- 學位論文
一針對不可見物體所設計的射頻辨識影像偵測系統
A RFID Image Detection System for Invisible Objects
摘要
本論文的主要目的在於研究運用RFID無線射頻辨識技術來設計針對不可見物體的影像辨識系統，我們利用UHF頻段的被動式RFID系統來實現此想法。UHF頻段的RFID系統其操作頻段為860MHz到960MHz，我們特別針對此需求設計其專屬的寬頻RFID讀取器天線，我們利用堆疊式的微帶天線結構來讓其產生寬頻的效果，並採用圓形圖案來設計，使其能在特殊的共振模態下產生全向性的輻射場形。我們也利用電路學上共軛匹配的觀念來設計其專屬的RFID標籤天線，設計的過程及實驗結果將在本文中做詳細的介紹。 在此研究中，我們提出了一個新的想法運用於物體偵測上，我們稱此概念為負感應偵測，此概念是本研究的主軸。我們利用RFID標籤當做感應器並將之散佈於監控的環境中，當有一物體經過此區域時，部份的RFID標籤將會被其經過的物體所遮蔽注，我們藉由判斷哪些標籤是沒有回送訊號的來達到一個物體偵測的功能，並可將其物體的移動軌跡給捕捉出來。在於黑暗或沒有光線的環境下，相較於一般需要在有光的環境下才能進行攝影功能的攝相機來說，利用此系統所完成的物體偵測功能將會來的較實用及方便。
並列摘要
The main purpose of this thesis is to design an object-detection system by RFID. We use the UHF band passive RFID system to implement this idea. Its operation frequency band is from 860 MHz to 960 MHz. We design the UHF broadband reader antenna by adopting the configuration of layer-stacked patch antenna to conform this requirement. And in order to make the omni-directional antenna radiation pattern, this antenna is a circular patch, so that the antenna radiation pattern will become omni-directional in the particular mode. We also design the RFID tag by the concept of complex conjugate. And its design process and experiment results will be introduced in the following chapters. In this thesis, we introduce a new concept of “negative-detection”. That is the main focus on this study. We use the passive RFID tags as the sensors and spread them all over the monitoring area. We can identify which tag is hided by its on-off echo response. And by capturing the locations of silent tags, the moving trace of this detected object can be presented. Even if the monitoring environment is dark, this system can still work normally. So when monitoring about the objects that is invisible for the video cameras, this system is more useful for the application than video cameras in security system.