The Journal “Radio Physics and Radio Astronomy” (RPRA) is a peer-reviewed quarterly scientific journal of the National Academy of Sciences of Ukraine. RPRA was established in 1995. State Registration Certificate for printing mass media is КВ №1231, 02.02.1995; re-registration: КВ 25208-15148 ПР from 20.07.2022 ISSN 2415-7007 (Online) ISSN 1027-9636 (Print) Abbreviated key title: Radio phys. radio astron. DOI: https://doi.org/10.15407/rpra URL: http://rpra-journal.org.uа Language of publishing: Ukrainian, English Founders: The National Academy of Sciences of Ukraine Institute of Radio Astronomy of the National Academy of Sciences of Ukraine O. Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine Publisher: The NAS-Ukraine Academperiodyka Publishing House The NAS-Ukraine Academperiodyka Publishing House replicates the RPRA within the NAS-Ukraine Journal Support Program. RPRA publishes papers, brief information and letters to the editors relating to the modern problems of radio physics, radio astronomy and astrophysics, containing the results of fundamental and applied researches, description of research methods, hardware implementation and practical application, as well as current information such as comments, events, men of science. The RPRA is included into the List of scientific professional editions of Ukraine, approved by the Decree No. 582 of 24.04.2024 of the Ministry of Education and Science of Ukraine, in which the results of Ph.D. and Doctoral theses (in physics and mathematics) are recommended to be published. Current Issue Volume 30, No.4 (2025) CONTENT
Since April 2018, all papers in RPRA are published under the terms of the Creative Commons Attribution 4.0 International (CC-BY) License with the authors retaining a copyright to their papers. This license permits anyone to copy, distribute, spread, and adapt the paper content, without obtaining permission from the author(s) or the Journal, provided the proper acknowledgement of the work used authorship and initial publication in this journal. Please see the full license terms and requirements at https://creativecommons.org/licenses/by/4.0/ The authors of the papers published prior to December 2018, have granted the Journal the right of the first publication and retain the copyright as the owners of the manuscript.
IMPACT OF THE NOVEMBER 3, 2013 SOLAR ECLIPSE ON THE STATE OF THE IONOSPHERE AS INVESTIGATED IN A RADIO ASTRONOMICAL TECHNIQUE
Subject and Purpose. This work examines eff ects of the November 3, 2013 solar eclipse, in particular the atypical increases in the level of radio interference and scintillations of the radio sources 3C 123 and Cas-A that were observed at 25 MHz. These phenomena might owe to the enhanced wave activity in the ionosphere during the eclipse and a reduced radio wave absorption. Methods and Methodology. The observations were conducted with the use of the low-frequency radio telescope URAN-4 (operative range 10—30 MHz). The observational data concerning radiation from cosmic radio sources and the accompanying interference are presented, for further analysis, in the form of time series. Wavelet analysis has been applied to the data arrays to identify the dominant periods of radio source scintillation. Results. A significant increase in interference intensity was observed on the day of the eclipse climax, as well as the next day. The radio source Cas-A exhibited quasi-periodic variations of intensity on a timescale of 3 to 7 minutes. The scintillation analysis performed for the source 3C 123 before and aft er the eclipse failed to provide conclusive evidence of eclipse-related effects. Conclusions. Despite the fact that the solar eclipse of November 3, 2013, was not optically visible in Ukraine (because the nearest visibility zone for the partial eclipse lay farther toward the South of the Crimea and further on toward Turkey), an anomalous rise in the level of interference was still recorded over the time window of observations from October 31 to November 7, 2013. No similar enhancements were observed either before or after the eclipse. This is likely the result of a combined effect involving reduced absorption in the ionospheric D-layer, the noticeable shift in the F-layer’s location (which leads to appearance of distant reflections), and appearance of active agents like TIDs. All of these together brought forth a sharp increase in interference levels at 25 MHz. Despite the fact that the eclipse stayed optically invisible, its generated ionospheric disturbances proved capable of reaching the URAN-4 facility, manifesting themselves through a strong burst of interference during zenith-oriented reception. Keywords: radio scintillations, ionosphere, ionospheric storm, geomagnetic storm, solar eclipse manifestations in the ionosphere, decameter-wavelength radio astronomy Manuscript submitted 25.02.2025 Radio phys. radio astron. 2025, 30(4): 217-231 REFERENCES 1. Galanin, V.V., Komendant, V.H., Yasinski, V.V., 2021. Observation control device for the Uran-4 decameter radio telescope. Odessa Astronomical Publscations, 34, pp. 74—75. DOI: https://doi.org/10.18524/1810-4215.2021.34.244382 2. Chernogor, L.F., 2013. Physical effects of solar eclipses in atmosphere and geospace. Monograph. Kharkiv: V.N. Karazin Kharkiv National University Publ. 480 p. 3. Lion, E.F., Bridge, H.S., Binsack, J.H., 1967. Explorer-35 Plasma Measurements in Vicinity of the Moon. J. Geophys. Res., 72(23), pp. 6113—6117. DOI: https://doi.org/10.1029/JZ072i023p06113 4. Ness, N.F., 1970. Interaction of the Solar Wind with the Moon. Preprint NASA-GSFC, X-692 70-141, Maryland 5. Interaction of the Solar Wind with the Terrestrial Planets. Section: The Solar Wind in the Near-Earth Environment. Studies of the Solar Wind Flow around the Moon. 1988. Adv. Sci. Technol. Ser. Astronomy, 35. 6. Chernogor, L.F., Barabash, V.V., 2011. The response of the middle ionosphere to the solar eclipse of 4 January 2011 in Kharkiv: some results of vertical sounding. Kosm. nauka tehnol., 17(4), pp. 41—52. DOI: https://doi.org/10.15407/knit2011.04.041 7. Typinski, D., Greenman, W., 2015. Things That Go Hump in the Night — A Fun Experiment [pdf]. NASA RadioJove Project. Available from: https://radiojove.gsfc.nasa.gov/radio_telescope/observing/observing_galactic_bkg.pdf 8. Mertsch, P., Sarkar, S., 2013. Loops and spurs: the angular power spectrum of the Galactic synchrotron background. J. Cosmol. Astropart. Phys., 06, 041. DOI: https://doi.org/10.1088/1475-7516/2013/06/041 9. Rapoport, Yu.G., Cheremnykh, O.K., Koshovyy, V.V, Melnik, M.O., Ivantyshyn, O.L., Nogach, R.T., Selivanov, Yu.A., Grimalsky, V.V., Mezentsev, V.P., Karataeva, L.M., Ivchenko, V.M., Milinevsky, G.P., Fedun, V.N., Tkachenko, Ye.N., 2017, Ground-based acoustic parametric generator impact on the atmosphere and ionosphere in an active experiment. Ann. Geophys., 35(1), pp. 53—70. DOI: https://doi.org/10.5194/angeo-35-53-2017 10. Galanin, V.V., Inyutin, G.A., Kvasha, I.M., Panishko, S.K., Pisarenko, Ya.V., Rashkovskij, S.L., Ryabov, M.I., Serokurova, N.G., Tsesevich, V.P., Sharykin, N.K., 1989. URAN-4 radio telescope as an element of VLBI system. Kinematika i Fizika Nebesnykh Tel, 5, pp. 87—90. 11. Lytvynenko, O.A., Panishko, S.K., Derevyagin, V.G., 2023. The Long-Term Observations of the Power Cosmic Radio Sources on the Radio Telescope URAN-4 at the Decameter Wave Range. Odessa Astronomical Publications, 36, pp. 118—121. DOI: https://doi.org/10.18524/1810-4215.2023.36.290139 12. Sukharev, A., Orlyuk, M., Ryabov, M., Sobitniak, L., Bezrukovs, V., Panishko, S., Romenets, A., 2022. Results of comparison of fast variations of geomagnetic field and ionospheric scintillations of 3C 144 radio source in the area of Odessa geomagnetic anomaly. Astron. Astrophys. Trans., 33(1), pp. 67—88. DOI: https://doi.org/10.17184/eac.6481 13. Madden, H.H., 1978. Comments on the Savitzky-Golay convolution method for least-squares-fi t smoothing and differentiation of digital data. Anal. Chem., 50(9), pp. 1383—1386. DOI: https://doi.org/10.1021/ac50031a048 14. Breaz, N., 2004. The cross-validation method in the smoothing spline regression. Acta Universitatis Apulensis 7. Research Gate. Available from: https://www.researchgate.net/publication/237262065_THE_CROSS-VALIDATION_METHOD_IN_THE_SMOOTHING_SPLINE_REGRESSION 15. Garimella, R.V., 2017. A Simple Introduction to Moving Least Squares and Local Regression Estimation. Report number: LA-UR-17-24975. United States, DOI: https://doi.org/10.2172/1367799 16. Tipton, C., 2022. Basics of Fourier Analysis of Time Series Data. Johnson Matthey Technol. Rev., 66(2), pp. 169—176. DOI: https://doi.org/10.1595/205651322X16433652085975 17. Popinski, W., Kosek, W., 1995. The Fourier transform band pass filter and its application for polar motion analysis. Artif. Satell., Planet. Geod., 24 (30(1)), pp. 9—25. 