Noise Temperature Measurement System of Normal and High Temperature Load Method

Abstract

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.

Adaptation of an IRAM W-Band SIS Receiver to the INAF Sardinia Radio Telescope: A Feasibility Study and Preliminary Tests

“…As described in Section 2, a two-load calibration subsystem is included in the original version of the ex-PdBI receiver, which is useful for the calibration when it is installed on the telescope, allowing the measurement of the receiver noise. In our laboratory, we performed noise temperature measurements at several frequencies using the cold and ambient load (Y factor) method [49], without using the internal cryogenic calibration load. Some photos of the experiment are shown in Figure 13.…”

“…The room temper and cold loads were alternately placed in front of the HDPE vacuum window (and sequently, in front of the feed of the receiver, as shown in Figure 13c). A power meter was used as back end and the noise temperature was calculated the following formulas [49]:…”

“…This aspect cau degradation of the receiver noise performance. However, the noise temperature re achieved in the frequency bandwidth 84-95 GHz are considered in line with the i A power meter was used as back end and the noise temperature was calculated using the following formulas [49]:…”