M.W. Indenbom

The far-field antenna radiation pattern reconstruction method is presented. This method is based on Fresnel zone complex meridional field distribution\'s decomposition by scalar spherical functions or cylindrical functions. The method has a feature of measuring noise and obstacle surroundings reflections suppression. Fresnel zone measurements are necessary for a big size antennas when its far-field distance exceeds stationary test setup\'s dimensions. Moreover, shorter AUT - probe distance allows decrease the obstacle surrounding reflections influence in measurement results. In contrast with near field measurement methods, which are based on the measured vector two-dimension surface field distribution, this method inputs only single-dimension field distribution on the circle. Consequently this method allows to decrease a measurement data volume and measurements duration. This method may be used for the linear antenna or in-line array which has directivity in the meridional plane including the longitudinal antenna axis and a wide beam in the orthogonal plane. The work shows possibility to reconstruct the far field meridional antenna pattern on base only the one meridional Fresnel zone field distribution whenever for considering class of the antennas. The method is based on the scalar spherical functions expansion or the cylindrical functions expansion of the measured Fresnel zone field distribution. In case of a cylindrical functions expansion it is used Feld\'s formula for the received antenna signal amplitude in an arbitrary incident field. This allows include in the consideration directive features of the probe. A cylindrical surface between the AUT and the probe is chosen as the surface of integration in Feld\'s formula. The integral is calculated by the stationary phase methods. The far field pattern is obtained as limit R → ∞ in the spherical functions expansion or as the AUT response at the plane wave in the cylindrical functions case. The investigation of the measuring noise and obstacle surrounding reflections reduction algorithm is studied in the united framework with the far field reconstruction algorithm. The mathematical model simulated results confirms correctness deduced expressions and the methods limitations, suppression of a noise, filtering of the reflections from the supporting details and the surroundings. The mathematical model is good instrument for the estimation of the methodical errors and for reconstruction and filtering algorithm parameters choice in the specific situation. Measurement setup and experimental results with application of the considered algorithm are presented for any linear arrays. The reconstruction and filtering algorithm are enough simple, it is realized on the Mathcad mathematical redactor. The time of the calculation is 8 c in case 3600 measured points and 350 spherical functions.