寬頻圓極化指數曲線型槽孔天線

Exponentially Curved Aperture Antenna for Broadband Circular Polarization Operation

趙芳翌(Fang-Yi Chao)

指導教授 ： 林怡成

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00417

摘要

本論文提出一種新穎的寬頻圓極化天線。此種天線，利用等角曲線的寬頻特性結合在槽孔天線的設計上。初步的想法來自一圓形槽孔天線，加入合適的等角曲線作為新槽孔的形狀，進而改進其圓極化頻寬的特性。本論文成功證實加入等角曲線的寬頻元素後，單一天線元件的正向軸長比可以達到49.1%。
在完成單一圓極化天線寬頻的目標之後，緊接著改善槽孔天線雙向輻射的問題。在此，我們利用兩種金屬共振腔：圓形金屬共振腔、同槽孔形狀金屬共振腔。在圓形金屬共振腔的設計方面，由於受其基頻共振模態之影響，因而降低天線圓極化寬頻的特性；在同槽孔形狀金屬共振腔的設計方面，不僅沒有圓形金屬共振腔的共振模態的問題，其輻射場形在正向上另具有對稱的效果。由於其特殊的共振腔形狀，不易實作在低頻段,故將其設計實現在60GHz低溫共燒陶瓷(LTCC)的製程上。

關鍵字

等角 ； 圓極化天線 ； 寬頻 ； 槽孔 ； 共振腔

並列摘要

This thesis presents a broadband circularly polarized (CP) aperture antenna using the equiangular curves as edges of the aperture shape. The previous work shows that the circular aperture antenna of traveling wave type has wider CP bandwidth compared to the resonant type of antennas like truncated patch or slot. The wideband characteristics are mainly attributed to a traveling wave excited and propagating along the aperture edge leading to a leaky wave radiation. It shows that CP radiation may be generated from an aperture of either circular or polygonal shape. In this thesis, we investigate the aperture antenna using the equiangular shape and successfully achieve the axial ratio bandwidth up to 49%.
In addition, the antenna design is extended to incorporating a backed cavity for unidirectional pattern usage. There are two kinds of cavities investigated: the circular cavity and the equiangular-shape cavity. The aperture antenna backed by a circular cavity performs a degraded axial ratio bandwidth mainly limited by the fundamental mode of the cavity. However, the equiangular aperture antenna backed by the same-shape cavity may generate a very wideband axial ratio and a stable unidirectional pattern with peak gain in the zenith direction. The design of equiangular-shape cavity is demonstrated with LTCC substrate at 60 GHz that the cavity wall is realized by a series of via wall along the aperture edge.

並列關鍵字

Equiangular ； circularly polarized antenna ； broadband ； aperture ； cavity

參考文獻

[1]V. H. Rumsey, “Frequency Independent Antennas,” IRE National Convention Record, Part I, pp. 114-118, March 1957.

[2]J. D. Dyson, “The Equiangular Spiral Antenna,” IRE Trans. Antenna Propag., Vol. 7, pp. 181-187, April 1959.

[4]S. K. Lin, "An Impedance-Transformation Embedded Sequential Rotation Feeder for Broadband Circularly Polarized Antenna Array", Master Thesis, National Taiwan University, Taiwan, June 2008.

[5]J. S. Row and S.W. Wu, “Circularly-Polarized Wide Slot Antenna Loaded with a Parasitic Patch,” IEEE Trans. Antenna Propagat., Vol. 56, No.9, pp. 2826-2832, Sep. 2008.

[6]N. C. Karmakar, M. E. Bialkowski, “Circularly-Polarized Aperture-Coupled Circular Microstrip Patch Antennas for L-Band Applications” IEEE Trans. Antenna Propagat., Vol. 47, No.5, pp. 933-940, May 1999.