Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-09-15
2001-10-02
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000
Reexamination Certificate
active
06297777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to surface-mounted antennas and communication apparatus using the same, such as cellular phones.
2. Description of the Related Art
With the recent expanding proliferation of cellular phones, the technological development race is heating up with the aims of miniaturization and high performance of the cellular phones. In order to accomplish there aims, it is essential to reduce the sizes of antennas incorporated in the cellular phones while improving the performance of the antennas.
Although various antenna structures have been designed and provided, no antenna can sufficiently satisfy the demands for both high performance and miniaturization. This type of antenna is yet to appear on the market.
As a promising compact and highly efficient antenna the present inventors have focused much attention on a surface-mounted antenna. The surface-mounted antenna, for example, can be made by disposing a pair of electrodes close to each other on a surface of a dielectric base chip. In this case, the pair of electrodes is comprised of a radiation electrode of an inverted-F antenna and a radiation electrode of a microstrip antenna. In order to reduce the size of the surface-mounted antenna, the pair of radiation electrodes needs to be disposed on the surface of the dielectric base chip with a narrow gap therebetween.
However, when the pair of radiation electrodes is disposed with a narrow distance therebetween without considering the structure in which the electrodes are disposed, signal interference occurs between the radiation electrodes. This creates a critical problem in that it is difficult for the antenna to have a wide frequency bandwidth. In order to solve the problem, it is only necessary to greatly increase the gap between the pair of electrodes so that the signal interference between the pair of electrodes can be suppressed. However, increasing the gap between the radiation electrodes leads to an increase in the size of the base dielectric substrate, thereby necessarily increasing the size of the surface-mounted antenna. In other words, miniaturizing the antenna and obtaining a wide frequency band for the antenna are mutually contradictory objectives. When either one of these two objectives is achieved, the other one is difficult to achieve. Thus, with such a simple structure in which the pair of electrodes is disposed together, it is unlikely that the demands on miniaturization of the antenna and on obtaining of a wide frequency band for the antenna can be met.
However, by conducting much research and development, the present inventors have successfully designed an antenna having an innovative electrode-arrangement structure, which can meet both demands mentioned above.
SUMMARY OF THE INVENTION
Accordingly, in view of the above situation, based on the designed electrode-arrangement structure, it is an object of the present invention to provide a surface-mounted antenna whose size can be reduced while obtaining a wide frequency band, and a communication apparatus using the surface-mounted antenna.
To this end, the following arrangement is provided to solve the above problems. According to a first aspect of the present invention, there is provided a surface-mounted antenna including a base dielectric substrate, a first radiation electrode formed on a part of the upper surface of the base dielectric substrate, a multi-layer dielectric substrate laminated on the upper surface of the base dielectric substrate to be integrated therewith, and a second radiation electrode formed on the upper surface of the multi-layer dielectric substrate in a position where the second radiation electrode is not opposed to the first radiation electrode. In this surface-mounted antenna, directions in which the first radiation electrode and the second radiation electrode excite intersect with each other.
In addition, in this surface-mounted antenna, the upper surfaces of both the base dielectric substrate and the multi-layer dielectric substrate may have quadrangular shapes. The first radiation electrode may be formed on substantially half of the region of the upper surface of the base dielectric substrate. The second radiation electrode may be formed on substantially half of the region of the upper surface of the multi-layer dielectric substrate, which is opposed to the side where the first radiation electrode is formed. Edges of the first and second radiation electrodes present on sides mutually opposing via the multi-layer dielectric substrate may be oblique lines.
According to a second aspect of the present invention, there is provided a surface-mounted antenna including a base dielectric substrate, a first radiation electrode and a second radiation electrode on the upper surface of the base dielectric substrate via a gap, at least one multi-layer dielectric substrate laminated on the upper surface of the base dielectric substrate to be integrated therewith, and another first radiation electrode and another second radiation electrode formed on the upper surface of the multi-layer dielectric substrate via a gap. In this arrangement, directions in which the first radiation electrode and the second radiation electrode formed on each of the base dielectric substrate and at least one multi-layer dielectric substrate excite intersect with each other, and directions in which the vertically adjacent first and second radiation electrodes on the upper and lower layers excite differ from each other. For example, at least the directions in which the first radiation electrodes of the vertically adjacent layers excite differ from each other. Similarly, at least the directions in which the second radiation electrodes of the vertically adjacent layers excite also differ from each other.
In addition, in the surface-mounted antenna of the second aspect of the invention, the upper surfaces of both the base dielectric substrate and the multi-layer dielectric substrate may have both quadrangular shapes. The edges opposing via the gaps between the first radiation electrodes and the second radiation electrodes of the individual layers may be oblique lines.
According to a third aspect of the present invention, there is provided a surface-mounted antenna including a base dielectric substrate, a first radiation electrode formed on the upper surface of the base dielectric substrate, a multi-layer dielectric substrate laminated on the base dielectric substrate to be integrated therewith, and a second radiation electrode formed on the upper surface of the multi-layer dielectric substrate. In this arrangement, directions in which the first and second radiation electrodes excite intersect with each other.
Moreover, in the surface-mounted antenna according to one of the first to third aspects of the invention, the permittivity of the multi-layer dielectric substrate may be set to be higher than the permittivity of the base dielectric substrate.
Furthermore, in the surface-mounted antenna according to one of the second and third aspects of the invention, the permittivity of the multi-layer dielectric substrate laminated at the top may be set to be higher than the permittivity of the dielectric substrate of any other layer.
In addition, according to a fourth aspect of the present invention, there is provided a communication apparatus incorporating one of the surface-mounted antennas according to the first to third aspects of the invention.
In the surface-mounted antenna of the present invention, the first radiation electrode is formed on the partial region of the upper surface of the base dielectric substrate, and the second radiation electrode is formed in the position where the second radiation electrode is not opposed to the first radiation electrode on the upper surface of the multi-layer dielectric substrate laminated on the base dielectric substrate to be integrated therewith. The direction in which the first radiation electrode excites intersects with the direction in which the second radiation electrode excites. In this situation, the first radi
Kawahata Kazunari
Nagumo Shoji
Tsubaki Nobuhito
Le Hoang-anh
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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