A dielectric film has a main surface and a back surface and is formed of resin. Electrodes that can receive or transmit an electromagnetic wave having a frequency of not less than 0.05 THz and not more than 10 THz in the terahertz band are formed on the main surface of the dielectric film. The electrodes constitute a tapered slot antenna. The dielectric film and the electrodes are formed of a flexible printed circuit board. A semiconductor device that is operable at a frequency in the terahertz band is mounted on the main surface of the dielectric film so as to be electrically connected to the electrodes.
