利用雙隙孔天線陣列設計之平面回波反射板的理論與量測

Abstract

一個利用Van Atta 回波天線陣列設計的寬回應角平面反射板, 在汽車 防撞系統的應用上佔有重要的地位.□這個反射板上包含了許多經過適當 安排的雙隙孔型天線, 這些天線由微波基板背面的微帶線來饋入.□天線 的結構參數由無限長導線饋入之單隙孔型天線配合傳輸線分析得到.□這 些先前算出的結構參數當做雙隙孔天線結構的初始值, 則正確的天線結構 尺寸可由積分方程與動差法解得.□從回波天線陣列所得之回波散射場包 含了從成對天線的再發射場, 等效隙孔型天線之感應電流的直接散射場與 金屬板之散射場.□最後, 我們製造及量測了一個反射板, 其中包含了4組 陣列天線又每一組陣列天線有6個雙隙孔型天線.□理論及量測的結果彼此 亦相當吻合.□ A planar reflector with a broad responding beamwidth, which has the potential in the applications of the automotive collision system, is designed using the Van Atta retrodirective antenna array. The arrayre flector contains several dual slot antennas appropriately fed and paired by microstrip lines on the back side of the substrate. By usinga mixed potential integral equation (MPIE) together with the method ofmoment, the structure parameters of the antenna are first determined byneglecting the air mutual coupling between the two slotsand by thetransmission line analysis. With these preliminary parameters as aninitial guess, the full-wave MPIE is then used to design the exact antenna dimensions. The total back-scattering field from the present retrodirective array is calculated by adding the reradiation fields from the paire dantennas, thescattering fields directly from the terminated antennas,and the scattering fieldfrom the ground plane. Finally, a reflector containing four antenna sub-arrays, each with six dual slot antennas,is fabricated and measured. Good agreement has been achieved betweenthe theoretical and measured results.