Glass bubbles can indeed be used as a lightweight filler material in electromagnetic wave absorbers. The key to their effectiveness lies in their composition and structure. Glass bubbles are hollow microspheres made of thin-walled glass, which makes them lightweight and highly compressible. When these bubbles are mixed into a polymer matrix and applied as a coating or a layer, they can help to absorb electromagnetic waves.
The hollow nature of glass bubbles allows them to deform under pressure, which helps to dissipate the energy of the electromagnetic waves. Additionally, the dielectric properties of the glass material can contribute to the absorption of the waves. By adjusting the size, density, and composition of the glass bubbles, it is possible to tailor the electromagnetic absorption properties of the material to meet specific requirements.