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Measured beam patterns from the scale model were compared with those from a numerical model based on the Kirchhoff integral theorem. In contrast, the scale model approach described allows for “bench testing” of many designs under controlled conditions, and efficient comparison with models. Design of the acoustic shielding is generally inhibited by the difficulty of testing on full-scale systems and uncertainty as to accuracy of models. Sodars, which use sound scattered by turbulence to profile the lowest few hundred meters of the atmosphere, need good acoustic shielding to diminish annoyance and to reduce unwanted reflections from nearby objects. The mean intensity in the zenith angle range 70°–90°, normalized to the central peak, for a beam tilted in the x– z plane, as a function of thnadners numbers and height.Ī 21:1 scaled sodar, operating at 40 kHz, has been built and tested in the laboratory. The maximum intensity in the zenith angle range 70°–90°, normalized to the central peak, for (a) a vertical beam and for (b) a beam tilted in the x– z plane, as a function of thnadners numbers and height. Intensity distribution for (a) the vertical beam and (b) the tilted beam, with the D = 9.5, H = 6.76 baffle, and with 40 thnadners of height 2.15. The maximum intensity in the zenith angle range 70°–90°, normalized to the central peak, for (top) a vertical beam and (bottom) a beam tilted in the x– z plane, as a function of baffle width and baffle height. Intensity distribution for (a) the vertical beam and (b) the tilted beam, with the D = 9.5, H = 6.76 baffle. The beam pattern in the x′– z plane without baffles (solid line) and with a D = 9.5, H = 6.76 baffle (dashed line). The measured (solid line) and calculated (dashed line) beam pattern of the phased array for the beam tilted in the x– z plane.
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The measured (solid line) and calculated (dashed line) zenith beam pattern with a half baffle, measured in (left) the x–z plane and (right) the x′– z plane. 2 for the definition of the x, x′, and z axes. The measured (solid line) and calculated (dashed line) beam pattern of the bare phased array for a beam tilted in the x– z plane. The measured (solid line) and computed (dashed line) polar pattern for the zenith beam of the bare phased array in (left) the x–z plane and (right) the x′ –z plane. The measured polar response of an individual microphone used in the scaled model (solid line) and the simple Legendre polynomial fit to this (dotted line). Surface and vector definition for the Kirchhoff integral theorem model. The measurement geometry with rotation of the microphone array around the y axis. The dimensions H, D, and h are indicated on the Metek sodar. (left) The Metek PCS-2000/24 LP sodar, (top right) scaled thnadners, and (bottom right) the view of the scaled microphone array and baffle in the − z direction.