Model Experiments with Acoustic van Atta Reflectors

Abstract

A van Atta reflector consists of an array of radiators which are interconnected by transmission paths in such a way that the energy of an incident wave is reradiated back into the direction of arrival. Model experiments on backscattering from acoustic van Atta reflectors are reported. Airborne sound waves in the frequency range between 2.5 and 9.0 kc were used in these measurements. The acoustic van Atta array consists of 36 conical horns (aperture 112 in.) arranged on a 9×9-sq-in. flat surface. The horns are inter-connected by plastic tubing with reinforced walls. In these measurements the van Atta reflector shows a uniform backscattering over a wider range of angular orientation than the conventional corner reflector in the frequency range between 2.5 and 6.0 kc. For higher frequencies the angular coverage of the van Atta reflector under test is limited by the directivity of the horns. Some tests on an assembly of two van Atta reflectors, mounted at an angle of 60° with respect to each other, are reported. They show a more uniform angular response as compared to a cluster of corner reflectors in the frequency range from 2.5 to 5.0 kc.