應用於極化分集之雙饋入60-GHz超大型微帶天線

本論文提出一種雙極化的超大型微帶天線，主要應用於60-GHz的點對點無線傳輸。所謂「超大型」乃指有別於傳統工作在基頻的天線，為了操作在共振頻率較高的高階模態，天線的尺寸被等比例放大。由於 60-GHz 頻段的特性，設計於60-GHz的傳統微帶天線大小與饋入的傳輸線尺寸相當，造成阻抗匹配困難。本論文提出的大型天線可有效解決此問題，不需要複雜的匹配電路即可達成理想的阻抗匹配。再者，由於較大的天線尺寸，低溫共燒陶瓷製程技術的良率以及製作誤差的容忍度可以因此提高。論文中的天線架構採用彼此垂直的兩條微帶線饋入，達成相互正交的雙線性極化，可有效應用於極化分集，以減少極化不匹配所造成的能量損失。由於較大天線的面積，此天線不需要使用天線陣列的形式，其天線增益即大於傳統的微帶天線。此外，在不破壞電流邊界條件的情形下，本論文採用開槽的方式增加兩個輸入埠之間的隔離度。而除了使用微帶線直接饋入之外，本論文亦設計T型微帶線耦合的饋入方式來提高隔離度。所有的設計已於5.8-GHz ISM 頻段實驗佐證完成，量測結果證實在天線的阻抗匹配頻段內可達到超過35-dB的隔離度，且單一一個天線即可達到9-dBi天線增益。最後本論文也提供60-GHz 的模擬結果以便未來實作並量測。

關鍵字

微帶天線；高階模態；雙極化；毫米波

並列摘要

The dual-feed dual polarized oversized patch antenna is presented in this thesis for 60-GHz applications. The term “oversize” means that unlike a conventional patch antenna which is operated at its fundamental mode, the proposed antenna is enlarged by exploiting higher-order modes. In 60-GHz bands, the dimensions of the antennas are usually comparable with their microstrip feed lines, resulting in feeding difficulties. The proposed oversized antennas can solve these problems effectively. Good input matching can be achieved without using complicated matching networks. Furthermore, owing to its enlarged size, the manufacturing error tolerance of fabrication based on the low temperature co-fired ceramics technology can be increased. The proposed antenna is fed by two vertically placed microstrip lines, exciting two similar modes with orthogonal linear polarizations for polarization diversity applications. The power loss due to the polarization mismatches can thus be reduced. Due to its enlarged size, the oversized antenna can also have higher antenna gain than the conventional one without using its array form. Moreover, in the modified designs, pairs of slots are etched on the patch to increase the port-to-port isolation with the current boundary condition maintained. In addition to the direct microstrip line feed, the microstrip-T coupled feed is also designed in this thesis to improve the isolation. All designs are verified by the experiment at 5.8-GHz ISM band. Up to 35-dB in-band isolation are achieved. Around 9-dBi antenna gain are obtained with a single antenna. Simulations for the 60-GHz version are provided for future experimental verification.

並列關鍵字

Patch antennas ； higher-order mode ； dual polarization ； millimeter wave

參考文獻

[1] T. Baykas, C. S. Sum, Z. Lan, J. Wang, M. A. Rahman, and H. Harada, “IEEE 802.15.3c: The ﬁrst IEEE wireless standard for data rates over 1 Gb/s,” IEEE Communication Mag., vol. 49, no. 7, pp. 114–121, Jul. 2011.

[2] A. E. I. Lamminen, J. Saily, and A. R. Vimpari, “60-GHz patch antennas and arrays on LTCC with embedded-cavity substrates,” IEEE Trans. Antennas Propag., vol. 56, no. 9, pp. 2865–2874, Sep. 2008.

[3] H. K. Pan, “Dual-polarized Mm-wave phased array antenna for multi-Gb/s 60GHz communication,” in Proc. IEEE AP-S Int. Symp., July 2012, pp.3-8, 3279-3282.

[4] M. Umehira, T. Sasame, and H. Sawada, “An Orthogonal Polarization Based MIMO Transmission for Advanced 60GHz WLAN,” in Proc. IEEE Vehicular Technology Conference , May 2012, pp.1,5, 6-9.

[7] D. Wang, H. Wong; K. B. Ng, and C. H. Chan, “Wideband shorted higher-order mode millimeter-wave patch antenna,” in Proc. Int. Symp Antennas Progag., July 2012, pp.1,2, 8-14.

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應用於極化分集之雙饋入60-GHz超大型微帶天線

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