| Popis: |
The substantial limitation for using sodars in areas with complex orography is local interferences, especially in the form of fixed echoes. In order for sodar to successfully work in such scenarios, the possibility of creation and development of a parametric acoustic antenna is discussed in this paper based on the accumulated experimental material. The antenna is supposed to be the virtual acoustic radiating one located over neighboring buildings and installations. The physical basis for such an antenna realization is a known mechanism of nonlinear interaction of powerful acoustic radiation with the atmospheric air. It is shown, on results of numerical and experimental investigations, that for the frequency interval whereat modern sodars operate, a unique parametric transmitting antenna with a high conversion efficiency and single-frequency pump wave can be created. |