18. Allen, J., 1977. Short term spectral analysis, synthesis, and modification by discrete Fourier transform. IEEE Trans. Acoust. Speech Signal Process., 25(3), pp. 235—238. DOI: https://doi.org/10.1109/TASSP.1977.1162950 19. Wang, Yun, He, Ping, 2023. Comparisons between fast algorithms for the continuous wavelet transform and applications in cosmology: the 1D case. RAS Tech. Instrum., 2(1), pp. 307—323. DOI: https://doi.org/10.1093/rasti/rzad020 20. Scholl, S., 2021. Fourier, Gabor, Morlet or Wigner: Comparison of Time-Frequency Transforms. DOI: 10.48550/arX-iv.2101.06707 21. NOAA Weekly Highlights and 27-Day Forecast. Available from: https://www.swpc.noaa.gov/products/weekly-highlights-and-27-day-forecast; Users Guide to The Preliminary Report and Forecast of Solar Geophysical Data. Available from: https://www.swpc.noaa.gov/sites/default/files/images/u2/Usr_guide.pdf 22. Esaenwi, S., Ofodum, C.N, Okere, B.I., Opara, F.E, Sigalo, F.B., Omaliko, K.C., Wali, C.B., Sigalo, M.B., Suraju, S., Eze, E.J., Okonkwo, H., Osuji, U., Omowa, E., Ogbonda, C., and Anuforom, A., 2016. The 3 November 2013 partial solar eclipse: the effect of Nigeria media popularization. Nig. J. Space Res., 14(1), 5 p. 23. Patel, D.B., Kotadia, K.M., Lele, P.D., Jani, K.G., 1986. Absorption of radio waves during a solar eclipse. Proc. Indian Acad. Sci. (Earth Planet. Sci.), 95(2), pp. 193—200. DOI: https://doi.org/10.1007/BF02871864 24. Bamford, R.A., 2001. The effect of the 1999 total solar eclipse on the ionosphere. Phys. Chem. Earth (C), 26(5), pp. 373—377. DOI: https://doi.org/10.1016/S1464-1917(01)00016-2 25. Knížova, K.P., Mošna, Z., 2011. Acoustic-Gravity Waves in the Ionosphere during Solar Eclipse Events. In: Beghi, M.G. ed., 2011. Acoustic Waves — From Microdevices to Helioseismology. ISBN: 978-953-307-572-3, InTech. Available from: http://www.intechopen.com/books/acoustic-waves-from-microdevices-to-helioseismology/acoustic-gravity-waves-in-the-ion-osphere-during-solar-eclipse-events 26. Kaladze, T.D., Pokhotelov, O.A., Shah, H.A., Khan, M.I., Stenflo, L., 2008. Acoustic-gravity waves in the Earth’s ionosphere. J. Atmos. Sol.-Terr. Phys., 70(13), pp. 1607—1616. DOI: https://doi.org/10.1016/j.jastp.2008.06.009 27. Nayak, Ch., Yiğit, E., 2018. GPS-TEC Observation of Gravity Waves Generated in the Ionosphere during 21 August 2017 Total Solar Eclipse. J. Geophys. Res. Space Phys., 123(1), pp. 725—738. DOI: https://doi.org/10.1002/2017JA024845 28. Sukharev, A.L., Ryabov, M.I., Galanin, V.V., Komendant, V.G., 2023. About research programs at the radio telescope "URAN-4" IRA NASU — monitoring of fluxes of powerful radio sources, study of the Sun’s supercorona, observations of solar eclipse. Odessa Astronomical Publications, 36, pp. 135. DOI: https://doi.org/10.18524/1810-4215.2023.36.290143 29. Chernogor, L.F., 2016. Propagating waves and processes associated with the March 20, 2015 solar eclipse in the ionosphere over Europe. Kinemat. Phys. Celest. Bodies, 32(4), pp. 60—72. DOI: https://doi.org/10.3103/S0884591316040024 30. Kaladze, T.D., Pokhotelov, O.A., Shah, H.A., Khan, M.I., Stenflo, L., 2008. Acoustic-gravity waves in the Earth’s ionosphere. J. Atmos. Terr. Phys., 70(13), pp. 1607—1616. DOI: https://doi.org/10.1016/j.jastp.2008.06.009 31. Crowley, G., Azeem, S.M.I., 2018. Extreme Ionospheric Storms and Their Effects on GPS Systems. In book: Buzulukova, N. ed., 2018. Extreme Events in Geospace. Elsevier, 2018, pp. 555—586. DOI: https://doi.org/10.1016/B978-0-12-812700-1.00023-6 32. Kozyreva, O., Kozlovsky, A., Pilipenko, V., Yagova, N., 2019. Ionospheric and geomagnetic Pc5 oscillations as observed by the ionosonde and magnetometer at Sodankylä. Adv. Space Res., 63(7), pp. 2052—2065. DOI: https://doi.org/10.1016/j.asr.2018.12.004 33. Eisenbeis, J., 2020. Ionospheric Dynamics by GNSS total electron content observations: the effect of Solar Eclipses and the mystery of Earthquake precursors. Doctoral thesis in Earth and Environmental Sciences. Université Paris Cité, 2020. English. NNT: 2020UNIP7027. Available from: https://theses.hal.science/tel-03181359v1/file/EISENBEIS_Julian_va2.pdf 34. Sun, Y.-Y., Shen, M.M., Tsai, Y.-L., Lin, C.-Y., Chou, M.-Y., Yu, T., Lin, K., Huang, Q., Wang, J., Qiu, L., Chen, C.-H, and Liu, J.-Y., 2021. Wave Steepening in Ionospheric Total Electron Density due to the 21 August 2017 Total Solar Eclipse. J. Geophys. Res. Space Phys., 126(3), e2020JA028931. DOI: https://doi.org/10.1029/2020JA028931
Copyright (c) 2025 RADIO PHYSICS AND RADIO ASTRONOMY
LARGE-SCALE DISTURBANCES IN THE TERRESTRIAL IONOSPHERE, WHICH ACCOMPANIED THE LAUNCHES AND FLIGHTS OF POWERFUL ROCKETS
Subject and Purpose. The ionosphere is the main channel for the propagation of radio waves. Its condition is determined bythe state of the atmospheric and space weathers, both of which depend on processes on the Sun, in the geospace, and in the Earth’s atmosphere. A serious impact on the state of the atmospheric and the space weather is produced by launches and flights of powerful rockets. The purpose of this paper is to present the results of observations and analyses of the disturbances in the ionosphere that accompanied launches and flights of heavy rockets from various cosmodromes around the world. Methods and Methodology. In order to monitor disturbances in the ionosphere, a vertical Doppler sounder was used. The radar is able to detect relative disturbances in the electron density about 10–3 to 10–2 per cent over oscillation periods of 102 to 103 s. The beat signal formed by the signal reflected from the ionosphere and the one from the local oscillator were subjected to spectral processing over time intervals of 1 min. Results. As follows from the observational data, the rocket launch from the Plesetsk cosmodrome (RF) was accompanied by an aperiodic disturbance of electron density, of duration about 20 minutes and speed of 1000 to 1140 m/s. The disturbance with a speed of 450 to 500 m/s was also aperiodic. A quasi-periodic disturbance with a period of 6 to 7 min and speed of 330 to 340 m/s was carried by a long-wave infrasound. The amplitude of the relative disturbance in electron density was δN≈ 1 percent. For atmospheric gravity waves with periods of 20 or 30 min the relative disturbance in electron density was δN≈ 6 to 14 per cent. At the start of the Proton M rocket, three groups of disturbances with speeds of 555, 240 and 170 m/s were observed. In their case, the estimate for δN is 1.5 to 3 per cent. During the rocket launch from the Wenchang (PRC) cosmodrome, three possible groups of disturbances were noted, with speeds of 560, 410 and 270 m/s. In the case of a quasiperiodic disturbance, an estimate for δN is 1.5 per cent. Th e disturbances recorded after the launch of the Falcon 9 rocket are, most likely, not related to the flight of the rocket. The aperiodic disturbances that followed the launch of the Ariane 5 rocket could be associated with the flight of the rocket. Conclusions. The disturbances that accompanied launches and flights of heavy rockets from several cosmodromes located at distances of 1500 to 2500 km from the observation site have been reliably identified. Keywords: rocket flight, large-scale disturbance, ionosphere, aperiodic and quasiperiodic disturbance, electron density Manuscript submitted 02.12.2021 Radio phys. radio astron. 