berkeman said:
Yikes! That looks like nonsense from what little I've translated from Italian...
I think this concept is still worthy of scientific experiment, though I would not fund it. It would make a good learning exercise.
Sibilo said:
Furthermore, ultrasound is also used to eliminate bacteria and fungi. tell me how long it will take to get the answer because I want to learn too
Do not place a clear reflector around the plant, because that will block the wind and the rain.
You have one point source of ultrasound, and I believe you want to make a cylinder of sound that will enclose the plant with an isotropic level of sound, that penetrates the surface of the soil from above, to about 30 mm depth.
A radiating wave, from a point source, can be converted to a parallel beam by a parabolic reflector. That is the same principal as a satellite receiver dish.
A dish reflector would point downwards from above the plant, with the transducer at the focus, pointing upwards at the dish. The diameter of the dish will keep some rain off the plant, but sunlight and wind will enter from the side.
The reflected wave will arrive at the soil surface as a plane wavefront, so it should penetrate the surface soil evenly. I would not expect the wave to be reflected efficiently from the soil surface, unless it was flat and wet. Energy will be dispersed and lost in an open-structured soil with a rough surface.
The height of the dish above the ground is not critical, it can be raised as the plant grows.
I expect the dish diameter will be about 300 mm, which is 10 wavelengths at 30 kHz ≈ 5° beam sides. The ratio of focal length, to the diameter of the dish, will be determined by the radiation pattern of the ultrasonic transducer selected. The theory is the same as that of microwave dish "illumination".
The transducer specification, and the power level required, have not been specified.