U.S. patent application number 10/385842 was filed with the patent office on 2003-11-20 for antenna apparatus and transmission and receiving apparatus using same.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Ishikawa, Yohei, Nakamura, Fuminori, Takakuwa, Ikuo, Tanizaki, Toru.
Application Number | 20030214457 10/385842 |
Document ID | / |
Family ID | 11486369 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030214457 |
Kind Code |
A1 |
Ishikawa, Yohei ; et
al. |
November 20, 2003 |
Antenna apparatus and transmission and receiving apparatus using
same
Abstract
An antenna apparatus such that a dielectric strip and a
dielectric resonator are provided for form a primary vertical
radiator, another dielectric strip is provided which is coupled to
the dielectric strip to form a directional coupler, and a radiation
beam is tilted by changing the relative position of the primary
radiator with respect to the dielectric lens by displacing the
primary vertical radiator in the direction coupler.
Inventors: |
Ishikawa, Yohei; (Kyoto-shi,
JP) ; Tanizaki, Toru; (Kyoto-shi, JP) ;
Nakamura, Fuminori; (Nagaokakyo-shi, JP) ; Takakuwa,
Ikuo; (Suita-shi, JP) |
Correspondence
Address: |
DICKSTEIN SHAPIRO MORIN & OSHINSKY, LLP
1177 Avenue of the Americas
New York
NY
10036
US
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
11486369 |
Appl. No.: |
10/385842 |
Filed: |
March 12, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10385842 |
Mar 12, 2003 |
|
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09960459 |
Sep 20, 2001 |
|
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6563477 |
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Current U.S.
Class: |
343/909 ;
343/911R |
Current CPC
Class: |
G01S 13/42 20130101;
H01Q 19/06 20130101; H01Q 19/062 20130101; G01S 2013/932 20200101;
H01Q 3/14 20130101; G01S 7/032 20130101; G01S 13/931 20130101; G01S
2013/93271 20200101; G01S 13/34 20130101 |
Class at
Publication: |
343/909 ;
343/911.00R |
International
Class: |
H01Q 015/02; H01Q
015/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 1997 |
JP |
9-893 |
Claims
What is claimed is:
1. An antenna apparatus comprising: a dielectric lens having a
focal plane; and a primary radiator, the dielectric lens and
primary radiator having a relative positional relationship, wherein
the dielectric lens and the primary radiator are arranged so that
the relative position relationship of the primary radiator within
the focal plane of the dielectric lens can be changed
Description
[0001] This is a divisional of U.S. patent application Ser. No.
09/960,459, filed Sep. 20, 2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an antenna apparatus. More
particularly, the present invention relates to an antenna apparatus
which is used in a radar or the like for transmitting and receiving
an electromagnetic wave of a millimetric-wave band and a
transmission and receiving apparatus using the same.
[0004] 2. Description of the Related Art
[0005] Millimetric-wave radars to be mounted in motor vehicles are
used in a system for supporting safe driving of automobiles. The
millimetric-wave radar is used to measure the distance between two
automobiles or between an obstacle in the path of an automobile and
the automobile. Based on the measurement data, the speed control
and braking of the automobile are performed so that collision into
another automobile or an obstacle is prevented.
[0006] Generally, a transmission and receiving module using a
millimetric-wave radar incorporates a millimetric-wave oscillator,
a circulator, a directional coupler, a mixer, an antenna, and so
on.
[0007] The vehicle on the right side in FIG. 21 (behind) radiates a
millimetric wave from a radar by an FM-CW (Frequency
Modulation-Continuous Wave) method to the automobile on the left
side (ahead) and receives a millimetric wave reflected by the
automobile on the left side. The distance between the right and
left automobiles and the relative speed between the right and left
automobiles are computed by a known computation method.
[0008] The computation is performed by a signal processing section
of the signal processing apparatus of FIG. 22. The result of the
computation is transmitted to a control and warning section. The
control and warning section causes a warning device to operate
when, for example, the driving velocity of the automobile on the
right is equal to or higher than a predetermined value and the
distance between the right and left automobiles is equal to or
lower than a predetermined value. Alternatively, the control
section may operate a braking apparatus of the right or trailing
automobile under given conditions.
[0009] Since the directivity of the antenna used in the
conventional millimetric-wave radar is fixed, problems such as
those described below occur.