2025, 30(4): 232–249 REFERENCES 1. Booker, H.G., 1961. A local reduction of F region ionization due to missile transit. J. Geophys. Res., 66(4), pp. 1073—1079. DOI: https://doi.org/10.1029/JZ066i004p01073 2. Jackson, J.E., Whale, H.A., and Bauer, S.J., 1962. Local ionospheric disturbance created by a burning rocket. J. Geophys. Res., 67(5), pp. 2059—2061. DOI: https://doi.org/10.1029/JZ067i005p02059 3. Mendillo, M., Hawkins, G.S., and Klobuchar, J.A., 1975. A Large-Scale Hole in the Ionosphere Caused by the Launch of Skylab. Science, 187(4174), pp. 343—346. DOI: https://doi.org/10.1126/science.187.4174.343 4. Mendillo, M., Hawkins, G.S., and Klobuchar, J.A., 1975. A sudden vanishing of the ionospheic F region due to the launch of Skylab. J. Geophys. Res., 80(16), pp. 2217—2228. DOI: https://doi.org/10.1029/JA080i016p02217 5. Mendillo, M., 1981. The effect of rocket launches on the ionosphere. Adv. Space Res., 1(2), pp. 275—290. DOI: https://doi.org/10.1016/0273-1177(81)90302-1 6. Zinn, J, Sutherland, C.D., Stone, S.N., Duncan, L.M., and Behnke, R., 1982. Ionospheric eff ects of rocket exhaust products: HEAO-C and Skylab. J. Atmos. Terr. Phys., 44(12), pp. 1143—1171. DOI: https://doi.org/10.1016/0021-9169(82)90025-3 7. Wand, R.H., and Mendillo, M., 1984. Incoherent scatter observations of an artificially modified ionosphere. J. Geophys. Res., 89(A1), pp. 203—215. DOI: https://doi.org/10.1029/JA089iA01p00203 8. Mendillo, M., Baumgardner, J., Allen, D.P., Foster, J., Holt, J., Ellis, G.R.A., Klekociuk, A., and Reber, G., 1987. Spacelab-2 plasma depletion experiments for ionospheric and radio astronomical studies. Science, 238(4831), pp. 1260—1264. DOI: https://doi.org/10.1126/science.238.4831.1260 9. Mendillo, M., 1988. Ionospheric holes: A review of theory and recent experiments. Adv. Space Res., 8(1), pp. 51—62. DOI: https://doi.org/10.1016/0273-1177(88)90342-0 10. Bernhardt, P.A., Kashiwa, B.A., Tepley, C.A., and Noble, S.T., 1988. Spacelab 2 Upper Atmospheric Modification Experiment Over Arecibo. I — Neutral Gas Dynamics. Astrophys. Lett. Comm., 27(3), pp. 169—181. 11. Bernhardt, P., Swartz, W., Kelly, M., Sulzer, M., and Noble, S.T., 1988. Spacelab 2 Upper Atmospheric Modification Experiment over Arecibo. II — Plasma dynamics. Astrophys. Lett. Comm., 27(3), pp. 183—198. 12. Bernhardt, P.A., Ballenthin, J.O., Baumgardner, J.L., Bhatt, A., Boyd, I.D., Burt, J.M., Caton, R.G., Coster, A., Erickson, P.J., Huba, J.D., Earle, G.D., Kaplan, C.R., Foster, J.C., Groves, K.M., Haaser, R.A., Heelis, R.A., Hunton, D.E., Hysell, D.L., Klenzing, J.H., Larsen, M.F., Lind, F.D., Pedersen, T.R., Pfaff, R.F., Stoneback, R.A., Roddy, P.A., Rodriquez, S.P., San Antonio, G.S., Schuck, P.W., Siefring, C.L., Selcher, C.A., Smith, S.M., Talaat, E.R., Thomason, J.F., Tsunoda, R.T., and Varney, R.H., 2012. Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere. IEEE Trans. Plasma Sci., 40(5), pp. 1267—1286. DOI: https://doi.org/10.1109/TPS.2012.2185814 13. Gritchin, A.I., Dorohov, V.L., Kapanin, I.I., Karpachov, A.I., Kostrov, L.S., Leus, S.G., Martynenko, S.I., Mashtaler, N.N., Milovanov, Yu.B., Misyura, V.A., Pakhomova, O.V., Podnos, V.A., Pokhilko, S.N., Protopop, E.N., Rozumenko, V.T., Somov, V.G., Tyrnov, O.F., Fedorenko, V.N., Fedorenko, Yu.P., Tsymbal, A.M., Chernogor, L.F., Chulakov, S.G., Shemet, A.S., 1995. Complex radiophysical investigations of ionospheric disturbances caused by launches and flights of spacecraft. Space Plasma Physics, pp. 161—170. Kyiv: SSAU Publ. 14. Chernogor, L.F., Garmash, K.P., Kostrov, L.S., Rozumenko, V.T., Tyrnov, O.F., and Tsymbal, A.M., 1998. Perturbations in the ionosphere following U.S. powerful space vehicle launching. Radio Phys. Radio Astron., 3(2), pp. 181—190. 15. Kostrov, L.S., Rozumenko, V.T., and Chernogor, L.F., 1999. Doppler Radar Measurements of the Disturbances in the Bottomside Ionosphere, Associated with Space Vehicle Launches and Maneuvering System Burns. Radio Phys. Radio Astron., 4(3), pp. 227—246. 16. Kostrov, L.S., Rozumenko, V.T., Chernogor, L.F., 2003. HF doppler observations of disturbances in geospace, which accompanied space vehicle launches. Kosm. nauka tehnol., 9(Supplement2), pp. 76—81. DOI: https://doi.org/10.15407/knit2003.02s.076 17. Kostrov, L.S., Rozumenko, V.T., Chernogor, L.F., 2002. Doppler radio sounding of disturbances in the E and F regions of the ionosphere during launches and flights of spacecraft. Kosm. nauka tehnol., 8(Supplement2), pp. 132—143. DOI: https://doi.org/10.15407/knit2002.02s.132 18. Burmaka, V.P., Kostrov, L.S., and Chernogor, L.F., 2004. Statistics of Signals of the HF Doppler Radar Sensing the Bottomside Ionosphere Disturbed by Rocket Launches and Solar Terminator. Telecommunications and Radio Engeneering, 61(2—6), pp. 150—177. DOI: https://doi.org/10.1615/TelecomRadEng.v61.i2.70 19. Burmaka, V.P., Taran, V.I., and Chernogor, L.F., 2003. Results of combined radio physical observations of wave disturbances in geospace which accompanied space vehicle launches and flights. Kosm. nauka tehnol., 9(Supplement2), pp. 57—61. DOI: https://doi.org/10.15407/knit2003.02s.057 20. Burmaka, V.P., Taran, V.I., and Chernogor, L.F., 2004. Clustered-Instrument Studies of Ionospheric Wave Disturbances Accompanying Rocket Launches against the Background of Nonstationary Natural Processes. Radio Phys. Radio Astron., 9(1), pp. 5—28. 21. Burmaka, V.P., Taran, V.I., and Chernogor, L.F., 2004. Radar observations of wave-like disturbances in ionosphere, associated with space vehicle flights. Space Sci. Technol., 10(5—6), pp. 113—117. DOI: https://doi.org/10.15407/knit2004.05.113 22. Burmaka, V.P., Chernogor, L.F., and Tcherniak, Y.V., 2005. Geospace Wave Disturbances Accompanying "Soyuz" and "Proton" Launches and Flights. Radio Phys. Radio Astron., 10(3), pp. 254—272. 23. Burmaka, V.P., and Chernogor, L.F., 2009. Complex Diagnostics of Ionospheric Plasma Disturbed by Far Rocket Launches. Radio Phys. Radio Astron., 14(1), pp. 26—44. 24. Garmash, K.P., Leus, S.G., Chernogor, L.F., and Shamota, M.A., 2009. Geomagnetic pulsations associated with rocket launches from different cosmodromes of the world. Space Sci. Technol., 15(1), pp. 31—43. DOI: https://doi.org/10.15407/knit2009.01.031 25. Zhivolup, T.G., and Chernogor, L.F., 2010. Ionospheric eff ects during rocket "Proton" flight: results of vertical sounding. Space Sci. Technol., 16(3), pp. 15—21. DOI: https://doi.org/10.15407/knit2010.03.015 26. Zhivolup, T.G., and Chernogor, L.F., 2010. Ionospheric Effects During Flights of the Rocket "Soyuz" Under Magnetically Quiet and Magnetically Disturbed Conditions. Space Sci. Technol., 16(3), pp. 22—31. DOI: https://doi.org/10.15407/knit2010.03.022 27. Zhivolup, T.G., and Chernogor, L.F., 2011. Comparative analysis of the disturbances in the ionosphere, caused by rocket launches "Proton" and "Soyuz". The Bulletin of NTU "KhPI". Radio Physics and Ionosphere, 44, pp. 18—26. 28. Chernogor, L.F., and Zhivolup, T.G., 2011. Comparative analysis of ionospheric effects as observed during "Proton" rocket flights under diff erent space weather conditions. Radio Phys. Radio Astron., 3(2), pp. 139—148. DOI: https://doi.org/10.1615/RadioPhysicsRadioAstronomy.v3.i2.60 29. Kakinami, Y., Yamamoto, M., Chen, C.-H., Watanabe, S., Lin, C., Liu, J.-Y., and Habu, H, 2013. Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012. J. Geophys. Res. Space Phys., 118(8), pp. 5184—5189. DOI: https://doi.org/10.1002/jgra.50508 30. Lin, C.H., Lin, J.T., Chen, C.H., Liu, J.Y., Sun, Y.Y., Kakinami, Y., Matsumura, M., Chen, W.H., Liu, H., and Rau, R.J., 2014. Ionospheric shock waves triggered by rockets. Ann. Geophys., 32(9), pp. 1145—1152. DOI: https://doi.org/10.5194/angeo-32-1145-2014 31. Ding, F., Wan, W., Mao, T., Wang, M., Ning, B., Zhao, B., and Xiong, B., 2014. Ionospheric response to the shock and acoustic waves excited by the launch of the Shenzhou 10 spacecraft. Geophys. Res. Lett., 41(10), pp. 3351—3358. DOI: https://doi.org/10.1002/2014GL060107 32. Nakashima, Y., and Heki, K., 2014. Ionospheric hole made by the 2012 North Korean rocket observed with a dense GNSS array in Japan. Radio Sci., 49(7), pp. 497—505. DOI: https://doi.org/10.1002/2014RS005413 33. Chernogor, L.F., 2009. Radiophysical and Geomagnetic Effects of Rocket Engine Burn. Monograph. Kharkiv: V.N. Karazin Kharkiv National University Publ. 34. Chernogor, L.F., and Blaunstein, N., 2013. Radiophysical and Geomagnetic Eff ects of Rocket Burn and Launch in the Nearthe-Earth Environment. Boca Raton, London, N. Y.: CRC Press. Taylor & Francis Group. 