Antenna apparatus
First Claim
1. An antenna apparatus, comprising:
- a plurality of non-overlapping helical antennas, each including at least one conductive wire disposed directly on a dielectric cylinder, said at least one conductive wire is spirally wound at equal intervals with a predetermined pitch, said plurality of the helical antennas being axially aligned so that the axes of said helical antennas substantially coincide end-to-end with each other; and
feeding means for feeding a signal to said at least one conductive wire of said helical antennas; and
wherein at least one cylindrical conductive pipe is disposed inside said dielectric cylinder and substantially coaxial with at least one of said helical antennas and said feeding means for said at least one conductive wire of said helical antennas are disposed through the inside of said at least one conductive pipe; and
wherein said at least one conductive pipe is electrically insulated from said helical antennas and said feeding means.
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Accused Products
Abstract
Herein is revealed a helical antenna apparatus wherein the direction of beam radiation hardly changes even if the frequency in use changes. Two helical antennas which are wound with two conductive wires spirally, respectively, at equal intervals with a specified pitch α in the form of a cylinder are disposed along the length of the helical antennas so that the axes thereof substantially coincide with each other. By determining the lengths of the feeders of the respective helical antennas appropriately in order to set the phase of supplied power, it is possible to form the beam of signals radiated into space in the shape of conical beam having a directivity oriented obliquely upward. Additionally, it is possible to obtain the conical beam in which the direction of beam radiation does not change even if the frequency in use is changed.
151 Citations
5 Claims
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1. An antenna apparatus, comprising:
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a plurality of non-overlapping helical antennas, each including at least one conductive wire disposed directly on a dielectric cylinder, said at least one conductive wire is spirally wound at equal intervals with a predetermined pitch, said plurality of the helical antennas being axially aligned so that the axes of said helical antennas substantially coincide end-to-end with each other; and feeding means for feeding a signal to said at least one conductive wire of said helical antennas; and wherein at least one cylindrical conductive pipe is disposed inside said dielectric cylinder and substantially coaxial with at least one of said helical antennas and said feeding means for said at least one conductive wire of said helical antennas are disposed through the inside of said at least one conductive pipe; and
wherein said at least one conductive pipe is electrically insulated from said helical antennas and said feeding means.
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2. An antenna apparatus comprising:
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at least one helical antenna which includes at least one conductive wire disposed in the form of a cylinder, wherein said at least one conductive wire is wound spirally at a specified pitch at equal intervals; feeding means for supplying signals to said at least one conductive wire of said at least one helical antenna; and at least one cylindrical dielectric radome separately disposed around said at least one helical antenna so as to be substantially coaxial therewith and not in contact with said at least one conductive wire, wherein said at least one cylindrical dielectric radome has a dielectric constant which changes the wavelength of a signal flowing in said at least one conductive wire so as to change the radiation direction of a conical beam of at least one of said helical antennas; and wherein the thickness of said radome is changed spirally at substantially the same pitch as the pitch of the helical antenna and the internal surface or the external surface of the dielectric radome is constructed to be of internal thread or external thread. - View Dependent Claims (3)
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4. An antenna apparatus comprising:
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at least one helical antenna which includes at least one conductive wire disposed directly on a dielectric cylinder, wherein said at least one conductive wire is wound spirally at a specified pitch at equal intervals; feeding means connected to a feed terminal of said at least one helical antenna in order to supply signal to said at least one conductive wire of said at least one helical antenna; and phase changing means which is disposed on said at least one conductive wire and is located at a distance away from the feed terminal of the at least one conductive wire of more than 1/2 the overall length of the at least one conductive wire of the at least one helical antenna, so as to create divided sections of the at least one conductive wire and which makes a phase difference between the beam radiated from one of the divided sections and the beam radiated from another divided section to be approximately 180°
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5. An antenna apparatus comprising:
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a first helical antenna which includes at least one conductive wire disposed directly on a dielectric cylinder wherein said at least one conductive wire is wound spirally at a predetermined pitch at equal intervals; and a second helical antenna which includes at least one conductive wire disposed directly on the dielectric cylinder wherein said at least one conductive wire is wound spirally at a different specified pitch from that of the at least one conductive wire of said first helical antenna; a first phase changing means which is located on said at least one conductive wire and is located at a distance away from the feed terminal of the at least one conductive wire of more than 1/2 the overall length of the at least one conductive wire of the first helical antenna, so as to create divided sections of the at least one conductive wire and which makes a phase difference between the beam radiated from one of the divided sections and the beam radiated from the other divided section to be approximately 180°
;a second phase changing means which is located on said at least one conductive wire of said second helical antenna and is located at a distance away from the feed terminal of the at least one conductive wire of more than 1/2 the overall length of the at least one conductive wire of the second helical antenna, so as to create divided sections of the at least one conductive wire and which makes a phase difference between the beam radiated from one of the divided sections and the beam radiated from the other divided section to be approximately 180°
; andfeeding means for sending a transmission signal to either of said at least one conductive wire of said first helical antenna or said second helical antenna and for receiving a reception signal from the other helical antenna.
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Specification