Back fire helical antenna

A back fire helical antenna including a radiation conductor disposed helically, comprising:

• a strip line including a dielectric substrate having a main surface and a back surface, a strip conductor formed on said main surface and having a width decreasing from a first end to a second end of said dielectric substrate, and a conductive search plate formed on said back surface and having a width decreasing from the first end to the second end of said dielectric substrate,
• said strip line having a function of balun with widths of said strip conductor and said conductive earth plate decreasing from the first end to the second end of said dielectric substrate,
• said radiation conductor disposed helically about said strip line set as a center,
• said radiation conductor having a first end electrically connected with a portion of said strip line located on the side of the second end of said dielectric substrate,
• said radiation conductor having a second end electrically connected with said conductive earth plate.

A back fire helical antenna including first and second radiation conductors arranged helically about a feeder set as a center, comprising:

• a radiation member including said first radiation conductor, said second radiation conductor disposed to be spaced apart from said first radiation conductor, a first end connecting member for electrically connecting a first end of said first radiation conductor and a first end of said second radiation conductor, and a second end connecting member for electrically connecting a second end of said first radiation conductor and a second end of said second radiation conductor, said first and second radiation conductors and said first and second end connecting members being integrally formed of the same material,
• said radiation member disposed such that said first and second radiation conductors form helicoid with said feeder set as a center, and
• said first and second end connecting members electrically connected with said feeder, wherein
• said feeder is a strip line including a dielectric substrate having a main surface and a back surface, a first strip conductor formed on said main surface, a second strip conductor formed on said main surface and electrically connected with said first strip conductor, and a conductive earth plate formed on said back surface, and
• said second strip conductor, said dielectric substrate and said conductive earth plate constitutes transformation means for matching impedance of said first radiation conductor and impedance of said strip line and matching impedance of said second radiation conductor and impedance of said strip line.

A back fire helical antenna including first and second radiation conductors arranged helically about a feeder set as a center, comprising:

• a radiation member including said first radiation conductor, said second radiation conductor disposed to be spaced apart from said first radiation conductor, a first end connecting member for electrically connecting a first end of said first radiation conductor and a first end of said second radiation conductor, and a second end connecting member for electrically connecting a second end of said first radiation conductor and a second end of said second radiation conductor, said first and second radiation conductors and said first and second end connecting members being integrally formed of the same material,
• said radiation member disposed such that said first and second radiation conductors form helicoid with said feeder set as a center, and
• said first and second end connecting members electrically connected with said feeder, wherein
• said feeder is a strip line including a dielectric substrate having a main surface and a back surface, a strip conductor formed on said main surface, and a conductive earth plate formed on said back surface, and
• an amplifier circuit for amplifying a current flowing through said strip line is formed on said dielectric substrate.

A back fire helical antenna including first and second radiation conductors arranged helically about a feeder set as a center, comprising:

• a radiation member including said first radiation conductor, said second radiation conductor disposed to be spaced apart from said first radiation conductor, a first end connecting member for electrically connecting a first end of said first radiation conductor and a first end of said second radiation conductor, and a second end connecting member for electrically connecting a second end of said first radiation conductor and a second end of said second radiation conductor, said first and second radiation conductors and said first and second end connecting members being integrally formed of the same material,
• said radiation member disposed such that said first and second radiation conductors form helicoid with said feeder set as a center, and
• said first and second end connecting members electrically connected with said feeder, wherein
• said feeder is a strip line including a dielectric substrate having a main surface and a back surface, a strip conductor formed on said main surface, and a conductive earth plate formed on said back surface, and
• said strip line functions as a balun with widths of said strip conductor and said conductive earth plate decreasing from a first end to a second end of said dielectric substrate.

A method of manufacturing a back fire helical antenna including first and second radiation conductors arranged helically about a feeder set as a center, said method comprising the steps of:

• by blanking a conductive plate member, forming a radiation member including said first radiation conductor, said second radiation conductor spaced from said first radiation conductor, a first end connecting member for electrically connecting a first end of said first radiation conductor and a first end of said second radiation conductor, and a second end connecting member for electrically connecting a second end of said first radiation conductor and a second end of said second radiation conductor, said first and second radiation conductors and said first and second end connecting members being formed integrally;
• bending said radiation member into a helical form;
• disposing said helical radiation member such that said first and second radiation conductors form helicoid about said feeder set as a center;
• and
• electrically connecting said first and second end connecting members to said feeder.