手機基地台天線輻射電場研究

Studies on Electric Fields Radiated from Cellular Phone Base Station Antennas

蘇祖彥(Tsu-Yen Su)

指導教授 ： 陳興義

元智大學/電機通訊學院/通訊工程學系/碩士(2008年)

https://doi.org/10.6838/YZU.2008.00028

摘要

本論文利用有限時域差分法、近場遠場轉換技術、和實驗量測來研究壹架設於七層樓屋頂水泥地板上之手機基地台天線所輻射出來的電場。 有限時域差分法輔以近場遠場轉換技術得到的天線輻射場形圖與實驗量測結果相當吻合。 論文中將報告並比較手機基地台天線輻射在頂樓樓板上1公尺的電場模擬結果與Narda高頻場強計的實測數據，比較結果再一次發現理論與量測非常吻合。在距離手機基地台50公尺範圍內之電場量測值與計算模擬值的範圍分別落在0.15~42.47和0.24~39.57 V/m。 即使最大值42.47 V/m仍低於IEEE/ANSI在1795 MHz時的輻射安全標準值 45% 以下。時域有限差分法亦被用來計算離手機基地台19公尺處壹鋼筋水泥所建構之小屋內之電場。小屋內經由模擬所得的電場值亦與量測值比較。比較結果發現數值計算結果與量測值令人滿意。研究中同時發現樓頂小屋屋內最大功率密度僅有IEEE/ANSI所建議的不可控制環境中在1795 MHz時輻射安全標準值的兩萬兩千分之一。

關鍵字

時域有限差分法 ； 手機基地台 ； 電場

並列摘要

In this thesis, electric fields radiated from a cellular phone base station antenna constructed on the rooftop of a concrete seven-story building are investigated by the finite-difference time-domain (FDTD) method, near zone to far zone transformation technique, and experimental measurements. From obtained radiation patterns, it is found that the theory of FDTD method implemented with near zone to far zone transformation technique makes a good agreement with the experiment. Simulation results of electric fields on the rooftop radiated from the cellular phone base station antenna are presented and compared with experimental data measured by a Narda Broadband Field Meter. It is again shown that simulation results calculated by the FDTD method make a good agreement with those obtained by measurements, for electric field distributions on a plane with a height of 1 meter above the rooftop of the seven-story building. Within 50 meters of the cellular phone base station, the electric fields obtained by measurements and calculations are in the range of 0.15~42.47 and 0.24~39.57 V/m, respectively. The maximum electric field strength of 42.47 V/m is less than 45 % of the ANSI/IEEE standard for public exposure at 1795 MHz.
The FDTD method is also used to calculate electric field in a small reinforced concrete house with a distance of 19 meters from the cellular phone base station. Simulation results of electric fields in the small reinforced concrete house are compared with those obtained by measurements. It is shown that the agreement of the numerical results with the measurement data is satisfactory. It is also found that the maximum power density in the small reinforced concrete house is twenty two thousands of time less than the exposure level recommended by the ANSI/IEEE for an uncontrolled environment at 1795 MHz.

並列關鍵字

FDTD ； cellular phone base station ； electric field

參考文獻

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