Obtaining stable characteristics description of signals scattered by complex objects through frequency averaging

Abstract

An analysis of the appearance of a complex dependence of the echo signal field on the observation conditions was performed. It was demonstrated that it is caused by the interference of electromagnetic fields of the local scattering area (LSA) of a complex object with the spatial coherence of the probe signal generated by the antenna with a limited aperture. Reducing of the variability of the informative features is associated with solving the problem of reducing the interference of the local scattering area, forming the signal reflected by the target. This is possible either by increasing the spatial resolution of the radar system or by averaging the received field over a particular set of parameters. It was demonstrated that the carrier parameter of quasi-monochromatic premises for spectral scanning of the probe signal is an effective parameter for the formation of stable informative features of averaging signal. It follows from the analysis that, for a sufficiently wide band in which the scanning probe is scanned and the object is in an arbitrary spatial location, the phases of the scattered signal are statistically independent and uniformly distributed. It increases robustness of characteristics of scattered signals to the variations in observation parameters due to the decrease of the sensitivity of frequency-averaged parameters to the spatial position of LSA. The criterion of sufficiency of the frequency band for approximate fulfillment of abovementioned statistical independence is provided. It has been demonstrated that the characteristics of complex radio-locative objects obtained utilizing the signal frequency-averaging satisfy the conditions of universality of the description, robustness to the spatial position of LSA, accessibility of their observation, and informativeness.