應用於無線區域網路之雙頻操作槽孔天線設計

Dual-band Slot Antenna Design for Wireless Local Area Network Application

許俊傑(Chun-Chieh Hsu)

指導教授 ： 王紳

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2013年)

摘要

本論文的主要架構，以設計一系列可應用於無線區域網路（WLAN）之雙頻操作槽孔天線為核心，藉由新穎的設計技術，於圓形槽孔及方形槽孔的結構中，實現雙頻、寬頻、多頻操作之縮小化槽孔天線設計。本論文的第一個研究重點是大幅縮小槽孔尺寸亦具有高頻率比之多頻、寬頻操作槽孔天線設計。藉由植入弧形金屬微帶於圓形槽孔中可激發出三個頻帶，其中第三頻帶是由未植入弧形金屬微帶的圓形槽孔所激發的共振模態，其中心頻率由槽孔的半徑來決定。同時，兩個新共振模態的操作頻帶分別被激發於頻率遠低於第三頻帶處，且其中心頻率分別是由不同槽孔位置上所植入的弧形金屬微帶之長度所決定，為一種新型的多頻槽孔天線設計。第二個研究重點是大幅增加操作頻寬亦可降低交叉極化輻射之雙頻、寬頻操作槽孔天線設計。藉由植入第一個環形金屬微帶於方形槽孔中，以激發出兩個頻帶，分別為中心頻率低於方形槽孔之基模態的第一頻帶，以及中心頻率高於方形槽孔之基模態的第二頻帶。分別以植入第二個環形金屬微帶以及使用結構不對稱的調整珠之方式，大幅增加第二頻帶的頻寬進而實現寬頻的操作。最後，於槽孔中植入一對金屬貼片以降低兩個操作頻帶之交叉極化輻射，使此槽孔天線的應用範圍更加廣泛。第三個研究重點，藉由植入螺旋形金屬微帶於方形槽孔中，以激發出兩個頻帶，分別為中心頻率低於方形槽孔之基模態的第一頻帶，以及中心頻率高於方形槽孔之基模態的第二頻帶，接著，使用 T 形調整珠的技術匹配第二頻帶並且增加其操作頻寬，最後，實現了雙頻操作之槽孔天線設計。上述的天線研究皆先以電磁模擬軟體 Ansoft HFSS 模擬器來分析天線的電場分布，並交互驗證討論模擬和實驗的結果，最後將所得之天線設計的各項特性呈現於本文之中。

關鍵字

雙頻天線 ； 寬頻天線 ； 多頻天線 ； 縮小化槽孔天線 ； 降低交叉極化輻射

並列摘要

The main structure of this thesis is proposed a series of dual-band slot antenna design for wireless local area network (WLAN) application as the core. By using novel design techniques, the design of the miniaturization slot antenna with the dual-band, multi-frequency and broadband characteristics in the circular and rectangular slot structure are achieved.
The first topic in this thesis focuses on the multi-frequency and broadband slot antenna design with significant slot size reduction and has a wider tuning range of dual-frequency ratio. By loading arc-shaped metallic strips along the circular slot, three resonant bands are excited. The operating frequency of the third frequency band associated with the resonant mode of the corresponding circular slot without arc-shaped metallic strips can be determined by the radius of the circular slot. In addition, two new resonant modes are founded to be excited at the frequencies much lower than that of the third frequency band. The operating frequencies of these new resonant modes are decided by the length of arc-shaped metallic strips which are from the different positions of slot. Is a novel technique of multi-frequency slot antenna design.
The second topic focuses on the dual-band and broadband slot antenna design for increasing the operating bandwidth and reducing cross-polarized radiation. By embedding the first ring-shaped metallic strips along the rectangular slot, two resonant bands are excited. The first frequency band is lower than the fundamental mode of the corresponding rectangular slot and the second frequency band is higher than that, respectively. By embedding the second ring-shaped metallic strips and using the asymmetrical tuning stub to enhance the bandwidth of the second frequency band, achieving a broadband operation. Finally, by adding two pairs of symmetrical slot patches inside the slot for reducing the peak cross-polarization level, to make this slot antenna wider range of applications.
The third topic, by embedding a pair of embedded spiral-shaped strips inside a rectangular slot, two resonant bands are excited. The first frequency band is lower than the fundamental mode of the corresponding rectangular slot and the second frequency band is higher than that, respectively. Then, by using the technique of the T-shaped tuning stub to achieve the second frequency band input impedance matching and increases the bandwidth of the second frequency band. Finally, a slot antenna design for dual-band operation is successfully developed.
All the abovementioned study works were performed by the analysis of the electric field distribution of the slot antenna designs obtained with the aid of the commercially available simulation software Ansoft HFSS. Details of the obtained dual-frequency characteristics from the simulated and experimental results of these proposed antenna designs are also discussed in this thesis.

並列關鍵字

dual-band antenna ； broadband antenna ； multi-frequency antenna ； miniaturization slot antenna ； reducing cross-polarized radiation

參考文獻

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