Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-05-22
2001-08-28
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000
Reexamination Certificate
active
06281848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface-mount antenna device that allows communication in two frequency bands and a communication apparatus such as a mobile telephone that uses the same.
2. Description of the Related Art
FIG. 9
shows a conventional antenna device that is adapted to communication in two frequency bands. In
FIG. 9
an antenna device
100
comprises two patch antennas
101
and
102
that have different resonant frequencies and are disposed side-by-side with a certain spacing to allow both of them to be connected to a single signal source
103
via capacitance coupling. It is thus possible to construct an antenna device that responds to two frequency bands by disposing two patch antennas with different resonant frequencies side-by-side.
However, in such type of antenna devices, too small a space between two patch antennas
101
and
102
tends to develop undesirable interference between the two patch antennas, preventing obtaining desired characteristics. It is necessary to widen the space between both of them to {fraction (3/10)}-wavelength or more to reduce the mutual interference between the two patch antennas to a negligible amount. This presents a problem of enlarging the size of the antenna device as a whole.
Recently, downsizing of communication apparatus such as a mobile telephone using the antenna device has been promoted and the configuration of two patch antennas disposed side-by-side will present difficulty for further promotion of downsizing of the communication apparatus. Thus, the present inventors have been engaged in developing the technology for manufacturing an antenna device in integrated circuit configuration to achieve further downsizing of the communication apparatus. In the first step of developing a surface-mount antenna device having two frequency bands, the present inventor produced a first surface-mount antenna device operating at a first frequency and a second surface-mount antenna device operating at a second frequency and tried to dispose two surface-mount antenna devices in proximity on a mounting board.
However, providing two surface-mount antenna devices reduces productivity in manufacturing the antenna device and presents a limit in achieving substantial downsizing of the communication apparatus. Also, a new problem arose in that gain is decreased if the antenna is downsized to make it of the surface-mount type. The new problem can be reduced by making the space between the antennas smaller but the smaller space between the antennas causes a problem of interference between them.
SUMMARY OF THE INVENTION
After various attempts in research and development, the present inventor has made a breakthrough by inventing a unique configuration of the antenna electrode prepared in the one-chip construction with capability to respond to two frequencies. It can reduce deterioration of gain and suppress mutual interference of signals between electrodes, even though two antenna electrode patterns are disposed in proximity on a surface of a single dielectric substrate. The present invention is made under such circumstances as above with an object of providing a high-performance small one-chip antenna device that has the above unique configuration of the antenna electrode with capability of responding to two frequencies and providing the communication apparatus using the same.
One preferred embodiment of the present invention provides an antenna device comprising a feeding radiation electrode and a non-feeding radiation electrode separately disposed on a surface of a dielectric substrate, a short circuit part of the feeding radiation electrode and a short circuit part of the non-feeding radiation electrode adjacently disposed to each other on one side surface of the dielectric substrate, an open end of the feeding radiation electrode and an open end of the non-feeding radiation electrode being disposed on mutually different surface sides of a dielectric substrate avoiding the surface on which the above-mentioned short circuit parts are formed.
In the above described antenna device, the open end of the feeding radiation electrode and the open end of the non-feeding radiation electrode may be disposed on mutually opposing surface sides of the dielectric substrate.
Furthermore, the feeding radiation electrode and the non-feeding radiation electrode may be disposed so as to cause the direction of oscillation of the feeding radiation electrode and the direction of oscillation of the non-feeding radiation electrode to cross each other in substantially perpendicular directions.
Furthermore, the dielectric substrate may be formed in a shape of a rectangular parallelepiped, either one of the feeding radiation electrode or the non-feeding radiation electrode may be disposed along an edge on the top surface of the dielectric substrate over a quadrilateral area that covers substantially the whole length of the edge, while the other electrode may be disposed within the remaining area of the top surface, the other electrode having an open end covering substantially the whole length of the other edge of the top surface opposed to the area on which the one electrode is disposed, the periphery of the one electrode adjacent to the other electrode being curved in a direction in which the distance between the periphery and the other electrode increases along the direction from one side of a width of the quadrilateral area of the one electrode to the other side.
Furthermore, at least one of the feeding radiation electrode and the non-feeding radiation electrode may be formed in a meandering shape.
Furthermore, the dielectric substrate may have a cavity or cavities inside thereof by being provided with a hole or holes inside thereof or an opening on the bottom side.
Furthermore, the dielectric substrate on which the feeding radiation electrode and the non-feeding radiation electrode are formed may be mounted on a corner portion of a mounting board having a shape of the quadrilateral and the above feeding radiation electrode and the above non-feeding radiation electrode disposed on the dielectric substrate may be disposed along the edge portion of the mounting board.
Furthermore, the mounting board may be formed in an elongated quadrilateral-shape and the non-feeding radiation electrode is disposed along an edge of the longer side of the mounting board.
Yet another preferred embodiment of the present invention provides a communication apparatus characterized by being provided with an antenna device in accordance with the invention.
According to the above structure and arrangement, since the open ends of the feeding radiation electrode and the non-feeding radiation electrode are formed on the sides of the dielectric substrate, it is possible to achieve a high degree of electromagnetic field coupling between those open ends and ground electrode (ground surface) on the mounting board, when the dielectric substrate is mounted on the mounting board. This serves to strengthen the intensity of the electric field at the open ends to allow suppressing reduction of gain in spite of downsizing the antenna by forming it on one chip.
Furthermore, since the open ends of the feeding radiation electrode and the non-feeding radiation electrode are formed on different surfaces, for example, opposite surfaces, of the dielectric substrate, the direction of oscillation of the feeding radiation electrode and that of oscillation of the non-feeding radiation electrode, represented by the directions connecting the short-circuit parts with the open ends (the directions of the resonant currents) cross in substantially perpendicular direction, or in like manner, (the directions of the surface of polarization of the radio wave radiated from the feeding radiation electrode and the surface of polarization of the radio wave radiated from the non-feeding radiation electrode assume directions crossing each other perpendicularly, or in like manner). As a result, this serves to suppress signal interference effectively between the feeding radiat
Kawahata Kazunari
Nagumo Shoji
Tsubaki Nobuhito
Ho Tan
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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