A.L. Buzov, Y.I. Kolchugin, M.Y. Spodobaev

This article is about the problems of calculating underground HF-band antenna arrays characteristics. Underground antennas features and operation are discussed. Rationale behind the decision to use underground antenna arrays containing autonomous underground antennas with feeder power systems is explained. Short analysis of underground antennas as electrodynamics objects is held. Two classes of underground antennas - immediate deposit antennas and antennas inside dielectric cover are discussed. Method of electrodynamics analysis of immediate deposit antenna is discussed. Using this method electrodynamic problem is reduced to single linear integral equation (for those antennas that aren-t arrays). This equation is Fredholm-s equation of 1st kind. To define the kernel and to derive matrix elements of system of linear equations known solution is used - the problem of radiating elementary vibrator near flat surface medium boundary. Method of electrodynamics analysis of antenna in dielectric cover is described. It is based on electrodynamics model with a few regions having different sources and boundary conditions. They are emitter lines (boundary condition for electric field longitudal component, linear currents), medium boundary, with second medium being earth (Leontowich impedance boundary condition, surface currents), dielectric cover (condition for equivalent currents volume equivalent currents). The result is a system of integral equations, its solution gives all sources which allow to find antenna characteristics. Problem of calculating direction patterns based on sources modification in dielectric cover is briefly addressed. The problems of electrodynamics analysis of underground antenna arrays are discussed. Method of considering emitters coupling of underground antenna arrays which is based on adding integral operators to equation that would formalize emitter processes in earth medium is founded.