| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 101 === 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.
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