Radiometer for non-invasive measurement of internal tissue temperature of biological objects. The radiometer comprises, connected in series, antenna, SPDT switch, circulator, receiver including amplifier with bandpass filters, amplitude detector, narrowband low-frequency amplifier and synchronous detector, integrator, direct current power amplifier, reference voltage generator connected to the SPDT switch and synchronous detector. A Peltier element is connected to the receiver output. First and second microwave loads are installed on the Peltier element and have thermal contact with it. There is at least one temperature sensor for measuring the temperature of microwave loads. The first microwave load is adapted for connection to the SPDT switch. The SPDT switch is adapted to connect either, to a first arm of the circulator, the antenna, or the first microwave load. A second arm of the circulator is connected to the receiver, and a third arm of the circulator is connected to the second microwave load.
