D. V. Tatarnikov - Dr.Sc. (Eng.), Professor, Department of Radiophysics, Antennas and Microwave Technique, Moscow Aviation In-stitute (National Research University); Antenna Design Chief, Topcon Positioning Systems, Inc. E-mail: DTatarnicov@topcon.com I. M. Chernetsky - Post-graduate Student, Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute (National Research University); Engineer, Topcon Positioning Systems, Inc. E-mail: IChernetskiy@topcon.com

Root-mean-square (RMS) positioning error with GPS/GLONASS signals in carrier-phase differential mode is currently 1-1,5 cm enabling positioning equipment to be used in diverse business domains, including automation machines. However, automatic and semi-automatic vehicles often operate in challenging environments when line-of-sight satellite signals are subject to fast-changing chaotic shadings. Such operation is specific for working near planted lands or directly under tree canopy. The main difficulty of applying natural testing facilities for purposes of adjusting the corresponding equipment is a failure of ensuring experimental repeatability, since the current properties of the natural obstructions (forest) are considerably and randomly varied. A multimode Fabry-Perot-type resonator is considered as an artificial obstruction, when the receiving positioning antenna being placed into a cavity formed by a semi-transparent mesh and a conducting ground. If the resonator dimensions considerably exceed the wavelength, in the resonator there is excited a nearly-continuous spectrum of eigenmodes whose interference is viewed as a mechanism of originating sharp and chaotic disturbances in the directional pattern (DP) of the antenna-obstruction system. A mathematical model for the cases of practical interest has been developed and some calculations of typical DPs have been performed. An experimental obstruction sample was built. An agreement between observed data and that of the natural forest has been shown in the paper.

 

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