In this work, the numerical steepest descent path (NSDP) method is proposed to compute the highly oscillatory physical optics (PO) scattered fields from the concave surfaces, including both the monostatic and the bistatic cases. Quadratic variations are adopted to approximate the integrands of the PO type integral into the canonical form. Then, on involving the NSDP method, we deform the integration paths of the integrals into several NSDPs on the complex plain, through which the highly oscillatory integrands are converted to exponentially decay integrands. The RCS results of the PO scattered field are calculated and are compared with the high frequency asymptotic (HFA) method and the brute force (BF) method. The results demonstrate that the proposed NSDP method for calculating PO scattered fields from concave surfaces is frequency-independent and error-controllable. Numerical examples are provided to verify the efficiencies of the NSDP method.

中文翻译：

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从凹面计算物理光学散射场的有效方法

在这项工作中，提出了数值最速下降路径（NSDP）方法来计算来自凹面的高振荡物理光学（PO）散射场，包括单静态和双静态情况。采用二次方差将PO型积分的被积近似为标准形式。然后，在涉及NSDP方法的情况下，我们将积分的积分路径变形为复杂平原上的几个NSDP，高振荡积分被转换为指数衰减积分。计算PO散射场的RCS结果，并​​将其与高频渐近（HFA）方法和蛮力（BF）方法进行比较。结果表明，所提出的用于计算凹面PO散射场的NSDP方法与频率无关且可控制误差。提供了数值示例，以验证NSDP方法的效率。