微帶陣列天線之設計與其輻射效率之分析

DESIGN AND RADIATION EFFICIENCY ANALYSIS OF MICROSTRIP ANTENNA ARRAY

周聖貴(Sheng-Kuei Chou)

指導教授 ： 黃啟芳

大同大學/電機資訊學院/通訊工程研究所/碩士(2012年)

摘要

在點對點長距離無線傳輸通訊中，單一天線輻射場型太寬，表示低天線增益和低指向性，因此單一天線並不適合拿來做長距離無線傳輸通訊。
本篇論文研究方向在於，微帶陣列天線之設計與輻射效率之分析。為了達到更好的天線增益、輻射效率和更高的指向性，使用了陣列天線來完成這個目的。同時使用了 Wheeler Cap Method 來量測天線的輻射效率。首先設計了單一的微帶天線，工作頻率在2.45 GHz，再來藉由模擬和實際測量不同的饋入網路架構、例如不同T型功率分歧器和在分歧器上彎曲不同的角度，對兩個和四個元素同相位的微帶陣列天線的影響，得到最佳的天線效能。最後量測兩個和四個元素的同相位陣列天線，在改變元素與元素之間不同的距離，在0.7、0.8、0.9倍工作頻率波長距離下量測天線的效能。
隨著增加元素之間的距離和元素的數量，雖然提高了天線增益和指向性，但同時也提高了旁辦準位和降低了天線輻射效率，並使得饋入網路更加複雜和更多損耗，導致饋入微帶天線的電流變小。最後在四個元素的陣列天線，元素距離0.9倍工作頻率波長情況下，得到最大的天線增益為8.02 dBi，天線輻射效率為69%.

關鍵字

微帶陣列天線 ； 輻射效率

並列摘要

For the point-to-point long distance wireless communication, single-element antenna has radiation patterns that are broad and hence have a low directivity and low gain. Hence it is not suitable for long distance communication.
This thesis presents design and radiation efficiency analysis of microstrip antenna array. In order to achieve better gain, efficiency, and directivity, antenna array is adopted and its radiation efficiency is measured by the Wheeler cap method. Firstly, a single-element patch antenna that operating frequency at 2.45GHz is utilized. Secondly, several different structural layouts on feed network like different T-junction and angle of bend on the T-junction are simulated and testified. Finally, different antenna’s efficiency performances are designed and tested for two-element antenna and four-element microstrip array that configured by different element spacing (wavelength) in 0.7λ, 0.8λ, and 0.9λ.
With the increase of the distance between the elements and overall number of elements, antenna gain and directivity is improved, meanwhile; however, the side beam is improved and the radiation efficiency is decreased. The feed network will be more complex and more loss, led to decrease of current on the patch. As a conclusion, the maximum microstrip antenna gain is determined to be 8.02 dBi in the four-element array; its layout element spacing is 0.9λ and relevant radiation efficiency is measured as 69%.

並列關鍵字

Microstrip antenna array ； Radiation efficiency

參考文獻

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