Tunable microwave reflection behavior of electrorheological fluids

The tunable character of microwave reflection in a quasi-periodic structure that was formed by particle chains in electrorheological fluids was investigated. The results showed that the reflection coefficient could be modulated by the external electric field. The magnitude of the reflection coefficient for TiO₂ coated kaolinite electrorheological fluid and Y-doped BaTiO₃ electrorheological fluid increased with the electric field. The magnitude of the reflection coefficient of BaTiO₃ electrorheological fluid reduced gradually when the particle concentration was low (25%), while it decreased to a minimum value and then increased when the particle concentration was higher than 25%. The phase angle of the reflection coefficient for TiO₂ coated kaolinite electrorheological fluid gradually increased to a maximum value and then decreased, while the phase angle increased gradually with the electric field for Y-doped BaTiO₃ and BaTiO₃ electrorheological fluids. These tunable characters of microwave reflection could be attributed to the changes of structure and dielectric constant of the electrorheological fluid with the electric field.