Carbon fiber composite (CFC) material is used for building antennas and microwave circuits as an effective alternative to metal. Two kinds of composite materials are considered, namely reinforced continuous carbon-fiber (RCCF) composites and carbon nanotube (CNT) composites. The effect of the conductivity tensor of anisotropic RCCF composite on the antenna performance is addressed. Highly conductive single wall carbon nanotube (SWCNT) buckypapers are used to build composite material for antennas. A new fabrication method is proposed to print an arbitrarily-shaped full-composite SWCNT antenna on any type of substrate.