Spatial Combining of Multiple Microwave Noise Radiators

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  • Author: Jiri Polivka
Noise generators are used to measure noise figure in receivers, to test system health in built-in test (BIT) circuits, in jamming, and in testing digital data transmission systems bit error rate (BER). Combining a noise generator with an antenna creates a noise radiator. Such a noise radiator generates a random (non-coherent) noise field in which near-field interference is not observed. A noise field can be utilized in various experiments: field distribution in waveguides, antennas and other structures, testing the properties of moving objects, etc. This paper discusses experiments to increase the noise temperature or power density by the spatial combination of noise sources. The experiments were done to evaluate this method as an alternative to using microwave amplifiers. The results confirm the independence of individual noise sources and the possibility of increasing the noise temperature as well, as possible focusing by adapting the form of the noise source matrix.