微機電堆疊式開槽耦合可控波束微帶天線陣列之研究

Study on Micromachined Stacked Aperture Coupled Microstrip Steering Beam Array

指導教授 : 黃榮堂、施勝雄   研究生 : 楊凱  機電整合研究所 91年


摘要

  本文旨在提出一種微機電技術製作方法,製作開槽耦合可控波束微帶天線陣列,首先研究開槽耦合微帶天線與傳統相移器的基本分析理論,採用精確度較高的全波分析法作探討,並利用FR4玻纖電路板製作用於C頻段的開槽耦合微帶天線、低相位誤差型與反射型相移器。由實驗結果得知,天線頻寬為7 %,增益為7dBi,交叉極化小於 -10dB,前後主波束功率密度比(F/B比)為8dB。而低相位誤差型與反射型相移器的插入損失分別在1.98dB~2.67dB與3.11dB~5.07dB之間,頻寬約為40 %與20 %,且在操作頻率附近,可減少約一半因為頻率升高所產生的相位誤差。
其次將二種相移器與開槽耦合微帶天線結合,設計成2 × 2的開槽耦合可控波束微帶天線陣列,當在天線陣元間饋入0度~180度的相位差時,結合相移器的兩種天線陣列,波束可掃描角度在E面分別為 ±31度與 ±30度,F/B比在7~9dB之間,增益則為8.8 及 9.2 dBi,且均有1~2GHz的頻寬。
最後利用IE3D設計Ka頻段的堆疊式開槽耦合微帶天線與可控波束微帶天線陣列,在模擬阻抗良好的匹配情況下,其頻寬有34 %及6 %,天線增益為7.9 dBi與9.98~12.15 dBi,F/B比為16dB及10~12dB,而可控波束微帶天線陣列的掃描角度為 ±30度。在製程設計時則應用微機電製程的微型開關來改善電子式的開關在高頻的缺點,並使天線陣列與微型開關皆使用微機電製程技術來完成。

ABSTRACT

  In this paper, the characteristics of aperture coupled microstrip patch antenna (MPA) and phase shifter are studied. The full-wave numerical analysis tool IE3D is used to simulate and calculate. Aperture coupled MPA , transmission type and reflective type phase shifter are built on a permittivity εr = 4.4, tanδ=0.0254 FR4 substrate. The measured antenna bandwidth is 7 %, whereas the front to back ratio is 8dB with the cross-polarized fields better than -10dB and antenna gain is about 7dBi. In addition, the bandwidth of the two type phase shifter we proposed is 40 % and 20 %, which reduce 50 % phase error compared with traditional ones at operating frequency. Whereas about 1.98~2.67dB and 3.11dB~5.07dB insertion loss is measured.
Two types of 2×2 Aperture coupled microstrip steering beam antenna array (MSBA) composed by foregoing two type phase shifter are built on FR4 substrate for C band application. The measured antenna gain are 9.2 dBi and 8.8 dBi, whereas the front to back ratio is 7~9dB with the beam scan angle in E plane is ±31degrees and ±30 degrees. The measured bandwidth of two type aperture coupled MSBA is 1~2GHz.
Finally, this paper propose a feasible method to fabricate Ka-band stacked aperture coupled MPA and MSBA built on a permittivity εr = 11.9, tanδ=0.001 silicon wafer by micromachined techniques. The results of 34 % and 6 % bandwidth, 7.9dBi and 9.98~12.15 dBi gain, F/B ratio 16dB and 10~12dB are simulated by IE3D for stacked aperture coupled MPA and MSBA, and the beam steered from –30 to +30 degrees at operating frequency.