To maximize the piezoelectric transducer reception/transmission power we must choose the correct backing/matching layer materials, I'm working on a project to measure a steel tank liquid level (non invasive from the bottom, sensor must be glued) and we have the electronic board finished and the ceramic piezoelectric disk, but we are lacking of knowledge of choosing this material that I mentioned.
The tank that we'll measure is a 3 meters tall, 8mm steel bottom wall.
As far as I read the material selection must take in consideration the acoustic impedance, am I right? Also someone recommend using closed cell foam as backing material and stainless steel as matching layer, but we're not sure about the thickness.
Do anyone have recommendations regarding the correct materials/layer thickness for this application?