雙極化背接金屬共平面波導槽孔洩漏波天線

Abstract

在背接金屬共平面波導（Conductor-backed coplanar waveguide，CBCPW）中以主模（共平面波導模態）傳播電磁波，而此結構於任何頻率下皆會產生洩漏波向兩側傳遞。通常對於此架構下有兩種應用：一種是利用波往兩側洩漏的特性來作為天線的設計；另一種是利用特定方式來抑制此洩漏波，使它不要在兩側的方向上產生不必要的耦合及串擾。 利用全波分析去分析背接金屬共平面波導結構，得知該洩漏波以某一角度偏離主軸傳遞，使波如同行進在平板金屬波導內。而在已知偏離角度下，我們沿該角度射線蝕刻矩形槽孔。利用矩形槽孔的特性，當槽孔長邊遠大於寬邊，並約等於二分之ㄧ波長（共振長度）時，電磁波便能有效地朝空氣輻射能量形成天線，最後可得一集中的邊射輻射場形，最後設計饋入電路產生兩種方向的線性極化，而形成一高增益主波束垂直於陣列平面之高效率雙極化天線。

Conductor-backed coplanar waveguide (CBCPW) propagates electromagnetic waves via dominant modes (coplanar waveguide mode), and excites leaky wave which propagates toward both sides despite the value of the frequency. In general, there are two applications based on this structure: first is to use such property to design the antenna; the other is to suppress the leaky wave through some methods in order to decrease the unnecessary couplings and crosstalk. Implementing the full wave analysis (Spectral Domain Approach) on the CBCPW structure, we can discover that the leaky wave propagates along a particular angle relative to the main CPW line, causing the wave to propagate as if in a parallel plate waveguide (PPW). Therefore, we can etch rectangular slots along the ground planes with the angle we have acquired. If the length of the slot is significantly longer than the width and approximately equals to half the guided wavelength, the slots fed by CBCPW will radiate power efficiently .We can thus obtain a centralized broadside radiation pattern and a dual-polarization antenna.