Junction structure of dielectric strip nonradiative dielectric waveguide and millimeter-wave transmitting/receiving apparatus

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 λ/2 (λ denotes a wavelength of high-frequency signals), high-frequency signals with a wavelength more than λ 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 λ 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 signals, so that the invention can be used in a wide band in a state where output levels of distributed high-frequency signals are almost equal to each other, thereby finding wide application to communication devices such as a cellular phone.

Further, the invention provides a nonradiative dielectric waveguide comprising the junction structure of dielectric strips disposed between parallel plate conductors placed at a spacing of λ/2 or less with respect to a wavelength λ of high-frequency signals.

With such a construction, the nonradiative dielectric waveguide of the invention can suppress radiation components from the dielectric strips to propagate high-frequency signals with high efficiency, and can be used in a considerably wider band, so that a general versatility thereof to a communication device, millimeter-wave radar or the like containing a millimeter-wave integrated circuit is increased.

The nonradiative dielectric waveguide of the invention comprises a first straight dielectric strip 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. Therefore, 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, 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 invention can be used in a wide band in a state where output levels of distributed high-frequency signals are almost equal to each other, thereby increasing a general versatility to a high-frequency circuit and finding wide application to a communication device such as a cellular phone, millimeter-wave radar or the like.

In the nonradiative dielectric waveguide of the invention it is preferable that the radius of curvature of the junction between the second dielectric strip and the first dielectric strip is in a range of from λ to 3λ.

According to the invention, the radius of curvature of the junction between the second dielectric strip and the first dielectric strip is selected to be in a range of from λ to 3 λ, whereby the nonradiative dielectric waveguide is capable of distributing high-frequency signals at nearly equal output strengths and therefore has an advantage in downsizing.

In the nonradiative dielectric waveguide of the invention it is preferable that in the case where the second dielectric strip is elongated along an arc from the junction toward the first dielectric strip, the second dielectric strip is formed so that a tangent of the elongated portion thereof comes in contact with a side wall of the first dielectric strip.

According to the invention, the tangent of the second dielectric strip elongated from the arc-shaped junction comes in contact with a side wall of the first dielectric strip, whereby the nonradiative dielectric waveguide is capable of equally distributing high-frequency signals.

In the nonradiative dielectric waveguide of the invention it is preferable that a frequency of the high-frequency signals is equal to or more than 50 GHz.

In the case where the nonradiative dielectric waveguide of the invention constructed as described above is disposed to automotive millimeter-wave radar, millimeter-waves are guided through the first dielectric strip and applied to an obstruction around the automobile and other automobiles, and intermediate frequency signals are generated by synthesizing reflection waves with high-frequency signals guided through the second dielectric strip, and then analyzed, whereby the distance from the automobile to the obstacle and other automobiles, the moving speeds, the moving directions and the like can be determined.

In the nonradiative dielectric waveguide of the invention it is preferable that the parallel plate conductors are made of Cu, Al, Fe, Ag, Au, Pt or stainless steel.

According to the invention, the parallel plate conductors are made of Cu, Al, Fe, Ag, Au, Pt or stainless steel, whereby the nonradiative dielectric waveguide can obtain high electric conductivity and processibility.

In the nonradiative dielectric waveguide of the invention it is preferable that the first dielectric strip and the second dielectric strip are made of an organic resin material, an organic-inorganic composite or ceramics.

According to the invention, the first dielectric strip and the second dielectric strip are made of an organic resin material, an organic-inorganic composite or ceramics, whereby the nonradiative dielectric waveguide can be easily processed so as to be low-loss with respect to high-frequency signals, and mass-produced.

As shown in

FIGS. 6-11

, the invention provides a millimeter-wave transmitting/receiving apparatus comprising:

(a) a voltage-controlled oscillating portion

21

comprising:

a high-frequency diode

33

for outputting high-frequency signals of millimeter-wave band, and

a variable capacitance diode

30

placed so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals, for outputting the high-frequency signals as frequency-modulated transmission millimeter-wave signals by periodically controlling bias voltage,

the voltage-controlled oscillating portion

21

being installed at an end of a first dielectric strip

37

b

(

37

a

);

(b) a second dielectric strip

75

which is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the voltage-controlled oscillating portion

21

in the direction

71

for transmitting the transmission millimeter-wave signals of the first dielectric strip

37

b

(

37

a

);

