Comparison of Site Attenuation Analysis Results between FDTD and Ray-Tracing Method Using Compact Anechoic Chamber

Masato KAWABATA
Yasuhiro ISHIDA
Kazuo SHIMADA
Nobuo KUWABARA

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B    No.8    pp.3152-3157
Publication Date: 2005/08/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.8.3152
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section of 2004 International Symposium on Electromagnetic Compatibility)
Category: Measurements
Keyword: 
FDTD method,  ray-tracing method,  compact anechoic chamber,  site attenuation,  

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Summary: 
The site attenuation is an important parameter to evaluate an anechoic chamber. The ray-tracing method has been applied to analyze it. However, the lowest applicable frequency has not been cleared. In this paper, the FDTD method has been applied to analyze the site attenuation of a compact anechoic chamber from 30 MHz to 250 MHz, and this has been compared with the calculated one by the ray-tracing method to evaluate the lowest frequency where the ray-tracing method could be applied. The compact anechoic chamber, where the absorbers are placed on the all walls, has been used for the calculation. For FDTD analysis, the dipole antenna and the absorber have been modeled by using the large cell, whose size is larger than the diameter of the antenna element. For verification, the site attenuation of a compact anechoic chamber has been measured and compared with the calculated values by the FDTD method and the ray-tracing method. As the results, the calculated values by the ray-tracing method have larger deviation than the ones by the FDTD method when the frequency is less than 180 MHz.