針對陣列天線系統之電波波束產生方法之研究

A Study of Beam-Pattern Generation Methods for Antenna Array Systems

本論文試圖針對陣列天線系統的波束產生演算法提供一個系統化的研究，在考慮最接近理想波束型態以及滿足最小平方誤差（MMSE）還有一些特殊的要求的情況下，天線的權值（weights）被推導出來，第一個演算法針對理想的空間響應在特定的區間內做取樣，並利用離散傅立葉（DFT）技術推導出天線的權值，第二個方法選擇適當的窗函數（window function）以達到旁波帶（sidelobes）衰減或過渡帶（transition）變陡。由模擬結果可推證其產生的合成波束可以有彈性地成為適當的形狀，並具有可調整性以及增益控制的特性更符合實際的需求。 This report aims to provide a systematic study of several beam-pattern generation algorithms in an antenna array system. The weights are derived to best approximate a desired array pattern, either in a minimum-mean-square-error (MMSE) sense or to satisfy specific array pattern requirements. By sampling the specified (desired) spatial response at regular intervals, the first method performs a discrete Fourier transform (DFT) directly on the sampled sequence to derive the weights. The second method is premised on choosing appropriate window functions to attain the goals of sidelobe attenuation and steep transition from passband to stopband. Simulation results demonstrate that the generated beam pattern can be flexibly shaped, steered, and gain-controlled for practical requirements.