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When searching for a non-contact level measurement, radar technology should be at the top of anyone’s list. Radar sensors are more focused than ever before, making them a reliable option, even in vessels with obstructions or applications that require isolation valves. This technology is used for measuring liquids and solids in industries ranging from chemical plants and refineries to ready-mix concrete facilities and wastewater treatment plants.
There’s a reason radar technology is so widely used: it provides accurate, reliable level measurements without the need for maintenance or recalibration, and the sensors are easy to set up. Once a radar sensor is properly installed, it can provide vital level control for years or even decades without requiring any further attention.
How radar level measurements work
Radar level technology uses time of flight to make a measurement. Radar sensors are installed at the top of the vessel and emit radio microwaves from the antenna system to the measured product surface where that signal is reflected back to the antenna.
The amount of time between emission and reception is proportional to the distance to the product surface — the longer the time of flight, the greater the distance. This distance is inversely proportional to the level in the tank, bin, silo or container, so a greater distance equates to a lower level and vice versa.
A radar sensor’s integrated electronics convert the measured value into an analog or digital signal for transmission. The signal can be used for an external display or a process control system. Additional components for hazardous areas, overvoltage protection or wireless communication enable a wide range of applications in all industrial sectors.
Better focus with 80 GHz technology
Back to basics: Explaining through-air radar level technology
The latest high-frequency radar level sensors use a transmission frequency of 80 GHz, a significant leap forward from the previous generation, which used 26 GHz. This is important because a radar sensor’s beam angle is dependent upon two factors: antenna size and transmission frequency.
When it comes to antenna size, a radar sensor’s microwave beam angle is inversely related. A smaller antenna will have a wider, less focused beam. Conversely, a larger antenna will have a narrower, more focused beam.
Process fittings can’t always be changed, so the beam angle of a radar level sensor is often determined by its installation location. While this may work in some applications, it can be a hinderance in small vessels or tanks with internal components like agitators or heating coils. These are the situations where 80 GHz radar level sensors outperform their 26 GHz counterparts.
Radar sensors with a higher transmission frequency have a narrower beam angle, which makes installations easier and measurements more reliable. A more focused signal can take measurements around internal obstructions, and with more microwave energy reaching the measured product, the radar sensor receives a stronger return signal. When paired with improved sensitivity, users can expect more reliable and accurate measurements.
Receiving a reliable signal
The strength of the radar’s return signal relies on several factors. The product surface, the distance between the surface and the sensor and product reflectivity all play a role. An agitated, turbulent product surface is more likely to reflect the radar signal in other directions away from the radar antenna. Partial signal loss can occur over longer distances, and this must be accounted for in tall tanks and silos. Finally, not all products reflect radio microwaves equally.
A product’s chemical composition is usually the most significant predictor of signal strength. Conductive products reflect nearly all microwave energy, while non-conductive products reflect only a portion of it. This reflective property is referred to as a product’s dielectric constant. Highly reflective products like water have a high dielectric constant, while poorly reflective products like oil have a low dielectric constant.
The range of signals a radar sensor can detect is called its dynamic range. Sensors with a large dynamic range are sensitive enough to register weak signals as well as strong ones. Radar sensitivity varies from manufacturer to manufacturer, and they even differ from sensor to sensor in a manufacturer’s instrument line.
A user may think a highly sensitive radar would be more susceptible to “noise” created by unwanted microwave energy reflecting back to the antenna. This unwanted noise could originate from buildup or condensation on the antenna, from internal structures within the vessel or from microwave energy bouncing off the side of the vessel itself. This noise can distort a level measurement, but it can be overcome with intelligent software capable of filtering out any interference.
The 6X: VEGA’s simple radar solution for better processes
Back to basics: Explaining through-air radar level technology
In 2022, VEGA launched the VEGAPULS 6X, a radar sensor that can handle any application. The VEGAPULS 6X now combines the best of the previous 80 GHz, 26 GHz and 6 GHz sensors into one device. Choosing the right level measuring instrument from a wide range of configurations is a thing of the past.
VEGAPULS 6X offers the best technology available in radar level measurement. It boasts an advanced radar chip that provides highly precise and reliable measurements combined with simple operation; this results in more application possibilities than ever before. It’s also VEGA’s safest radar yet, available in Safety Integrity Level-certified configurations and compliant with IEC 62443-4-2 cybersecurity standards.
Ethernet APL — unmatched connectivity for modern industry
Digitalization is changing the status quo in the process industry, but many users have so far paid little attention to the topic of cybersecurity. Recognizing the importance of increased security standards, VEGA has integrated Ethernet APL into the VEGAPULS 6X, offering lightning-fast, secure data transmission even in the most challenging industrial environments.
Ethernet APL provides the following benefits:
- Effortlessly transmits data up to 1000 meters, even in hazardous (Ex) areas
- Delivers process updates at blazing fast speeds of 10 Mbit/s
- Easy access to diagnostics, settings and protocols using a standard web browser
- Secure data transmission using HTTPS encryption
The value of simplicity
Users who have steered away from radar in the past should give it a second look, and users currently relying on an older radar may want to consider an upgrade to a high frequency unit. Radar technology has come a long way since its inception and today’s sensors are providing more accurate, reliable level measurements than ever before.
The VEGAPULS 6X continues to set the standard in non-contact radar level measurement technology. The ultimate purpose of VEGAPULS 6X is maximum simplification: simplifying industrial processes, the process of selecting and installing a sensor and the security of data. It is truly the perfect measuring instrument for the application.
More information is available at vega.com/radar.