(c) a circulator

76

which has an input end

78

, an input/output end

79

and an output end

80

,

the circulator

76

being connected to the other end of the first dielectric strip

37

b

at the input end

78

,

for outputting transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and

outputting reception signals inputted into the input/output end

79

to the output end

80

;

(d) a third dielectric strip

77

, one end of which is connected to the input/output end

79

of the circulator

76

, and on the other end side of which is disposed a transmission/reception antenna

24

;

(e) a fourth dielectric strip

81

, one end of which is connected to the output end

80

of the circulator

76

;

(f) a mixer

82

for connecting the second dielectric strip

75

and the fourth dielectric strip

81

to mix respective signals transmitted to the second and fourth dielectric strips

75

,

81

to generate intermediate frequency signals; and

(g) a pair of conductor plates

84

,

85

which are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in which spacing are disposed the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

81

, the voltage-controlled oscillating portion

21

, the circulator

76

and the mixer

82

.

The invention provides a millimeter-wave transmitting/receiving apparatus comprising:

(a) a high-frequency diode

33

which outputs high-frequency signals of millimeter-wave band;

(b) a first dielectric strip

37

b

(

37

a

), one end of which is connected to the high-frequency diode

33

, for propagating high-frequency signals outputted from the high-frequency diode

33

;

(c) a pulse-modulating diode interposed between the first dielectric strip

37

b

(

37

a

) or installed therealong, so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals, for outputting transmission millimeter-wave signals which are pulse-modulated signals of the high-frequency signals by on-off of bias voltage;

(d) a second dielectric strip

75

which is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the high-frequency diode of the first dielectric strip

37

b

(

37

a

) in the transmission direction

71

of the transmission millimeter-wave signals;

(e) a circulator

76

which has an input end

78

, an input/output end

79

and an output end

80

,

the circulator

76

being connected to the other end of the first dielectric strip

37

b

at the input end

78

,

outputting transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and

outputting reception signals inputted into the input/output end

79

to the output end

80

;

(f) a third dielectric strip

77

, one end of which is connected to the input/output end

79

of the circulator

76

, and on the other end side of which is disposed a transmission/reception antenna

24

;

(g) a fourth dielectric strip

81

, one end of which is connected to the output end

80

of the circulator

76

;

(h) a mixer

82

for connecting the second dielectric strip

75

and the fourth dielectric strip

81

to mix respective signals transmitted to the second and fourth dielectric strips

75

,

81

to generate intermediate frequency signals; and

(i) a pair of conductor plates

84

,

85

which are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in which spacing are disposed the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

81

, the pulse modulating diode, the circulator

76

and the mixer

82

.

In the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the portion

37

b

1

of the first dielectric strip

37

b

on the downstream side is curved so as to make an arc having the radius of curvature r and the second dielectric strip

75

is linearly connected to the arc-shaped portion.

As shown in

FIG. 8

, in the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction of electromagnetically coupling an arc-shaped portion

87

midway in a transmitting direction

86

of the second dielectric strip

75

to a straight or arc-shaped portion

89

midway in a transmitting direction

88

of the fourth dielectric strip

81

, so as to be in close proximity to each other.

As shown in

FIG. 9

, in the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction of joining, to a straight portion

91

of the fourth dielectric strip

81

, the second dielectric strip

75

along an arc-shaped portion

92

having the radius of the curvature r.

In the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction in which the second dielectric strip

75

is connected to the arc-shaped portion

91

of the fourth dielectric strip

81

, having the radius of curvature r, so as to make a straight portion

92

.

According to the invention, high-frequency signals of millimeter-wave band outputted by the high-frequency diode

33

are passed through the first dielectric strip

37

a

, a bias voltage of the variable capacitance diode

30

by a modulated wave which is periodically varied by a triangular wave or the like, transmission millimeter-wave signals from the voltage-controlled oscillating portion

21

composed of the high-frequency diode

33

and the variable-capacitance diode

30

are passed through the first dielectric strip

37

b

and outputted from the straight portion

37

b

1

of the first dielectric strip

37

b

through the input end

78

of the circulator

76

to the input/output end

79

of the circulator

76

to be radiated from a transmission/reception antenna

24

to a target

104

. Reflection waves by the target

104

are supplied from the transmission/reception antenna

24

through the third dielectric strip

77

and guided from the input/output end

79

to the output end

80

of the circulator

76

, and the fourth dielectric strip

81

and the second dielectric strip

75

of the mixer

82

are coupled, whereby intermediate frequency signals can be obtained. The mixer

82

may be constructed as shown in

FIG. 8

mentioned later, or may be constructed as shown in FIG.

