PURPOSE: To make it possible to inform driver of action failure of radar itself by detecting that the sections between the predetermined number of electrodes are conducted due to adhesion of conducting substance on the surface of a radome and outputting the detection signal.
CONSTITUTION: A Mills cross antenna which has good directivity of the V character type is used, and one of the V character type becomes a transmission antenna 11 and the other becomes a receiving antenna 12. Also, these antennae 11, 12 are covered by a radome 13, and a plural number of electrodes 14 are attached independently on the whole surface of the radome 13. A conductivity detection circuit 16 detects the conductivity condition by detecting current or voltage and outputs a detection signal S8 when the sections between the predetermined number of electrodes 14 come in the conductivity condition due to adhesion of muddy water 17 on the surface of the radome 13 and freezing of the surface. Thus, it is possible to detect action failure of the radar due to adhesion of muddy water 17 or freezing.
IKUNO MASAYOSHI
SHIRATORI HIDEKI
FUJITSU TEN LTD