新式微機電技術應用於天線設計與掃描洩漏波天線陣列設計

Abstract

本篇論文包含兩大部分: 使用微機電技術與特性所製作出的高頻微波天線與有壓制反射波功能的主動式二維掃描天線陣列。第一部分描述了低成本輕巧的單極天線之研究成果，包含兩種微機電單極天線的設計、製作與性能的量測結果。其中一種是製作於parylene薄膜上之曲折式單極天線，另一種是製作於Pyrex 7740玻璃基板兩側之三維立體單極天線。首先，可撓式雙頻單極天線被設計成曲折狀的金屬線，可縮小天線之物理尺寸並同時維持其電性長度。因parylene之低介電常數、高電阻係數與化性安定等等之優點，本實驗採用parylene薄膜做為天線之基板。根據實驗與量測結果，此天線具有小尺寸、低成本、雙頻特性與寬頻等優點。另外，立體的微機電立體單極天線亦成功地被設計出來，此天線製作在Pyrex 7740玻璃基板之兩側，兩側之金屬線以微機電電鍍銅連接孔連結，量測結果與模擬結果經過適當匹配後有相當程度之吻合。此小尺寸與容易製作之立體天線適合於無線通訊系統之應用。 第二部份描述可抑制反射波二維掃描式相位微帶洩漏波天線陣列，此結構經由實驗結果可知此主動掃瞄天線有許多功能，可以在空間中進行雙波束掃瞄、降低反射波影響的回饋式電路以及發展出孔隙饋入式結構以減少主、被動電路間干擾之技術與成果。在可抑制反射波功能的孔隙饋入式Patch 天線與短洩漏波天線之間加入移相器串接在一起，即可分別於上下空間個別產生兩個掃瞄的發射場型，短洩漏波天線本身隨著頻率改變會有掃描的窄波束，而Patch天線在相位改變時有掃瞄寬波束。

This thesis consists of two parts: Microelectromechanical technology based novel antenna design and the study of suppression of the reflected wave and beam-scanning features of the leaky-wave antenna array. In the first part, the design, fabrication and measurement of two types of micromachined antennas were presented. One is a flexible monopole antenna which was fabricated on parylene substrate, and the other is a 3D monopole antenna which was fabricated on both sides of a Pyrex 7740 glass wafer with through-hole connections. Flexible dual-band (2.4/5.2 GHz) monopole antennas were designed with meander-shaped metal tracks, because this can efficiently reduce the physical dimensions of the overall antenna size and maintaining the required electrical path-length. Due to parylene’s excellent physical, mechanical and chemical properties such as low dielectric constant, high resistivity, and inertness to chemicals, it can serve as a substrate for an antenna in our study. The advantages of these antennas are their small size, light weight, low cost, dual-band characteristics, broad bandwidth, and flexible. A compact 3D MEMS monopole antenna was also demonstrated. In order to reduce the size, the meandered monopole antenna was fabricated on both sides of a Pyrex 7740 glass wafer, and the metal lines on both sides were connected through via-holes. Measured performances of the fabricated 3-D antenna are in good agreement to the designed values in terms of operating frequency at 2.45 GHz and with a bandwidth of 190 MHz. This simple fabricated size low cost antenna is suitable for communication applications. In the second part of the dissertation, a two-directional linear scanning array was demonstrated by integrating a short leaky-wave antenna (LWA) with aperture-coupled patch antenna arrays on the backside. This active scanning antenna has many special functions known by experimental results. This architecture proposes a technique not only having the advantage of suppressing the back-lobe due to the reflected wave of the short LWA but also producing two separate linearly scanned beams in a different region of space. By tuning the backside individual phase shifter, the phase of this coupled signal to each antenna element can electronically control the patch antenna main beam on the backside. And simultaneously by changing the operating frequency, the main beam of the short LWA can scan on the front side. As a result, the two linear beam-scanning radiation patterns of individual direction can be created independently, which includes a narrow beam in the elevation plane at the front side and a broadside beam in the cross plane on the backside. This designed array scanning capability is suitable for military application, air traffic control, collision avoidance system, or radiolocation, etc. Thus, there is great potential for application in the future.