使用契比雪夫T型阻抗轉換器設計4x1毫米波天線陣列

A Millimeter Waves 4x1 Antenna Array Based on The Ultra-Wide Chebyshev Type Powr Divider

以契比雪夫多級阻抗匹配器(Chebyshev Multi-stage Matching Transformer)去設計功率分配器(Power Divider)，使用多段式微帶線研製24GHz多層T型架構來實現超寬頻之功率分配器。此寬頻功率分配器可以調整天線陣列中的電流分佈，使得天線陣列的增益級指向性能大幅提高。除此之外，亦能降低天線陣列的旁波束與減少天線的交叉極化，在這可以應用於高解析度之車用雷達。本文中功率分配器可以將以等功率均勻輸出至4x1天線陣列之輸入埠，T型功率分配器之中心頻率設計在24GHz，以50Ω的饋入線結合雙臂步階T型阻抗轉換器、饋入T型阻抗轉換器及契比雪夫多級阻抗轉換器來進行比較。這三種不同T型阻抗轉換器操作在24GHz，其-10dB頻寬皆超過29GHz，HFSS模擬結果顯示，4x1天線陣列迴波損耗-10dB頻帶範圍為24.49 ~24.94GHz，頻帶寬度450MHz與最小電壓駐波比VSWR為1.13，最大反射回損為-23.72dB。主波束最高增益值為8.75dBi，第一旁波束之最大增益值為-11.67dBi，主波束與旁波束差約為20.47dB，主波束範圍角度約-35°~ 27.02°。

 

The Chebyshev Multi-stage Matching Transformer implemented inside the power divider is used to modify the current distribution of the output ports and improve the directivity of the antenna array. The amplitude of the first side lobes is further reduced. In this paper, a millimeter waves 24 GHz 4x1 antenna array based on the ultra-wide Chebyshev type power divider is designed and simulated. It is observed that the designed antenna array have operation bandwidth of 450MHz (from 24.49 to 24.94GHz) and minimum VSWR of 1.13. The magnitude discrepancy between the main lobe and the first side lobe is about 20.47dB. The E-plane half-power beam width is 62° (from -35° to 27.02°).