[0010] As shown in FIG. 18, when separate automobiles are driving
on two parallel traffic lanes, a millimetric wave transmitted from
a radar of an automobile Cm may reach an automobile Ca and an
automobile Cb in front. This is because adjustments cannot be made
such that the directivity of the antenna is varied so that the
millimetric wave is radiated only to the automobile within the
traffic lane in which the automobile Cm is driving.
[0011] The millimetric wave which reaches the respective
automobiles is reflected and received by the automobile Cm. Since
the automobiles Cb and Cm are driving in separate traffic lanes,
even if the automobiles Cb and Cm come too close to each other, the
automobile Cm does not need to perform special safety control.
[0012] However, in the automobile Cm, it is not possible to
identify from which automobile Ca or Cb the received wave has been
reflected. Therefore, when the vehicle-to-vehicle distance between
the automobiles Cb and Cm is smaller than an allowable distance,
control for safety is performed by the automobile Cm. Further, when
the directivity of the antenna is fixed, inconveniences such as
those described below occur.
[0013] An automobile Cm driving near the entrance of a curve in
FIG. 19 radiates a millimetric wave B1; however, the millimetric
wave does not reach the automobile Ca driving near the exit of the
curve.
[0014] Also in the case where a road has inclines and declines, as
shown in FIG. 20, in the automobile Cm driving before a slope while
radiating the millimetric wave B1, the automobile Ca moving on the
slope is not detected.
[0015] Therefore, the following method may be used in which the
direction of a radiation beam is changed to solve the
above-described problems.
[0016] For example, in FIG. 18, radiation beams B1, B2, and B3 are
radiated respectively so as to make measurements for each
direction. By comparing these results, it is possible to detect the
automobiles Ca and Cb individually.
[0017] In the example shown in FIG. 19, the presence of a curve in
front of the automobile Cm is recognized based on the
steering-wheel operation, and the millimetric wave B1 is switched
to the millimetric wave B2. There is also a method for detecting a
curve by analyzing the image input from a camera. Also in the
example shown in FIG. 20, a slope is detected by analyzing the
image input from the camera, and the millimetric wave B1 is
switched to the millimetric wave B2.
[0018] In the conventional radar system, the direction of radiation
of a radiation beam of an electromagnetic wave is changed by
rotating the housing of the transmission and receiving apparatus
which incorporates an antenna by a motor or the like. Since the
housing includes parts other than the antenna, it is difficult to
reduce the size of the mechanism for rotating the housing.
Therefore, it is difficult to rotate the housing at a high speed
and to scan the radiation beam at a high speed.
SUMMARY OF THE INVENTION
[0019] An object of the present invention is provide an antenna
apparatus and a transmission and receiving apparatus using the same
having a small size and being capable of switching the directivity
of the antenna at a high speed.
[0020] An antenna apparatus according to a first aspect of the
present invention comprises a primary radiation element for
radiating a radar wave and a dielectric lens for focusing a radar
wave, wherein the primary radiation element is movable within the
focal plane of the lens.
[0021] The change of the position with respect to the lens of the
primary radiation element causes the directivity of a radar beam
radiated from the primary antenna apparatus to vary. Since the
primary radiation element is relatively lightweight, an element
driving apparatus may be of a small scale. Further, since the
AAAAinertia of the primary radiation element is small, it is
possible to move the primary radiation element at a high speed,
making high-speed scanning of the radar beam possible.
[0022] In an antenna apparatus according to another aspect of the
present invention, the direction of the center axis of the
dielectric lens with respect to the radiation plane of the primary
radiation element is variable.
[0023] In an antenna apparatus according to still another aspect of
the present invention, in order to displace the position of the
primary radiator within the focal plane of the dielectric lens, the
primary radiator comprises a first dielectric line serving as an
input/output section, a dielectric resonator which is coupled to
the first dielectric line, and an opening section from which an
electromagnetic wave is radiated or is made to enter in the axial
direction, a second dielectric line is provided close to the first
dielectric line in order to form a directional coupler, and the
relative positional relationship between the dielectric lens and
the primary radiator is changed in the coupled section of the first
and second dielectric lines. Since a movable section which inputs
and outputs signals to and from the primary radiator as described
above is formed of a directional coupler formed of a dielectric
line on the primary radiator side and another dielectric line, it
becomes possible to change the relative position between the
primary radiator and the dielectric lens while maintaining the
coupling relationship.
