PURPOSE: To reduce weight and to increase a frequency range by converting incident radio wave into a current, consuming it as heat, and shielding the opposite radio wave to the incident radio wave.

CONSTITUTION: An element 1 made of a current converter, i.e., a flat platelike conductor for converting radio wave into a current is disposed perpendicularly to an electric field E. Even if the conductor is disposed perpendicularly to the electric field E in this manner, a magnetic field is not disordered at all. Accordingly, the way of propagating the radio wave does not change before entering the element 1 or after entering it, and similar propagating state is obtained. A resistor R is disposed between a current converter 1a and a shielding element 1b. The resistor R is of a thermal converter 2, which converts the current from the element 1a to heat to consume it. A space is formed of the element 1a, the converter 2 and the element 1b, and air or nonconductive material is filled in the space. For example, a glass plate is employed as filler, i.e., supporting element 5, and the element 1a of metal thin film formed by depositing metal such as chromium or the like is provided on its rear face.