CORE MATERIAL FOR ANTENNA

摘要

PROBLEM TO BE SOLVED: To obtain the core material in which a resin flow at injection molding is not localized and by which a large adhering force with a gap material is obtained by providing a head part whose cross section is larger than the cross section of the core material and having a flat face at least at part of its side face to one end of the core material. SOLUTION: A head part 3 whose cross section is larger than the cross section of the core material 1 and having a flat face 2 at least at part of its side face is provided to one end of the metal-made core member 1 to form an antenna by fixing a resin-made cap to the one end. This is more effective when a relation of D/d=1.3-3.0 is in existence, where (d) is a diameter of the core material 1 and a maximum diameter D of the head part 3. Furthermore, the cross section of the core material 1 at the border between the core material 1 and the head part 3 is shaped spread gradually toward the head part 3 in the longitudinal direction and the radius (r) of the curvature of an outer circumferential face of the cross section spread gradually in this way in the longitudinal direction selected to be r<=0.2mm is further more effective.