發(fā)布時間：2018-02-16 07:52

  本文關鍵詞： 相控陣 UHF RFID 圓極化 微帶天線 四臂螺旋天線　出處：《電子科技大學》2014年碩士論文　論文類型：學位論文

【摘要】：RFID作為一種非接觸式的自動識別技術,近年來廣泛應用在商品零售,交通物流,倉儲管理,門禁控制等領域。UHF RFID特指800/900MHz頻段的無源射頻設別技術,由于其讀寫速率快、可識別高速運動的物體、識別目標數(shù)量多、工作距離較遠、標簽成本低等優(yōu)點受到各國重視,正在高速發(fā)展。讀寫器天線作為RFID系統(tǒng)關鍵部件,將直接影響RFID系統(tǒng)的性能,讀寫器天線通常要求是圓極化的,同時根據(jù)一些應用需要,還要求做到寬頻帶,小型化等性能。相控陣天線具有增益高,波束掃描靈活快速的特點,因此本文將相控陣天線應用到無源UHF RFID系統(tǒng)中,以提高讀寫器對標簽的識別范圍和設別率等性能。本文首先闡述了相控陣天線的基本理論和UHF RFID技術的原理,提出一種可以應用于RFID的小型相控陣系統(tǒng),該系統(tǒng)包括天線陣列,移相功分饋電網(wǎng)絡,移相器控制電路。而本文的主要研究內容是設計圓極化的天線單元和陣列。為了滿足不同應用場合需要,本文設計了兩種不同類型的圓極化天線,可單獨用于讀寫器上,并且還將這兩種天線單元組合成陣列形式,用于小型的相控陣系統(tǒng)。第三章設計了一款寬頻帶高增益的圓極化天線,主要用于固定式RFID系統(tǒng),該天線選擇圓形微帶貼片天線的類型。在對微帶天線圓極化技術和寬頻帶技術研究的基礎上,通過對圓形貼片正交雙饋實現(xiàn)圓極化,通過增加耦合貼片和使用空氣介質來拓寬頻帶,該天線工作頻帶到達860MHz-960MHz,覆蓋了全球各標準劃分的UHF RFID操作頻帶。第四章設計了一款小型化的圓極化天線,主要用于便攜式讀寫器場合,該天線采用諧振式四臂螺旋天線結構,將天線的諧振臂改進為印制于PCB上的彎折倒F天線,以縮小尺寸和改善阻抗匹配,并通過一分四的移相功分網(wǎng)絡饋電。該天線尺寸小,重量輕,圓極化性能強且穩(wěn)定,波束寬,工作頻率覆蓋目前國內外應用最廣泛的902MHz-928MHz頻帶標準。第五章分別將前面設計的兩款天線單元組合成陣列天線,分為1×4線陣和2×2面陣,分析了天線陣列的性能,比如增益,波束掃描特性,并對陣列的低副瓣性能進行優(yōu)化。仿真結果表明,設計的天線陣增益高,副瓣低,可實現(xiàn)波束掃描,為相控陣技術在RFID領域的應用奠定了良好的基礎。
[Abstract]:As a non-contact automatic identification technology, RFID has been widely used in recent years in the fields of commodity retail, transportation logistics, warehouse management, access control and other fields. UHF RFID specifically refers to the passive radio frequency (RF) setting technology in 800 / 900MHz band, because of its fast reading and writing rate. As a key component of RFID system, the reader antenna, as a key component of RFID system, will directly affect the performance of RFID system, because of its advantages such as large number of targets, long working distance, low tag cost and so on, which can be used to identify objects with high speed motion. The reader antenna is usually required to be circularly polarized, at the same time according to some application needs, it is also required to achieve broadband, miniaturization, etc. The phased array antenna has the characteristics of high gain, flexible and fast beam scanning, etc. Therefore, the phased array antenna is applied to passive UHF RFID system in order to improve the performance of the reader in the identification range and the setting rate of tags. Firstly, the basic theory of phased array antenna and the principle of UHF RFID technology are described in this paper. A small phased array system, which can be applied to RFID, is proposed. The system includes antenna array, phase-shifted power division feed network. Phase shifter control circuit. The main research content of this paper is to design circularly polarized antenna elements and arrays. In order to meet the needs of different applications, this paper designs two different types of circularly polarized antennas, which can be used separately on readers and writers. In chapter 3, a circular polarization antenna with wide band and high gain is designed, which is mainly used in fixed RFID system. This antenna selects the type of circular microstrip patch antenna. On the basis of research on circular polarization technology and broadband technology of microstrip antenna, circular polarization is realized by orthogonal doubly-fed circular patch. By adding coupling patches and using air media to broaden the frequency band, the antenna operates in a frequency band up to 860MHz-960MHz, covering the global standard UHF RFID operating band. Chapter 4th designs a miniaturized circularly polarized antenna. The antenna is mainly used in portable reader. The resonant four-arm helical antenna structure is adopted in this antenna. The resonant arm of the antenna is modified into a bending inverted F antenna printed on PCB to reduce the size and improve the impedance matching. The antenna is small in size, light in weight, strong in circular polarization and stable in beam width. The operating frequency covers the 902MHz-928MHz frequency band standard, which is widely used at home and abroad. Chapter 5th combines the two antenna elements designed previously into an array antenna, which is divided into 1 脳 4 linear array and 2 脳 2 plane array. The performance of the antenna array, such as gain, is analyzed. The simulation results show that the antenna array with high gain and low sidelobe can realize beam scanning, which lays a good foundation for the application of phased array technology in the field of RFID.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TP391.44;TN820

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本文編號：1515022