Microwave non-destructing testing of rubber at X-band

In this paper, the measurement of complex dielectric constant of natural rubber at microwave frequencies is reported. A free space, non-destructive technique was used to measure the parameter for several rubber samples at X band. The samples were prepared using different amounts of carbon filler to alter the dielectric properties so that the relation between filler content and ε_r can be investigated. Our studies show that ε_r and tan δ increase with the filler content. In addition, ε_r showed a decreasing trend, while tan δ increased with frequency.