Indoor Ray Tracing Algorithm And Application Research

Under the existing computer computing power,the conventional precise electromagnetic field algorithm is difficult to quickly analyze the electromagnetic field distribution of electrically large and complex scenes,and as more and more antennas are placed in the same large-scale space scene,due to the coupling effect between the antennas become stronger,which will inevitably lead to degradation of antenna performance.If the full-wave method(such as the MOM)is used for accurate calculation,the computing resources required are very huge.Under such circumstances,there is an urgent need for a solution that can quickly and accurately analyze the electromagnetic characteristics of complex spaces.The combination of uniform geometric diffraction theory(UTD)and ray tracing method can carry out rapid simulation under the premise of maintaining high accuracy,and is particularly suitable for quickly analyzing the characteristics of indoor radio wave propagation.This method does not need to mesh the objects in space,and the amount of calculation is independent of frequency.The advantage of using it in high frequency bands is more prominent.In this thesis,based on the reverse ray tracing algorithm,the path between the field point and the source point is searched.The electromagnetic field at the field point is calculated by the consistent geometric diffraction theory applicable to the medium,and the complex indoor scene is numerically simulated.In addition,in order to expand the application scenarios of the proposed algorithm and solve the electromagnetic compatibility problem for multiple antennas working together in the same scenario,the established consistent geometric diffraction method is combined with the spherical wave expansion algorithm to form a new hybrid algorithm(SWE+UTD)quickly analyzes the mutual coupling between two antennas on a finite large ideal conductor platform.The main work of this article is as follows:1.By expressing the room structure and rays with parametric equations,a reverse ray tracing algorithm based on an optimization algorithm is proposed for the path search between the source point and the field point under any number of plane interfaces;A strict occlusion judgment method eliminates the occlusion rays,and uses a "visible surface matrix" method to preprocess the occlusion judgment,speeding up the screening process of invalid paths,and effectively reducing the tracking time.In addition,the UTD theory of the dielectric structure was studied in detail,and the numerical results of multiple structures were verified.According to the comparison results of numerical examples,this method can accurately determine the occlusion relationship,has a faster speed and better accuracy,and can quickly analyze the electromagnetic field distribution in a complex medium environment.2.Combining spherical wave expansion theory,reciprocity theorem and UTD,a new fast hybrid algorithm is proposed,which can efficiently analyze the mutual coupling between two antennas on the platform.The core of the method is to calculate the mutual coupling between the antennas through the reciprocity theorem.Secondly,the spherical wave expansion theory is used to accurately calculate the direct field on the antenna and the scatterer,which can improve the calculation accuracy of the scattering field.In this algorithm,the input data is only the electromagnetic field on a sphere surrounding the antenna,which is convenient for docking with the measurement data or simulation results,and can easily handle the rotation and translation of the antenna.It is especially suitable for optimizing and analyzing the mutual coupling of the antenna at different relative attitudes.Finally,the results of numerical examples show that using this fast algorithm to analyze the influence of the platform on antenna mutual coupling,the results are better than those without considering the influence of the platform,and the calculation efficiency of the algorithm is higher than that of the fast multipole method.