摘要:
本文分析了三维圆柱形基阵波束垂直栅瓣形成机理,导出波束垂直扫描极限波长和基阵其他参数的关系,指出指向性函数通常是复数,并用子阵相移法来调节复合子阵的相位特性,在圆环阵指向性图适当位置插入零点,以消除垂直栅瓣、扩大基阵波束扫描范围。对不同基阵,找出相移参数β的最佳值,一般取kβ≈0.5为宜。以两个弧面阵为例作了数值计算,证明对全圆阵导出的极限波长也适用于弧面阵;和相同条件下未相移基阵相比,可将波束垂直扫描范围扩大到间距d为五个波长左右,或将基元数减少2—4倍;当未相移基阵指向性图出现栅瓣时,并可将指向性指数提高1.7到5.5dB。
Abstract:
By analyzing the principle of a grating lobe forming of the three-dimensional cylindrical arrays, the relationship between the limit wavelength of the vertical beam scanning and other parameters of the arrays is derived, and the directivity functions are shown complex. In order to eliminate vertical grating lobes of a cylindrical array and expand beam scanning region, the nullr are interposed in the directivity patterns of the ring arrays by means of the sub-arrays phase shift.
The optimum values of the phase shift parameter β are found. In general, it is better to take Kβ≈0.5. As an example, numerical values are calculated for two different partial cylindrical arrays, the results show that the limit wavelength derived for full cylindrical arrays can also be applied to partial cylindrical arrays. Compared with the arrays without phase shift under the same conditions, vertical beam scanning region is expanded to a extent that the beam can scan ±20° when d≈5λ, or the number of elements is decreased 2 to 4 times; and the directivity index is increased 1.7 to 5.5 dB when the grating lobes present in the directivity patterns of the arrays without phase shift.