低背瓣短洩漏波天線、雙輻射波瓣掃描微帶天線，與雙頻高隔離度多輸入多輸出天線之研製

Abstract

本論文主要包含四大部分： 低背瓣輻射特性之短形洩漏波天線、具雙瓣輻射掃描功能之微帶天線，具高隔離度雙頻多輸入多輸出天線及共平面波導饋入架構晶片型天線。 第一部分提出短形洩漏波天線，首先利用漸進式架構，擾亂其電流分布，以達到降低正向反射波的效果。同時再引入互補形開口諧振環架構，嵌入於洩漏波天線的開路端部分，使得在天線開路端所產生的反射波訊號至此能夠產生抵消效果，進而達到抑制背波瓣輻射的目的。本章節提出兩個架構，一是將互補形開口諧振環架構嵌在天線主體接近開路端的部份，而另一個架構則是將互補形開口諧振環架構嵌於天線的接地面上。兩種架構都可以達到抑制背瓣輻射的效果。 第二部分所提出的，是具雙瓣輻射效果同時具掃描特性之微帶天線設計。在本設計當中，天線主體架構是由傳統式洩漏波天線為主軸。另外在天線的接地面上嵌入兩組L形的槽孔，在天線的下半平面，可以獲得另一個輻射波瓣，藉此得以產生雙瓣輻射的特性。由於在接地面嵌入兩組L形之槽孔，因此將對於洩漏波天線產生極大之影響。其一是洩漏波天線的相位係數與衰減係數會因此改變，進而使得洩漏波天線的操作頻帶會往低頻移動。另一影響則是下半平面的輻射波瓣會因此而增強。而本設計即是將此波瓣極大化，使該輻射波瓣也同樣具有和原本上半平面輻射波瓣相同的掃描特性。在此，兩組L形槽孔是本設計的重要參數，分別是該槽孔在天線主體中的所在位置、槽孔長度、槽孔寬度，以及相距位置皆是設計的參數考量。 第三部分提出具高隔離度雙頻多輸入多輸出天線系統設計。本章節中，先以去耦合理論來簡單闡明如何達到兩元件之間的去耦合效應。在此設計裡，以兩支簡單雙頻單極天線為基礎，利用具中和化之傳輸線架構，將兩支天線之間的耦合效應降低，以達到提升隔離度之效果。 第四部分則是提出晶片型天線之應用。第一支提出的天線為實作在被動元件整合玻璃板材製程上，為一共平面波導饋入摺疊式偶極天線設計。而第二支所提出的天線則是實作在台積電 0.18微米製程上，差動式共平面波導饋入偶極天線設計。兩支天線都是特別針對特定頻帶應用而設計之晶片天線。第一支摺疊式偶極天線是應用在24GHz 頻帶，第二支偶極天線則是應用於PDH 微波通訊系統頻帶。 第一支天線為單一天線設計，輻射場形則是以天線鉛直面全向性輻射設計。而第二支天線則是與射頻混波器整合在單一晶片上，因此輻射場形則是以前端輻射場形設計，以降低天線輻射對射頻電路的干擾。

This thesis consists of four parts: low back-lobe short leaky wave antenna, dual-beam scanning microstrip antenna, dual-band high isolation MIMO antenna and CPW on-chip antenna designs. In the first part, the low back-lobe short leaky wave antenna is proposed. Firstly, in order to reduce the reflected wave of the antenna, the tapering technology is utilized on the antenna design since the technology can disturb the current distribution. Next, the complementary split ring resonator (CSRR) structure is embedded on the open-end of the antenna. Because of the CSRR structure, the reflected wave caused by the open-end of the antenna can be suppressed. Hence, the back lobe radiation pattern of the antenna can also be suppressed effectively. There are two antenna configurations are proposed in this chapter. One of them is that the CSRR structure is on the antenna plane. For the other one, the CSRR is on the ground plane. Both of them can achieve the suppression of the back lobe radiation. In the second part, dual-beam scanning microstrip antenna is proposed. The antenna design is based on the conventional leaky wave antenna. The difference is that there two L-shaped slots are embedded on the ground plane of the antenna. Due to these two slots, another radiation beam beneath the antenna plane can be obtained. By this characteristic, the dual-beam radiation pattern is generated. The characteristic of the leaky wave antenna has been great significant affected since the L-shaped slots is embedded on the ground plane. One of the effects is that the propagation constant of the antenna is changed. Hence, the operating frequency band of the antenna shifts to lower frequency band. Another effect is the radiation beam beneath the antenna plane which is usually called side lobe is enhanced. However, the beam is enlarged greatly in this design to let the beam have the same characteristic with the beam above the antenna plane. Meanwhile, the two slots are the key parameters of this design such as the position, length, width and the spacing of the slots. The third part presents a dual-band high isolation MIMO antenna design. In this section, the decoupling theory is brief described that how to achieve the decoupling effect between two elements. In this design, the two elements are utilized by two dual-band monopole antenna. Next, the neutralizing transmission line structure is implemented in this design to reduce the coupling effect between the two monopole antennas. Therefore, the high isolation can be obtained for this MIMO antenna design. The fourth part proposes the applications of the on-chip antenna. The first design is the CPW on- chip folded dipole antenna which is fabricated by the Glass Substrate Integrated Passive Device (GIPD) process. This antenna is designed for 24GHz ISM band. The second design is the differential CPW on-chip dipole antenna which is implemented by the TSMC 0.18μm CMOS process. This antenna is designed for the PDH microwave communication system. The design of the radiation pattern of the first one is omni-directional on the vertical plane of the antenna. For the second design, the radiation pattern is designed as the end-fire configuration since this design is integrated with RF mixer circuit in one chip. This pattern is designed for reducing the interference which is caused by the antenna in circuit region.