Short range clear air turbulence induced angle-of-arrival error measurements at 10 GHz

Clear air turbulence is known to induce angle-of-arrival errors in microwave wavefronts. Several researchers have measured clear air turbulence over ranges of hundreds to thousands of meters. We present measurements made over a much shorter range of less than two meters using fan generated turbulence. We used a two channel X-band interferometer at 10 GHz to measure angle-of-arrival errors. We calculated values for the refractive index structure constants on the order of 10^-13 (m^-2/3) using our observed angle-of-arrival error variance results. Our observed results compare favorably with the geometric optics theory although additional measurements to independently calculate the refractive index constant using log amplitude fluctuation measurements are desirable. We discuss these results and our plans for future work. The measurements described in this paper were made under a Naval Innovative Science and Engineering (NISE) research project. The knowledge gained from these measurements is aimed at developing applications for clear air turbulence in areas including electronic warfare, aviation safety, and atmospheric science.