介电常数对雷达液位计选型的影响
The influence of dielectric constant on the selection of radar level gauge
雷达波到达液位表面被反射时，雷达波会被吸收而发生衰减，当衰减过多时，雷达液位计接收不到足够的信号，导致测量不准确，这就是被测介质的介电常数对雷达液位计的测量所产生的影响。
When the radar wave arrives at the liquid level surface and is reflected, the radar wave will be absorbed and attenuated. When the attenuation is too much, the radar liquid level meter cannot receive enough signals, resulting in inaccurate measurement. This is the effect of the dielectric constant of the measured medium on the measurement of the radar liquid level meter.
各种油品介质的介电常数所示。为了克服介电常数的影响，提高反射波能量，对于使用内（外）浮顶罐的介质，对于汽油、煤油等相对介电常数较小的介质必须使用导波管。而对于液化气球罐的液位测量，一方面液化气的介电常数较低，对雷达波的反射能力很弱；另一方面液化气气相组分会吸收部分雷达波造成信号衰减严重，影响雷达液位计的准确测量。因此，通常选用另一种测量精度较高的接触式仪表——伺服液位计
The dielectric constants of various oil media are shown in. In order to overcome the influence of dielectric constant and improve the reflected wave energy, for the medium with internal (external) floating roof tank, for the medium with relatively small dielectric constant, such as gasoline, kerosene, etc., a waveguide must be used. For the liquid level measurement of liquefied gas spherical tank, on the one hand, the dielectric constant of liquefied gas is low and the reflection ability of radar wave is weak; on the other hand, the liquefied gas phase group absorbs part of radar wave and causes serious signal attenuation, which affects the accurate measurement of radar liquid level gauge. Therefore, another contact instrument with high measurement accuracy, servo level meter, is usually selected