Method for calibrating microwave radiometer

A microwave radiometer, comprising:

• a primary radiator configured to receive a radio wave emitted from an object to be measured depending on a temperature of the object to be measured;
• a receiver, which is connected to the primary radiator, and is configured to amplify a signal input from the primary radiator and to output the amplified signal;
• a power measurement unit configured to measure a power density of the output signal of the receiver;
• and
• a result output unit configured to output the power density measured by the power measurement unit as a brightness temperature of the object to be measured,
• wherein the microwave radiometer further comprises, at a preceding stage of an input side of the receiver, a plurality of calibration sources configured to function as references for calibrating a noise temperature of the receiver appearing on an output side of the receiver, and
• wherein the microwave radiometer includes, as the plurality of calibration sources, a calibration source having a known brightness temperature and a radio wave reflector configured to totally reflect noise radiated from the receiver to the input side of the receiver.