V. H. Avetisyan - Dr.Sci. (Eng.), Professor, Head of Telecommunication Department, Institute of Mathematics and High Technologies of Russian - Armenian (Slavonic) University; Deputy Director by Science of Yerevan Telecommunication Research Institute (Yerevan, Republic of Armenia). E-mail: avahan@mail.ru
M. V. Markosyan - Dr.Sci. (Eng.), Professor, Director of Yerevan Telecommunication Research Institute (Yerevan, Republic of Armenia). E-mail: mark@yetri.am
V. V. Grigoryan - Post-graduate Student, Telecommunication Department, Institute of Mathematics and High Technologies of Russian - Armenian (Slavonic) University (Yerevan, Republic of Armenia). E-mail: vahangrig1989@gmail.com

In the context of general problem of multipath propagation of radio waves the reception problem is considered. The problem's statement is the following. Transmitting antenna with gain is fed by the input power . Only spatial waves are considered, each of the misattributed to propagating beam, while possible rapidly decaying surface waves are neglected. In the space around the antenna there are the reradiating objects, which, in result of single and multiple reradiations of beams falling on them, create a bunch of N beams in number indirection of receiving antenna with gain . The following is assumed: antennas operate with matching linear polarization which is horizontal for example; distance between the antennas exceeds the minimal far-field distance of either of the antenna; in a considered multipath propagation model any reradiating object or its reradiating part is attributed to lumped object and its distance from the transmitting antenna, a distance from the receiving antenna and a distance from another reradiating object are known; in the considered model of multipath propagation, the complex transformation (in amplitude and phase) of every beam in a process of any reradiation is known, and each beam suffers no amplitude or phase fluctuations along the path. The aim of the paper is to solve of the reception problem in conditions of multipath propagation of waves the in explicit dependence on number of the reradiating objects, on their reradiating properties, on their locations relative to each other and the antennas, and on directional properties of the transmitting and receiving antennas. The problem is solved with the method named as the method of virtual antennas. This method is based on beam tracing method and the known statement that antenna is a linear device which obeys to the principle of superposition. At solving of problem a constructed evident equivalent model of reception is used which simply takes into account a number of reradiating objects, their reradiating properties, their locations, directivities of the radiating and the receiving antennas and interference of waves in multipath reception mode. In such reception model the receiving antenna is replaced hypothetically by a set of virtual receiving antennas which are mutually spaced by special manner and with accordance to the beams falling on the replaced receiving antenna. In the paper the some possible simplified propagation scheme of beams and relative positioning of the transmitting and the receiving antennas is considered in the case of four ( ) reradiating objects which include possible specular reflective area of the Earth. The principals of construction ofequivalent model of the reception are stated in conditions of multipath propagation and the constructed reception model is presented which corresponds to the above mentioned scheme of propagation of beams. As a result of the problem solution an analytical expression of output power of the receiving antennas was obtained in explicit dependency on directional properties of the transmitting and the receiving antennas as well as on locations and properties of the set of the lumped reradiating objects. On the basis of the obtained expression an expression of attenuation coefficient is obtained for the accepted model of multi path propagation with the lumped reradiating objects. The results, arising from the general solution in the special cases, are compared with the earlier known. Coincidence of the results, following from the general solution of the problem for the special case with availability of reradiation in the form only of specular reflection from the Earth, with the earlier known results for this case proves the validity of proposed method of the solution of the problem and the obtained analytical expressions.