9

.

It is possible that high-frequency signals of millimeter-wave band from the high-frequency diode

33

are pulse-modulated to be converted into transmission millimeter-wave signals. In this case, a pulse-modulating diode such as a pin diode or schottky-barrier diode is interposed midway in a transmitting direction

71

of the first dielectric strips

37

a

,

37

b

, or installed therealong, so that a bias voltage applying direction coincides with an electric field direction of the high-frequency signals, for converting the high-frequency signals into pulses by on-off of bias voltage. In the case where the pulse-modulating diode is interposed between the first dielectric strips

37

a

,

37

b

, as the pulse-modulating diode is used a pin diode having a constitution as shown in FIG.

11

. In the case where the pulse-modulating diode is installed along the first dielectric strips

37

a

,

37

b

, another circulator is interposed between the first dielectric strips

37

a

,

37

b

, to an input/output end of which is connected another dielectric strip, at an end of which a schottky-barrier diode having a constitution as shown in

FIG. 11

is provided. In this case, to input and output ends of the circulator are connected the first dielectric strips

37

a

,

37

b

. The millimeter-wave transmitting/receiving apparatus of the invention may comprise both the voltage-controlled oscillating portion

21

and the pulse modulating diode.

As shown in

FIGS. 12-14

, the invention provides a millimeter-wave transmitting/receiving apparatus comprising:

(a) a voltage-controlled oscillating portion

21

comprising:

a high-frequency diode

33

for outputting high-frequency signals of millimeter-wave band, and

a variable capacitance diode

30

placed so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals, for outputting the high-frequency signals as frequency-modulated transmission millimeter-wave signals by periodically controlling bias voltage,

the voltage-controlled oscillating portion

21

being installed at an end of a first dielectric strip

37

b

(

37

a

);

(b) a second dielectric strip

75

which is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the voltage-controlled oscillating portion

21

in the direction

71

for transmitting the transmission millimeter-wave signals of the first dielectric strip

37

b

(

37

a

);

(c) a circulator

76

which has an input end

78

, an input/output end

79

and an output end

80

,

the circulator

76

being connected to the other end of the first dielectric strip

37

b

at the input end

78

,

outputting transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and

outputting reception signals inputted into the input/output end

79

to the output end

80

;

(d) a third dielectric strip

77

, one end of which is connected to the input/output end

79

of the circulator

76

, and on the other end side of which is disposed a transmission/reception antenna

121

;

(e) a terminator

112

which is connected to the output end

80

of the circulator

76

;

(f) a fourth dielectric strip

114

having an end at which a reception antenna

122

is provided, for guiding received millimeter-wave signals;

(g) a mixer

82

for connecting the second dielectric strip

75

and the fourth dielectric strip

114

to mix respective signals transmitted to the second and fourth dielectric strips

75

,

114

to generate intermediate frequency signals; and

(h) a pair of conductor plates

84

,

85

which are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in which spacing are disposed the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

114

, the voltage-controlled oscillating portion

21

, the circulator

76

and the mixer

82

.

A millimeter-wave transmitting/receiving apparatus of the invention comprises:

(a) a high-frequency diode

33

which outputs high-frequency signals of millimeter-wave band;

(b) a first dielectric strip

37

b

(

37

a

), one end of which is connected to the high-frequency diode

33

, for propagating high-frequency signals outputted from the high-frequency diode

33

;

(c) a pulse-modulating diode interposed between the first dielectric strip

37

b

(

37

a

) or installed therealong, so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals, for outputting transmission millimeter-wave signals which are pulse-modulated signals of the high-frequency signals by on-off of bias voltage;

(d) a second dielectric strip

75

which is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the high-frequency diode of the first dielectric strip

37

b

(

37

a

) in the transmission direction

71

of the transmission millimeter-wave signals;

(e) a circulator

76

which has an input end

78

, an input/output end

79

and an output end

80

,

the circulator

76

being connected to the other end of the first dielectric strip

37

b

at the input end

78

,

for outputting transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and

outputting reception signals inputted into the input/output end

79

to the output end

80

;

(f) a third dielectric strip

77

, one end of which is connected to the input/output end

79

of the circulator

76

, and on the other end side of which is disposed a transmission antenna

121

;

(g) a terminator

112

which is connected to the output end

80

of the circulator

76

;

(h) a fourth dielectric strip

114

having an end at which a reception antenna

122

is provided, for guiding received millimeter-wave signals;

(i) a mixer

82

for connecting the second dielectric strip

75

and the fourth dielectric strip

114

to mix respective signals transmitted to the second and fourth dielectric strips

75

,

114

to generate intermediate frequency signals; and

(j) a pair of conductor plates

84

,

85

which are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in which spacing between the conductor plates

84

,

85

are disposed the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

114

, the pulse-modulating diode, the circulator

76

and the mixer

82

.

