In this work I write about the developement of a radiofrequency levelling radar. After the examination of several theories applied at industrial levelling systems, a method of submillimeter accuracy was found. Measurements were taken with a rectangular waveguide placed into the fluid. The surface of the liquid reflects the incident waves. We measure the phase of the reflected waves in dependence of frequency.
The resolution of this methon depends upon the number of the points were measured in the selected bandwidth.
At the beginning I simulated this measurement on various type of coaxial cables, industrial waveguide and also on a self-made waveguide.
According to the simulations I made a block diagram for the future device. After I realised a test-device which is controlled by a microcontroller unit. It consists of a frequency synthesizer (ADF4350) with two channel output, one channel for reference signal, other is led to the probe. The reflected and the reference signal is mixed by the LT5575 unit which is a double channel mixer. The signal of it is converted to digital. Finally we can use the digital phase data for further calculations done by a program at computer.