In wave physics and engineering, directional emission sets a fundamental limitation on conventional simple sources as their sizes should be sufficiently larger than their wavelength. Artificial metamaterial and animal biosonar both show potential in overcoming this limitation. Existing metamaterials arranged in periodic microstructures face great challenges in realizing complex and multiphase biosonar structures. Here, we proposed a physical directional emission model to bridge the gap between porpoises’ biosonar and artificial metamaterial. Inspired by the anatomical and physical properties of the porpoise's biosonar transmission system, we fabricated a hybrid metamaterial system composed of multiple composite structures. We validated that the hybrid metamaterial significantly increased directivity and main lobe energy over a broad bandwidth both numerically and experimentally. The device displayed efficiency in detecting underwater target and suppressing false target jamming. The metamaterial-based physical model may be helpful to achieve the physical mechanisms of porpoise biosonar detection and has diverse applications in underwater acoustic sensing, ultrasound scanning, and medical ultrasonography.

中文翻译：

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通过混合超材料对鼠海豚定向发射的物理建模和验证

在波浪物理学和工程学中，定向发射对传统的简单源设置了一个基本限制，因为它们的尺寸应该比它们的波长大得多。人工超材料和动物生物声纳都显示出克服这一限制的潜力。以周期性微结构排列的现有超材料在实现复杂和多相生物声纳结构方面面临巨大挑战。在这里，我们提出了一种物理定向发射模型来弥合江豚生物声纳和人造超材料之间的差距。受江豚生物声纳传输系统解剖和物理特性的启发，我们制造了一个由多种复合结构组成的混合超材料系统。我们通过数值和实验验证了混合超材料在宽带宽上显着增加了方向性和主瓣能量。该装置在检测水下目标和抑制虚假目标干扰方面表现出高效。基于超材料的物理模型可能有助于实现海豚生物声纳探测的物理机制，并在水声传感、超声扫描和医学超声检查中具有多种应用。