Scattering of electromagnetic waves against acoustic waves has been studied in acousto-optics and radio acoustic sounding of the atmosphere, among others. Strong interaction requires phase matching, which occurs at two angles between waves. These depend on the wavelength ratio. The scattered electromagnetic wave is frequency shifted by the acoustic frequency, either up or down depending on the angle between waves. This work presents experimental verification of this scattering for 27.3 GHz microwaves and 40 kHz ultrasound in air. Both up- and down-shifting of the scattered wave is shown. Previous work has mostly focused on either nearly perpendicular or parallel incidence. In contrast, this work considers oblique incidence with frequencies differing from those used in acousto-optics and radio acoustic sounding.

中文翻译：

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倾斜入射时空气中超声波对微波散射的测量

已经在大气的声光和无线电声测深中研究了电磁波对声波的散射。强烈的相互作用需要相位匹配，相位匹配发生在波之间的两个角度处。这些取决于波长比。散射的电磁波根据声波之间的角度向上或向下偏移声频。这项工作对27.3 GHz微波和40 kHz超声在空气中的散射进行了实验验证。显示了散射波的上移和下移。先前的工作主要集中在几乎垂直或平行的入射角上。相反，这项工作考虑的倾斜入射频率不同于声光和无线电声测探中使用的频率。