Apparatus for processing signal by means of electromagnetic waves and method for controlling the apparatus

A method of processing a signal using a plurality of channels, the method comprising:

• a first operation of, when a water tank is filled with a liquid and a radio frequency (RF) signal is radiated toward the liquid through any one of the plurality of channels, receiving radiated RF signals reflected or scattered by the liquid or an RF signal transmitted through the liquid through the plurality of channels other than the channel through which the RF signal has been radiated, and generating first data including phases and amplitudes of the received RF signals;
• a second operation of, when a medium is inserted into the water tank filled with the liquid and the RF signal is radiated toward the medium through any one of the plurality of channels, receiving radiated RF signals reflected or scattered by the medium or an RF signal penetrating the medium through the plurality of channels other than the channel through which the RF signal has been radiated, and generating second data including phases and amplitudes of the received RF signals;
• and
• a third operation of calculating permittivity and conductivity information of the medium based on a difference between the first data and the second data,
• wherein the RF signals reflected or scattered by the liquid or the medium or transmitted through the liquid are simultaneously received through all of the plurality of channels other than the channel through which the RF signal has been radiated.