新型主動洩漏波天線與商用晶片型天線

Abstract

本論文包括兩大部份：主動頻率掃瞄洩漏波天線和縮小微帶晶片型天線。在論文第一部份內容，三種微帶主動洩漏波天線分別被提出與研製，利用奇對稱饋入結構來激發第一高階模，產生空間波來輻射能量。上述天線為洩漏波天線陣列、兩端饋入洩漏波天線與自振式倍頻器積體整合單端饋入式洩漏波天線。天線陣列方面，一個壓控震盪器主動模組分別結合一、二或四個天線輻射單元，藉由對稱分佈的天線陣列架構，不僅能夠有效地抑制反射波，同時也可以提高天線的功率增益，而洩漏波天線所具有頻率掃瞄的特性不會被影響。接下來我們提出了應用一條簡單的金屬微帶線結合振盪器或壓控振盪器，可以在空間中產生雙波束對稱式掃瞄輻射場型，此一架構具有兩倍掃瞄覆蓋區域、天線長度即為行進路徑與反射波抑制等優點，且因其為平面設計，非常適合單晶毫米波積體電路。此外，我們也提出一種可以作為洩漏波天線用來增強掃瞄角度和提昇操作頻率的方法，運用非對稱饋入結構的微帶洩漏波天線結合一個自振式倍頻器來說明此方法。自振式倍頻器可以直接產生二階諧波的訊號源，可以操作在較高頻處，且不需要外來的輸入源，電路架構簡單又精巧。二階倍頻所產生的頻率差為基模的兩倍，這對於因操作頻率改變才能掃瞄的洩漏波天線而言理論上可以增加其掃瞄角度。 論文第二部份在於研製適用於行動通訊之縮小型晶片型天線。設計理念在於將微帶線圍繞在基版上，藉以將天線長度縮小。我們分別以兩種不同基板材質來分別測試此種設計方法，所得實驗數據驗證我們的設計理念正確且可行，的確可以應用在相關無線通訊系統。首先我們以一般微波基版(RT-Duriod)為天線主體；另一個樣本為應用低溫共燒陶瓷材料（LTCC）所研製而成的晶片型天線。在相關實驗所得數據顯示此種設計理念的天線具有多個振盪頻帶、寬頻和體積小等優點，在空間的場型為全方向性，適用於一般個人通訊、無線區域網路與藍牙系統。

This thesis consists of two parts: The development of active frequency-scanning leaky-wave antennas (LWA) and compact microstrip chip antennas. In the first part of the dissertation, three types of the microstrip active frequency-scanning leaky-mode antennas that employ the first higher order mode (the space wave) of odd symmetry in their leaky wave region are presented. In order to excite the first higher order mode, the antennas are fed asymmetrically. These antennas includes the topologies of leaky-wave antenna (LWA) arrays, a two-terminal feeding LWA and a single feeding LWA integrated with a self-oscillating doubler. The antenna arrays are integrated one, two and four microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Using the symmetric configuration of this leaky-wave antenna array not only can effective reduce the reflected wave coming from the open end of a finite-length LWA, but it also can increase the power gain. A two-terminal feeding LWA is integrated with a varactor-tuned HEMT VCO. This design creates a dual-beam radiation pattern and has the advantages of the double scanning covered region and the suppression of the reflected wave. A new method which can enhance the scanning angle and elevate the operating frequency for the active LWA is proposed. We demonstrate an asymmetrically feeding LWA integrated with a self-oscillating doubler on a RT/Duriod substrate. The self-oscillating doubler generates the signal source at the second-harmonic frequency. The operating frequency 2FX (the second harmonic frequency) and the double frequency variation 2ΔFX are twice ΔFX at the fundamental band FX . This feature, combined with the advantage of no external injection power, is useful for millimeter-wave applications of the LWA and to obtain a wider scanning angle. In the second part of the dissertation, a new design of miniaturized microstrip helical antennas is proposed for the mobile communication. The antenna-size reduction is achieved by folding the microstrip line around a substrate. We use the RT-Duriod microwave substrate, the dielectric constant = 10.2 and the height H = 25 mil to fabricate a small microstrip monolithic antenna for the PCS and cellular phones. For the other sample, we use the Low Temperature Co-fired Ceramic (LTCC) technology to fabricate a compact dual-band chip antenna. We have carried out experimental studies on these antennas, which have the large bandwidth and the multiple frequency resonant bands. The chip antenna is suitable for the applications of the wireless network communication and the bluetooth system. In order to increase the resonant bandwidth, the antennas support the helical mode and the monopole mode. The radiation pattern in the E plane of the antenna is quasi-omnidirectional and the characteristic is like as the monopole.