RF noisy environment measurement and throughput measurement by superconducting cryogenic receiver

We report on the improvement brought about by applying a cryogenic receiver to a mobile phone system. The cryogenic receiver consists of a high-Tc superconducting bandpass filter and a cryogenic low-noise amplifier operating at 77 K. Firstly, we measure the RF noisy environment in the horizontal direction in an urban area. The measured result indicated a lower noise characteristic in the cryogenic receiver than in the conventional receiver. As a result, the cryogenic receiver can be expected to improve the signal-to-noise ratio (SNR). Next, we evaluate the communication throughput by using a base station with the cryogenic receiver and demonstrate the superiority of the cryogenic receiver. Throughput improvement in the case of 77 K thermal noise input for the cryogenic receiver was measured to be 6.1 dB compared with the conventional receiver. This result almost agrees with the ideal improvement of SNR by temperature difference. The throughput improvement of the cryogenic receiver by actual radio wave was 1.5 dB to 3.5 dB compared with the conventional receiver at room temperature. This result almost agrees with the improvement of the measured difference of the external environment noise. The cryogenic receiver can be expected to realize high-speed communication.