35. Lin, C.C.H., Shen, M.-H., Chou, M.-Y., Chen, C.-H., Yue, J., Chen, P.-C., and Matsumura, M., 2017. Concentric traveling ionospheric disturbances triggered by the launch of a SpaceX Falcon 9 rocket. Geophys. Res. Lett., 44(15), pp. 7578—7586. DOI: https://doi.org/10.1002/2017GL074192 36. Chou, M.-Y., Shen, M.-H., Lin, C.C.H., Yue, J., Chen, C.-H., Liu, J.-Y., and Lin, J.-T, 2018. Gigantic Circular Shock Acoustic Waves in the Ionosphere Triggered by the Launch of FORMOSAT-5 Satellite. Space Weather, 16(2), pp. 172—184. DOI: https://doi.org/10.1002/2017SW001738 37. Chou, M.-Y., Lin, C.C.H., Shen, M.-H., Yue, J., Huba, J.D., and Chen, C.-H., 2018. Ionospheric Disturbances Triggered by SpaceX Falcon Heavy. Geophys. Res. Lett., 45(13), pp. 6334—6342. DOI: https://doi.org/10.1029/2018GL078088 38. Li, G., Ning, B., Abdu, M.A., Wang, C., Otsuka, Y., Wan, W., Lei, J., Nishioka, M., Tsugawa, T., Hu, L., Yang, G., and Yan, C., 2018. Daytime F-region irregularity triggered by rocket-induced ionospheric hole over low latitude. Prog. Earth Planet. Sci., 5(1), 11. DOI: https://doi.org/10.1186/s40645-018-0172-y 39. Ssessanga, N., Kim, Y.H., Choi, B., and Chung, J.-K., 2018. The 4D‐var estimation of North Korean rocket exhaust emissions into the ionosphere. J. Geophys. Res. Space Phys., 123(3), pp. 2315—2326. DOI: https://doi.org/10.1002/2017JA024596 40. Zhu, J., Fang, H., Xia, F., Wan, T., and Tan, X., 2019. Numerical Simulation of Ionospheric Disturbance Generated by Ballistic Missile. Adv. Math. Phys., 2019, 7935067. DOI: https://doi.org/10.1155/2019/7935067 41. Savastano, G., Komjathy, A., Shume, E., Vergados, P., Ravanelli, M., Verkhoglyadova, O., Meng, X., and Crespi, M., 2019. Advantages of geostationary satellites for ionospheric anomaly studies: Ionospheric plasma depletion following a rocket launch. Remote Sens., 11(14), 1734. DOI: https://doi.org/10.3390/rs11141734 42. Bowden, G.W., Lorrain, P., and Brown, M., 2020. Numerical Simulation of Ionospheric Depletions Resulting From Rocket Launches Using a General Circulation Model. J. Geophys. Res. Space Phys., 125(6), e2020JA027836. DOI: https://doi.org/10.1029/2020JA027836 43. Saha, K., De, B. K., Paul, B., and Guha, A., 2020. Satellite launch vehicle effect on the Earth’s lower ionosphere: A case study. Adv. Space Res., 65(11), pp. 2507—2514. DOI: https://doi.org/10.1016/j.asr.2020.02.026 44. Zhu, J., and Fang, H., 2020. Research on the disturbance of ballistic missile to ionosphere by using 3D ray tracing method. Adv. Space Res., 65(3), pp. 933—942. DOI: https://doi.org/10.1016/j.asr.2019.10.028 45. Ma, X., Fang, H., Wang, S., and Chang, S., 2021. Impact of the ionosphere disturbed by rocket plume on OTHR radio wave propagation. Radio Sci., 56(4), e2020RS007183. DOI: https://doi.org/10.1029/2020RS007183 46. Chernogor, L.F., Garmash, K.P., Podnos, V.A., and Tyrnov, O.F., 2013. Th e V.N. Karazin Kharkiv National University Radio Physical Observatory — the tool for ionosphere monitoring in space experiments. Space Project "Ionosat-Micro". Kyiv, Ukraine: Academperiodika Publ., pp. 160—182.
OFF-AXIS TARGET ILLUMINATION IN RADAR OVER-SEA TRACKING USING AN ACTIVE PHASED ARRAY ANTENNA
Subject and Purpose. Th is paper addresses the challenge of measuring the angular coordinates of over-sea low-altitude targets and strives to improve the measurement accuracy of radar systems that employ high-resolution algorithms implemented through active phased array antennas (APAAs). The primary purpose is to substantiate the eff ectiveness of off-axis target illumination in the context of sea clutter and multipath. Off-axis target illumination reduces the depth of the probing signal interference fading over the radar-to-target path. The investigated illumination method focuses on mitigating errors in target angle measurements by multi-channel methods based on high-resolution algorithms, such as root-MUSIC. One of the main spoilers of measurement accuracy when using those algorithms is the noise in the radar receiving channels. Off-axis target illumination helps avoid a deep fade of the signal, thereby enhancing the signal-to-noise ratio (SNR) in the receiving channels of APAA-equipped radar systems, which contributes to target tracking stability despite destructive multipath interference. Methods and Methodology. The study employs computer simulations within a multipath radio-wave propagation model for a rough sea surface, allowing for both specular and diffuse reflections. The power distribution of diffuse reflections and their mapping along the propagation path are evaluated using the empirical glistening-surface model, the most advanced to date. Results. Quantitative assessments of the effectiveness of off-axis target illumination have been obtained in the context of fading conditions produced by multipath radio wave propagation over the sea surface. The optimal illumination angles have been identified. They help avoid deep fades over a wide range of sea states. These optimal angles are confined within 0.6 to 0.75 of the beamwidth of the radiation pattern. The lower end of the indicated range refers to the diffuse sea clutter, and the upper end corresponds to the specular reflection of the probing signal. In the most adverse cases, a gain in the SNR reaches 6—8 dB. Conclusions. It has been confirmed that off-axis illumination allows decreasing the depth of the illumination signal fades, which ensures more stable target tracking by angular coordinates. Recommendations for selecting off-axis illumination angles have been formulated. Key words: illumination level, off-axis illumination, active phased array antenna (APAA), low-altitude target, rough sea surface, multipath propagation, elevation angle, antenna pattern, computer modeling Manuscript submitted 15.06.2025 Radio phys. radio astron. 2025, 30(4): 250-257 REFERENCES 1. Rao, B.D., Hari, K.V.S., 1989. Performance analysis of Root-MUSIC. IEEE Trans. Acoust. Speech Signal Process., 37(12), pp. 1939—1949. DOI: https://doi.org/10.1109/29.45540 2. Sarkar, T.K., Pereira, O., 1995. Using the matrix pencil method to estimate the parameters of a sum of complex exponentials. IEEE Antennas Propag. Mag., 37(1), pp. 48—550. DOI: https://doi.org/10.1109/74.370583 3. Logvinov, Yu.F., Pedenko, Yu.O., Reznichenko, M.G., 2024. On the achievable upper limit of the elevation angles of effective direction finding of targets over the sea by the root-MUSIC method provided with adequate a priori parameters. Radio Phys. Radio Astron., 29(4), pp. 281—292 (in Ukrainian). DOI: https://doi.org/10.15407/rpra29.04.281 4. Yang, Yong, Yang, Boyu, 2024. Overview of radar detection methods for low altitude targets in marine environments. J. Syst. Eng. Electron., 35(1), pp. 1—13. DOI: https://doi.org/10.23919/JSEE.2024.000026 5. Yunhe, Cao, Shenghua, Wang, Yu, Wang, Shenghua, Zhou, 2015. Target detection for low angle radar based on multi-frequency order-statistics. J. Syst. Eng. Electron., 26(2), pp. 267—273. DOI: https://doi.org/10.1109/JSEE.2015.00032 6. Yang, Yong, Wang, Xue-Song, 2023. Enhanced Radar Detection in the Presence of Specular Reflection Using a Single Transmitting Antenna and Three Receiving Antennas. Remote Sens., 15(12), pp. 3204—3214. DOI: https://doi.org/10.3390/rs15123204 7. Quoc, An Nguyen, 2017. On a solution to improve the object detection ability of radars by dynamic polarization method. ASEAN Journal on Science and Technology for Development (AJSTD), 23(1), 4. DOI: https://doi.org/10.29037/ajstd.97 8. Dax, P.R., 1976. Keep Track of that Low-Flying Attack. Microwaves, 15(4), pp. 36—38, 40, 41. 9. Barton, D.K., 1974. Low-Angle Tracking. Proc. IEEE, 62(1), pp. 687—704. DOI: https://doi.org/10.1109/PROC.1974.9509 10. Barton, D.K., Ward H.R., 1984. Handbook of Radar Measurement. Artech House Publishers. 11. Razskazovskiy, V.B., Pedenko, Yu.A., 2003. A model for millimeter- and centimeter-waves field over a sea surface designs for investigation the methods for low-flying targets elevation angle measurement. In: V.M. Yakovenko, ed. 2003. Radiofizika i elektronika. Kharkov: IRE NAS of Ukraine Publ. 8(1), pp. 22—33. 12. Becкman, P., and Spizzichino, A., 1963. The scattering of electromagnetic waves from rough surfaces. London: Pergamon Press.
