Simulation of Digital and Analog Spatial Filtering of VHF Signals in Channel with Losses due to Multipple Diffraction

The paper describes digital antenna arrays (DAA) equipped with directional elements for spatial filtering in the azimuthal and elevation planes. In particular, the digital beamforming is investigated for VHF communication channels in the range below 1 GHz, taking into account the occurrence of obstacles in the path of direct propagation. Thus the paper presents the results of simulation of the signal propagation in the VHF range depending on diffraction. It is assumed that a symmetrical dipole is used on the transmitting side, and the Yagi-Uda directional antenna is used on the receiving digital antenna array. The circular and semi-dodecahedral geometries of the arrangement of the elements of the receiving digital antenna array are modeled. The bit error rate is estimated depending on the transmitter power. The Epstein-Peterson method is described in conjunction with the International Telecommunication Union (ITU) single knife-edge obstacle model for calculating multiple diffraction losses. The study was conducted for thirteen isolated knife-edge obstacles located along a propagation path of 70 km.