[0024] In the directional coupler, if the amount of coupling is
made approximately 0 dB, transmission loss in the directional
coupler is suppressed by as much as possible, and the efficiency of
the antenna is not reduced.
[0025] Further, in the antenna apparatus of the present invention,
a transmission section, a receiving section, and a circulator for
separating a transmission signal and a received signal are
connected to the second dielectric line so that the antenna
apparatus is used for both transmission and reception. As a result,
the primary radiator formed of the first dielectric line and the
dielectric resonator coupled to the first dielectric line, and a
second dielectric line coupled to the first dielectric line can be
used for both transmission and reception, thereby preventing a
larger size because the movable section is formed by using the
directional coupler.
[0026] Furthermore, in the present invention, a driving section for
changing the relative positional relationship between the
dielectric lens and the primary radiator may be provided so that a
transmission and receiving apparatus is formed. As a result, a
small transmission and receiving apparatus capable of scanning in
the orientational direction of the antenna can be obtained.
[0027] The above and further objects, aspects and novel features of
the invention will become more apparent from the following detailed
description when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIGS. 1A, 1B, 1C, 1D, 1E, and 1F show the relationship
between a dielectric lens and a primary radiator of an antenna
apparatus, and the relationship to the tilt angle of a radiation
beam according to a first embodiment of the present invention;
[0029] FIGS. 2A, 2B, and 2C show another relationship between a
dielectric lens and a primary radiator of an antenna apparatus, and
another relationship to the tilt angle of a radiation beam
according to the first embodiment of the present invention;
[0030] FIGS. 3A and 3B show the measurement result of the tilt
angle of the radiation beam with respect to the offset of the
primary radiator from the dielectric lens;
[0031] FIGS. 4A and 4B show the measurement result of the tilt
angle of the radiation beam when the angle of the dielectric lens
with respect to the primary radiator is varied;
[0032] FIG. 5 is a sectional view illustrating an example of the
construction of a transmission and receiving apparatus according to
the first embodiment of the present invention;
[0033] FIG. 6 is a sectional view illustrating another example of
the construction of the transmission and receiving apparatus
according to the first embodiment of the present invention;
[0034] FIG. 7 is a plan view of the transmission and receiving
apparatus according to the first embodiment of the present
invention;
[0035] FIG. 8 is a schematic diagram of a transmission and
receiving apparatus according to a second embodiment of the present
invention;
[0036] FIGS. 9A, 9B, 9C, and 9D show the construction of a
dielectric line for use in the transmission and receiving
apparatus;
[0037] FIGS. 10A and 10B are a plan view and a sectional view,
respectively, showing the construction of a primary vertical
radiator;
[0038] FIG. 11 shows the relationship between the primary vertical
radiator and a dielectric-line apparatus;
[0039] FIG. 12 is a partial perspective view of a directional
coupler;
[0040] FIGS. 13A and 13B show the construction of the directional
coupler and the relationship to the characteristics thereof;
[0041] FIG. 14 is a diagram showing the transmission and receiving
apparatus according to the second embodiment of the present
invention;
[0042] FIG. 15 is a plan view illustrating the construction of a
transmission and receiving apparatus according to a third
embodiment of the present invention;
[0043] FIGS. 16A, 16B, and 16C show three examples of a directional
coupler in a movable section of an antenna apparatus according to a
fourth embodiment of the present invention;
[0044] FIG. 17 shows an example of the directional coupler in the
movable section of an antenna apparatus according to a fifth
embodiment of the present invention;
[0045] FIG. 18 shows the situation in which the radiation beam is
tilted in the horizontal direction in a vehicle-mounted radar;
[0046] FIG. 19 shows the situation in which the radiation beam is
tilted in the horizontal direction in the vehicle-mounted radar due
to a curve in the road;
[0047] FIG. 20 shows the situation in which the radiation beam is
tilted in the vertical direction in the vehicle-mounted radar;
[0048] FIG. 21 shows the way the vehicle-mounted radar is used;
and
[0049] FIG. 22 is a block diagram of the vehicle-mounted radar.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0050] The construction of an antenna apparatus and a transmission
and receiving apparatus according to a first embodiment of the
present invention will be described below with reference to FIGS.
1A, 1B, 1C, 1D, 1E, and 1F to 7.
