Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
1999-08-06
2001-06-19
Sotomayor, John B. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C342S175000, C343S7000MS
Reexamination Certificate
active
06249242
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a high-frequency transmitter-receiver apparatus which can be employed as a radar for an automobile or motor vehicle, a communication device in a wireless LAN (local area network) and others. Further, the present invention is concerned with an antenna unit incorporating a high-frequency transmitter-receiver device and a vehicle-onboard radar system incorporating the same.
For the high-frequency transmitter-receiver apparatus employed as the vehicle radar, the wireless LAN or the like, it is important to realize the high-frequency transmitter-receiver apparatus in a miniaturized and simplified structure from the standpoint of mountability and portability of the apparatus.
As one of the conventional high-frequency transmitter-receiver apparatuses designed for use as a radar for a motor vehicle, there can be mentioned the apparatus disclosed in “Proceedings of 1997 IEICE (Institute of Electronics, Information and Communication Engineers) Convention, Paper No. C-2-121: 60 GHz-BAND MILLIMETER-WAVE BAND RADAR UNIT” (hereinafter referred to as the prior art reference 1). In this known transmitter-receiver apparatus, a millimeter-wave (60 GHz band) transmitter-receiver circuit or transceiver circuit is realized as a discrete transmitter-receiver unit encased within a housing. On the other hand, an antenna unit is also realized as a discrete unit and adapted to be connected to the transceiver circuit unit. More specifically, a waveguide terminal serving as input/output terminal for the radio-frequency or RF signal is provided on a rear or bottom surface of the transmitter-receiver unit. Similarly, the antenna unit is equipped with a corresponding waveguide terminal. Thus, the transmitter-receiver unit and the antenna unit can be electrically interconnected by using a waveguide.
Further, in JP-A-8-250913 (hereinafter referred to as the prior art reference 2), there is disclosed a high-frequency transmitter-receiver apparatus in which a planar antenna is formed on an outer surface of a package in which a monolithic microwave integrated circuit (hereinafter referred as MMIC) is hermetically accommodated.
FIG. 18
of the accompanying drawings shows a structure of the same. As can be seen in the figure, an antenna
142
is mounted on a bottom surface
141
of the package while a MMIC
143
is mounted as embedded within the package in opposition to the antenna
142
. The bottom surface of the MMIC package
143
, that is, the top surface of the MMIC package
143
as viewed in the figure, is provided with a slot
146
formed by removing partially a ground conductor layer
145
. A conductor pattern
144
constituting a part of a high-frequency circuit and provided on the bottom surface of the MMIC package
143
and the antenna
142
are coupled electromagnetically through the medium of the slot
146
. A bonding pad
147
provided on the surface of the MMIC package
143
and a power source terminal
149
also provided on the same surface for receiving external power supply are electrically interconnected by a bonding wire
148
.
SUMMARY OF THE INVENTION
According to the technique described in the prior art reference 1, the transceiver unit and the antenna unit designed and realized discretely from each other are interconnected for constituting the high-frequency transmitter-receiver apparatus. This structure is certainly advantageous in that the characteristics of the transceiver unit and the antenna unit can be evaluated independently of each other. However, a large number of parts are required with the structure being complicated, which makes it difficult to realize the high-frequency transmitter-receiver apparatus in a miniaturized and simplified structure. In particular, coupling of the discrete units through the waveguide in a very high frequency band such as a millimeter wave band involves complexity in machining the waveguide, terminals and others, giving rise to a problem of high manufacturing cost.
On the other hand, according to the teachings disclosed in the prior art reference
2
, the high-frequency transceiver circuit and the antenna are electromagnetically coupled through the slot. With such contactless coupling, insertion loss of the high-frequency signal tends to increase. In order to suppress such insertion loss, the thickness of the electrically conductive plate
141
disposed between the antenna and the high-frequency transceiver circuit has to be reduced to be as thin as possible. By way of example, it is reported that in the case of the high-frequency transmitter-receiver apparatus for the signal of 10 GHz, the thickness of the electrically conductive plate mentioned above is on the order of 0.5 to 0.7 mm. Thus, for the signal of millimeter wave band (ca. 60 GHz), the thickness of the electrically conductive plate has to be further decreased. Consequently, a great difficulty will be encountered in sustaining a desired mechanical strength with the structure in which the antenna and the high-frequency circuit are provided, respectively, on both surfaces of the conductive plate. In other words, some reinforcing mechanism or structure will be required. Besides, the electromagnetic coupling of the signal of short wavelength such as millimeter-wave requires high dimensional precision for realizing the slot as well as high-precision positioning of the antenna pattern
142
and the high-frequency circuit pattern
144
, which of course imposes not a little burden on the assembling work. Additionally, in order to assure reliability of the MMIC, the whole package must be implemented in a hermetically sealed structure, which renders the assembling work more difficult.
In the light of the state of the art described above, it is an object of the present invention to provide a high-frequency transmitter-receiver apparatus which can essentially evade the problems of the conventional apparatus mentioned above.
Another object of the present invention is to provide an antenna unit which incorporates as an integral part thereof a high-frequency transmitter-receiver device and in which the problems such as mentioned above are solved satisfactorily.
It is yet another object of the present invention to provide a radar system in which the antenna unit mentioned above is employed.
In view of the above and other objects which will become more apparent as the description proceeds, there is provided according to an aspect of the present invention, a high-frequency transmitter-receiver apparatus in which a high-frequency transceiver circuit composed of an oscillator, an amplifier, a mixer circuit and the like is realized in the form of a planar circuit structure by using a dielectric substrate and a semiconductor chip, while an antenna for transmitting and receiving a high-frequency signal is realized as a planar antenna by using a dielectric substrate, wherein the dielectric substrate constituting a part of the planar circuit structure and the dielectric substrate constituting a part of the planar antenna are directly bonded on first and second surfaces, respectively, of a single electrically conductive base plate, the first and second surfaces being opposite to each other, and wherein high-frequency signal lines of the planar circuit and the planar antenna, respectively, are interconnected by an coaxial line which extends through the base plate.
By virtue of the arrangement described above, there can be realized a unitary structure in which the transceiver circuit and the antenna are combined integrally with each other, whereby the factors contributing to deterioration of the characteristics can be diminished with the number of parts being decreased. Besides, the apparatus can be miniaturized as a whole.
In a mode for carrying out the present invention, those portions of the coaxial line (coaxial cable) where the coaxial line is connected, respectively, to the dielectric substrate constituting a part of the planar circuit structure and the dielectric substrate constituting a part of the planar antenna structure should preferably
Kamozaki Keigo
Kondoh Hiroshi
Matsuura Kazuo
Nagaishi Hideyuki
Nakazawa Terumi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Sotomayor John B.
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