應用仿樣函數於漸變槽孔天線之設計

Application of Spline Functions for the Design of a Novel Tapered Slot Antenna

林峻劭(Jun-Shao Lin)

指導教授 ： 李慶烈

淡江大學/工學院/電機工程學系碩士班/碩士(2017年)

https://doi.org/10.6846/TKU.2017.00985

摘要

本論文利用直交表的模擬實驗與響應表的結果進行驗證比較，用以找出優化解，並將搜尋範圍以等差逐代縮減的過程，以達到迭代的設計，且稱其為等差田口最佳化法，並將其應用於仿樣函數結合漸變槽孔天線的輪廓設計。
首先，我們探討傳統韋瓦第天線(Vivaldi Anteann)結構，使用一樣五次迭代的優化過程進行設計，並檢視其超寬頻特性。
接著，我們探究仿樣線漸變槽孔天線(TSA)，應用上述的等差式田口最佳化法進行五次迭代的優化設計，目標在保留類似傳統韋瓦第天線的遞增形狀，但稍做修正，用以調降最低頻率fL；亦即，本論文將引進多段三次方仿樣曲線來建構漸變輪廓以取代韋瓦第天線的指數輪廓。
當設計的超寬頻段設定在0.3~3GHz時， 結果顯示，韋瓦第天線的-10dB頻段落在1.65~3GHz結果，而仿樣曲線漸變槽孔天線則落在0.96~3GHz，兩者的尺寸都是240mm*120mm。由此實測結果可知，韋瓦第天線的最低頻率fL在1.65GHz(勉強可看成 ~1.1GHz—如果-8dB為基準)，而仿樣曲線漸變槽孔天線的最低頻率fL在0.96GHz，後者的最低頻率fL有明顯的向低頻方向推進。
此外，當直接將上述兩種天線進行超寬頻量測，兩者在最低頻率fL一直至8GHz皆有符合展現出漸變天線該有的S11超寬頻特性，且大體上以仿樣曲線進行設計的漸變槽孔天線，其S11仍比傳統的韋瓦第天線要好一些。至於場型的部份，仿樣曲線漸變槽孔天線朝開口輻射的指向性，可以從1.5 GHz左右開始一直到後面接續的高頻都沒問題，和一般文獻所陳述的一致，也是比韋瓦第天線要良好。

關鍵字

韋瓦第天線 ； 漸變槽孔天線 ； 仿樣曲線 ； 直交表 ； 田口最佳化法 ； 響應表

並列摘要

In this thesis, we compare the results of the simulated experiments of an orthogonal table with that of the corresponding response table, and then keep the better result for that next iteration to be performed. For the consecutive iterations the search ranges are reduced gradually in an arithmetical way to converge to the optimum solution. The method is thus called arithmetical Taguchi's optimization method (ATOM). This method is then applied for the design of profile with cubic spline for a tapered slot antenna.
First, we investigate the traditional Vivaldi Antenna and use five-iteration optimization process of ATOM for design, and examine its ultra-wideband characteristics.
Then, we explore the tapered slot antenna whose profile is described by cubic spline, and use the same method of ATOM to perform the five iterations for the optimal design. The target is to retain similar incremental profile as the traditional Vivaldi antenna, but with slightly change to reduce the minimum frequency fL. In other words, in this thesis a cubic spline curve is introduced to replace exponential curve to construct a new tapered profile for the TSA.
As the design of the ultra-wide band (UWB)is set at 0.3~3GHz, the experimental results show that the -10dB frequency range is 1.65~3GHz for the Vivaldi antenna as compared with 0.96~3GHz for the newly proposed TSA with spline curve. The size of both antennas are 240mm*120mm. The results show that the lowest frequency fL of the Vivaldi antenna is ~1.65 GHz (or ~1.1GHz if -8dB fre. range is considered), as compared to 0.96 GHz for the newly proposed TSA. Thus the proposed design for the TSA really is able to reduce the lowest frequency fL.
In addition, when the S11 measurement is made for the above two antennas concerned using vector network analyzer, both exhibits UWB characteristics, starting from fL up to 8GHz (the upper limit of the NWA employed). However, the S11 characteristic of proposed design for TSA is in general better than the traditional Vivaldi antenna. As the pattern is concerned, the proposed TSA exhibits its main radiation toward the opening direction consistently starting from 1.5 GHz all the way to frequency more than 8GHz, which is consistent with the literatures.

並列關鍵字

Vivaldi Antenna ； OA Table ； Cubic Splines ； Tapered Profile ； Taguchi Method

參考文獻

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