Measurement Techniques for High-Frequency Electronic Systems

The accurate characterisation of electronic systems operating at frequencies from several gigahertz into the sub-terahertz domain is fundamental to advances in communications, sensing and radar applications. High-frequency measurement techniques must contend with challenges such as signal attenuation, dispersion, parasitic effects and device nonlinearities. Central approaches include frequency-domain network analysis using vector network analysers, time-domain sampling oscilloscopes and equivalent-time sampling systems, as well as energy-domain methods employing directional couplers and power meters. Emerging electro-optic and photonic probes offer minimally invasive sampling with bandwidths beyond electronic limits, while broadband capacitor dividers extend voltage measurement into the gigahertz regime. Calibration strategies, including through-reflection-line error correction models, are crucial for tracing measurements to primary standards and quantifying uncertainty. Recent advances integrate digital post-processing and machine-learning algorithms to de-embed instrumentation error and enhance sensitivity. Together, these measurement techniques underpin the development of millimetre-wave 5G/6G infrastructures, high-speed data converters, terahertz imaging systems and precision metrology tools, ensuring global connectivity, improved spectral efficiency and robust device characterisation.

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A vector network analyser was employed to calibrate and characterise sub-terahertz channel sounding instruments in over-the-air scenarios around 200 GHz and 300 GHz. By comparing a calibrated error model to correlation-based channel sounders, researchers quantified uncertainty under both line-of-sight and non-line-of-sight conditions, assessed the impact of DC offset and in-phase/quadrature imbalance, and evaluated multipath effects. The study reported combined uncertainty figures of ±0.22 dB and ±0.51 dB for different waveguide bands, demonstrating high-precision sub-THz measurement capability.

In high-power microwave systems for particle accelerators, a dual-coupler arrangement with auxiliary circuits has been introduced to cancel interference from reflected waves under standing-wave conditions. By careful adjustment of amplitude and phase in the outputs of two directional couplers, the method reduced incident power measurement uncertainty from ±20 % to between −1.5 % and +3.5 % across a full standing-wave cycle at 162.5 MHz. This approach provides a practical solution for accurate power monitoring in mismatched and high-reflection environments.

A high-frequency measurement system based on equivalent-time sampling was developed to capture periodic signals with sub-nanosecond resolution using a low-cost voltage-tracking circuit paired with commercial waveform generators and digital multimeters. The successive-approximation technique transforms different phase points of the test signal into equivalent DC levels, achieving a non-linearity error as low as 0.002 % and a bandwidth up to 200 MHz. This architecture significantly reduces the influence of random noise and timing jitter, offering a scalable method for precise amplitude and timing characterisation.

Measurement Techniques for High-Frequency Electronic Systems publication trend

The graph below shows the total number of articles in measurement techniques for high-frequency electronic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Vector Network Analyser: An instrument that measures complex scattering parameters of a device under test across frequency, enabling determination of reflection and transmission characteristics.

Directional Coupler: A passive microwave component that samples a defined fraction of forward or reverse travelling power, used for monitoring and measurement without significant signal disturbance.

Equivalent-Time Sampling: A technique that reconstructs high-frequency waveforms by aggregating samples taken at incrementally delayed phases across multiple cycles, achieving effective sampling rates beyond the real-time limits of analogue-to-digital converters.

References

1. Characterization of Sub-THz Channel Sounding Systems in OTA Measurement Scenarios Using a Vector Network Analyzer. IEEE Transactions on Antennas and Propagation (2025).
2. Field analysis of electro-optic probes for minimally invasive microwave sampling.. Optics Express (2014).
3. A Practical Method for Measuring Incident Microwave Power in RF Systems of Particle Accelerators. International Journal of Antennas and Propagation (2025).
4. A novel broadband capacitor voltage divider for measurement of ultrafast square high voltage pulse transmitted in transmission line. AIP Advances (2020).
5. Precision Measurement System of High-Frequency Signal Based on Equivalent-Time Sampling. Electronics (2022).