Radar level gauges can continuously measure different material levels and are suitable for harsh environments such as high temperature, steam, high dust, and volatile gases. They are also suitable for situations with large changes in dust, temperature, pressure, and the presence of inert gases and steam. Widely used in industries such as chemical, energy, petrochemical, pharmaceutical, cement, etc.

Radar level gauges can be divided into non-contact and contact types according to their working modes.

Non contact microwave level gauges commonly use horn or pole antennas to transmit and receive microwaves. The instrument is installed at the top of the silo and does not come into contact with the measured medium. Microwaves propagate and return in the upper space of the silo. Easy installation, minimal maintenance, and not affected by gas composition, dust, temperature changes, etc. inside the silo.

Contact type microwave level meters generally use metal wave conductors (rods or steel cables) to conduct microwaves. The instrument is installed from the top of the warehouse, and the wave conductor rod reaches the bottom of the warehouse. The emitted microwaves propagate downward along the outside of the wave conductor, are reflected when they reach the material surface, and return to the transmitter along the wave conductor for reception.

Types of antennas for radar level gauges

1Rod antenna

Insulated rod antennas are usually made of polymer materials such as polytetrafluoroethylene and polypropylene, which have good corrosion resistance and can be used for measuring media such as strong acids and alkalis. But the microwave emission angle is relatively large (about30°)Moreover, there are many side lobes, and for complex structures inside the tank, there will be more interference echoes, low signal-to-noise ratio, and low accuracy. But it is easy to clean and is usually used for measuring tanks and corrosive media with good operating conditions, large diameters, and small measurement ranges. If the tested medium is prone to volatilization and condensation, it is best to choose a rod antenna or a droplet antenna.

2Horn shaped antenna

At the same frequency, the larger the diameter of the horn, the smaller the emission angle. If it is a high-frequency radar level gauge, the emission angle is smaller and the accuracy is higher. Many buffer tanks, storage tanks, reaction tanks, etc. use this type of antenna, but it is not suitable for measuring corrosive media. Although increasing the size of the horn antenna can reduce the transmission angle, it is inconvenient to install due to its increased volume, and the improvement is limited. If a large horn antenna radar level gauge is selected for a large range measurement site, a small horn antenna is suitable for small containers. If the flowability of the measured medium is poor and there is a hanging phenomenon, then choose a horn or rod type radar level gauge.

3Parabolic antenna

This is a recently launched new type of antenna, commonly used in high-frequency radar transmission. Due to its emission angle of only7° is very suitable for measuring precise targets and passing obstacles for measurement. But its antenna size is large, if usedXBand, diameter up to Φ454mmThe opening size should be greater than500mmInstallation and use are not very convenient.

4Flat antenna

The planar antenna adopts planar array technology, that is, multi-point transmission source. Compared with a single point transmission source, measuring it on a plane instead of a determined point, combined with corresponding electronic circuits, can make the measurement accuracy of the radar level gauge reach ±1mmIt can be used for precision measurement of storage tanks, mainly for measuring grade radar level gauges. Flat antennas are suitable for various working conditions.

5Guided wave radar antenna

Transmitting and receiving electromagnetic waves through guided metal or cable belongs to contact measurement. Due to its minimal impact on dust, steam, and adhesive media on waveguide rods, it is more widely used in measuring solid material levels and liquid levels with low dielectric constants. The dual cable guided wave radar level gauge measures the height of the liquid level by measuring the changes in capacitance. The medium between the two electrodes is liquid and the gas above it. It is suitable for measuring the level of corrosive and high-pressure media, fundamentally solving the influence of factors such as temperature, humidity, pressure, and material conductivity on the measurement process. Therefore, it has high anti-interference and reliability. A guided wave radar level gauge with a coaxial tube probe installed on the coaxial tube radar level gauge is used for level measurement and control of liquids with low dielectric constants or surface fluctuations; If the dielectric constant of the tested material is too low, general types of radar level gauges are not suitable.