A NEW METHOD FOR SIDELOBE SUPPRESSION IN THE AMBIGUITY FUNCTION OF SIGNALS MODULATED BY PSEUDO-RANDOM SEQUENCES
Subject and Purpose. One of the main challenges in achieving high-accuracy radar target parameter determination and improving radar system noise immunity is the presence of sidelobes in the ambiguity function of the used signals, especially when these signals are periodic Pseudo-Random m-Sequences (PRS) of maximum length. In this work, a new method for completely suppressing ambiguity function sidelobes is developed through theoretical analysis with cross-correlation processing of PRS-modulated signals and a specially tailored reference signal. Methods and Methodology. The suggested approach to suppressing sidelobes of the PRS ambiguity function addresses cross-correlation processing of the received signals. These are PRS modulated using a reference signal tailored so that zero values of the sidelobes of the correlation function fall beyond the zone of high correlation in the signals. Results. The proposed method can completely suppress all ambiguity function sidelobes along the time delay axis for the PRS of maximum length. Compared to traditional processing, the sidelobe level along the Doppler shift axis of the carrier is slightly higher. However, this is so when the number of PRS elementary pulses is too small. As their quantity increases, the difference tends to be negligible. The signal-to-noise ratio at the correlator output and the range resolution performance have been estimated for both the proposed and traditional processing methods Conclusions. A new algorithm for PRS cross-correlation processing has been developed, accompanied by a straightforward method for tailoring a reference signal. The innovation enables sidelobe elimination regardless of the PRS length, while maintaining both range resolution and signal energy efficiency. It has been demonstrated that the signal-to-noise ratio at the correlator output remains unchanged compared to traditional processing. These points highlight a significant advantage over traditional methods. These methods often need to extend the sequence and/or use weight processing, which can reduce the radar energy efficiency. Keywords: pseudo-random sequences, sidelobes, radar ambiguity function, autocorrelation function, cross-correlation function Manuscript submitted 12.01.2025 Radio phys. radio astron. 2025, 30(4): 258-267 REFERENCES 1. Richards, M.A., 2022. Fundamentals of Radar Signal Processing. 3rd ed. Publishing house: McGraw-Hill, New York, USA. ISBN-13: 9781260468717. 2. Skolnik, M.I., 2008. Introduction to Radar Systems. 3th ed. Publishing house: McGraw-Hill, New York, USA. ISBN-13: 978-0070445338. 3. Proakis, J.G., Manolakis, D.K., 2014. Digital Signal Processing: Principles, Algorithms, and Applications. Publishing house: Pearson Education Limited. Edinburgh, England. ISBN-13: 978-1292025735. 4. Oppenheim, A.V., Schafer, R.W., 2009. Discrete-Time Signal Processing. 3rd ed. Publishing house: Prentice Hall. ISBN-13:978-0131988422. 5. Lukin, K.A., 1997. Noise Radar Technology for Civil Applications. In: Proc. 1st EMSL User Workshop. JRC-Ispra, Italy, 23–24 April 1996. Ed. by G. Nesti, Organised by Space Application Institute, Advanced Techniques Unit, ECSC-EC-EAEC Brussels, Luxembourg, pp. 105—112. 6. Lukin, K.A., 1998. Advanced Noise Radar Technology. In: Proc. of PIERS Workshop on Advances in Radar Methods. Hotel Dino, Baveno, Italy, 20—22 April 1998. Ed. Ann Franchois, Organized by EC, JRC, Space Application Institute, Brussels, Luxembourg, pp.137—140. 7. Lukin, K.A., 2001. Noise Radar Technology. Telecommunications and Radio Engineering, 55(12), pp. 8—16. DOI: https://doi.org/10.1615/TelecomRadEng.v55.i12.20 8. Zhao, Y., Hu, J., Xu, S., Feng, L., 2022. CNN-based radar communication integrated signal sidelobe suppression method. In: Proc. of SPIE Int. Conf. on Signal Processing and Communication Technology, 12178, 121780D, DOI: https://doi.org/10.1117/12.2631826 9. Da, Li, Bo, Tang, Lei, Xue, 2023. Multi-Spectrally Constrained Low-PAPR Waveform Optimization for MIMO Radar Space-Time Adaptive Processing. IEEE Trans. Aerosp. Electron. Syst., 59(5), pp. 719—731. DOI: https://doi.org/10.1109/TAES.2023.3247976 10. Zhong-Jie, Wu, Chen-Xu, Wang, Pei-He, Jiang, Zhi-Quan, Zhou, 2020. Range-Doppler Sidelobe Suppression for Pulsed Radar Based on Golay Complementary Codes. arXiv: 11726. DOI: 10.48550/arXiv.2003.11726 11. Haykin, S., 2000. Communication Systems. 4th ed. John Wiley & Sons, USA. ISBN-13: 9780471178699. 12. Simon, M.K., Omura, J.K., Scholtz, R.A., & Levitt, B.K., 1994. Spread Spectrum Communications Handbook. Revised Edition, McGraw-Hill, New York, USA. ISBN-13: 978-0070576292.
