Antenna problems with radar level meters

The key to measuring liquid level by radar level meter is to choose the right antenna. There are 3 types of commonly used non-contact radar level meter antennas: flared, parabolic and planar antennas. Horn antenna transmits spherical wave through point source, which is suitable for liquid level measurement of vault tank without wave guide tube. Because it has the same ambient temperature as the tank, it prevents condensation.

The parabolic antenna also transmits spherical waves from a point source and can be installed close to the tank wall. It is commonly used in vault tanks to measure viscous, condensable oils. The high temperatures inside the tank tend to produce condensate and hang-ups, which can affect the measurement. But the parabolic antenna design can prevent condensation and hanging material. It has narrow beam, concentrated energy, good focusing and more accurate measurement.

Plane antenna (also called array antenna) with multi-source transmission, radar wave is a plane spiral wave, mainly used for internal and external floating roof tank level measurement with wave guide tube. Its radar wave beam is narrow, energy concentration, by the waveguide tube roughness and oil hanging wall of the influence are small, more accurate measurement.

Radar level measurement, radar wave is absorbed by the medium attenuation, attenuation is too much when the level meter signal is not enough, measurement is not allowed. Different oil medium dielectric constant is different, affecting the measurement. In order to measure more accurately, for the dielectric constant of the medium (such as gasoline, paraffin), to use the waveguide. Liquefied gas dielectric constant is low, the reflection is weak, and the gas phase components absorb radar waves, also affects the measurement.

Can the radar level meter antenna be shortened? This question can not be generalised. Specific problems are analysed. Non-contact radar antenna length affects the pulse width, can not be arbitrarily shortened, or affect the use. The guided wave radar to shorten the antenna generally has no effect. When shortening the antenna, it is necessary to ensure that there is no obstacle in the transmitting angle, avoiding strong eddy current and material mouth, in order to prevent the false reflection echo from affecting the accuracy of measurement.