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Estimation of the Electromagnetic Background Created by Low-Earth Orbit Satellites, Based on the Prediction of the Ground Area Traffic Capacity
Vladimir Mordachev, Dzmitry Tsyanenka
Belarusian State University of Informatics and Radioelectronics, Belarus
A technique for analysing levels of the ground electromagnetic background (EMB), created by constellations of low-earth orbit communication satellites (LEOS), based on estimates of the average area traffic capacity generated by them at the earth's surface, and available system characteristics of LEOS and their constellations, such as orbit altitude, characteristics of antenna patterns, limitations on the angle of LEOS antenna main lobe direction to the earth’s surface, and features of servicing scenarios for ground subscriber terminals. Obtained estimates of the average EMB levels, corresponding to the expected values of the average area traffic capacity generated by LEOS constellations, are sufficiently higher than the levels of natural microwave EMB on the earth's surface, which agree with estimates obtained earlier using data on the LEOS total radiated power and their quantity in the constellation, and confirms the adequacy of the presented technique
Radiation-Tolerant RF Performance Enhancement of AlxGa1-xN Graded Composite Barrier GaN HEMTs for Radio Astronomy Applications
Ruihao Zhang, Fayu Wan
Nanjing University of Information Science and Technology, China, People's Republic of
This study investigates the design and radiation resistance of an AlxGa₁₋ₓN graded composite barrier GaN high-electron-mobility transistor (GB-HEMT) compared to a conventional fixed-barrier GaN HEMT (FB-HEMT). Using Silvaco TCAD simulations, the GB-HEMT demonstrates a wider 2DEG channel and flatter transconductance (gm) profile, resulting in a saturation drain current of 1.73 A/mm², significantly improved turn-off characteristics, and superior RF performance. Specifically, the GB-HEMT achieves a peak power-added efficiency (PAE) of 44.4%, a gain of 18.7 dB, and a power density of 3.8 W/mm under large-signal operation.
Furthermore, proton irradiation simulations (1.8 MeV protons) reveal that the GB-HEMT exhibits reduced DC parameter degradation compared to the FB-HEMT, highlighting its enhanced radiation tolerance. This improvement is attributed to the optimized electron transport properties and minimized interface trap formation in the graded structure. The results suggest that the GB-HEMT design effectively balances high RF performance with robustness against particle radiation, making it a promising candidate for millimeter-wave power amplifiers in extreme environments such as radio astronomy.
Interference Analysis of 5G NR on Radio Astronomy in the Upper 6 GHz Frequency Range: Mitigation Techniques and Strategies
Alexander Pastukh1, Evgeny Devyatkin1, Valery Tikhvinskiy2, Aliaksandr Svistunou3
1Institute of Radio and Information System (IRIS), Austria; 2International Information Technology University (IITU), Kazakhstan; 3Belarusian State University of Informatics and Radioelectronics, Belarus
This article addresses interference mitigation strategies for radio astronomy service (RAS) within the 6650-6675.2 MHz frequency band, focusing on the 5G NR network deployment and its potential impact on RAS operations. Guided by ITU-R recommendations and methodologies, the study explores both generic and site-specific interference cases. Using Monte-Carlo simulations and propagation models, including Recommendations ITU-R P.2001 and ITU-R P.2108, it estimates interference levels from 5G NR base stations, highlighting necessary separation distances across various deployment scenarios. The results indicate that urban IMT deployment requires a minimum separation of 55-60 km, while rural and suburban setups may necessitate 30-70 km based on terrain shielding and adjacent channel conditions. This study is useful for regulators and network planners that plane to implement 5G NR networks in the countries where the frequency band 6650-6675.2 MHz is in use by RAS, providing adaptable separation guidelines according to local environments and 5G NR deployment specifics.
Total levels of anthropogenic and natural microwave electromagnetic background in areas with intensive information servicing by constellations of low-orbit communication satellites
Vladimir Mordachev, Dzmitry Tsyanenka
Belarusian State University of Informatics and Radioelectronics, Belarus
A technique for analyzing the averaged intensity of the electromagnetic background (EMB) created at the earth's surface by subscriber terminals of communication systems using constellations of low-orbit satellites has been developed. Using previously obtained results of the analysis of EMB created by radiation from the space segment of these systems, estimates have been made of the total levels of the ground anthropogenic and natural EMB. The results indicate that the radiation from subscriber terminals of these systems makes the main contribution to the ground EMB intensity, exceeding by several orders of magnitude other EMB components formed by both natural sources of microwave radiation and radiation from multitude of low-orbit satellites, changing the physical characteristics of the habitat and ground electromagnetic environment