PASSIVE RADAR LOCATION OF A SURFACE TARGET CARRYING A ROTATING RADIATION ANTENNA
Subject and Purpose. The authors recently proposed a passive radar method for determining ranges and coordinates of surface targets using a single reference receiving point. The work is directed at further developing this method with a focus on scenarios where the surface target incorporates a radar with a rotating radiation antenna, such as a pulse omnidirectional radar. Methods and Methodology. The previously proposed passive radar method for determining the distance to a target is extended to the case where a surface object can have a rotating radiation antenna. Still, the method is based on using a radio buoy, which creates a supplementary radio wave propagation path. The receiving device is installed on the shore and detects two signals. One is the radio buoy signal travelling the supplementary propagation path. The other is the target direct signal travelling the primary path. The time delay between the two signal arrivals is measured, and the distance to the target is calculated using a specially developed algorithm. The system operation is analyzed and evaluated. Results. The previously proposed passive radar method for determining the target distance employs a radio buoy equipped with a transmitter and an amplifier-repeater. The method has been refined enough to range targets carrying rotating radiation antennas. As before, an additional radio wave propagation path from the target to the amplifier-repeater arises and is caught by the ground-based receiver on the shore. The task of determining the time delay between the radio beacon signal and the main signal from the target faces challenges associated with the movement of the target’s rotating antenna. The challenges can be effectively managed through a technique that is presented in the paper and expertly addresses the time delay between signals traveling along the primary and supplementary paths, as detailed in the paper. For practical implementation, the proposed principle of passive radar operation is supported by a surface target ranging algorithm. Conclusions. A method has been proposed for constructing a passive radar system that can measure the distance to a target carrying a rotating radiation antenna. Among other innovations, it was suggested to equip the radio buoy with an amplifier-repeater. To implement the method developed, a functional diagram of a rangefinder for surface objects was introduced. Keywords: passive radar, rotating radiation antenna, radio buoy, amplifier-repeater Manuscript submitted 02.06.2025 Radio phys. radio astron. 2025, 30(4): 268-275 REFERENCES 1. Skolnik, M.I. ed., 1990. Radar handbook. 2nd ed. Publisher. McGraw-Hill Professional. ISBN 0-07-057913-X 2. Howland, P.E., 1994. A Passive Metric Radar Using the Transmitters of Opportunity. In: 1994 Int. Conf. on Radar: proc. Paris, France, May 1994, pp. 251—256. 3. Nordwall, B.D., 1998. Silent Sentry A New Type of Radar. Aviat. Week Space Technol., 30, pp. 70—71. 4. Meyer, M.G., and Sahr, J.D., 2003. Passive coherent scatter radar interferometer implementation, observations, and analysis. Radio Sci., 39(3). DOI: https://doi.org/10.1029/2003RS002985 5. Willis, N., 2004. Bistatic Radar. 2nd ed. SciTech Publishing, Institution of Engineering and Technology. 329 p. ISBN 1-891121-45-6 6. Willis, N.J., Griffiths, H.D., and Davis, M.E., 2007. Advances in Bistatic Radar. Institution of Engineering and Technology. 494 p. ISBN 978-1-891121-48-7. 7. Besedin, O.M., Zelenskiy, O.O., Kulemin, G.P., Lukin, V.V., 2005. Processing of random signals and processes. National aerospace university "KhAI", Kharkiv, 2005. 469 p. 8. Mytsenko, I.M., Roenko, O.M., 2023. Environmentally safe over-the-horizon radar of the meter range for the protection of territorial waters. Radio Phys. Radio Astron., 28(4), pp. 287—295. DOI: https://doi.org/10.15407/rpra28.04.287 9. Mytsenko I.M., Roenko O.M.,2025. Determining the distance to the target during passive radar detection of surface objects. Radio Phys. Radio Astron., 30(2), pp. 101—108. DOI: https://doi.org/10.15407/rpra30.02.101 10. Van Trees, H.L., 2001. Detection, Estimation, and Modulation Theory. Part I: Detection, Estimation, and Linear Modulation Theory. Copyright 2001 John Wiley & Sons, Inc., ISBNs: 0-471-09517-6 (Paperback); 0-471-22108-2 (Electronic). 11. Spectrum and Signal Analyzers /Selection Guide. Keysight Technologies, 2014. Publishedin USA, September 30, 2014, 5968-3413RURU. Available from: https://www.testunlimited.com/pdf/an/keysight_N9010A_selection%20guide.pdf 12. Curry, G.R., 2005. Radar System Performance Modeling, ISBN 978-1-58053-816-9, S.168.
A FIBER-OPTIC HYDROACOUSTIC PRESSURE SENSOR BASED ON INTERMODE INTERFERENCE
Subject and Purpose. The use of the two-mode operation of an optical fi ber in fiber-optic sensors simplifies the interferometerdesign and enhances the reliability of sensing. Methods and Methodology. The mechanism behind the appearance of intermode phase shifts of the light modes Lp01 and Lp11 under various types of optical fiber deformation is examined. A mathematical model of a hydroacoustic sensor based on a two-mode optical fiber is proposed and experimentally validated. The intermode phase-acoustic sensitivity of the optical fiber to hydroacoustic pressure is evaluated for the Lp01 and Lp11 modes. A segment of a multimode optical fiber is fusion-spliced to the output of the two-mode fiber. This method creates conditions for the interference of the Lp01 and Lp11 modes and increases the modulation depth of the light flux at its output. Results. The heart of a hydroacoustic pressure-sensitive element in this research is an optical fiber with a core diameter of 18 μm and a numerical aperture of 0.0592. With the use of a 0.86 μm laser, propagation conditions are created for the two modes, Lp01 and Lp11 . The alteration of the mode content when a mode mixer is installed at the input of the optical fiber has been studied. For the fiber-optic sensor with a signal-to-noise ratio of 1:1 at the photodetector output and a frequency bandwidth of 100 Hz, the minimum detectable acoustic pressure inside the sensitive element is 55 Pa, and the intermode phase-acoustic sensitivity is 5.2*10-9 Pa. Conclusions. It has been shown that the two-mode operation of the optical fiber enables the development of interferometric fiber-optic sensors that are sensitive to mechanical deformations of the fiber. These sensors are characterized by a simpler design compared to traditional fiber-optic sensors based on Mach–Zehnder interferometers. It has been demonstratez that using a single-mode optical fiber with a reduced optical radiation wavelength ensures propagation conditions for the two lowest-order modes of the fiber. Keywords: optical fiber, fiber-optic sensor, intermode interference, phase-acoustic sensitivity, pressure Manuscript submitted 25.07.2025 Radio phys. radio astron. 2025, 30(4): 276-284 REFERENCES 1. Culshaw, B., Kersey, A., 2008. Fiber-optic sensing: A historical perspective. J. Lightwave Technol., 26(9), pp. 1064—1078. DOI: https://doi.org/10.1109/JLT.0082.921915 2. Miliou, A., 2021. In-fiber interferometric-based sensors: overview and recent advances. Photonics, 8(7), 265. DOI: https://doi.org/10.3390/photonics8070265 3. Li, X., Chen, N., Zhou, X., Gong, P., Wang, S., Zhang, Y., Zhao, Y., 2021. A review of specialty fiber biosensors based on interferometer configuration. J. Biophotonics, 14(6), e202100068. DOI: https://doi.org/10.1002/jbio.202100068 4. Wu, Q., Qu, Y., Liu, J., Yuan, J., Wan, S.-P., Wu, T., He, X.-D., Liu, B., Liu, D., Ma, Y., Semenova, Y., Wang, P., Xin, X., Farrell, G., 2021. Singlemode-Multimode-Singlemode fiber structures for sensing applications — A review. IEEE Sens. J., 21(11), pp. 12734—12751. DOI: https://doi.org/10.1109/JSEN.2020.3039912 5. Sadeque, M.S.B., Chowdhury, H.K., Rafique, M., Durmuş, M.A., Ahmed, M.K., Hasan, M.M., Erbaş, A., Sarpkaya, İ., Inci, F., Ordu, M., 2023. Hydrogel-integrated optical fiber sensors and their applications: A comprehensive review. J. Mater. Chem. C, 11, pp. 9383—9424. DOI: https://doi.org/10.1039/D3TC01206A 6. Morshed, A.H.E., 2024. Multimode interference sensors for static and dynamic monitoring. In: S.W. Harun (ed.) Optical technologies for advancing communication, sensing, and computing systems. Intech Open. DOI: https://doi.org/10.5772/intechopen.1008340 7. Zhuang, F., Li, Y., Guo, T., Yang, Q., Luo, Y., Wang, J., Wang, Sh., 2025. Review on in-situ marine monitoring using physical and chemical optical fiber sensors. Photonic Sens., 15, P. 250230. DOI: https://doi.org/10.1007/s13320-024-0731-3 8. Vali, V., Shorthill, R.W., 1976. Fiber ring interferometer. Appl. Opt., 15(5), pp. 1099—1100. DOI: https://doi.org/10.1364/AO.15.001099 9. Giallorenzi, T.G., Bucaro, J.A., Dandridge, A., Sigel, G.H., Cole, J.H., Rashleigh, S.C., Priest, R.G., 1982. Optical fiber sensor technology. IEEE Trans. Microw. Theory Tech., 30(4), pp. 472—511. DOI: https://doi.org/10.1109/JQE.1982.1071566 10. Engholm, M., Hammarling, K., Andersson, H., Sandberg, M., Nilsson, H.E., 2019. A bio-compatible fiber optic pH sensor based on a thin core interferometric technique. Photonics, 6(1), 11. DOI: https://doi.org/10.3390/photonics6010011 11. Liu, Z., Li, G., Zhang, A., Zhou, G., Huang, X., 2021. Ultra-sensitive optical fiber sensor based on intermodal interference and temperature calibration for trace detection of copper (II) ions. Opt. Express, 29(15), pp. 22992—23005. DOI: https://doi.org/10.1364/OE.434687 12. Noman, A.A., Dash, J.N., Cheng, X., Tam, H.Y., Yu, C., 2022. Mach-Zehnder interferometer based fiber-optic nitrate sensor. Opt. Express, 30(21), pp. 38966—38974. DOI: https://doi.org/10.1364/OE.468944 13. Yang, M., Zhu, Y., Ren, J., 2024. Hourglass-shaped fiber-optic Mach-Zehnder interferometer for pressure sensing. Opt. Fiber Technol., 84, 103746. DOI: https://doi.org/10.1016/j.yofte.2024.103746 14. Wang, W., Pei, Y., Ye, L., Song, K., 2020. High-sensitivity cuboid interferometric fiber-optic hydrophone based on planar rectangular fi lm sensing. Sensors, 20(22), 6422. DOI: https://doi.org/10.3390/s20226422 15. Dass, S., Jha, R., 2021. Underwater low acoustic frequency detection based on in-line Mach–Zehnder interferometer. J. Opt. Soc. Am. B: Opt. Phys., 38(2), pp. 570—575. DOI: https://doi.org/10.1364/JOSAB.410440 16. May-Arrioja, D.A., Ruiz-Perez, V.I., Bustos-Terrones, Y., Basurto-Pensado, M.A., 2016. Fiber optic pressure sensor using a conformal polymer on multimode interference device. IEEE Sens. J., 16(7), pp. 1956—1961. DOI: https://doi.org/10.1109/JSEN.2015.2510360 17. Li, Y., Jiang, Y., Tang, N., Wang, G., Tao, J., Zhang, G., Ge, Q., Zhang, N., Wu, X., 2023. Fiber optic temperature and strain sensor using dual Mach–Zehnder interferometers. Appl. Opt., 62(8), pp. 1977—1983. DOI: https://doi.org/10.1364/AO.480414 18. Yi, D., Liu, F., Geng, Y., Li, X., Hong, X., 2021. High-sensitivity and large-range fiber optic temperature sensor based on PDMS-coated Mach-Zehnder interferometer combined with FBG. Opt. Express, 29(12), pp. 18624—18633. DOI: https://doi.org/10.1364/OE.428384 19. Bian, C., Cheng, Y., Zhu, W., Tong, R., Hu, M., Gang, T., 2020. A novel optical fiber Mach-Zehnder interferometer based on the calcium alginate hydrogel film for humidity sensing. IEEE Sens. J., 20(11), pp. 5759—5765. DOI: https://doi.org/10.1109/JSEN.2020.2973290 20. Bhardwaj, V., Singh, V.K., 2016. Fabrication and characterization of cascaded tapered Mach-Zehnder interferometer for refractive index sensing. Sens. Actuators A Phys., 244, pp. 30—34. DOI: https://doi.org/10.1016/j.sna.2016.04.008 21. Unger, H.-G., 1977. Planar optical waveguides and fi bers. Oxford engineering science series. Vol. 5. New York : Clarendon Press.
