Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2002-06-14
2003-03-25
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S248000, C333S001100
Reexamination Certificate
active
06538530
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a junction structure of dielectric strips which are built in a millimeter-wave integrated circuit and the like to transmit, branch and synthesize high-frequency signals, a nonradiative dielectric waveguide using the junction structure, and a millimeter-wave transmitting/receiving apparatus.
2. Description of the Related Art
A nonradiative dielectric waveguide (hereinafter referred to as an NRD guide) S
1
using a conventional dielectric strip for transmitting high-frequency signals of tens GHz is shown in FIG.
17
.
FIG. 17
is a partially cutaway perspective view of the NRD guide S
1
, which is formed by joining, above and below a dielectric strip
2
having a rectangular section, parallel plate conductors
1
,
3
each having a major surface larger than the top and bottom surfaces of the dielectric strip
2
. In the NRD guide S
1
, in the case where the spacing between the parallel plate conductors
1
,
3
is equal to or less than &lgr;/2 (&lgr; denotes a wavelength of high-frequency signals), high-frequency signals with a wavelength more than &lgr; are cut off and incapable of entering the spacing between the parallel plate conductors
1
,
3
. The dielectric strip
2
is interposed between the parallel plate conductors
1
,
3
, whereby high-frequency signals can propagate inside and along the dielectric strip
2
, and radiation waves from high-frequency signals are suppressed by a cut-off effect of the parallel plate conductors
1
,
3
. The value &lgr; is equal to a wavelength of high-frequency (electromagnetic wave) signals propagating in the air. In addition,
FIG. 17
is illustrated by cutting away part of the upper parallel plate conductor
3
in order to make the inside visible.
In order to branch high-frequency signals at a midway point of a dielectric strip in such an NRD guide, as shown in
FIG. 18
, a technique of mounting dielectric strips
11
,
12
for branching high-frequency signals in the vicinity of a terminal of a dielectric strip
10
in which high-frequency signals are entered and propagated, and further mounting dielectric strips
13
,
14
for propagating high-frequency signals in the vicinity of terminals of the dielectric strips
11
,
12
, respectively, has been put forth (refer to Papers of the Institute of Electronics, Information and Communication Engineers, C-I Vol.J75-C-I No.1, pp.35-41, January 1992). In this case, the dielectric strip
10
and the dielectric strips
11
,
12
, and the dielectric strips
11
,
12
and the dielectric strips
13
,
14
are placed at predetermined spacings so that high-frequency signals are spatially electromagnetically coupled. Besides, at the terminal of the dielectric strip
10
and the tips of the dielectric strips
13
,
14
, mode suppressors
15
for eliminating unnecessary transmission modes are placed.
FIG. 18
is illustrated in perspective of the inside.
Further, as another construction of branching high-frequency signals at a midway point of a dielectric strip in an NRD guide, as shown in
FIG. 19
, a technique of installing a straight dielectric strip
20
and a curved (U-shaped) dielectric strip
21
so that a curved protrusion of the dielectric strip
21
is in proximity to a midway point of the dielectric strip
20
is well-known (see Japanese Unexamined Patent Publications JP-A 6-174824 (1994) and JP-A 8-8621 (1996), and IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, Vol. MTT-31, No.8, August 1983, pp.648-654). In this NRD guide S
3
, part of high-frequency signals entered from an input port
20
a
of the dielectric strip
20
are propagated in the dielectric strip
20
and outputted from an output port
20
b
, and the rest thereof are spatially electromagnetically coupled at the curved protrusion of the dielectric strip
21
and outputted from an output port
21
c
. The dielectric strip
21
, which is called a coupler, has a nonreflective terminator
22
at an end thereof opposite to the output port
21
c
and suppresses reflection of high-frequency signals at the nonreflective terminator
22
. Here,
FIG. 19
is illustrated in perspective of the inside.
The spacing L between the two dielectric strips
20
,
21
at the proximate portion thereof is regulated, whereby high-frequency signals can be distributed at a desired branching ratio. It has been general in an NRD guide to distribute high-frequency signals by using a coupler as shown in FIG.
19
.
On the other hand, the NRD guide S
2
as shown in
FIG. 18
, in order to match the electromagnetic coupling among the dielectric strips
10
-
14
, needs to place the dielectric strips
10
-
14
by precisely regulating the spacing thereof, and the component count thereof is considerably high, so that the practical utility thereof is low.
Therefore, an NRD guide using a coupler as shown in
FIG. 19
is dominant, whose transmission property of high-frequency signals by frequency is shown in FIG.
20
. Regulation is made in a manner that, when high-frequency signals of 60 GHz are entered from the input port
20
a
, the high-frequency signals are divided into halves with almost the same levels and outputted from the output ports
20
b
,
21
c
. Sba denotes an output level of high-frequency signals exiting from the output port
20
b
, and Sca denotes an output level of high-frequency signals exiting from the output port
21
c
. As shown in
FIG. 20
, the output levels Sba, Sca are largely varied, respectively, when the frequency is shifted from 60 GHz. Therefore, the conventional NRD guide S
3
can be used only within a bandwidth of about 1 GHz centered at 60 GHz, exhibiting an insufficient frequency response in the field of communication devices such as a cellular phone which need to be usable in a wide band.
Further, in the NRD guide S
3
, the output levels Sba, Sca are largely varied when the spacing L between the dielectric strips
20
,
21
is varied in
FIG. 19
, and hence the dielectric strips need to be placed with high accuracy, so that mass productivity of the NRD guide S
3
has been prevented from enhancing. In addition, the dielectric strip
21
need to have the nonreflective terminator
22
at one end thereof, and in the case where the NRD guide is used at 60 GHz, the nonreflective terminator
22
becomes approximately 4-20 mm long, whereby downsizing of the NRD guide S
3
has been hindered, and design thereof has been restricted.
SUMMARY OF THE INVENTION
Therefore, the present invention, which was made in view of the circumstances mentioned above, is aimed at providing an NRD guide which can be used in a wider band than the conventional one and hence applicable to devices used in a wide band such as communication devices, does not require precise positioning of a dielectric strip and thereby enhances mass productivity thereof, and does not need a nonreflective terminator disposed to a dielectric strip and hence can be designed with high flexibility and downsized.
The invention provides a junction structure of dielectric strips comprising a first straight dielectric strip for propagating high-frequency signals and a second dielectric strip which is joined to the first dielectric strip at a midway point thereof, wherein a junction between the second dielectric strip and the first dielectric strip is formed along an arc and the radius of curvature thereof is equal to or more than the wavelength of the high-frequency signals.
With the construction mentioned above, the invention can be produced in a state where the first dielectric strip and the second dielectric strip are integrated, and does not require precise positioning as in the case of individually placing these dielectric strips, so that mass productivity thereof is enhanced. Moreover, the second dielectric strip does not need to have a nonreflective terminator, so that the invention is highly flexible in design and advantageous for downsizing. In addition, the radius of curvature of the junction of the second dielectric strip is set to be equal to or more than the wavelength of high-frequency
Hiramatsu Nobuki
Kii Hironori
Hogan & Hartson LLP
Kyocera Corporation
Pascal Robert
Takaoka Dean
LandOfFree
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