Biologically inspired virtual aperture extension method of small aperture HFSWR multielement array

We propose a method for extending the virtual aperture of the small aperture high-frequency surface wave radar multielement array inspired by a fly namedOrmia ochracea. Despite the tremendous incompatibility between its ear and the incoming wavelength,Ormiacan accurately local the sound of its host cricket. This ability benefits from the coupled structure ofOrmia's ears which have been modelled as a mechanical vibration system. In this paper, we first design a two-degree of freedom biologically inspired coupled system by mimickingOrmia's coupled ears. We quantitatively analyze its extension capability to the array aperture and construct the received signal model of the virtual array. We then analyze its response characteristic and available frequency band. To achieve the applications of arbitrary desired frequencies, we propose a frequency conversion algorithm. Moreover, we design two multi-degree of freedom biologically inspired coupled systems for the multielement array We summarize the criteria for extending the degree of freedom and optimize these two systems to address their respective shortcomings. Numerical results give the optimal system parameters for our desired frequency and validate the frequency conversion algorithm. By comparing the radiation pattern of the inspired arrays (arrays with the proposed systems) with that of an ordinary array, we demonstrate the virtual aperture extension capability of our proposed method. We also verify the effectiveness of proposed method by processing the actual received signals of the array.