Dielectric constant estimation device and microwave heating apparatus provided with dielectric constant estimation device

A microwave heating device comprising:

• a heating chamber for storing an object to be heated;
• a microwave oscillation part configured to generate a microwave for heating the object to be heated by dielectric heating;
• a microwave emission part configured to emit a microwave generated by the microwave oscillation part to the inside of the heating chamber through a microwave guide;
• a transmitting antenna configured to emit an electromagnetic wave at a predetermined antenna angle with respect to the object to be heated;
• a transmitting antenna control part configured to switch a polarized wave of the electromagnetic wave emitted from the transmitting antenna to a TE wave or a TM wave;
• a dielectric constant estimating oscillation part configured to output a high frequency signal which forms the electromagnetic wave emitted from the transmitting antenna;
• a receiving antenna configured to receive a reflected wave of the electromagnetic wave reflected from the object to be heated with a predetermined antenna angle;
• a receiving antenna control part configured to switch a polarized wave of the electromagnetic wave received by the receiving antenna to a TE wave or a TM wave;
• an arithmetic operation part configured to calculate a TM/TE reflection ratio based on respective reflected waves of the TE wave and the TM wave from the object to be heated received by the receiving antenna;
• a memory part configured to store in advance theoretical value data indicating a relationship between the antenna angle and the TM/TE reflection ratio relating to a plurality of substances which differ from each other in a dielectric constant as a database;
• and
• a control part configured to output a control signal for performing a switching control for switching to a TE wave or a TM wave in the transmitting antenna and the receiving antenna, an angle control of an antenna angle of the transmitting antenna and an antenna angle of the receiving antenna, and a frequency control of a microwave generated by the microwave oscillation part to the transmitting antenna control part, the receiving antenna control part, and the microwave oscillation part, wherein
• the control part is configured to estimate a dielectric constant of the object to be heated by comparing the TM/TE reflection ratio calculated by the arithmetic operation part with the data of the theoretical value in the database stored in the memory part, and
• the control part is configured to perform the frequency control of the microwave generated by the microwave oscillation part based on an estimated dielectric constant of the object to be heated.