The present disclosure relates to forming a dispersion of metamaterial particles in an atmosphere. The metamaterial particles can be dispersed into the atmosphere, for example, from an aircraft or another type of platform, to form the dispersion. The resulting dispersion can interact with electromagnetic signals in the atmosphere. The particles may strongly interact with both the magnetic and electric field components of the electromagnetic signals. In some implementations, the dispersion absorbs electromagnetic signals in a frequency range. In some implementations, the dispersion modifies electromagnetic signals in a frequency range, for example, by applying a phase shift, a polarization shift, a frequency shift, or a reflection angle to the electromagnetic signals.