The Method of Eestimating the Parameters of the Electromagnetic Fields Scattered by the Object with Complex Form in the Near Zone of Wireless Sensor Networks

Abstract

At present time, many applications are connected with wireless sensor networks. Through such networks it is possible to determine the coordinates of various objects based on the analysis of the electromagnetic field distribution in space. This paper is based on the methodology that uses the representation of an object of complex shape as a set of facets, we investigate the characteristics of electromagnetic field scattered by this object in its near zone. It is shown how the calculated data are used to explore the effect how the spatial configuration of the field influences the accuracy of measurement of angular coordinates of the object. The calculated relative field amplitude of the object and the plate depends from the angle for the near zone to the far zone. The graphical analysis of the dependencies shows that in addition to monotonic at-tenuation length fields there exist oscillating damped oscillations. It is supposed that the antenna is moved around the object at random to get averaged characteristics over all measurement angles of the scattered field. After calculating the parameters of the distribution law of a random variable from section to section, we can conclude about how the process is changing after time. The analysis demonstrates that when we move from the far zone to the near, there is a shift of peak values of amplitudes and there is an extension of the main lobe of the secondary radiation. The histograms of the distributions of amplitudes and phases of a complex object were elaborated. After analysis it was found that the distribution of instantaneous values of the amplitudes of the scattered field by the object is described by Rayleigh law. If we consider the distribution of the instantaneous phase of the scattered field, the shape of the histogram is close in form to the histogram of a uniform law. The analysis of the results allows to assert that the regularities of the distribution of amplitude and phase values of the scattered field related to the far and near zones are the same. Regressive function will be linear and its parameter is an angle of object, which coordinates are computed. The results will be useful to improve the accuracy of determining the coordinates of objects in wireless sensor networks.