Ventral-aspect radar cross sections and polarization patterns of insects at X band and their relation to size and form

A data set of ventral-aspect insect radar cross-sections (RCSs) and polarization patterns, measured at X band (9.4 GHz, linear polarization) in laboratory rigs, has been collated from a number of sources. The data have been analysed to identify relationships between RCS parameters (one representing size and two the polarization-pattern shape) and the insects’ masses and morphological dimensions and forms. An improved mass-estimation relationship, with appropriate asymptotes for very small and very large insects, is presented. This relationship draws only on the RCS size parameter and it is shown that incorporating one or both of the RCS shape parameters provides little additional benefit. Small insects have polarization-pattern shapes that fall within a relatively limited region of the range of parameter values allowed by electromagnetic scattering theory. Larger insects have shapes that extend beyond this region, following a broad trajectory as size and mass increases; at masses above ~0.6 g, the pattern becomes ‘perpendicular’, with maxima when the E-field is orthogonal to the body axis rather than parallel to it. RCS shape can be used to infer morphological form for small insects (

本数据集从多个来源整合而来，包含实验室台架中于X波段（9.4 GHz，线极化）下测得的昆虫腹面雷达散射截面（Radar Cross Section，RCS）与极化模式数据。研究人员对该数据集开展分析，以明确RCS参数（1个参数表征尺寸，2个参数表征极化模式形状）与昆虫质量、形态尺寸及形态特征之间的关联。本文提出了一种改进的质量估算关系，该关系针对极小与极大昆虫设置了适配的渐近线，且仅依托RCS尺寸参数；同时研究表明，引入一个或两个RCS形状参数几乎无法带来额外增益。小型昆虫的极化模式形状处于电磁散射理论所允许的参数值范围内的一个相对有限的区域内；体型更大的昆虫的模式形状则超出该区域，随着尺寸与质量的增加呈现出宽泛的变化轨迹：当质量超过约0.6 g时，该模式变为‘垂直型’，此时电场与虫体轴正交时出现峰值，而非平行时。RCS形状可用于推断小型昆虫的形态特征（