In addition to theoretical studies, a measurement system for airborne coverage measurement was proposed and its functionality demonstrated. Not only signal power was measured, but also the audio quality of the entire signal chain in both directions. The system was optimised for effective use of flight time and was able to measure coverage from several remotely controlled ground radio stations connected to an IP network with VoIP voice transmission, each possibly operating at multiple frequencies during a single test flight. A reusable concept of synchronisation between the air and ground segments, without any direct connection between them, was developed. The synchronisation was based on precise clocks synchronised to GPS time. It was also necessary to incorporate instruments without guaranteed response times, such as measurement instruments controlled via SCPI commands and the remotely controlled radios. This problem was solved by introducing suitable time margins into the measurement schedule, recording precise timestamps of command transmission and acknowledgement reception, and verifying that each command was executed in the required time window during postrpocessing. Even in the case of occasional time slips, only a few measured values were marked as invalid rather than discarding the entire record. This concept can also be applied to other distributed, time-synchronised systems that include devices not originally designed for precise timing.
Measurement of intermodulation products generated by passive radio devices, such as duplexers or lightning arresters, was an interesting application of top-class vector network analysers from Rohde & Schwarz. The required dynamic range is extreme. The complete system for such a measurement is quite expensive and is typically designed for a specific frequency band. It contains not only general-purpose instruments, but also highly specialised components to achieve the required dynamic range.
Measurement of power-line RF interference filters was another application of Rohde & Schwarz vector network analysers. The otherwise standard task of measuring transmission was complicated by the requirement to measure filter performance when loaded with extreme impedance combinations, such as 0.1 Ω and 100 Ω. Furthermore, the number of filter ports exceeded the number of network analyser ports. The impedance problem was addressed by performing measurements in a 50 Ω environment, followed by mathematical embedding of the measured filter between two virtual ideal transformers. The remaining challenges were solved by designing an application-specific test jig with a switch matrix controlled by the vector network analyser and a set of calibration standards inserted in place of the measured filter.
Measurement of a ferrite-core magnetic antenna in a Helmholtz coil was a classical, almost “poetic,” radio-measurement task that required me to gain a deeper understanding of electrically small resonant antennas.
Recording and real-time replay of automotive anticollision radar signals via antenna was a fairly standard, but technically demanding, task. A setup composed of commercially available instruments was created to record and replay the full 4 GHz frequency band of automotive radars centered near 80 GHz.