PURPOSE: To provide damage of an amplifier in a converter due to an induced current caused by the falling of a thunderbolt or a strong noise by providing a surge absorber to a specific position in a travelling type plane antenna formed by a microwave strip line.

CONSTITUTION: The surge absorber 11 is connected in parallel with a termination resistor 9. Thus, a disturbing current due to a sudden generation on a strip antenna induced by the falling of a thunderbolt or strong noise is discharged to a grounding point 10 by the surge absorber 11. Thus, the damage of an amplifier in a converter connected to a power feeding section 8 is prevented. Moreover, since the electromagnetic wave radiation energy near the termination resistor 9 is very small, the effect of the absorber 11 onto the antenna radiation characteristic is not given.