無線傳輸裝置的廣泛應用改善了人與人的溝通以及人與環境的變遷，透過無線射頻的技術，增加生活的便利性，改善生活科技的可行性，減少架設資料線路的成本，不論是在倉儲管理、生醫技術、運輸監控、保全管制上皆能看到其巨大的影響，然無線傳輸射頻裝置並非無所不能，在使用上尚有部分的缺點及限制，以無線傳輸射頻辨識系統(RFID)為例，當讀取機(Reader)在讀取標籤(Tag)時，存在有兩項干擾因素，包括金屬與水的干擾以及操作頻率的干擾。 近年來無線傳輸射頻辨識系統更廣泛應用於生醫裝置的應用上，而人體各部組織裡，水分就佔了人體全身的70%，所以如果要研發體內植入式生醫裝置的話，水分子吸收無線電波的因素是不可忽略的，本研究透過時域有限差分法(FDTD)先分析溼度環境下RF天線之傳輸模擬，並調整其發射功率及觀察其接收之傳輸情形，求得變化環境下之功率、頻率、距離與人體電磁波吸收率(SAR)之效能關係。 本研究之結果將應用時域有限差分法模擬RF於不同環境變數下的傳輸結果之研究，對於生醫裝置的環境設置上能提供參考，減少電磁波過強之傷害或是訊號微弱之情況發生。 The popularity of wireless transmission technology has improved the efficiency of communication and information in daily life. The radio frequency transmission provides the conveniences and the feasibility of environment, that helps to reduce the cost the system setup for information technologies in industries such as storage management, biomedical technology, logistics control, and security monitor. However, wireless radio frequency device is not perfect and omnipotent; there are some disadvantages and limitations. RFID as an example, metal, water and operating frequencies are the interference factors while the Reader retrieve data from Tag. In recent years, RFID is more widely used in biomedical device applications. The human body contains 70% of water, this is an important factor that can not be ignored because the water molecules absorb radio waves and malfunction to implantable biomedical devices. The simulation experiment of radiofrequency transmission via finite difference time domain method (FDTD) is conducted in this study to analyze humidity effects under various environments and adjust its transmission power and frequency to achieve the maximum efficiency of receiver and best SAR performance. The results of this study will provide information of the radio frequency performance associated with various harshness environments; these references will be helpful for implantable biomedical devices and reduce the harm of over powered electromagnetic waves or under performance by too weak signals.
