Communications: radio wave antennas – Antennas – Including magnetic material
Patent
1991-12-19
1993-06-15
Wimer, Michael C.
Communications: radio wave antennas
Antennas
Including magnetic material
343788, 343895, H01Q 708
Patent
active
052203387
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to antenna elements, and, more specifically, it relates to an antenna element comprising a core which comprises a hollow pipe made of a magnetic material and a metal bar made of aluminum, titanium, copper, or an alloy of those metals, and a wire of electrically conductive material which is wound on a surface of the core.
BACKGROUND ART
Recent development and popularization of a portable TV, such as car TV and handy TV, equipment for satellite communication, movable telephone, etc. requires smaller and lighter antennas with high performance than traditional Yagi Antennas for VHF/UHF and parabola antennas for micro waves, considering convenience for users and outlook.
Additionally, each unit of traditional antennas suites to a limited range of wave length, so that two antennas are necessary to receive VHF and UHF waves for TV, where very careful adjustments of the length of antenna elements is very essential. This leads to complication and high costs of receiving units. An example has been taken for car TV, where a combination of a dipole antenna or whip antenna and a diversity circuit has been developed and commercially available. This type of antenna is, however, very sensitive to reflection noises from buildings, etc. and the performance to receive UHF wave is not satisfactory.
Further, plane antennas or print antennas for receiving satellite broadcasting and/or for mobility communication, that offer smaller size than the parabola antenna, have been commercially available. Such antennas also have the limitation of maintaining the performance.
An improvement was proposed to use a ferrite core with electrically conductive coil, that has the disadvantage of strong directivity and narrow range of receivable wave length to be used leading to limitation of application to radio but not to TV.
The object of this invention is to provide a small sized and light antenna element which has high fidelity and less directivity, and is suitable with wide range wave length.
DISCLOSURE OF INVENTION
The present inventor made intensive studies in an attempt to achieve the object in view of the above problems of the prior art and, as the result of his studies, he found that an antenna element comprising a core which comprises a hollow pipe made of a magnetic material, a metal bar made of aluminum, titanium, copper or an alloy thereof and being inserted into the hollow pipe, and an insulating material located between the hollow pipe and the metal bar; and an electrically conductive wire which is wound on a surface of the core can achieve the above object. This invention is based on the above finding.
The antenna element of the present invention is characterized in that it comprises a hollow pipe made of a magnetic material said hollow pipe having an axial bore extending therethrough; a solid or hollow metal bar made of at least one metal selected from the group consisting of aluminum, titanium, copper and alloys thereof, said metal bar being inserted into the axial bore; an insulating material located between the hollow pipe and the metal bar; and an electrically conductive wire being wound on at least a part of an outer surface of the hollow pipe, said electrically conductive wire having been coated with an insulating material.
The magnetic materials to be used for this invention are preferably those with high magnetic permeability, with less sensitivity to the frequency of electromagnetic wave, with high saturation magnetic flux density, with less coercive force, and with magnetostriction, and more preferably having a maximum magnetic permeability of about 100,000 .mu..sub.max or more, and most preferably about 500,000 .mu..sub.max or more. Using the magnetic materials with higher permeability and less sensitivity to frequency, the performance of the antenna tends to be improved.
Various kinds of magnetic materials can be used for this invention but amorphous metals are preferable due to its high strength, hardness and anti-corrosion property in addition to above general magnetic
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patent: 2748386 (1956-05-01), Polydoroff
patent: 4205318 (1980-05-01), Pisano
patent: 4375642 (1983-03-01), Dorrie et al.
patent: 4442438 (1984-04-01), Siwiak
patent: 4458248 (1984-07-01), Lyasko
patent: 5065138 (1991-11-01), Lian et al.
patent: 5081469 (1992-01-01), Bones
Creatic Japan, Inc.
Ho Tan
Wimer Michael C.
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