In the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the portion

37

b

1

of the first dielectric strip

37

b

on the downstream side is curved so as to make an arc having the radius of curvature r and the second dielectric strip

75

is linearly connected to the arc-shaped portion.

As shown in

FIG. 13

, in the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction of electromagnetically coupling an arc-shaped portion

115

midway in a transmitting direction

86

of the second dielectric strip

75

to a straight or arc-shaped portion

116

midway in a transmitting direction

88

of the fourth dielectric strip

114

, so as to be in close proximity to each other.

As shown in

FIG. 14

, in the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction of joining, to a straight portion

118

of the fourth dielectric strip

114

, the second dielectric strip

75

along an arc-shaped portion

119

having the radius of curvature r.

In the millimeter-wave transmitting/receiving apparatus of the invention it is preferable that the mixer

82

has a construction in which the second dielectric strip

75

is connected to the arc-shaped portion

118

of the fourth dielectric strip

114

, having the radius of curvature r, so as to make a straight portion

119

.

According to the invention, high-frequency signals of millimeter-wave band outputted by the high-frequency diode

33

are passed through the first dielectric strip

37

a

, and transmission millimeter-wave signals which are obtained by modulating the bias voltage of the variable capacitance diode

30

by a modulated wave which is periodically varied by a triangular wave or the like, are supplied through the first dielectric strip

37

b

to the input end of the circulator

76

. The transmission millimeter-wave signals outputted from the input/output end

79

of the circulator

76

are radiated, through the third dielectric strip

77

, from a transmission antenna

121

toward a target

104

.

It is possible that high-frequency signals of millimeter-wave band are pulse-modulated to be converted into transmission millimeter-wave signals. In this case, a pulse-modulating diode such as a pin diode or schottky-barrier diode is interposed midway in a transmitting direction

71

of the first dielectric strips

37

a

,

37

b

, or installed therealong, so that a bias voltage applying direction coincides with an electric field direction of the high-frequency signals, for converting the high-frequency signals into pulses by on-off of bias voltage.

Reflection waves by the target

104

are received by a reception antenna

122

and supplied through a fourth dielectric strip

114

to the mixer

82

. To the mixer

82

, transmission millimeter-wave signals from the second dielectric strip

75

joined along an arc to the straight portion

37

b

1

of the first dielectric strip

37

b

are supplied. Thus, with the mixer

82

, intermediate frequency signals mixed the reflection waves received from the reception antenna

122

and the transmission millimeter-wave signals from the second dielectric strip

75

can be obtained.

The reflection waves by the target

104

are also supplied to the transmission antenna

121

, and supplied from the circulator

76

via the output end

80

of the circulator

76

to a terminator

112

. The signals supplied to the terminator

112

are heat-consumed without generating reflection waves.

The mixer

82

may be constructed as shown in

FIG. 13

, or may be constructed as shown in FIG.

14

.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:

FIG. 1

is a perspective view showing the inside of an NRD guide S with a junction structure of a dielectric strip of the invention;

FIG. 2

is a plan view showing the junction structure of a dielectric strip as shown in

FIG. 1

;

FIG. 3

is a front view of a NRD guide S as shown in

FIGS. 1 and 2

;

FIG. 4

shows an embodiment of the junction structure of the invention, and is a plan view thereof with a U-shaped second dielectric strip;

FIG. 5

shows an embodiment of the junction structure of the invention and is a plan view thereof with two second dielectric strips;

FIG. 6

is a block diagram showing a construction of part of a radar system

101

as an embodiment of the invention;

FIG. 7

is a view of assistance in explaining operating principles of a millimeter-wave radar module

102

in

FIG. 6

;

FIG. 8

is a plan view showing the simplified construction of the millimeter-wave radar module

102

mentioned before with reference to

FIGS. 6 and 7

;

FIG. 9

is a simplified plan view of another millimeter-wave radar module

102

a

which can be embodied instead of the embodiment of

FIGS. 6-8

;

