A systematic approach to synthesize the flat-topped beam (FTB) with arbitrary beam directions for uniform linear arrays (ULAs) is proposed, illustrated, and demonstrated. Based on the correspondence between the far-field pattern of ULAs and the response function of finite impulse response (FIR) filters, both the broadside and end-fire FTBs can be synthesized using window method, whereas the oblique FTB synthesis is failed due to the appearance of grating lobes. A mathematical analyzation indicates that two grating lobes are conjugate to each other. Thus, a linear phase method (LPM) is proposed to apply progressive excitation phases to each individual array element, which can eliminate the grating lobes by manipulating the two conjugate beams to overlap with each other. The proposed LPM is generalized to the synthesis of broadside, oblique and unidirectional end-fire FTBs, and the corresponding inter-element spacing constraints are addressed. The proposed approach is experimentally verified using a 16-element substrate-integrated waveguide slot antenna array. Comparing with the conventional Fourier series method and Woodward-Lawson method, the proposed approach has advantages of both smaller ripples in the main beam and controllable side-lobe levels. The proposed approach is promising for offering efficient beamforming functionalities for wireless communications, imaging, and radar applications.

中文翻译：

---

具有任意光束方向的均匀线性阵列的广义平顶光束合成方法

提出、说明和演示了一种用于合成具有任意光束方向的平顶光束 (FTB) 以用于均匀线性阵列 (ULA) 的系统方法。基于ULA的远场模式与有限脉冲响应（FIR）滤波器的响应函数之间的对应关系，可以使用窗口方法合成宽边和端射FTB，而倾斜FTB合成失败是由于栅瓣的出现。数学分析表明两个栅瓣彼此共轭。因此，提出了一种线性相位法（LPM），将逐行激发相位应用于每个单独的阵列元素，该方法可以通过操纵两个共轭光束相互重叠来消除栅瓣。所提出的 LPM 被推广到宽边的合成，解决了倾斜和单向端射 FTB 以及相应的元件间距限制​​。使用 16 元件基板集成波导缝隙天线阵列对所提出的方法进行了实验验证。与传统的傅里叶级数法和伍德沃德-劳森法相比，该方法具有主波束纹波较小和旁瓣电平可控的优点。所提出的方法有望为无线通信、成像和雷达应用提供有效的波束成形功能。与传统的傅里叶级数法和伍德沃德-劳森法相比，该方法具有主波束纹波较小和旁瓣电平可控的优点。所提出的方法有望为无线通信、成像和雷达应用提供有效的波束成形功能。与传统的傅里叶级数法和伍德沃德-劳森法相比，该方法具有主波束纹波较小和旁瓣电平可控的优点。所提出的方法有望为无线通信、成像和雷达应用提供有效的波束成形功能。