Method and apparatus for substantially total acoustic transmission between water and air using a solid material

An apparatus for acoustic transmission between water and air, comprising:

• three parallel elastic plates of substantially the same length and width, including a water-facing plate, an air-facing plate, and a center plate disposed therebetween;
• a first plurality of periodically spaced solid acoustic transmission mechanisms disposed between the water-facing plate and center plate and extending from a front portion of a side wall to a rear portion of the side wall;
• a second plurality of periodically spaced solid acoustic transmission mechanisms is disposed between the center plate and air-facing plate extending from the front portion of the side wall to the rear portion of the side wall;
• the side wall enclosing space between the plates;
• the water-facing plate having a thickness h1 and a mass density ρ1, the air-facing plate having a thickness h2 and a mass density ρ2, and the center plate having a thickness h3 and a mass density ρ3, where h3>>h1>h2, and ρ1, ρ2, and ρ3 are substantially similar to each other;
• the first plurality of periodically spaced solid acoustic transmission mechanisms being separated from each other by a distance d1,
• the second plurality of periodically spaced solid acoustic transmission mechanisms being separated from each other by a distance d2, where d1 and d2 are selected to yield substantially full transmission of a desired frequency f0.