Higher frequency shorter range

As the wavelength is decreased (or frequency is increased) the ultrasound beam will have a shallower penetration. Low frequency ultrasound has superior penetration . Since wavelength and frequency are inversely related, so to, are resolution and penetration inversely related.

One of the most fundamental laws of physics, as it relates to wireless, is that lower frequencies travel farther and penetrate buildings deeper (or propagate better) than higher frequencies .

Are higher frequencies better? The main advantage of higher frequencies is that they require shorter antennas for decent reception quality , and that’s important for mobile devices. But high frequencies are more sensitive to reflection, so they will have a harder time passing through walls and obstacles in general.