Guided Wave Radar for Continuous Level Measurement

Posted by TechStar on Aug 15, 2022 11:25:20 AM

Guided wave radar technology is a method of measuring the level of liquids with radio waves. It is used in continuous measurement systems for various applications, from the chemical industry to oil and gas production, water treatment plants, and more.

What is guided wave radar technology?

Guided wave radar (GW-R) is a remote sensing method used to measure tank level and other flow characteristics. It is one of the most accurate methods available for measuring tank levels. Guided wave radar technology can measure both liquids and gases.

2O6A8869Guided wave radar systems are also known as microwave propagation systems or microwave line-of-sight systems. They use high-frequency radio waves (typically X band or Ku band) to determine the level or concentration of liquids or gases within pipes or containers by measuring their reflection coefficient at different points along their path.

As the name suggests, these systems use electromagnetic waves that have been "guided" through an external transmission medium before reaching an antenna at some distance from the source transmitter. A receiver antenna picks up reflected signals from the same location where they were transmitted and returns them back for processing and analysis by computer software.

How does level measurement with guided wave radar sensors work?

Guided wave radar (GW-R) is a non-contact measurement technique that uses a low-frequency electromagnetic field to measure the level of liquid in tanks, vessels, and other large containers. The system uses a transmitter and receiver, the transmitter being positioned above the vessel and the receiver being positioned below the vessel. As the liquid surface moves up and down with variations in load or temperature, so does the electric field around it.

Guided wave radar technology is a form of radar that uses electromagnetic waves to measure distance. The waves are guided along a surface, rather than transmitted through the air. This makes them less vulnerable to atmospheric interference, so they can be used for continuous level measurement, even in harsh environments.

The GW-R system measures this movement by detecting changes in the dielectric constant of the liquid as it moves between two electrodes at either end of an electrical probe. The probe is lowered into the vessel until it touches its surface, where it becomes part of its circuit.

Guided wave radar technology works best when conditions are stable and there is little interference from objects or other signals. This makes it ideal for continuous-level measurement applications, where there may be moving parts in the process or other sources of interference.

What are the advantages of guided wave radar?

Guided wave radar has many advantages over traditional technologies:

Continuous level measurement: Guided wave radar can be used for continuous level measurement of liquids (such as petroleum products, water, crude oil, and natural gas) with high accuracy. This makes the system suitable for applications where measurements need to be taken continuously over long periods, without interruption by maintenance or installation issues.

Longer range: Guided wave radar has a longer range than conventional radar because it uses larger antennas that radiate more energy into the atmosphere. This allows you to measure levels at greater distances from the tank or container itself. It also allows you to measure deeper levels inside large tanks or containers, without having to install additional probes. 

Accuracy: Guided wave radar’s accuracy has been demonstrated as high as +/- 0.5 mm, which makes it suitable for use with highly viscous liquids (such as lubricating oils) or highly agitated liquids (such as fuel). This high accuracy means guided wave radar can be used for non-intrusive measurements (where there is no need to penetrate the surface of the liquid).

Reliability: Guided wave radar does not require any moving parts for operation, so there are no moving parts that could fail over time or wear out. This means your system will remain in working order for years to come.

Cost: Guided wave radar systems are less expensive than traditional systems because they do not require pre-installed sensors in tanks.

When to Use Guided Wave Radar Technology

When to Use Guided Wave Radar Technology

There are many situations where GWR technology is an ideal solution for a continuous level measurement requirement. Some examples include:

  • Process control systems that require real-time measurement of liquid levels for process control and closed-loop feedback control systems
  • Process monitoring applications where the fluid being monitored may vary significantly over time, or where vibration and other environmental conditions may affect the accuracy of conventional methods, such as ultrasonic or float switches.
  • Applications where it is desirable to have a level measurement technology that does not require any direct contact with the liquid being measured.
  • Continuous level measurement in open tanks or vessels that are difficult or impossible to fill completely with liquid
  • Continuous level measurement in tanks or vessels that contain hazardous materials such as radioactive waste, acids, or oxidizers.
  • Measurement of flow rate in pipes and channels where flow direction cannot be determined.

Selection Considerations

The selection of a guided wave radar for continuous level measurement depends on the application and the specific needs of your business. The following considerations should be made:


The range of a guided wave radar is determined by the length of the antenna, which determines its frequency (lower frequencies for longer antennas) and frequency accuracy (higher frequencies for higher accuracy). In addition, environmental conditions can affect range.


Accuracy is typically given as a percentage. For example, if an instrument has an accuracy of 0.5%, then it will be within this range 95% of the time. This means that 5% of readings could be outside this range, but still within specification if all other conditions are met. 


The resolution depends on how finely a device can take measurements. When looking at resolution in terms of distance, there are two types: lateral resolution and depth resolution. Lateral resolution refers to how well a measurement can be taken from side to side or across an object. Depth resolution refers to how well one can measure from top-to-bottom or bottom to top in an object.

The selection of appropriate radar technology for continuous level measurement is an important step in designing a successful manufacturing process. The preceding considerations should be taken into account when selecting the appropriate equipment for your company’s needs. To speak to an expert about your GW-R needs, contact Techstar today!  

Topics: Condition Monitoring, techstar

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