Helical antenna and portable communication terminal

A portable communication terminal comprising:

• a portable communication terminal casing which houses a radio transmitting and receiving circuit;
• and
• a helical antenna provided at an upper end of the portable communication terminal casing and connected to the radio transmitting and receiving circuit, the helical antenna comprising:
• an antenna element containing a bottom is portion formed into a helical portion and a top portion formed into a linear portion, the linear portion being positioned along a screw axis of the helical portion;
• a cap housing the antenna element if the cap covers the antenna element from a top end of the antenna element;
• and
• a position portion provided in the cap, the position portion positioning the linear portion of the antenna element along the screw axis of the helical portion.

A helical antenna for use in a portable communication terminal containing a radio unit which transmits and receives a radio signal, comprising:

• an antenna element connectable to the radio unit and containing a bottom portion formed into a helical portion and a top portion formed into a linear portion, the linear portion extending to a screw axis of the helical portion;
• a cap housing the antenna element;
• and
• a position portion provided in the cap, the position portion positioning the linear portion of the antenna element along the screw axis of the helical portion.

A portable communication terminal comprising:

• a portable communication terminal casing which houses a radio transmitting and receiving circuit;
• and
• a helical antenna provided at an upper end of the portable communication terminal casing and connected to the radio transmitting and receiving circuit, the helical antenna comprising:
• an antenna element containing a bottom portion formed into a helical portion and a top portion formed into a linear portion, the linear portion extending to a screw axis of the helical portion;
• a cap housing the antenna element;
• and
• a position portion provided in the cap, the position portion positioning the linear portion of the antenna element along the screw axis of the helical portion.