FIG. 10

is a perspective view showing the entire construction of an example of the voltage-controlled oscillating portion

21

;

FIG. 11

is a perspective view of a wiring board

38

included by the voltage-controlled oscillating portion

21

;

FIG. 12

is a block diagram showing the entire construction of millimeter-wave radar of another embodiment of the invention;

FIG. 13

is a simplified plan view showing a specific construction of a millimeter-wave radar module

102

b

as shown in

FIG. 12

;

FIG. 14

is a simplified plan view showing a millimeter-wave radar module

102

c

of another embodiment of the invention;

FIG. 15

is a view showing a structure of a terminator

112

disposed at one end of a fifth dielectric strip

113

as shown in

FIGS. 13 and 14

;

FIG. 16

is a graph of the frequency response of the NRD guide S of the invention;

FIG. 17

is a partially cutaway perspective view showing a conventional single-strip type of NRD guide S

1

;

FIG. 18

is a perspective view showing the inside of an NRD guide S

2

constituting a straight branch circuit;

FIG. 19

is a perspective view of the inside of an NRD guide S

3

constituting a distribution circuit by a directional coupler; and

FIG. 20

is a graph of the frequency response of the conventional NRD guide S

3

as shown in FIG.

19

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now referring to the drawings, preferred embodiments of the invention are described below.

A junction structure of a dielectric strip and an NRD guide of the present invention will be explained below.

FIG. 1

is a perspective view of the inside of an NRD guide S of the invention, and

FIG. 2

is a plan view of a junction structure of a dielectric strip of the invention.

FIG. 3

is a front view of a NRD guide S as shown in

FIGS. 1 and 2

. In

FIG. 1

, reference numerals

1

,

3

denote a pair of parallel plate conductors, reference numeral

2

denotes a first straight dielectric strip, and reference numeral

4

denotes a second dielectric strip which is joined to the first dielectric strip

2

at a midway point thereof so as to branch and a junction of which is formed like an arc. Further, reference numeral

2

a

denotes an input port of the first dielectric strip

2

, reference numeral

2

b

denotes an output port of the first dielectric strip

2

, and reference numeral

4

c denotes an output port of the second dielectric strip

4

. Here,

FIG. 1

is illustrated in perspective of the inside. Along one side surface

72

of the first dielectric strip

2

, the second dielectric strip

4

, one side surface

73

inward in the radius direction of which is bent, ranges in the tangent direction. The first dielectric strip

2

and the second dielectric strip

4

have the same section shape, which is rectangular or square.

In the invention, the second dielectric strip

4

is formed like an arc at least at the junction

4

a

thereof, and may be formed by modifying in a manner that the rest

4

b

thereof other than the junction

4

a

is formed straight, the overall shape of the second dielectric strip

4

is formed like an arc, or the rest thereof other than the junction

4

a

is formed like a curve such as an elliptic curve, a hyperbolic curve, a quadratic curve, or a waveform curve. Then, as shown in

FIG. 2

, the radius of curvature r of the junction of the second dielectric strip

4

is set to be equal to or more than a wavelength λ of high-frequency signals propagating within the dielectric strips

2

and

4

, whereby the high-frequency signals can be distributed by the first dielectric strip

2

and the second dielectric strip

4

at almost equal output levels. Besides, the radius of curvature r of the junction

4

a

is preferred to be equal to or less than

3

λ. In the case where the radius of curvature is more than

3

λ, the junction structure gets large, so that a merit of downsizing cannot be attained.

On the contrary, in the case where the radius of curvature r of the junction

4

a

is set to be less than the wavelength λ, a branching strength to the second dielectric strip

4

gets small.

Further, the second dielectric strip

4

is preferred to have a shape such that in the case where the arc-shaped junction

4

a

is imaginarily elongated as shown by a dot line in

FIG. 2

, the tangent thereof comes in contact with a side wall

74

of the first dielectric strip

2

. This is optimal for equal distribution of high-frequency signals.

