Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-08-14
2001-12-25
Phan, Tho G. (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S713000, C343S828000, C343S872000
Reexamination Certificate
active
06333714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to antennas, for example, mounted on vehicles and used for receiving terrestrial TV broadcasting.
2. Description of the Related Art
FIG. 9
shows a conventional on-vehicle antenna for receiving terrestrial TV broadcasting. This conventional antenna
50
is basically configured such that a rod-shaped radiating conductor
51
is adjusted so as to resonate at a desired frequency, and the radiating conductor
51
is mounted so that the mounting angle against a support base
52
with a support section
53
being used as a fulcrum can be adjusted freely. As shown in FIG.
10
A and
FIG. 10B
, the antenna
50
is usually mounted at a window section
61
or a roof section
62
of a car
6
.
In general, to remedy a drawback of fading, which occurs during mobile reception, a plurality of the antennas
50
are used to form a diversity-reception antenna system and the antenna having the maximum receiving level is selected.
Since the conventional antenna has a not-wide operation frequency band itself, however, additional circuits such as a tuning circuit and an amplifier circuit are used to receive a desired frequency band if it is necessary to cover a wide frequency range for TV broadcasting receiving and other purposes. In addition, since the conventional antenna needs a large space for installation and hence it is mounted outside a vehicle, it may be broken or stolen, or it may spoil the appearance of the vehicle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an antenna which covers a wide frequency range, which can be made compact, and when the antenna is installed inside a vehicle, which is free from breakage, to decrease the probability of being stolen and which does not spoil the appearance of the vehicle.
The foregoing object is achieved according to the present invention through the provision of an antenna including at least two radiating conductors disposed in parallel and having different lengths; a feeding conductive section connected to the radiating conductors at the same side ends in the parallel direction of the radiating conductors; and a grounding conductive plate disposed almost in parallel to the radiating conductors.
Since the antenna having the above structure is provided with a plurality of radiating conductors having different lengths, a plurality of resonance points are generated by the plurality of radiating conductors and the grounding conductive plate. The overall frequency characteristics of the antenna are improved in the frequency bands corresponding to the plurality of resonant frequencies, and thus the operation frequency band of the antenna is extended. In addition, since each of the plurality of radiating conductors contributes to radiation, the substantial area contributing to radiation becomes large, and the radiation efficiency of the antenna can be increased.
When each of the plurality of radiating conductors is arranged in parallel, a more compact antenna is made than a general dipole antenna, where radiating conductors are disposed in line on the same straight line.
Therefore, according to an antenna of the present invention, since the radiating conductors are arranged in parallel, the antenna resonates at a plurality of frequencies to extend the operation bandwidth of the antenna. In addition, since the antenna can be made compact, it can be installed inside a vehicle to avoid breakage, to decrease the probability of being stolen and not to spoil the appearance of the vehicle.
It is preferred that the feeding conductive section have a shape which extends its width from a feeding point toward a connection end connected to the radiating conductors in the antenna according to the present invention in terms of wider bandwidth.
When the feeding conductive section has a shape which extends its width from the feeding end toward the connection end connected to the radiating conductors, the path length of a current flowing though the feeding conductive section becomes more flexible. In other words, since the resonant length can have a range, the antenna can be used in a wider bandwidth.
It is preferred that the radiating conductors be installed on an inner surface of a first case made from an insulating material, the grounding conductive plate be installed on an inner surface of a second case made from an insulating material, and the first case and the second case be combined to form the antenna, in terms of the protection of each conductive member constituting the antenna.
It is preferred that an insulating material used for the first case and the second case have a not-large loss and a good heat resistance, for example, that ABS resin be used.
It is preferred that the radiating conductors and the grounding conductive plate be installed on an inner surface of any one of a plurality of divided, insulating cases, in terms of easy connection work for connecting each conductive member to the feeder.
Also in this case, it is preferred that an insulating material used for the plurality of divided, insulating cases have a not-large loss and a good heat resistance, for example, that ABS resin be used.
It is preferred that the radiating conductors and the feeding conductive section be formed by bending one metal plate, in terms of reducing the number of machining processes.
When the radiating conductors and the feeding conductive section are formed by bending one metal plate, electric losses at the connection sections of the radiating conductors and the feeding conductive section are reduced.
The radiating conductors are made from highly conductive metal plates, such as copper and aluminum.
It is preferred that the radiating conductors, the feeding conductive section, and the grounding conductive plate be formed on a surface of a base member made from an insulating material, in terms of making a support for each conductive member robust. It is also possible that conductive film formed on the whole surfaces of the base member is etched to generate each conductive pattern at a time.
It is preferred that the base member be made from high frequency, relatively-small-loss, dielectric ceramic or resin.
REFERENCES:
patent: 4800392 (1989-01-01), Garay et al.
patent: 4907006 (1990-03-01), Nishikawa et al.
patent: 5291210 (1994-03-01), Nakase
patent: 5365246 (1994-11-01), Rasinger et al.
patent: 5523768 (1996-06-01), Hemmie et al.
patent: 6002367 (1999-12-01), Engblom et al.
patent: 6014112 (2000-01-01), Koscica et al.
patent: 6166694 (2000-12-01), Ying
patent: 11-4113 (1999-01-01), None
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Phan Tho G.
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