恒定束宽换能器(CBT)阵列工作频率上限分析

摘要

Constant beamwidth transducer (CBT) array achieves broadband constant beamwidth using frequency-inde-pendent element weightings. Conventional methods usually underestimate the upper limit of the operating frequency for the CBT array. Therefore, the upper limit of the operating frequency for various CBT arrays is analyzed. Firstly, the upper limit of the operating frequency is analyzed theoretically. The results indicate that the upper limit of the operating frequency for the delayed-curved straight-line CBT array can be achieved by array theory, but it is quite complicated in the case of circular CBT array. Secondly, the upper limit of the operating frequency for the circular CBT array is analyzed using numerical meth-od, and the fitting model is also provided. Thirdly, the upper limit of the operating frequency for the two-dimensional CBT array is analyzed, and the effects of mainlobe ripple and sidelobe amplitude are also discussed. The results indicate that the upper limit of the operating frequency is greater than the result achieved by the array theory for the circular, spherical and cylindrical CBT arrays.%恒定束宽换能器(CBT)阵列可以在宽频带范围内采用不随频率变化的简单阵元权重实现恒定束宽的波束特性.传统的方法通常低估了CBT阵列的工作频率上限,因此分析了各种类型的CBT阵列的工作频率上限.首先,从理论上分析了CBT阵列的工作频率上限,结果表明延时直线形CBT阵列的工作频率上限可由阵列理论得到,而圆弧形CBT阵列的工作频率上限较为复杂.其次,采用数值方法分析了圆弧形CBT阵列的工作频率上限,并给出了具体的拟合公式.最后,讨论了二维CBT阵列的工作频率上限,以及不同条件对CBT阵列工作频率上限的影响.结果表明,圆弧形CBT阵列、球面CBT阵列和柱面CBT阵列的工作频率上限大于由阵列理论得到的结果.