A. V. Ashihmin, Yu. G. Pasternak, Yu. A. Rembovskiy

Earlier it was demonstrated that to evaluate electromagnetic field distribution around random diffusers is possible even if you do not have geometrical or material data about those diffusers. This enables using the so-called virtual antenna arrays for different technical purposes. E.g. they can be used in mobile and stationary detection finding equipment, to mitigate instrumentation errors in direction finding and to increase resolution in angular coordinates mode. However, procedures for formation of virtual antenna arrays were not 100% substantiated in terms of classical electrodynamics: they were based on an assumption that a field can be approximated via analytical function of complex variable or complex-valued harmonic functions or via linear combination of functions describing radiation from point sources or linear combination of plane EM waves. In the course of studies it was established that virtual antenna arrays could be formed by both heuristic methods (on the assumption that a field can be described as a linear combination of complex variable analytical functions based on field approximation via point sources or plane waves) and by methods based on classic electrodynamics (e.g. Kirchhoff integral). Applicability of integral-differential equation system based on Kirchhoff integral during virtual antenna arrangement was tested by numerical modeling method. The calculation experiment was based on a rigorous solution for diffraction of vertically polarized EM waved using Veiland finite integration method. According to frequency dependencies for calculated bearings obtained via "real" and "virtual" antenna arrays, emitters direction finding error will be 1.426 times less when a virtual antenna array was based on traditional electrodynamics (Kirchhoff integral). Also, some possibilities were identified to improve virtual antenna array techniques through application of harmonic and analytical functions for measured field description.