扇形合成波束單一導體洩漏波天線陣列於基地台之應用

Abstract

本論文中，提出了一單一導體洩漏波天線，透過SDA分析我們得到此天線之傳播常數，其中，相位常數β與空氣中之波常數k0之比值接近於1，由洩漏波天線洩漏角度之關係式可得知此一天線之洩漏角度接近end-fire角度。利用此一單一導體洩漏波天線為陣列天線之單位元素，組合成向end-fire方向輻射之扇形天線陣列。於本文中提出一扇型陣列場型合成法，透過此方法，經過計算可簡單的利用單位元素之天線，進而模擬估算出扇形陣列天線之輻射場型，不僅能有效找出較佳的扇形陣列之排列角度以及排列半徑，更能利用此法有效壓低扇形輻射場型之漣波(ripple)。 利用扇形陣列場型合成法，我們設計出2組扇形天線陣列，分別由5支單位元素、6支單位元素組成。其半功率波束寬角度分別為70度、90度，其中我們取4支第一組天線陣列，以角度互相間隔90度之方式擺設，再搭配本文中所製作之一對四射頻切換器，透過開關切換達到半功率波束寬角度達280度之陣列天線。利用4支第二組天線陣列，以角度互相間隔90度之方式擺設，再搭配一對四射頻切換器，透過開關切換達到半功率波束寬角度達360度之陣列天線。於本文中設計之第一組天線陣列之實作量測結果與模擬結果相當吻合，而第二組天線陣列由於製程上之困難，僅附上模擬結果。

In this thesis, a single-conductor leaky-wave antenna(SCLWA) is proposed. By using spectral domain approach(SDA) analysis, we obtain the propagation constant of this antenna. We find that the phase constant β of this antenna is close to the wave number in the air k0. By the leakage angle equation of leaky-wave antenna, we find that this antenna radiate toward end-fire direction. We use this SCLWA to be the unit element and design sector beam antenna arrays which radiate toward end-fire direction. We also propose a sector antenna array beam composite method. Using this method, we easily estimate the radiation patterns of sector antenna array. By changing the radius and spacing angle and the length of antenna, we obtain the desire half power beamwidth(HPBW) radiation pattern and reduce the ripple effect. Then we design two sets of single-conductor leaky-wave sector antenna arrays, which have five-,and six-elements, respectively. Beamwidth are 70° and 90° respond to the above antenna arrays. Then we place four identical sector antenna array toward different direction. After adding an RF single pole four throw (SP4T) switch fabrication, the HPBW of the switchable sector antenna arrays are 280° and 360°. Because of the limitation of fabrication technology, the second set of sector antenna array is not achieved. The simulation and measurement result will be presented.