AXIALLY SYMMETRIC MODES IN AN OPEN RESONATOR
Subject and Purpose. The behavior of axially symmetric oscillations in a hemispherical open resonator (OR) integrated into a waveguide transmission line and operating in pass-through mode is studied. The apertures of the OR mirrors are 60 mm. The radius of curvature of the spherical mirror is 85 mm. Two 3.6×0.17 mm slot coupling elements are positioned symmetrically about the OR axis and 13.2 mm away from it. The axially symmetric oscillations excited in a hemispherical OR by slotted coupling elements are analyzed with the view of characterizing dielectric materials using resonant methods in the EHF range. Methods and Methodology. Basic quasi-optical techniques are adopted. Namely, the electric-field structures of oscillation types are measured by the perturbation method. The resonant transmission coefficients of open oscillatory systems and the physical phenomena occurring within them are experimentally studied using standard microwave measurement techniques. Results. In the experimental study conducted at 70.622 GHz, OR oscillations with large transverse indices were identifi ed from amplitude distributions. The perturbation method was used with a 1 mm diameter probe. It has been shown that in non-axial OR excitation, axially symmetric oscillations, among others, are excited. Experimentally, a distinctive feature of those axially symmetric oscillations has been established, which is an area with zero electric-field intensity at the center of the cavity. For the investigated TEM*0,1,12 oscillation, this area is 6 mm in diameter. Conclusions. It has been demonstrated that an open resonator with axially symmetric oscillations is effective for measuring the electrophysical parameters of materials, including liquids. It has been established that the placement of a disk-shaped sample or a liquid-filled cuvette at the center of the flat mirror of a hemispherical OR not only does not disrupt the working oscillation but additionally contributes to the angular mode selection of the OR oscillation spectrum. The hemispherical OR, as considered, can also be used for dynamic quality control of various liquids. In this case, the holder, like a quartz glass tube, is positioned along the OR axis. Keywords: millimeter-wave range, open resonator, modes, coupling element, transmission coefficient, probe Manuscript submitted 14.09.2025 Radio phys. radio astron. 2025, 30(4): 285-295 REFERENCES 1. Wang, Y., and Afsar, M.N., 2003. Measurement of Complex Permittivity of Liquids Using Waveguide Techniques. Progress in Electromagnetics Research (PIER), 42(1), pp. 131—142. DOI: https://doi.org/10.2528/PIER03010602 2. Gennarelli, G., Romeo, S., Scarfi, M.R., and Soldovieri, F., 2013. A Microwave Resonant Sensor for Concentration Measurements of Liquid Solutions. IEEE Sens. J., 13(5), pp. 1857—1864. DOI: https://doi.org/10.1109/JSEN.2013.2244035 3. Arumugam, J., Edhayaraj, N.R., Shanmugavadivelu, S., and Sathyanarayanan, V., 2023. Design of Microwave Electromagnetic Sensor for Liquid Characterization. Journal of High-Frequency Communication Technologies, 1(3), pp. 73—83. DOI: https://doi.org/10.58399/TLCX9900 4. Volkov, V.V., Suslin, M.A., and Dumbolov, J.U., 2020. Microwave Resonance Method for Measuring Microliter Volumes of Free Moisture of Aviation Fuels. Meas. Tech., 63(7), pp. 226—234. DOI: https://doi.org/10.1007/s11018-020-01775-3 5. Al-Mously, S.I.Y., 2012. A Modified Complex Permittivity Measurement Technique at Microwave Frequency. Int. J. New Comput. Archit. Appl. (IJNCAA), 2(2), pp. 389—401. Available from: https://scispace.com/papers/a-modified-complex-permittivity-measurement-technique-at-2mhob8 glc2 6. Yashchyshyn, Ye., and Godziszewski, K., 2018. A New Method for Dielectric Characterization in Sub-THz Frequency Range. IEEE Trans. Terahertz Sci. Technol., 8(1), pp. 19—26. DOI: https://doi.org/10.1109/TTHZ.2017.2771309 7. Jebbor, N., Bri, S., Mediavilla, A., and Chaib,i M., 2013. A Fast Calibration-Independent Method for Complex Permittivity Determination at Microwave Frequencies. Measurement, 46(7), pp. 2206—2209. DOI: 10.1016/j.measurement.2013.04.009 DOI: https://doi.org/10.1016/j.measurement.2013.04.009 8. Elmajid, H., Terhzaz, J., and Ammor, H., 2014. Optimization Technique to Estimate the Complex Permittivity of Dielectric Materials at X-Band Using Rectangular Waveguide. Int. J. Appl. Eng. Res., 9(24), pp. 26709—26718. Available from: http:// www.ripublication.com/Volume/ijaerv9n24.htm 9. Benali, L.A., Tribak, A., Terhzaz, J., and Mediavilla, A., 2020. An Accurate Method to Estimate Complex Permittivity of Dielectric Materials at X-band Frequencies. Int. J. Microw. Opt. Technol., 15(1), pp. 10—16. Available from: https://www. ijmot.com/VOL-15-NO-1.aspx 10. Krupka, J., 2021. Microwave Measurements of Electromagnetic Properties of Materials. Materials, 14(17), pp. 1—21. DOI:https://doi.org/10.3390/ma14175097 11. Breslavets, A.A., Eremenko, Z.E., Rudnev, G.O., Natarov, M.P., Glamazdin, V.V., Shubnyi, O.I., Voitovych, O.A., Gang, Zhu, Rong, Li, and Prokopenko, A.A., 2022. Hemispherical X band Microwave Small Sized Open Resonator for Wide Range from 1 to 20 Permittivity Characterization of Solid-State Dielectrics. Low Temp. Phys., 48(1), pp. 43—50. DOI:https://doi.org/10.1063/10.0008963 12. Alimenti, A., Pittella, E., Torokhtii, K., Pompeo, N., Piuzzi, E., and Silva, E., 2023. Dielectric Loaded Resonator for the Measurement of the Complex Permittivity of Dielectric Substrates. IEEE Trans. Instrum. Meas., 72(1), pp. 1—9. DOI: https://doi.org/10.1109/TIM.2023.3236301 13. Drobakhin, O.O., 2025. Development of Measurement Methods in Microwave and Terahertz Ranges of Electromagnetic Waves in Ukraine (Review). Radio Electron. Commun. Syst., 67(4), pp. 161—179. DOI: https://doi.org/10.3103/S0735272724040034 14. Kumar, A., and Sharma, S., 2007. Measurement of Dielectric Constant and Loss Factor of the Dielectric Material at Microwave Frequencies. Prog. Electromagn. Res., 69, pp. 47—54. DOI: https://doi.org/10.2528/PIER06111204 15. Bendaoued, M., Terhzaz, J., and Mandry, R., 2017. Determining the Complex Permittivity of Building Dielectric Materials using a Propagation Constant Measurement. Int. J. Electr. Comput. Eng., 7(4), pp. 1681—1685. DOI: https://doi.org/10.11591/ijece.v7i4.pp1681-1685 16. Stumper, U., 1973. A TE01n Cavity Resonator Method to Determine the Complex Permittivity of Low Loss Liquids at Millimeter Wavelengths. Rev. Sci. Instrum., 44(2), pp. 165—169. DOI: https://doi.org/10.1063/1.1686073 17. Abbas, Z., Pollard, R.D., and Kelsall, R.W., 2001. Complex Permittivity Measurements at Ka-Band Using Rectangular Dielectric Waveguide. IEEE Trans. Instrum. Meas., 50(5), pp. 1334—1342. DOI: https://doi.org/10.1109/19.963207 18. Vuks, M.V., 1984. Electrical and Optical Properties of Molecules and Condensed Media. Leningrad, USSR: Leningrad University Publishing House, 1984, pp. 60—62. 