Guided Radar Level Measurement

Guided Radar Level Measurement

Guided radar (guided wave radar / TDR) instruments deliver continuous level measurement in liquids and bulk solids using a probe that guides the measurement signal. They are frequently chosen to combine radar-grade performance with stable operation in vessels where foam, turbulence, or internal structures complicate non-contact measurements. The technology is also widely applied for interface measurement, where identifying a boundary between two phases is critical for separation and quality control.

The measuring principle uses high-frequency radar pulses that are emitted and guided along the probe. When the pulse reaches the medium surface, part of the signal reflects due to a change in relative dielectric constant, and the instrument measures the time-of-flight between launch and return. That time directly represents distance from the process connection to the product surface, enabling accurate level calculation. Additional diagnostics such as end-of-probe evaluation can add measurement security.

Guided radar’s benefits are tied to its controlled signal path. The surface condition is of minor importance because the waves are guided, so turbulent surfaces, foam formation, angled surfaces, and outflow funnels in solids have limited influence on the reading. It is presented as reliable around obstacles or baffles and can provide stable measurement even during filling. These characteristics make guided radar a strong choice for demanding vessels without resorting to invasive mechanical devices.

Typical applications include storage tanks and process vessels handling corrosive or aggressive media, heavy-duty industrial services, and bulk solids silos where funnels and variable surfaces are common. Interface measurement in separators, settlers, and product/water boundaries is a frequent driver for guided radar selection. It also fits well where consistent performance is needed across varying operating states, including agitation, recirculation, and foam-prone conditions.

Key design considerations include probe type (rod vs. cable), dielectric constant limits, and mechanical installation geometry. Probe anchoring, nozzle length, and clearance to walls or internals affect echo quality and long-term reliability. While guided radar is tolerant, extreme coating or bridging conditions may still warrant probe and signal-processing choices optimized for buildup. With correct probe engineering and mounting, guided radar provides a high-confidence level signal across a broad range of applications.

Instrumentation and Controls., an exclusive authorized representative of sales and service for Endress+Hauser.