Are there any detailed information about it? I roughly know what it is from the product datasheets but i'd like to know it in more depth especially the theory behind it and may be some practical knowledge. Thanks.
Ok i already made a small research but i did not get the idea clearly. They say that the system also measures the resistance. What resistance? I don't think we can measure the resistance directly (by applying a dc voltage) in most cases. Do they measure the capacitance and the impedance and ignore the inductance and then extract the resistance? And how it helps to know the resistance?
In most cases, an RF signal is sent dowm two conductors. The level being measured, usually water, forms a capacitor at the top level with respect to the two conductors. The two conductors also form an inductor. You then have an LC circuit in which the values of L & C vary according to the liquid level. Varying L & C values change the admittance seen by the RF generator.
Are you sure about the L-C? Because they don't mention about L but they do about R (resistance). And what's the mechanical structure? Are 2 condcutors is a must or can it be realized by one conductor like one probe capacitive sensors?