Patent ID: 7052176

Claim:
A system for remotely measuring the temperature of an object using microwave radiometry, comprising: antenna for receiving microwave power radiated from the object; switch means connected to the antenna and operable in a PASS mode and a BLOCK mode, means for switching the microwave switch means between the PASS mode and BLOCK mode at a specified system switch frequency; ambient temperature load that generates noise power reflective of the ambient temperature; means for amplifying the microwave power it receives; wherein, in the PASS mode, the microwave switch passes the object power to the amplification means for amplification and, in the BLOCK mode, the switch means blocks the object power to the amplification means and reflects the load noise power to the amplification means; injection means for injecting additional noise power into the amplifier means during the Block mode; detector means for detecting the output power of the amplification means; means for generating an output signal proportional to the difference between the noise powers detected and measured in the PASS mode and in the BLOCK mode; loop means for generating a feedback signal to the injection means, the feedback signal having a duty cycle proportional to the output signal to cause the injection means to inject sufficient noise power into the amplification means during the BLOCK mode to automatically maintain a balance between the noise power measured in the PASS MODE and the combination of noise powers measured in the BLOCK mode; and means for computing the temperature of the source from the output signal.