| 摘要 |
First and second reflectors, having a parabolic concave reflective surface and a conical reflecting surface, respectively, are vertically spaced on co-linear axis. An energy source, such as a loudspeaker mounted atop the frusto-conical second reflector near the apex of the conical reflective surface thereof is at or proximate the focal point of the concave reflective surface of the parabolic reflector. It is desirable for the major diameters of the reflectors to be approximately twice the wave-length of the lowest frequency sound for which the device is applicable. The shapes of the reflective surfaces are established to provide essentially equal path lengths of energy radiated from the source to a wave front to provide coherent omnidirectional energy propagation from the assembly or, in an alternative use of the apparatus, receive radiant energy and focus it on target instead of a loudspeaker at the focal point of the parabolic reflective surface.
|
