Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
1999-10-28
2002-01-29
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S91100R, C343S7000MS
Reexamination Certificate
active
06342863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to antenna apparatus used in an automatic driving system for automobiles and the like. More particularly, the present invention relates to an antenna apparatus using a nonradiative dielectric waveguide using a high frequency band such as the milliwave band.
2. Description of the Related Art
A known antenna apparatus is described with reference to FIG.
14
.
FIG. 14
is an exploded perspective view of the known antenna apparatus.
Referring to
FIG. 14
, a known antenna apparatus
110
includes an upper conductor plate
111
and a lower conductor plate
112
made of aluminum, a dielectric strip
113
made of polytetrafluoroethylene, which is held between the upper conductor plate
111
and the lower conductor plate
112
, and a cylindrical dielectric resonator
127
disposed at a distance from an end of the dielectric strip
113
. A two-slot aperture
114
is formed on the upper conductor plate
111
at a position where the dielectric resonator
127
is disposed.
With this configuration, a nonradiative dielectric waveguide is formed by the upper conductor plate
111
, the lower conductor plate
112
, and the dielectric strip
113
. By adjusting the distance between the upper conductor plate
111
and the lower conductor plate
112
to half a propagating wavelength or less, only the dielectric strip
113
operates as a signal propagation area. An electromagnetic wave input from the outside is propagated through the dielectric strip
113
in a longitudinal-section magnetic (LSM) mode, which in turn is connected with the dielectric resonator
127
. The dielectric resonator
127
resonates in an HE
111
mode. The electromagnetic wave is radiated from the dielectric resonator
127
via the aperture
114
on the upper conductor plate
111
.
Recently, a high frequency band, such as the milliwave band, has been used for automatic driving systems for automobiles. Accordingly, there is an increasing demand for high accuracy in the antenna apparatus, such as by miniaturization of the dielectric resonator. However, the known antenna apparatus includes the dielectric strip and the dielectric resonator disposed at a predetermined separation in accordance with an operating frequency. Disposition of the dielectric resonator in order to satisfy the required characteristics is very difficult.
Polytetrafluoroethylene employed for the dielectric strip has a relatively large coefficient of linear expansion. Variations in temperature cause variations in the distance between the dielectric strip and the dielectric resonator, thus failing to match the operating frequency and increasing return loss. Specifically, the distance between the dielectric strip and the dielectric resonator is small in the milliwave band, so that slight variations in the distance exert a powerful influence on the characteristics of the antenna apparatus.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an antenna apparatus, and an antenna and a transceiver using the same, in which disposition of component parts including a dielectric strip is simple, and characteristics of the antenna apparatus are not susceptible to temperature variations even in a high frequency band, e.g., in the milliwave band.
To this end, according to an aspect of the present invention, there is provided an antenna apparatus including two substantially parallel conductors, a dielectric strip held between the two conductors, an aperture formed on one of the two conductors in the vicinity of the dielectric strip, and a matching section for matching impedance between the dielectric strip and the aperture. The matching section is continuously connected to the dielectric strip in the vicinity of the aperture.
Electromagnetic waves are radiated from the matching section continuously connected to the dielectric strip. There is no need to dispose a dielectric resonator at a distance from the dielectric strip, as in known antenna apparatus. In the antenna apparatus of the present invention, the dielectric strip and the matching section are integrated, eliminating detailed working to dispose the dielectric strip and the dielectric resonator at a predetermined separation. The antenna apparatus of the present invention is stable in characteristics relative to temperature variations.
A stub formed of a dielectric may be continuously connected to the matching section. Thus, reflection characteristics of the antenna apparatus may be improved.
The stub may have a length of ¼&lgr;g where &lgr;g represents a propagating wavelength. Thus, the reflection characteristics of the antenna apparatus are optimized.
A connecting dielectric strip having a sectional shape differing from that of the dielectric strip may be continuously connected in the vicinity of the matching section. Variations in the shape of the connecting dielectric strip permit variations in an amount of connection between the dielectric strip and the matching section, thereby adjusting the matching between the dielectric strip and the matching section.
The connecting dielectric strip may have a length of ¼&lgr;g relative to the propagating wavelength &lgr;g. Thus, the amount of connection and the matching between the dielectric strip and the matching section are optimized.
In accordance with another aspect of the present invention, there is provided an antenna including the antenna apparatus and a dielectric lens disposed in the upper part of the aperture of the antenna apparatus.
In accordance with another aspect of the present invention, there is provided a transceiver including the antenna and a transceiver circuit connected to the antenna.
Accordingly, productivity is increased, and the antenna and the transceiver with stable characteristics relative to temperature variations are obtained.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 4775866 (1988-10-01), Shibata et al.
patent: 6008771 (1999-12-01), Tanaka et al.
patent: 6052087 (2000-04-01), Ishikawa et al.
patent: 0743697 (1996-11-01), None
patent: 0817394 (1998-01-01), None
Japanese Abstract vol. 1997 No. 05, May 30, 1997 & JP 09 008542 A (Matsushita Electric Independent Co LTD). Jan. 10, 1997.
Izumi Uchida et al.: Miniaturization of 35-GHZ NRD-Guide Transmitters and Receiver Electronics, US, Scripta Technic. vol. 77, No. 2.
Higashi Kazutaka
Kitamori Nobumasa
Dinh Trinh Vo
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Wong Don
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