Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2001-05-25
2002-03-19
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S767000, C343S771000, C343S785000
Reexamination Certificate
active
06359590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric waveguide line which is used as a feeder line for any kinds of antenna device suitable for communication using high-frequency signals within a microwave band, a millimeter wave band or the like, and more particularly, to an antenna feeder line capable of feeding power to the antenna device with high efficiency by reducing reflection of high-frequency signals at a connection of the feeder line and the antenna device, and an antenna module provided with the antenna feeder line.
2. Description of the Related Art
An example of methods proposed as methods of feeding power to an antenna device that emits electromagnetic waves such as microwaves or millimeter waves is a slot fed antenna where power is fed from a feeder line to the antenna device through a slot which is a conductor non-formed portion. The slot-fed system is widely used because of having a simple structure, and antennas using a line such as a microstrip line, a strip line, a coplanar line or a waveguide line as the feeder line have been proposed. Moreover, it is widely performed to arrange a plurality of antenna devices into an array in order to obtain a desired antenna emission pattern. In doing this, it is necessary to branch the feeder line in accordance with the number of the antenna devices to feed power in series or in parallel. In the case of the microstrip line, strip line and coplanar line, there are such problems that unnecessary electromagnetic wave emission or an interaction between lines occurs where there is a portion in which the impedance is discontinuous.
To solve this problem, the inventors of the invention have proposed in Japanese Unexamined Patent Publication JP-A 10-303612 (1998) a structure in which power is fed to an antenna device with a slot being provided in a conductor layer of a dielectric waveguide line having a multilayer structure and comprising the conductor layer and a via hole (via conductor). According to the feeder line structure, since electromagnetic waves propagate only through an area surrounded by conductors, no unnecessary emission occurs, whereby an interaction between lines can be prevented.
However, even in the feeder line disclosed in JP-A 10-303612, with which power is fed to the antenna through the slot provided in the dielectric waveguide line, the impedance is discontinuous in the slot portion. Consequently, the reflection is large at frequencies in the vicinity of the resonance frequency of the slot, and particularly in a series-feed antenna, waves reflected at the power-fed slot in each device are accumulated, resulting in an extremely large total reflection.
SUMMARY OF THE INVENTION
The invention is made to solve the above-mentioned problem of the prior art, and an object thereof is to provide an antenna feeder line capable of feeding power to an antenna device with high efficiency by suppressing the reflection loss of high-frequency signals of a desired frequency at a conductor non-formed portion.
Another object of the invention is to provide an antenna module capable of feeding power with high efficiency and excellent emission characteristics.
As a result of examinations of the above-mentioned problem, the inventors of this application have found that reflection of high-frequency signals that occurs at the slot which is a conductor non-formed portion can be reduced by disposing at least one conductor comprising a conducting bar of a via hole and a conductor layer of a metalized pattern in a position at a distance within a predetermined range from the slot.
The invention provides an antenna feeder line comprising: a dielectric substrate composed of a lamination of a plurality of dielectric layers; a first main conductor layer formed on one surface of the dielectric substrate; a second main conductor layer formed on the other surface of the dielectric substrate; two through conductor groups in two rows formed within the dielectric substrate, each of the two through conductor groups being composed of a plurality of through conductors electrically connecting the first main conductor layer and the second main conductor layer at predetermined intervals; and sub conductor layers for electrically connecting the through conductor groups, interposed between the dielectric layers, wherein the first main conductor layer, the second main conductor layer, the two through conductor groups and the sub conductor layers form a dielectric waveguide line where a high-frequency signal is transmitted through a transmission area surrounded by the first main conductor layer, the second main conductor layer, the through conductor groups and the sub conductor layers, a conductor non-formed portion is provided in the first main conductor layer of the dielectric waveguide line, the high-frequency signal is fed to an antenna device disposed above the conductor non-formed portion, through the conductor non-formed portion, and a grounding conductor for electrically connecting the first and second main conductor layers constituting H surfaces is disposed in a position which is perpendicular to a signal transmission direction and at a distance substantially not more than ½ a distance between the side surfaces constituting E surfaces of the dielectric waveguide line from the side surfaces, within a distance substantially the same as a wavelength of the high-frequency signal from the conductor non-formed portion to a high-frequency signal input side or a side opposite thereto.
The invention provides an antenna module comprising: the antenna feeder line of the above-described structure; and an aperture antenna or linear antenna, disposed on the first main conductor layer of the antenna feeder line and fed with the high-frequency signal through the conductor non-formed portion.
According to the antenna feeder line of the invention, for the problem that since the impedance is discontinuous because of the provision of the conductor non-formed portion which is a power feeding slot on the dielectric waveguide line, the electromagnetic wave of the high-frequency signal is reflected at the slot, the grounding conductor for suppressing reflection comprising a conducting bar and/or a conductor layer and electrically connecting the first and second main conductor layers constituting the H surfaces of the dielectric waveguide line is disposed in a position at a distance within the distance substantially the same as the wavelength of the transmitted high-frequency signal from the slot to the signal input side or the side opposite thereto in parallel to the signal transmission direction and in a position which is perpendicular to a signal transmission direction and at the distance substantially not more than ½ the distance between the side surfaces constituting the E surfaces of the dielectric waveguide line from the E surfaces of the dielectric waveguide line, whereby the reflection of the electromagnetic wave can be reduced. That is, the above-mentioned position in which the grounding conductor including a conducting bar and/or a conductor layer is disposed is set so that the following effect is obtained: The amplitude of the electromagnetic wave reflected at the slot and the amplitude of the electromagnetic wave reflected at the grounding conductor comprising a conducting bar and/or a conductor layer are made the same so that the phases thereof are different by 180 degrees, whereby the electromagnetic waves cancel out each other. Consequently, power can be fed to the antenna device with high efficiency.
Moreover, according to the antenna module of the invention, power can be fed to the antenna device with high efficiency because the antenna module comprises the antenna feeder line of the above-described structure; and an aperture antenna (a multilayer aperture antenna, a horn antenna or the like) or linear antenna (a patch antenna, a microstrip antenna, a printed dipole antenna or the like) which is an antenna device disposed on the first main conductor layer of the antenna feeder line and fed wi
Ho Tan
Hogan & Hartson L.L.P.
Kyocera Corporation
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