Extraction of Farfield Radiation Pattern of an Antenna with Nearfield Planar Measurment Modeling

Measured far-field radiation pattern of the antenna is one of the major issues in the antenna fabrication. The purpose of this article is finding the far-field pattern of an antenna by using planar near-field measurement simulation. Examination of the effective criteria is another point of consideration. Distance between probe and antenna under test, spacing grid and measurement plane dimensions are effective criteria that have been examined, that measurement to be modulated in a smaller space, with less time and simpler mathematical calculations. To achieve these goals, radiation pattern of X_band horn antenna has been simulated with full wave software. Near-field of this antenna is examined by using three different types of open ended wave-guide probes. Then near-field to far-field transformation is runed with software code and is compared with simulation results. It has been showed that rectangular probe has resulted better far-field pattern. The best distance between probe and antenna under test 3 wave length and best spacing grid 0.3 wave length are obtained. Finally the effect of probe pattern on test antenna pattern is examined and a method is suggested for probe pattern correction and antenna pattern in a large angular rang is implemented to far-field pattern of full wave software.