A measuring method for determining the noise temperature of a two-terminal network, independently of its impedance

摘要

The invention relates to a measuring method for determining the noise temperature of a two-terminal network, independently of its impedance, and a noise temperature measuring device for carrying out the method. The input ports of a compensating radiometer of conventional construction (for example thickness radiometer, correlation radiometer) are connected, according to Figure 1, to a circuit consisting of two couplers (K1, K2), two reference noise sources (R1, R2), an auxiliary noise source (R3) and the attenuating section (D) and the object being measured (MO). Further developments relate to the preamplifiers used in the radiometer in order to reduce the influence of their inherent noise on the measurement result. In contrast to methods previously known, it is possible, using this measuring system, to determine the noise temperature of mismatched two-terminal networks without a circulator or other passive non-reciprocal components being needed. The method is therefore particularly suitable for measurements in a frequency range below 1 GHz.