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1、上海交通大学 硕士学位论文 毫米波MEMS天线研究 姓名：陈伟强 申请学位级别：硕士 专业：微电子学与固体电子学 指导教师：丁桂甫 20080101 iii 毫米波毫米波 MEMS 天线研究天线研究 摘 要 近几年来，随着智能手机等无线终端设备的普及，人们对无线通讯也提出 了更高的要求，如：功耗低、传输速度快、体积小等。在集成电路线宽向着 65nm 发展的今天，大部分射频电子元器件都能在集成电路上实现，如：电阻， 电容，传输线等。但是作为自由空间与导波装置之间连接元件的天线却还未能 达到集成化制造的程度。天线是整个无线通讯系统中尺寸最大的一个，天线性 能的好坏影响着移动设备的功耗、传输质量等功
2、能。同时，由于卫星通信的发 展和无线电频道的日益拥挤，无线电技术朝越来越短的毫米波、亚毫米波方向 发展。在毫米波波段，波长变短，对加工精度的要求也相应的提高了，传统的 精密机械加工已经不能满足这样的高精度要求了。因此，集成化的天线设计以 及高精度的天线加工技术成为研究人员关注的重点。 MEMS(Micro-Electro-Mechanical Systems)微细加工技术是半导体平面加 工技术；此外，MEMS 微细加工具有微米级的加工精度，完全能够用于集成 化毫米波天线的加工。本文在传统平面贴片和缝隙天线基本理论的基础上，结 合三维非硅 MEMS 微加工工艺的高精度、可立体加工、高集成度等特点
3、，提 出了三种新型 MEMS 毫米波天线，使用有限元仿真工具，对每种天线设计进 行了系统全面的仿真优化，并最后确定了天线尺寸参数，进行了加工制作以及 测试验证。 设计一研究了一种工作在 Ka 波段，微带共面缝隙耦合馈电，利用 3dB 电 iv 桥移相器实现圆极化，基于 MEMS 微加工工艺的圆极化微带天线。可以在不 改变贴片与馈线本身的尺寸且无需额外增加匹配网络的情况下， 经过调节耦合 缝隙宽度以及 3db 电桥移相器端口调配枝尺寸， 两级调节圆极化天线的阻抗匹 配，显著的改善了辐射单元与微带馈线的阻抗匹配度与可调性，结构简单，圆 极化效果好。设计的天线中心频率为 35GHz，增益为 6.86
4、dB，阻抗带宽（驻 波比2）为 4GHz，约 11.4%，轴比带宽（AR3）约为 5.9GHz，约 16.9%， 实现了较高的增益与带宽。 设计二研究了一种基于 MEMS 微加工技术制作，共面波导馈电的单向宽 带毫米波平面缝隙天线。 辐射单元采用平面矩形缝隙， 可实现约 80%的阻抗带 宽（驻波比2） ，通过增加波束引导缝隙和多层反射截止缝隙，基本实现了单 向辐射，增益可由原来的 3.8dB 提高到约为 6.8dB。该设计充分利用了三维非 硅微加工的技术特点，同时巧妙融合了贴片天线和缝隙辐射的一系列性质，是 一种有明显创新特色的毫米波小型宽带天线设计形式。 设计三提出了一种新型共面波导馈电的单
5、向宽带圆极化毫米波平面缝隙 天线的设计。天线基于 MEMS 三维微加工技术制造，具有多层结构与三维悬空 结构。 辐射部分通过新型的短路微扰法实现了平面圆环形缝隙天线的单馈宽带 圆极化，驻波比2 时的实测阻抗带宽达到约 20%，AR2 时的轴比带宽约为 17.6。并提出了一种新型近似理想磁导体表面截止波导反射缝隙结构作 为电磁波反射表面。 通过增加新型的波束引导缝隙结构与截止波导反射缝隙结 构，在实现了平面化、低剖面与宽频带、圆极化目标的同时，缝隙天线的增益 可由原来的约 5.2dB 提高约为 7.5dB，解决了平面缝隙天线单向辐射，提高增 v 益的问题。 天线阵列相对于单元结构更容易获得高增益
6、和低副瓣，且结构相对紧凑， 因而广泛应用在雷达和微波通信系统中。 因此最后本文研究了基于前面提出的 天线单元采用并馈网络组成的 14 以及 22 两种四元阵列天线。根据激励要 求和阵列结构结合阵列各单元的激励幅度和相位值进行馈电网络的设计。 关键词：关键词：MEMS 天线，贴片天线，微带天线，缝隙天线，微机电系统 vi Study of Millimeter Wave MEMS Antenna ABSTRACT In recent years, wireless communication systems, such as smart mobile and PDA, are more and
7、more popular. On the other hand, wireless communication systems meet more and more demands, such as low power consumption, high transmission speed, small device volume and etc. Now the IC process is reaching 65nm, most RF circuits devices, such as resistor, capacitors and transmission lines, can be
8、integrated in a single chip. However antenna linking the device and free space cant be integrated in the chip, so the whole system volume is largely dependent of the size of antenna. The performance of the antenna has a significant influence on the system performance: power consumption, transmission
9、 quality, and etc. At the same time, wireless communication frequency is now moving to millimeter-wave and sub-millimeter-wave band because the communication channel is becoming more and more crowded. In millimeter-wave band, the wavelength is only several millimeters, so the accuracy of fabrication
10、 process is most critical. Traditional precise machining cant meet the requirements of the high precision of millimeter-wave fabrication. As a result, researchers have paid more and more attention to the design and fabrication of integrated antenna. Based on semiconductor process, MEMS (Micro-Electr
11、o-Mechanical Systems) micro-fabrication technology is compatible with IC process. In addition, MEMS vii micro-fabrication technology has an accuracy of 1m, so it can be used for the fabrication of millimeter-wave antenna. According to antenna theory, combining with features of MEMS fabrication proce
12、ss, this article gives several designs of millimeter-wave antennas. And the numerical simulation is performed for each design using Ansoft HFSS, which is a simulation software based on Finite Element Method (FEM). The first design introduces a circularly polarized microstrip antenna fed by coplanar
13、coupling microstrips. Through the coupling method the radiation efficiency and impedance matching are improved, while the coupling efficiency is not affected. The circular polarization is implemented by the 3dB microstrip bridge. The second design introduces a broadband unidirectional coplanar waveg
14、uide (CPW) fed rectangular slot millimeter wave antenna based on MEMS micro-fabrication technology. A wide impedance bandwidth of 75% (S11-10dB) was obtained. A special method based on MEMS process for CPW-fed slot antennas to obtain unidirectional radiation and higher gain is introduced. By adding
15、3 layers of wave cut-off slots and a guiding slot, the antenna achieves unidirectional radiation, and the max gain of the antenna increases from 3.8dB to 6.8dB. In the third design a novel MEMS-based CPW-fed millimeter wave slot antenna for broadband circularly polarized and unidirectional radiation
16、 with multilayer 3D structures is proposed. Through a special short-circuiting stub perturbation method, the circular ring slot antenna generates circularly polarized viii radiation and achieves a broad impedance bandwidth of 20%. To obtain unidirectional radiation and relatively higher gain, a special method based on MEMS micro-fabrication technology is introduced. By adding special wave guiding slot s
