Patent ID: 6346926
Filing Date: 2002-02-12
Classification: H01Q

Abstract:
A helical antenna, at least comprising:a bobbin having a peripheral side surface in which helical protrusion portions are formed, thereby forming helical groove portions between the protrusion portions; an attachment fitting provided with a first collar portion at an intermediate portion of the attachment fitting and with a second collar portion at an end of the attachment fitting, the attachment fitting being attached to a lower end of the bobbin; and a helical element screwed into the helical groove portions, so that a lower surface of the helical element contacts the first collar portion; a leading end of the helical protrusion portions formed at the lower end of the bobbin has substantially the same outer diameter as the second collar portion, which is connected to this leading end; and a depth of the helical groove portions becomes gradually shallower toward the leading end of the helical protrusion portions; wherein the inner peripheral surface of the helical element beyond the leading end is in contact with a side surface of the second collar portion.