Noise Temperature Measurement System of Normal and High Temperature Load Method

Microwave receiver is a special equipment used to receive radio signals in radio telescope. The noise temperature of receiver is an important target to test sensitivity. The lower the noise temperature is, the higher the sensitivity is. Therefore, the measurement of noise temperature is very important. The classical cold and ambient load method can measure noise temperature well, but it can not be carried out during observation. In addition, the performance of microwave devices is not unchanged, and noise temperature will vary with the ambient temperature and test equipment, so real-time measurement of noise temperature is important. We set up a noise temperature measurement system based on normal and high temperature load method. Through this system, noise temperature can be calculated by measuring the radiation power and temperature of blackbody at normal temperature and after heating to 150°C. Compared with results of the cold and ambient load method, the maximum test error is 12.3% in five tests, and the other test errors are less than 10%. The results can confirm that the normal and high temperature load method could be hopeful to satisfy the normal test requirements of centimeter-band normal temperature receiver. (paper)