Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
1999-02-26
2001-02-13
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S770000, C343S872000
Reexamination Certificate
active
06188368
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slot antenna adapted to transmitting or receiving high-frequency signals of chiefly microwaves or millimeter waves.
2. Description of the Prior Art
In recent years, data have been transmitted in a wireless manner and on a personal basis as represented by portable telephones. Under such circumstances, it has been desired to transmit large amounts of data at higher speeds. For this purpose, semiconductor elements (high-frequency semiconductor elements) have been developed that operate in high-frequency regions such as of millimeter waves (30 to 300 GHz).
There have further been proposed various applied systems using high-frequency semiconductor elements that work on millimeter electromagnetic waves, as represented by a between-the-car radar and a wireless LAN. For example, in the Electronics Society, Japanese Academy of Electronic Data Communication, 1995, a between-the-car radar (see SC-7-6), a cordless camera system (see C-137), a high-speed wireless LAN (see C-139) and the like systems have been proposed.
These systems all utilize radio waves, and signals are exchanged through antennas between the system and space in which radio waves propagate. A variety kinds antennas have heretofore been studied for dealing with high-frequency signals as can be represented by a microstrip antenna, a horn antenna, a slot antenna and the like antennas.
The slot antenna has a structure in which a high-frequency signal transmission line such as a microstrip line is formed on one surface of a dielectric substrate, a ground layer is formed on the other surface thereof, a slot is formed in the ground layer at a position opposed to an open end of the transmission line, and the transmission line and the slot are electromagnetically coupled together. The slot antenna having such a structure is advantageous in that it can be easily produced by utilizing a general layer-laminating technology, it is particularly cheaply produced among the above-mentioned various kinds of antennas, and it is very suited for the systems that must be constructed in small sizes and in light weights.
However, the existing slot antennas have a defect of low efficiency (signal transmission characteristics) and, hence, it has been demanded to improve the efficiency.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a slot antenna capable of transmitting high-frequency signals maintaining a high efficiency.
According to the present invention, there is provided a slot antenna comprising a dielectric substrate, a high-frequency signal transmission line formed on one surface of said dielectric substrate and having an open end, and a ground layer formed on the other surface of said dielectric substrate, said ground layer having a slot at a position opposed to the open end of said transmission line, wherein
a dielectric plate for impedance matching is laminated on the surface of said ground layer on the side where said slot is formed so as to cover said slot.
In the conventional slot antenna, it is considered that there exists a mismatching between the impedance of the slot portion and the impedance of external space in which the electromagnetic waves propagate, high-frequency signals are reflected by the slot portion due to the mismatching and, as a result, the efficiency of the antenna remains low. According to the present invention, on the other hand, the dielectric plate for impedance matching is provided so as to cover the slot, whereby mismatching of the impedance is suppressed, high-frequency signals are not reflected by the slot portion, and a high antenna efficiency is accomplished.
REFERENCES:
patent: 4130822 (1978-12-01), Conroy
patent: 4197545 (1980-04-01), Favaloro et al.
patent: 4431996 (1984-02-01), Milligan
patent: 5392152 (1995-02-01), Higgins et al.
patent: 5489913 (1996-02-01), Raguenet et al.
patent: 5631659 (1997-05-01), Evans et al.
Kitazawa Kenji
Koriyama Shin-ichi
Minamiue Hidehiro
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