Helical antenna, antenna unit, composite antenna

A helical antenna comprising:

• a cylindrical dielectric core made of insulator, said cylindrical dielectric core having a center axis extending in a longitudinal direction and an outer peripheral surface;
• first through N-th antenna lead members each made of conductor where N represents a predetermined positive integer which is not less than two, each of said first through N-th antenna lead members being wound around the outer peripheral surface of said cylindrical dielectric core in a helix fashion except for a tip portion of said cylindrical dielectric core;
• and
• first through N-th resonance frequency adjustment portions each made of additional conductor, said first through N-th resonance frequency adjustment portions being formed on the outer peripheral surface of said cylindrical dielectric core at the tip portion of said cylindrical dielectric core adjacent to said first through said N-th antenna lead members, respectively;
• wherein an n-th resonance frequency adjustment portion comprises the additional conductor which is apart from a tip of an n-th antenna lead member with a primary gap and which comprises a train of conductor segments with subsidiary gaps between adjacent conductor segments, where n represents a variable between 1 and N, so as to enable a length of an antenna lead to be varied by electrically connecting said n-th antenna lead member with said additional conductor of said n-th resonance frequency adjustment portion at the primary and the subsidiary gaps.

A method of adjusting a resonance frequency of a helical antenna comprising a cylindrical dielectric core made of insulator, an antenna lead member made of conductor, and a resonance frequency adjustment portion made of additional conductor, said cylindrical dielectric core having a center axis extending a longitudinal direction and an outer peripheral surface, said antenna lead member being wound around the outer peripheral surface of said cylindrical dielectric core in a helix fashion except for a tip portion of said dielectric core, said resonance frequency adjustment portion being formed on the outer peripheral surface of said cylindrical dielectric core at the tip portion of said cylindrical dielectric core adjacent to said antenna lead member, said resonance frequency adjustment portion comprising the additional conductor which is apart from a tip of said antenna lead member with a primary gap and which includes a train of conductor segments with subsidiary gaps between adjacent conductor segments, said method comprising:

• electrically connecting said antenna lead member with said additional conductor at the primary gap and of electrically connecting between said adjacent conductor segments at the subsidiary gaps in order of being apart from the tip of said antenna lead member so as to vary a length of an antenna lead, thereby adjusting the resonance frequency of said helical antenna.

A helical antenna comprising:

• a cylindrical dielectric core made of insulator, said cylindrical dielectric core having a center axis extending in a longitudinal direction and having an outer peripheral surface;
• an antenna lead member made of conductor, said antenna lead member being wound around the outer peripheral surface of said cylindrical dielectric core in a helix fashion except for a tip portion of said cylindrical dielectric core;
• and
• a resonance frequency adjustment portion made of additional conductor, said resonance frequency adjustment portion being formed on the outer peripheral surface of said cylindrical dielectric core at the tip portion of said cylindrical dielectric core adjacent to said antenna lead member;
• wherein said resonance frequency adjustment portion comprises the additional conductor which is apart from a tip of said antenna lead member with a primary gap and which comprises a train of conductor segments with subsidiary gaps between adjacent conductor segments, so as to enable a length of an antenna lead to be varied by electrically connecting said antenna lead member with said additional conductor at the primary and the subsidiary gaps.

An antenna unit comprising:

• a helical antenna comprising a hollow cylindrical member made of insulator and an antenna lead member made of conductor, said hollow cylindrical member having a center axis extending in a longitudinal direction, an outer peripheral surface, and an inner peripheral surface, said antenna lead member being wound around the outer peripheral surface of said hollow cylindrical member in a helix fashion;
• a main circuit board mounted inside said hollow cylindrical member near one end of said hollow cylindrical member in the longitudinal direction;
• and
• a low-noise amplifier mounted on said main circuit board, said low-noise amplifier having an amplifier input terminal connected to an end of said antenna lead member.

An antenna unit comprising:

• a helical antenna comprising a hollow cylindrical member made of insulator and an antenna lead member made of conductor, said hollow cylindrical member having a center axis extending in a longitudinal direction, an outer peripheral surface, and an inner peripheral surface, said antenna lead member being wound around the outer peripheral surface of said hollow cylindrical member in a helix fashion;
• a main circuit board mounted inside said hollow cylindrical member near one end of said hollow cylindrical member in the longitudinal direction, said main circuit board having a principal surface which extends in parallel with the longitudinal direction;
• and
• a low-noise amplifier mounted on the principal surface of said main circuit board, said low-noise amplifier having an amplifier input terminal connected to an end of said antenna lead member.

An antenna unit comprising:

• a helical antenna comprising a hollow cylindrical member made of insulator and a plurality of antenna lead members made of conductor, said hollow cylindrical member having a center axis extending in a longitudinal direction, an outer peripheral surface, and an inner peripheral surface, said antenna lead members being wound around the outer peripheral surface of said hollow cylindrical member in a helix fashion;
• a main circuit board mounted inside said hollow cylindrical member near one end of said hollow cylindrical member in the longitudinal direction, said main circuit board having a principal surface which extends in parallel with the longitudinal direction;
• a phase shifter supported on said hollow cylindrical member, said phase shifter having a plurality of shifter input terminals connected to ends of said antenna lead members and a shifter output terminal;
• and
• a low-noise amplifier mounted on the principal surface of said main circuit board, said low-noise amplifier having an amplifier input terminal connected to the shifter output terminal.

An antenna unit comprising:

• a helical antenna comprising a hollow cylindrical member made of insulator and a plurality of antenna lead members made of conductor, said hollow cylindrical member having a center axis extending in a longitudinal direction, an outer peripheral surface, and an inner peripheral surface, said antenna lead members being wound around the outer peripheral surface of said hollow cylindrical member in a helix fashion;
• a main circuit board mounted inside said hollow cylindrical member near one end of said hollow cylindrical member in the longitudinal direction, said main circuit board having a principal surface which extends in parallel with the longitudinal direction;
• a phase shifter mounted on the principal surface of said main circuit board, said phase shifter having a plurality of shifter input terminals connected to ends of said antenna lead members and a shifter output terminal;
• and
• a low-noise amplifier mounted on the principal surface of said main circuit board, said low-noise amplifier having an amplifier input terminal connected to the shifter output terminal.

An antenna unit comprising:

• a helical antenna comprising a hollow cylindrical member made of insulator and a plurality of antenna lead members made of conductor, said hollow cylindrical member having a center axis extending in a longitudinal direction, an outer peripheral surface, and an inner peripheral surface, said antenna lead members being wound around the outer peripheral surface of said hollow cylindrical member in a helix fashion;
• a main circuit board mounted inside said hollow cylindrical member near one end of said hollow cylindrical member in the longitudinal direction, said main circuit board having a main principal surface which extends in parallel with the longitudinal direction;
• a subsidiary circuit board mounted within said hollow cylindrical member, said subsidiary circuit board having a subsidiary principal surface which extends in parallel with of the main principal surface of said main circuit board;
• a phase shifter mounted on the subsidiary principal surface of said subsidiary circuit board, said phase shifter having a plurality of shifter input terminals connected to ends of said antenna lead members and a shifter output terminal;
• and
• a low-noise amplifier mounted on the main principal surface of said main circuit board, said low-noise amplifier having an amplifier input terminal connected to the shifter output terminal via a connection pin.