The effect of filler on the temperature coefficient of the relative permittivity of PTFE/ceramic composites

High permittivity and low-loss ceramic fillers have been prepared by means of the solid state ceramic route. Ceramic-filled composites were prepared by the Sigma Mixing, Extrusion, Calendering, which was followed by the Hot pressing (SMECH) process. The microwave dielectric properties of the composites were studied using X-band wave guide cavity perturbation technique. The temperature coefficient of the relative permittivity of the composites was investigated in the 0-100 degrees C temperature range using a hot and cold chamber coupled with an impedance analyzer. The temperature coefficient of the relative permittivity of the composites showed strong dependence on the temperature coefficient of the relative permittivity of the filler material. In the present study, a high-permittivity polymer/ceramic composite, having tau(epsilon r) similar to 63 ppm/K, has been realized. This composite is suitable for outdoor wireless applications. (C) 2011 Elsevier B.V. All rights reserved.