A synthesis procedure for realizing a cosecant-squared pattern in leaky-wave antennas (LWAs) is presented. In this method, the antenna is divided into a number of sections, each with an appropriate phase constant, length and leakage rate. The phase constant of the radiating sections is obtained such that their beam pointing angles would arrange on an appropriate layout in the shaped region. The two latter parameters are determined such that the radiation intensity of each section would decay with a cosecant-squared profile. Finally, using an optimization algorithm, i.e., a genetic algorithm (GA) optimization, the initial values of the leakage rate are adjusted to achieve the desired shaped region. The synthesis procedure is applied to a slotted substrate integrated waveguide (SIW) LWA, and a prototype of the antenna is designed to achieve the cosecant-squared pattern within the range of 10° to 30°. The results show that the antenna has low ripples (≤2 dB) in the shaped region with a low level of sidelobes (≤-18 dB) outside the region. The antenna is fabricated and measured. Measurements show a good agreement with the simulation results. The obtained results reveal that the proposed synthesis procedure can be utilized in designing cosecant-squared pattern LWAs to use in air-surveillance radar systems.

提出了一种在漏波天线（LWA）中实现余割平方图的合成过程。在这种方法中，天线被分为多个部分，每个部分具有适当的相位常数，长度和泄漏率。获得辐射部分的相位常数，使得它们的光束指向角将在成形区域中布置在适当的布局上。确定后两个参数，以使每个部分的辐射强度以正割平方轮廓衰减。最后，使用优化算法，即遗传算法（GA）优化，调整泄漏率的初始值以获得所需的成形区域。该合成过程应用于开槽衬底集成波导（SIW）LWA，天线的原型被设计为在10°到30°的范围内实现余割平方的方向图。结果表明，天线在整形区域中具有低纹波（≤2dB），而在该区域之外具有较低水平的旁瓣（≤-18dB）。天线被制造和测量。测量结果与仿真结果吻合良好。所得结果表明，所提出的综合程序可用于设计用于航空监视雷达系统的余割平方型LWA。