[0051] FIGS. 1A to 1F show the positional relationship between a
dielectric lens and a primary radiator, and the relationship with
the directivity of a radiation beam. In FIGS. 1A to 1F, reference
numeral 1 denotes a primary radiator, with a dielectric lens 2
being disposed with its radiation direction as the center axis.
FIGS. 1A, 1B, and 1C show an example in which the dielectric lens 2
is fixed and the primary radiator 1 is movable. As shown in FIG.
1A, when the center axis of the dielectric lens 2 coincides with
the radiation direction of the primary radiator 1, a radiation beam
B is directed toward the front of the dielectric lens 2. However,
when the primary radiator 1 is displaced within the focal plane of
the dielectric lens 2 as shown in FIGS. 1B and 1C, the radiation
beam B is directed in a direction opposite to the displacement
direction. FIGS. 1D, 1E, and 1F show an example in which the
primary radiator 1 is fixed and the dielectric lens 2 is movable.
When the center axis of the dielectric lens 2 coincides with the
radiation direction of the primary radiator 1, a radiation beam B
is directed toward the front of the dielectric lens 2. However,
when the dielectric lens 2 is displaced in a direction
perpendicular to the center axis thereof as shown in FIGS. 1E and
1F, the radiation beam B is directed toward the displacement
direction.
[0052] FIGS. 2A, 2B and 2C show a case in which the angle between
the dielectric lens and the primary radiator is varied to vary the
direction of the radiation beam. As shown in FIG. 2A, when the
radiation direction of the primary radiator 1 is directed in the
direction of the center axis of the dielectric lens 2, the
radiation beam B is directed toward the front of the dielectric
lens 2. However, by varying the axial direction of the dielectric
lens with respect to the primary radiator 1 as shown in FIGS. 2B
and 2C, the radiation beam B is directed in that direction.
[0053] FIGS. 3A and 3B show the measurement result of the
directional angle (tilt angle) of the radiation beam when the
amount of displacement (offset) within the focal plane of the
primary radiator 1 with respect to the dielectric lens 2 is varied.
Here, as the dielectric lens 2, PE (polyethylene) of a relative
dielectric constant r=2.3 is used, the open aperture N thereof is
set at 75 mm, the focal distance d thereof is set at 22.5 mm, and
as the primary radiator 1, a horn antenna is used. By varying the
amount of offset of the primary radiator 1 in a range of 0 to 5 mm
as described above, the tilt angle of the radiation beam can be
varied in a range of 0 to 7 degrees as shown in FIG. 3B.
[0054] FIGS. 4A and 4B show the measurement result of the
directional angle (tilt angle) of the radiation beam when the axial
direction of the dielectric lens 2 with respect to the primary
radiator is varied. Here, as the dielectric lens 2, PE of a
relative dielectric constant r=2.3 is used, the open aperture N
thereof is set at 75 mm, the focal distance d thereof is set at
21.0 mm, and as the primary radiator 1, a primary vertical radiator
formed of a dielectric resonator which is excited by a
non-radiative dielectric line (NRD guide) is used. By varying the
angle of the dielectric lens 2 in a range of 0 to 5 degrees as
described above, the tilt angle of the radiation beam can be varied
in a range of 0 to 9 degrees as shown in FIG. 4B.
[0055] FIG. 5 is a sectional view illustrating the construction of
a transmission and receiving apparatus. In FIG. 5, reference
numeral 3 denotes a housing which houses a transmitting and
receiving section, including the primary radiator 1, with the
dielectric lens 2 being mounted to the opening section (the upper
part in FIG. 5). Within the housing 3, the primary radiator 1 is
mounted via a driving section 4, which causes the primary radiator
1 to be displaced in a planar direction perpendicular to the
radiation direction. This driving section 4 is formed of, for
example, a linear motor or a solenoid. With this construction, as
shown in FIGS. 1A to 1C, the relative positional relationship
between the dielectric lens 2 and the primary radiator 1 is varied
to tilt the radiation beam.
[0056] FIG. 6 is a sectional view illustrating another example of
the construction of the transmission and receiving apparatus. In
FIG. 6, within the housing 3, the whole of the transmitting and
receiving section, including the primary radiator 1, is fixed, with
the dielectric lens 2 being mounted onto the opening section of the
housing 3 via the driving section 4. This driving section 4, which
is formed of a linear motor, a solenoid, and the like, causes the
dielectric lens 2 to be displaced in a planar direction normal to
the center axis thereof. As a result, as shown in FIGS. 1D to 1F,
the dielectric lens is displaced with respect to the primary
radiator in order to tilt the radiation beam.
