A system and method is provided for downhole wired-pipe communication and/or power transmission. The system includes first and second couplers each comprising a dielectric substrate, an electric dipole arranged on the dielectric substrate, a dielectric encapsulation surrounding the dielectric substrate and the electric dipole, and an electric shield surrounding the dielectric encapsulation. In operation, the electric dipoles are adapted to exchange radiofrequency signals and/or electrical power at radiofrequencies with each other by means of near-field dipole-dipole interaction. The one or more electric dipoles may be of the quarter-wavelength dipole type or of the half-wavelength dipole type. In a first embodiment, the dielectric substrate may form a generally circular ring and the coupler may be adapted to be rotatably movable against another coupler. In another embodiment, the dielectric substrate may form a generally linear structure and the coupler may be adapted to be linearly movable against another co
