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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Discrete and Continuous Models and Applied Computational Science</journal-id><journal-title-group><journal-title xml:lang="en">Discrete and Continuous Models and Applied Computational Science</journal-title><trans-title-group xml:lang="ru"><trans-title>Discrete and Continuous Models and Applied Computational Science</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2658-4670</issn><issn publication-format="electronic">2658-7149</issn><publisher><publisher-name xml:lang="en">Peoples' Friendship University of Russia named after Patrice Lumumba (RUDN University)</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">26137</article-id><article-id pub-id-type="doi">10.22363/2658-4670-2021-29-1-14-21</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Статьи</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Normal modes of a waveguide as eigenvectors of a self-adjoint operator pencil</article-title><trans-title-group xml:lang="ru"><trans-title>Нормальные моды волновода как собственные векторы самосопряжённого операторного пучка</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Malykh</surname><given-names>Mikhail D.</given-names></name><name xml:lang="ru"><surname>Малых</surname><given-names>М. Д.</given-names></name></name-alternatives><bio xml:lang="en"><p>Doctor of Physical and Mathematical Sciences, Assistant Professor of Department of Applied Probability and Informatics</p></bio><email>malykh_md@pfur.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Peoples’ Friendship University of Russia (RUDN University)</institution></aff><aff><institution xml:lang="ru">Российский университет дружбы народов</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2021-03-30" publication-format="electronic"><day>30</day><month>03</month><year>2021</year></pub-date><volume>29</volume><issue>1</issue><issue-title xml:lang="en">VOL 29, NO1 (2021)</issue-title><issue-title xml:lang="ru">ТОМ 29, №1 (2021)</issue-title><fpage>14</fpage><lpage>21</lpage><history><date date-type="received" iso-8601-date="2021-03-30"><day>30</day><month>03</month><year>2021</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2021, Malykh M.D.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2021, Малых М.Д.</copyright-statement><copyright-year>2021</copyright-year><copyright-holder xml:lang="en">Malykh M.D.</copyright-holder><copyright-holder xml:lang="ru">Малых М.Д.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">http://creativecommons.org/licenses/by/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.rudn.ru/miph/article/view/26137">https://journals.rudn.ru/miph/article/view/26137</self-uri><abstract xml:lang="en"><p style="text-align: justify;">A waveguide with a constant, simply connected section <math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mi>S</mi></math> is considered under the condition that the substance filling the waveguide is characterized by permittivity and permeability that vary smoothly over the section <math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mi>S</mi></math>, but are constant along the waveguide axis. Ideal conductivity conditions are assumed on the walls of the waveguide. On the basis of the previously found representation of the electromagnetic field in such a waveguide using 4 scalar functions, namely, two electric and two magnetic potentials, Maxwell’s equations are rewritten with respect to the potentials and longitudinal components of the field. It appears possible to exclude potentials from this system and arrive at a pair of integro-differential equations for longitudinal components alone that split into two uncoupled wave equations in the optically homogeneous case. In an optically inhomogeneous case, this approach reduces the problem of finding the normal modes of a waveguide to studying the spectrum of a quadratic self-adjoint operator pencil.</p></abstract><trans-abstract xml:lang="ru"><p style="text-align: justify;">В статье рассматривается волновод постоянного односвязного сечения <math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mi>S</mi></math> при условии, что заполняющее волновод вещество характеризуется диэлектрической и магнитной проницаемостями, меняющимися плавно на сечении <math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mi>S</mi></math>, но постоянными вдоль оси волновода. На стенках волновода взяты условия идеальной проводимости. На основе найденного ранее представления электромагнитного поля в таком волноводе при помощи четырёх скалярных функций — двух электрических и двух магнитных потенциалов — уравнения Максвелла записаны относительно потенциалов и продольных компонент поля. Из этой системы удаётся исключить потенциалы и записать пару интегро-дифференциальных уравнений относительно одних продольных компонент, расщепляющихся на два несвязанных волновых уравнения в оптически однородном случае. В оптически неоднородном случае этот подход позволяет свести задачу об отыскании нормальных мод волновода к исследованию спектра квадратичного самосопряжённого операторного пучка.</p></trans-abstract><kwd-group xml:lang="en"><kwd>waveguide</kwd><kwd>normal modes</kwd><kwd>hybridization of normal modes</kwd><kwd>eigenvalue problem</kwd><kwd>quadratic operator pencils</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>волновод</kwd><kwd>нормальные моды</kwd><kwd>гибридизация нормальных мод</kwd><kwd>задача на собственные значения</kwd><kwd>квадратичные пучки</kwd></kwd-group><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>A. G. Sveshnikov and I. E. 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