Electric field regulating behaviour of microwave propagation in ER fluids

A model for microwave propagation through electrorheological (ER) fluids is established on the basis of the experimentally shown fact that the structure and the dielectric properties of ER fluids change with the external electric field. The theoretical simulation shows that the microwave transmittance increases with the dielectric constant of ER fluids if the dielectric constant of the ER fluids is larger than that of the container. Otherwise it decreases with the dielectric constant. The experimental results reveal that the microwave transmittance in the ER fluids can be adjusted by changing the dc field strength. The microwave transmittance increases with the field strength when the concentration of the fluid is low, but it decreases when it is high. The phenomenon that the microwave transmission can be adjusted in the ER fluids is attributed to the changes of the structure and the dielectric properties of the ER fluids under the external electric field. (Author)