PURPOSE: To allow a resonance circuit to absorb reflected electromagnetic energy by coupling a tuning circuit which resonates with a reflected radio wave closely with the metallic structure where the radio wave is reflected.

CONSTITUTION: A circuit electrically equivalent to an absorbing coil in a figure allows a coil 8 to resonate at the tuning frequency which is the sum of the electrostatic capacity 7' between metallic fixtures at both ends of an insulator 7 and the electrostatic capacity 3 formed between the tip 2 of the coil 8 and the pole 9 of the structure. This resonance circuit forms a parallel resonance circuit to the tuning frequency, so when a resonance current corresponding to its effective Q flows, the induced voltage of the pole 9' of the structure is absorbed by this circuit. The degree of coupling is high because the part from 1 to 6 of the pole 9' of the structure is used in common, and the induced voltage of the pole 9' of the structure is absorbed efficiently.