[0057] Also in the case where the angle of the dielectric lens with
respect to the primary radiator is varied as shown in FIG. 2,
basically, the construction shown in FIG. 6 may be adopted. That
is, in FIG. 6, each of two of the right and left driving sections 4
may be displaced to vary the axial direction of the dielectric
lens. Further, when the angle of the primary radiator with respect
to the dielectric lens is varied, basically, the construction shown
in FIG. 5 may be adopted. That is, in FIG. 5, each of two of the
right and left driving sections 4 may be displaced to vary the
axial direction of the primary radiator. In the above-described
examples, for the sake of description, the primary radiator or the
dielectric lens is displaced in directions within the plane of the
paper surface, and as shown in FIGS. 18 to 20, the primary radiator
or the dielectric lens may be displaced in the two-dimensional
direction when the radiation beam is tilted not only in the
right-to-left direction but also in the up-and-down direction as in
a millimetric-wave radar which detects a vehicle in the forward
direction. FIG. 7 is a plan view of the transmission and receiving
apparatus when viewed from the axial direction of the dielectric
lens. In this case, by displacing the primary radiator 1 relatively
in the x-axis and y-axis directions with respect to the dielectric
lens, the radiation beam is tilted in the x-axis and y-axis
directions.
[0058] Next, the construction of an antenna apparatus and a
transmission and receiving apparatus according to a second
embodiment of the present invention will be described with
reference to FIGS. 8 to 14.
[0059] FIG. 8 is a schematic diagram illustrating the construction
of the entire transmission and receiving apparatus. In this second
embodiment, by displacing the primary radiator 1 in the
right-to-left direction in the figure within the housing 3, the
radiation beam is tilted in the right-to-left direction in the
figure.
[0060] FIGS. 9A, 9B, 9C, and 9D are partial perspective views
illustrating the construction of a dielectric line for use in the
transmission and receiving apparatus according to the second
embodiment of the present invention. In FIGS. 9A, 9B, 9C, and 9D,
reference numerals 101 and 102 each denote a conductor plate. In
the examples shown in FIGS. 9B and 9D, the dielectric line is
formed with a dielectric strip 100 being sandwiched between these
two conductor plates. In the examples shown in FIGS. 9A and 9C, a
substrate 103, together with dielectric strips 100a and 100b, are
provided between the conductor plates 101 and 102, and a substrate
having a surface parallel to the transmission direction of the
dielectric strip is formed at the same time. The difference between
FIGS. 9A and 9B and FIGS. 9C and 9D is the presence or absence of
the grooves for the dielectric strips in the conductor plates 101
and 102. When grooves are formed as in FIGS. 9A and 9B, the spacing
between conductor plates in the propagation area formed of a
dielectric strip and a non-propagation area having no dielectric
strip and the dielectric constant of the dielectric strip are set,
the cut-off frequency of the LSM01 mode is set to be lower than the
cut-off frequency of the LSE01 mode, and transmission becomes
possible always in a single mode of the LSM01 mode regardless of
the radius of curvature or the like of the bend section of the
dielectric strip. As a result, a smaller size can be achieved as a
whole, and a lower loss can be achieved. The dielectric lines of
each construction shown in FIGS. 9A, 9B, 9C, and 9D may be used as
required.
[0061] FIGS. 10A and 10B show the construction of a primary
vertical radiator. FIG. 10A is a plan view when viewed from the
radiation direction, and FIG. 10B is a sectional view of the
essential portion thereof. A dielectric strip 12 and a cylindrical
dielectric resonator 11 are provided between conductor plates 41
and 42, with a hole 43, which is coaxial with the dielectric
resonator 11, being formed in the conductor plate 41. Then, a slit
plate 44 having a slit formed in the conductor plate is interposed
between the dielectric resonator 11 and the hole 43. As a result,
in the LSM mode in which occur an electric field having components
at right angles (in the x-axis direction in the figure) to the
length of the dielectric strip 12 and parallel (in the y-axis
direction in the figure) to the conductor plates 41 and 42 and a
magnetic field having components perpendicular (in the z-axis
direction in the figure) to the conductor plates 41 and 42, an
electromagnetic wave propagates within the dielectric strip 12.
