Near Field Error Correction Of Multiple Vector Synthesis

RF guided simulation system is an important means to test missile guidance systems. Its target echo signal generating portion can realistically simulate the complex electromagnetic environment and target characteristics on the battlefield.It has great significance to the development of weapon systems.This thesis mainly researchs the relationship between the phase front of the synthesis signal on the seeker position and the feed amplitudes or feed phases of the array elements.Researching the "near-field error" of the synthesis signal on the seeker position and the correction methods for this error.Firstly, this thesis explains the differences between the "near-field" of the synthesis signal radiated by array elements and the "near-field" of antenna measurement. Analyzing the causes and nature of the "near-field error" generated in the seeker semi-physical simulation system.Calculating the positioning formula of two-tuples, and showing the relationship between the target location errors and the feed phases or feed amplitudes of two array elements, showing the relationship between the target position errors and the feed amplitudes errors of the array elements.Calculateing the error caused by parallel lines approximation in the course of deducing the positioning formula,and the error caused by the center of the turntable don’t coincide with the center of the sphere.Analyzing the target signal’s simulation methods by using the triad of antenna-array in the simulation system.Deducing the equivalent radiation center position of the triad of antenna-array with analytic-geometry method, phase-gradient method and the poynting-vector method.These methods all contain the impacts of the feed phase variables for the location of the equivalent radiation center.Calculating the target location errors caused by the triad of antenna-array feed amplitudes and phases errors. In this paper, we put forward a new "near-field error" correction method according to the relationships between the positioning formula and array elements’ position, feed amplitudes and phases.Then, this thesis simulates the changing trends and ranges of the triad of antenna-array’s equivalent radiation center with the three array elements’ feed phases and amplitudes changing.Explaining the single equivalent radiation center’s changing range with changing the feed amplitudes or the feed phases simply or changing the feed amplitudes and phases together. From the simulation results,we find the equivalent radiation center of the triad of antenna-array becoming more freedom when increased the variable of the array-element feed phase.Single triad of antenna-array not only can simulate the target signal in it also can simulate the target signal out it. When the target out of the triad of antenna-array, the simulate results reveale that the target location is more far from the center of the triad of antenna-array, the target signal strength is more weaker, the target signal position error is more worse. This suggests that it is more difficult to simulate the target signal which is far from the center of triad of antenna-array.And this need the hardwares have more greater performance in the system.