19. Afsar, M.N., Button, K.J., 1985. Millimeter Wave Dielectric Measurement of Materials. Proc. IEEE, 73(1), pp. 131—153. DOI: https://doi.org/10.1109/PROC.1985.13114 20. Afsar, M.N., Li, X., and Chi, H., 1990. An Automated 60 GHz Open Resonator System for Precision Dielectric Measurements. IEEE Trans. Microwave Theory Tech., 38(12), pp. 1845—1853. DOI: https://doi.org/10.1109/22.64565 21. Afsar, M.N., Chen, S., and Wang, Y., 2005. An Improved 60 GHz Open Resonator System for Accurate Measurement of Dielectric Permittivity. In: AP-S Int. Symp., Conf. Proc. Washington, DC, USA, 03—08 July 2005, pp. 1—5. DOI: https://doi.org/10.1109/APS.2005.1552842 22. Vlasov, S.N., Parshin, V.V., and Serov, E.A., 2010. Methods for Investigating Thin Dielectric Films in the Millimeter Range. Tech. Phys., 55(12), pp. 1781—1787. DOI: https://doi.org/10.1134/S1063784210120121 23. Yang, B.B., Katz, S.L., Willis, K.J., Weber, M.J., Knezevic, I., and Hagness, S.C., 2012. A High-Q Terahertz Resonator for the Measurement of Electronic Properties of Conductors and Low-Loss Dielectrics. IEEE Trans. Terahertz Sci. Technol., 2(4), pp. 449—459. DOI: https://doi.org/10.1109/TTHZ.2012.2199578 24. Parshin, V.V., and Serov, E.A., 2012. Resonance Method for Studying Dielectric Liquids in Millimeter and Submillimeter Wave Ranges. Radiophys. Quantum Electron., 54(8–9), pp. 632—637. DOI: https://doi.org/10.1007/s11141-012-9324-x 25. Karpisz, T., Salski, B., Kopyt, P., and Krupka, J., 2019. Measurement of Dielectrics from 20 to 50 GHz with a Fabry–Pérot Open Resonator. IEEE Trans. Microwave Th eory Tech., 67(5), pp. 1901—1908. DOI: https://doi.org/10.1109/TMTT.2019.2905549 26. Givot, B.L., Gregory, A.P., Salski, B., Zentis, F., Pettit, N., and Karpisz, N., 2021. A Comparison of Measurements of the Permittivity and Loss Angle of Polymers in the Frequency Range 10 GHz to 90 GHz. In: 15th European Conf. Antennas and Propagation (EuCAP), Conf. Proc. Dusseldorf, Germany, 22—26 March 2021, pp. 1—5. DOI: https://doi.org/10.23919/EuCAP51087.2021.9411298 27. Kayro, N.S., Teterina, D.D., Badin, A.V., and Bilinskii, K.V., 2021. Automated system based on open resonator for measuring the electrophysical parameters of sheet dielectrics. J. Phys.: Conf. Ser., 1989(1), pp. 012020 (1—5). DOI: https://doi.org/10.1088/1742-6596/1989/1/012020 28. Karpisz, T., Salski, B., Kopyt, P., Krupka, J., and Wojciechowski, M., 2022. Measurement of uniaxially anisotropic dielectrics with a Fabry-Perot open resonator in the 20—50 GHz range. IEEE Microw. Wirel. Compon. Lett., 32(5), pp. 441—444. DOI: https://doi.org/10.1109/LMWC.2022.3155938 29. Elwood, B.D., Grimes, P.K., Kovac, J., Eiben, M., and Meiners, G., 2024. Fabry–Perot Open Resonant Cavities for Measuring the Dielectric Parameters of mm-Wave Optical Materials. ArXiv:2411.01058v1 [physics.optics], pp. 1—12. DOI: https://doi.org/10.1117/12.3019149 30. Chigryai, E.E., Garin, B.M., and Denisyuk, R.N., 2018. Measurement of Dielectric Loss at Millimeter Range in the Low Loss Materials with Arbitrary Ratio of Wavelength and Sample Thickness. Journal of Radio Electronics (JRE), 10, pp. 1—7. DOI: https://doi.org/10.30898/1684-1719.2018.10.10 31. Kuzmiche v, I.K., and Popkov, A.Yu., 2018. Resonant Systems for Measurement of Electromagnetic Properties of Substances at V-Band Frequencies. Chapter 3. In: Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing. London, United Kingdom: Intech Open Publ., 2018, pp. 27—53. DOI: https://doi.org/10.5772/intechopen.73643 32. Kuzmicho v, І.К., Кogut, О.Е., Muzychishin, B.І., Popkov, O.Yu., and Senkevych, O.B., 2023. The TE01 wave excitation in a circular waveguide using higher-order modes of an open resonator. Radio Phys. Radio Astron., 28(3), pp. 243—256. DOI: https://doi.org/10.15407/rpra28.03.243 33. Menzel, R., 2007. Photonics: Linear and Nonlinear Interactions of Laser Light and Matter. 2nd ed. Berlin, Germany: Springer-Verlag Berlin and Heidelberg GmbH & Co. KG, pp. 395—409. DOI: https://doi.org/10.1007/978-3-540-45158-7 34. Muzychishin, B.I., Kuzmichev, I.K., Senkevych, O.B., and Pogarsky, S.A., 2022. Spectrum of OR Oscillations with a Segment of a Circular Waveguide. In: 2022 IEEE 9th Int. Conf. Problems of Info communications Science and Technology (PICS&T ‘2022): Conf. Proc. Kyiv, Ukraine, 10—12 Oct. 2022, pp. 524—528. DOI: https://doi.org/10.1109/PICST57299.2022.10238663 35. Valitov, R.A. (ed.), Dyubko, S.F., Kamyshan, V.V., Kuzmichev, V.M., Makarenko, B.I., Sokolov, A.V., and Sheiko, V.P., 1969. Submillimeter Wave Technique. Moscow, USSR: Sov. radio Publ., pp. 219—229. 36. Yang, Z., Lin, C., and Zho, Y., 1985. A Method for Measurement of Q-Factor at Millimeter Wavelength. In: 10th Int. Conf. Infrared and Millimeter Waves, Conf. Proc. Lake Buena Vista, Florida, USA, 9—13 Dec. 1985, pp. 350—351. DOI: https://doi.org/10.1109/IRMM.1985.9126718 37. Kuzmiche v, I.K., 2002. The Probe Diameter Choosing for the Investigation of the Field Distribution in the Small Aperture Open resonator. Telecommunications and Radio Engineering, 58(7—8), pp. 59—63. DOI: https://doi.org/10.1615/TelecomRadEng.v58.i7-8.50 38. Tarasov, L.V., 1981. Physics of processes in coherent optical radiation generators. Moscow, USSR: Radio i Svyaz’ Publ., 1981, pp. 141—212. 39. Weber, H., Herziger, G., Poprawe, R. (eds.), 2006. Laser Physics and Applications. Laser Fundamentals. Part 2. Group VIII, Vol. 1. Berlin, Germany: Springer-Verlag, Berlin, Heidelberg, New York, pp. 149–161 ISSN 1619-4802. 40. Kogelnik, H., 1964. Coupling and conversion coefficients for optical modes. In: Quasi-Optics, Proc. Symp. New York, NY, 8—10 June 1964. Microwave Research Institute Symposia Series. Vol. 14. Brooklyn, NY: Polytechnic Institute of Brooklyn, Polytechnic Press, pp. 333–347. ISBN 10 0470274298.