Principles of Operation
This sensor was developed to use the principle of guided microwave measurement to measure interface. Microwave pulses are transmitted along the surface of a stainless steel cable, rod or coaxial system. The pulse travels in a field of 20" around this guide. When the pulse reaches the surface of the upper product, some energy is reflected back to the sensor. The remaining energy passes through the upper product and is reflected from the interface of the two products back up the cable or rod to the sensor. This is possible due to the differing dielectric constant of the second product. The two reflections are then able to be evaluated as level and interface.
The pulses are reflected off of the interface within the process. The amount of signal reflected from the surface of the product is based on the Dielectric Constant of the interface being measured.
The transit time of the pulse is measured and used to calculate the distance to the interface within the process. The signal is independent of density, and is insensitive to steam and condensation.