FMCW Radar
FMCW radarFMCW radar transmits a continuously swept frequency and measures the beat signal produced by delayed reflections, enabling distance, thickness, and depth-resolved imaging with compact coherent hardware. More converts a controlled frequency sweep into depth information. The measured beat signal can separate reflections from successive interfaces, but the quality of that separation depends on more than nominal bandwidth. Sweep linearity, phase stability, material dispersion, multiple reflections and the reconstruction model all influence the final profile.
A 150 GHz homodyne harmonic-mixing architecture developed for non-contact testing demonstrated measurement rates up to 7.62 kHz and a dynamic range up to 100 dB. Subsequent work examined how coherent synthetic-aperture reconstruction can improve lateral resolution, how fast beam steering can reduce the mechanical cost of point-by-point imaging, and how model-based estimation can measure thicknesses below the conventional air-range resolution in a validated configuration.
These results make FMCW radarFMCW radar transmits a continuously swept frequency and measures the beat signal produced by delayed reflections, enabling distance, thickness, and depth-resolved imaging with compact coherent hardware. More particularly relevant to layered dielectrics and contactless inspection, while also defining the conditions that must be controlled. Surface curvature, roughness, refractive index and internal reverberation can shift or broaden echoes. The expertise therefore combines radar integration with calibration, inverse modelling and application-specific reference samples.
Frequency-modulated continuous-wave radar for depth-resolved inspection, guided reflectometry, teaching, and application-driven demonstrators.
FMCW Radar across the measurement chain
The workflow can include requirement definition, instrument selection or development, calibration, acquisition, signal processing, reconstruction, and interpretation. The first decision is rarely the choice of an instrument. It is the identification of the physical quantity that could answer the research question: an interface delay, a spectral feature, a complex refractive index, a local field component, a surface profile, or a volumetric morphology.
Once that quantity is defined, source bandwidth, detector architecture, numerical aperture, scan geometry, dynamic range, sample environment, and reference measurements can be considered together. This system-level approach is particularly important in the terahertz range, where propagation loss, diffraction, atmospheric absorption, coherent artefacts, and material dispersion may all influence the same dataset.
Calibration, interpretation and validation
A capability is meaningful only when its limits are explicit. Work therefore asks which contrast mechanism is physically interpretable, what bandwidth and geometry are required, how repeatability is measured, and which independent method can serve as a reference. Reconstruction may improve access to phase, depth, or morphology, but it does not remove the need to test model assumptions and uncertainty.
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