Then, the dielectric strip 12 and the dielectric resonator 11 are
electromagnetically coupled to each other, and an HE111 mode having
electric-field components in the same direction as that of the
electric field of the dielectric strip 12 occurs within the
dielectric resonator 11. Then, a linearly polarized electromagnetic
wave is radiated in a perpendicular direction (in the z-axis
direction) via the hole 43 to the conductor plate 41. When,
conversely, an electromagnetic wave enters from the hole 43, the
dielectric resonator 11 excites in the HE111 mode, and the
electromagnetic wave propagates to the dielectric strip 12, which
is coupled to the dielectric resonator 11, in the LSM mode.
[0062] FIG. 11 shows the relationship between the primary vertical
radiator and a dielectric-line apparatus comprising a dielectric
line coupled to the primary radiator. The top half of FIG. 11 is a
plan view of the coupled section of a primary radiator 40 and a
dielectric-line apparatus 50. However, in FIG. 11, a state in which
the upper conductor plate is removed is shown. The bottom half of
FIG. 11 is a sectional view illustrating the relationship between
the primary radiator 40 and the dielectric lens 2. A dielectric
strip 13 is provided in the dielectric-line apparatus 50 as shown
in the top half of the figure, and the dielectric strip 12 of the
primary radiator 40 is brought close to the dielectric strip 13,
forming a directional coupler formed of a dielectric line in the
portion surrounded by the broken line in the figure. This
directional coupler using the dielectric strips 12 and 13 causes an
electromagnetic wave propagated from port #1 to propagate to port
#4 at approximately 0 dB, that is, a 0-dB directional coupler is
formed. Even if the primary vertical radiator 40 moves in the
right-to-left direction in the figure in this state, the coupling
relationship of the directional coupler does not vary, and the
electromagnetic wave propagated from port #1 is output to port #4
always at approximately 0 dB. Conversely, the electromagnetic wave
which is made to enter from port #4 because of the excitation of
the dielectric resonator is propagated to port #1 at approximately
0 dB. In the state shown in the figure, portions indicated by o and
o' of the dielectric strip 12 correspond to a and b portions. When
the primary vertical radiator 40 is displaced at a maximum to the
right in the figure, the points n and n' coincide with the a and b
portions. When, conversely, the primary vertical radiator 40 is
displaced at a maximum to the left in the figure, the points p and
p' coincide with the a and b portions. Even if the primary vertical
radiator 40 is displaced in this manner, since that portion of the
dielectric strip 12 which is coupled to the dielectric strip 13 is
a straight-line portion, these are maintained always at a fixed
amount of coupling.
[0063] FIG. 12 is a partial perspective view of a directional
coupler formed between the primary vertical radiator and the
dielectric-line apparatus. In FIG. 12, reference numerals 51 and 52
each denote a conductor plate. Since these two conductor plates 51
and 52 are close to the conductor plates 41 and 42 on the primary
vertical radiator side, the continuity of the planes of the upper
and lower conductors in which a dielectric strip is sandwiched is
maintained. As a result, the directional coupler operates in nearly
the same way as a directional coupler in which two dielectric
strips are provided side-by-side between two conductor plates.
[0064] FIGS. 13A and 13B show the directional coupler and the
relationship of the power distribution ratio thereof, respectively.
If the phase constant of the even mode of the coupling line formed
of the dielectric strips 12 and 13 is denoted as $e, the phase
constant of the odd mode is denoted as $o, and )$=*$e-$o* is set,
the power ratio of the electromagnetic wave output to port #2 to
the electromagnetic wave input from port #1 is expressed as
P2/P1=1-sin 2( )$z/2), and the power ratio of the electromagnetic
wave output to port #4 to the electromagnetic wave input from port
#1 is expressed as P4/P1=sin 2( )$z/2). Therefore, if the
relationship of ( )$z/2)=nB+B/2 [n:0, 1, 2 . . . ] is satisfied,
all of the input from port #1 is output to port #4, and thus a 0-dB
directional coupler is formed.
