A Fast Near- to Far-Field Transform Algorithm
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Electrical and Computer Engineering Honors Theses; 2007
A frequent problem in computational electromagnetics is to calculate the electromagnetic field far from a radiating object. This has numerous applications, such as antenna analysis and determining the radar cross sections of airplanes, ships, etc. Another application to converting near field measurements, taken in an indoor measurement range for instance, and transforming them to the far-zone. However, when the field of a large object needs to be calculated in many directions, however, this computation can take too long to be practical. The goal of this project is to develop an algorithm to greatly speed up this calculation by using a divide-and-conquer approach. First, the necessary background information in electromagnetics and numerical methods is presented. Then, a near to far field transform with potential for O(N^1.5) time complexity is discussed, where N is the number of basis elements used to approximate the object’s surface. Finally, the running time and accuracy of the algorithm is discussed, with comparisons to another near to far field computer program for two problem geometries, a VFY-218 airplane with N = 53,054 and an antenna array with N = 106,792. The results show the fast near to far transform can be 30 times faster with an RMS relative error of 2.05e−5, compared to traditional methods. Advisor: Jin-Fa Lee
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