Primary standard of the spectral power density unit of noise radio emission in the 220–300 GHz frequency range: experimental prototype

The manuscript discusses the challenges of metrological support for rapidly developing technologies, including electronics, radio vision, and security systems. To foster successful technological advancement, it is essential to expand the state standard base into a higher frequency range of 100–1000 GHz. This expansion is crucial for the verification and certification of devices and measuring instruments operating in the terahertz (millimeter) frequency range. Currently, the frequency range of the State Primary Standard for the unit of spectral power density of radio noise radiation, as defined in GET 21-2021, spans from 0.002 to 178.3 GHz. However, this frequency range is insufficient for the precise testing and certification of the high-precision devices and measuring instruments that are currently being developed. The manuscript presents the results of the development and study of the experimental sample of the primary standard of the unit of spectral power density of radio noise radiation in the frequency range of 220–300 GHz. The experimental sample includes a radiometer, a signal generator for the local oscillator channel, a low-temperature noise generator, a matched load, and a standard attenuator. The following characteristics of the experimental sample are achieved: the equivalent noise temperature of a low-temperature noise generator is from 103 K (220 Hz) to 120 K (300 GHz). The sensitivity of the comparator based on the radiometer is 0.86 K. The characteristics of the experimental sample are comparable with the characteristics of similar devices from the world's leading manufacturer, Radiometer Physics (Germany). The developed experimental sample can be used to calibrate low-noise receiving and amplifying devices of the terahertz range, which are finding increasing application in various fields of science and technology. An important area of application of the developed standard is also the verification of radiometers used in passive radar systems. Additionally, it is noteworthy that the developed radiometer (operating within 220–300 GHz) holds potential for scientific problems related to conducting radio astronomical terrestrial observations in the terahertz range, in particular in atmospheric transparency windows at wavelengths of 1.3 and 0.8 mm, where many spectral lines of atoms and molecules are concentrated.

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