[0065] FIG. 14 shows the construction of the dielectric-line
apparatus, including a transmission and receiving section, and the
whole primary vertical radiator, with the upper conductor plate
being removed. In FIG. 14, reference numeral 53 denotes a
circulator, in which a signal input from port #1 is output to port
#2, and a signal input from port #2 is output to port #3. A
dielectric line formed by a dielectric strip 14 is connected to
port #1, and a dielectric line formed by a dielectric strip 15 is
connected to port #3. An oscillator 55 and a mixer 54 are connected
to the respective dielectric lines formed by the dielectric strips
14 and 15. Further, a dielectric strip 16 which is coupled to each
dielectric line to form each directional coupler is disposed
between the dielectric strips 14 and 15. Terminaters 21 and 22 are
provided at both end portions of this dielectric strip 16. A
varactor diode and a Gun diode are provided in the mixer 54 and the
oscillator 55, and a dielectric line having a substrate shown in
FIG. 9A or 9C interposed therein is formed to provide a circuit for
applying a bias voltage to the varactor diode and the Gun
diode.
[0066] With such a construction, an oscillation signal of the
oscillator 55 is propagated along the path of the dielectric strip
14, the circulator 53, the dielectric strip 13, the dielectric
strip 12, and the dielectric resonator 11, and an electromagnetic
wave is radiated in the axial direction of the dielectric resonator
11. Conversely, the electromagnetic wave which enters the
dielectric resonator 11 is input to the mixer 54 along the path of
the dielectric strip 12, the dielectric strip 13, the circulator
53, and the mixer 54. A part of the oscillation signal is provided
as a local signal, together with the received signal, to the mixer
54 via the two directional couplers formed of the dielectric strips
15, 16, and 14. As a result, the mixer 54 generates a frequency
component of the difference between the transmission signal and the
received signal as an intermediate frequency signal.
[0067] Next, the construction of an antenna apparatus and a
transmission and receiving apparatus according to a third
embodiment of the present invention will be described with
reference to FIG. 15. In this third embodiment, a primary vertical
radiator can be moved in two dimensions. As shown in the plan view
of FIG. 15, a dielectric line formed by the dielectric strip 13 is
provided in a dielectric-line apparatus 60, and a dielectric line
formed by a dielectric strip 17, a circulator 53, and the like are
formed in the dielectric-line apparatus 50. The dielectric strip 12
provided in the primary radiator 40 and the dielectric strip 13 on
the side of the dielectric-line apparatus 60 form one 0-dB
directional coupler, and the dielectric strips 13 and 17 form
another 0-dB directional coupler. The primary radiator 40 is
provided in such a manner as to be movable in the right-to-left
direction in the figure with respect to the dielectric-line
apparatus 60, and the dielectric-line apparatus 60 is provided in
such a manner as to be movable in the vertical direction in the
figure with respect to the dielectric-line apparatus 50. In this
case, the dielectric-line apparatus 50 is fixed. This makes it
possible to move the position of the dielectric resonator 11 in a
two-dimensional direction in a state in which there is hardly any
loss in the coupler.
[0068] FIGS. 16A, 16B, and 16C are plan views showing other
examples of a directional coupler in the movable section of an
antenna apparatus according to a fourth embodiment of the present
invention, with an illustration of the upper and lower conductor
plates being omitted. In the example of FIG. 16A, the dielectric
strip 12 on the side which couples to the dielectric resonator 111
is formed as a straight line. In the example of FIG. 16B, the
dielectric strip 13 on the side which couples to the dielectric
resonator 12 is formed as a straight line. In the example of FIG.
16C, one end of the dielectric strip 12 which is coupled at its
other end to the dielectric resonator 11 is kept at a fixed
distance to and in parallel to the mating dielectric strip 13 up to
the end portion.
[0069] FIG. 17 shows an example of the construction of a
directional coupler in the movable section of an antenna apparatus
according to a fifth embodiment of the present invention. Although
in the above-described examples a 0-dB directional coupler is
formed as a directional coupler in the movable section, as shown in
FIG. 17, terminaters 23 and 24 may be provided in one end of the
dielectric strips 12 and 13, respectively, without forming one end
portion of the dielectric strips 12 and 13 as an open end.
[0070] Although the above-described embodiments describe a primary
vertical radiator using a dielectric resonator and a dielectric
line, or a horn antenna as examples of the primary radiator, in
addition to these, a microstrip antenna, such as a patch antenna,
may be used.
[0071] Many different embodiments of the present invention may be
constructed without departing from the spirit and scope of the
present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
this specification. To the contrary, the present invention is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the invention as hereafter
claimed. The scope of the following claims is to be accorded the
broadest interpretation so as to encompass all such modifications,
equivalent structures, and functions.
* * * * *