基于共形阵列的和差波束测向算法研究

Due to easy realization, strong robustness and high angle measurement accuracy, direction finding via sum and difference beams is widely used in the regular planar array. When direction finding via sum and difference beams is extended to the conformal array, the particularity of the array structure will make the existing algorithms no longer applicable or the algorithm performance difficult to be determined，and makes the direction finding via sum and difference beams of the wide-band signals more complex. Moreover, in the application of direction finding via sum and difference beams to the continuous wave radar or communication system, because the desired signal is always present in the received data, direction finding methods via adaptive sum and difference beams are faced with some problems, such as the desired signal suppression, the angle curve linear maintaining and zero constraint on difference beam of the sub array and so on..This project intends to make an in-depth study of the above scientific problems. On the basis of full consideration of the characteristics of the conformal array structure, a direction finding method via sum and difference beams based on the joint linear constraint will be studied to realize the direction finding of the full array or subarray level. To carry out the anti-interference direction finding via sum and difference beams, the adaptive beamforming algorithm with ability of suppressing interferences only and remaining the desired signal will be developed. Achievements and methods obtained in this project can be widely used in used in the conformal array-based applications including radar, communication, measurement and control.

和差波束测角由于易实现，强稳健，高精度，在规则平面阵中得到广泛应用。当将和差波束测角拓展到共形阵列时，阵列结构的特殊性会使得已有方法不再适用或性能难以确定，并令宽带信号的和差测向变得更加复杂。此外，将和差波束测角应用到连续波雷达或通信中时，由于期望信号一直存在于接收数据中，自适应和差波束测向方法面临着期望信号被抑制，鉴角曲线线性关系难以保证和子阵级差波束零点约束困难等问题。.本申请项目拟对上述科学问题进行深入研究，在充分考虑共形阵列结构特点的基础上，拟采用基于联合线性约束的和差测向方法来实现全阵级或子阵级的测向，并研究指向不准时只抑制干扰不抑制期望信号的自适应波束形成方法，以进行抗干扰的和差波束测向。本项目取得的成果和提出的方法，可广泛应用于基于共形阵的雷达、通信、和测控等领域。

共形阵列由于阵元极子的摆放的特殊性使得各阵元方向图可能不再一致。已有的和差波束测向方法应用在共形阵列时，性能有待确认。且某些共形结构的特殊性限制了已有和差波束测向方法的应用，需要发展新的和差测向方法。本项目主要研究共形阵和差波束测向关键技术，主要研究内容和贡献为：. 1）针对一种共形于机翼的阵列结构，其中该阵列结构的各阵元方向图不一致，研究了基于最大似然理论的和差测角方法和三点约束的自适应单脉冲测角方法的性能。研究结果表明，两种方法在该阵列情况下仍然可以正常工作，且都具有一定的抗主瓣干扰的测向能力，其中多点约束的鉴角曲线拟合的自适应单脉冲测角方法在当前仿真情况下要优于基于最大似然理论的和差测角方法。但是相比平面阵来说，两种方法性能稍微有所下降。. 2）针对一个由双正交极子构成的均匀圆环阵列，研究了常规双指向的和差测向性能。仿真结果表明测向精度和期望信号极化模式与阵列预设极化模式的极化距离有关。当极化距离逐渐增大时，水平极化通道和垂直极化通道的测向精度都逐渐下降。. 3）发展了一种基于联合约束的自适应抗干扰的和差波束测向方法。该方法通过一个优化问题可以把和波束与差波束同时求解出来，且对阵列结构没有太大的特殊要求。针对均匀线阵，均匀面阵和均匀圆阵分别进行了仿真，仿真结果表明该方法相对于其它算法具有更好的性能。. 4）研究了一种改进的多点约束的鉴角曲线拟合的自适应单脉冲测角方法。相对于传统的3点约束法，该方法通过多点约束使得约束范围内的鉴角曲线线性度更高，从而使得整个约束范围内的测角精度更高更好。. 这些研究成果为以后的共形阵列的和差测向方法的实际应用提供了理论指导。