Then, the first dielectric strip

2

and the second dielectric strip

4

integrated in the construction described above are installed between the parallel plate conductors

1

,

3

, whereby without precise positioning, a dielectric strip for propagating high-frequency waves, an NRD guide S, and the like which have a preferable frequency response can be produced with ease. Further, the NRD guide S of the invention can be applied to a high-frequency circuit using high-frequency signals in a band of 20 to 500 GHz, and can be preferably used in a high-frequency band of, specifically, 50 GHz or more, more specifically, 70 GHZ or more. To be specific, the NRD guide S of the invention is to be used in a cellular phone, automotive millimeter-wave radar and the like. For example, by guiding millimeter-waves through the first dielectric strip

2

to irradiate to obstacles and automobiles around an automobile, synthesizing reflection waves with high-frequency waves from the second dielectric strip

4

to obtain intermediate frequency signals, and analyzing the intermediate frequency signals, the distances to the obstacles and the automobiles, the moving speeds thereof, the moving directions thereof and the like can be found.

The parallel plate conductors

1

,

3

used in the invention, in view of a high electric conductivity and a processibility, maybe conductor plates made of Cu, Al, Fe, SUS (stainless steel), Ag, Au, Pt or the like, or insulation plates with such conductor layers formed on the surfaces thereof.

Further, the first dielectric strip

2

and the second dielectric strip

4

are preferred to be made of a fluororesin, e.g., an organic resin material of low loss such as Teflon (trade name), an organic-inorganic composite, or a ceramics material having low permittivity such as cordierite, alumina or glass ceramics, which are low-loss to high-frequency waves, easy to process, and suitable to mass production. To be more specific, the dielectric strips

2

,

4

are preferred to be made of a ceramics material, and the first dielectric strip

2

and the second dielectric strip

4

can be integrally molded and sintered, so that workability is increased and the strips are complete as compared with the case of individually producing and joining the strips.

Then, in the case of producing the first dielectric strip

2

and the second dielectric strip

4

by a ceramics material, the strips can be produced by, for example, preparing a mold for the construction described above, charging powder of ceramics into the mold and pressurizing to produce a molded member, and thereafter sintering the member.

With another method, the strips can be produced by printing and coating a slurry containing powder of ceramics for the construction described above, drying and thereafter sintering the slurry. Otherwise, such a method may be adopted as pouring an organic resin for binder containing powder of ceramics into a mold, hardening the resin, and thereafter taking out to sinter the resin. Besides, the first dielectric strip

2

and the second dielectric strip

4

may be individually produced, and thereafter adhered by an adhesive.

Further, in the case where the material of the first dielectric strip

2

and the second dielectric strip

4

is an organic resin material or an organic-inorganic composite, the strips can be produced by well-known methods such as a stamping method, an injection molding method or a print-coating method.

Another embodiment of the invention will be shown in

FIGS. 4 and 5

.

FIG. 4

shows a NRD guide S

4

in which a pair of U-shaped second dielectric strips

5

is disposed to switch an input/output direction of high-frequency signals in reverse, and

FIG. 5

shows a NRD guide S

5

in which two dielectric strips

6

a

,

6

b

are disposed so that high-frequency signals are branched into three. In

FIG. 5

, the radius of curvature ra of the second dielectric strip

6

a

and the radius of curvature rb of the second dielectric strip

6

b

may be equal to or different from each other. Moreover, three or more second dielectric strips

6

a

,

6

b

may be disposed.

Further, in the embodiments mentioned above, a case of branching high-frequency signals is illustrated, whereas the input port of high-frequency signals may be reversed to synthesize high-frequency signals. Moreover, the junction structure of a dielectric strip of the invention can be applied not only to a NRD guide, but also to various types of electronic components, electronic circuits, optical electronic circuits and the like which use a dielectric strip for transmitting high-frequency signals.

Thus, the invention can be produced with the first dielectric strip and the second dielectric strip integrated and does not require precise positioning, 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 flexible in design and advantageous for downsizing. In addition, the invention can be used in a wide band in a state where output levels of distributed high-frequency signals are almost equal, whereby application thereof to communication devices such as a cellular phone is broadened.

Here, the invention is not limited to the embodiments mentioned above, and may be modified within the scope of the invention.

An experiment regarding the invention will be explained below.

Experiment

The NRD guide S and the junction structure of a dielectric strip as shown in

FIGS. 1

to

3

were constructed in the following manner. The first straight dielectric strip

2

was made of cordierite ceramics having a dielectric constant of 4.8 and a dielectric loss of 2.7×10

−4

(at a measurement frequency of 77 GHz) and having a section of 1.0 mm width×2.25 mm height, and the second dielectric strip

4

was joined to the first dielectric strip

2

at a midway position thereof so as to be branched along an arc and bent at an angle of 90°, which were integrally produced. At this moment, the radius of curvature r of a junction (branched portion)

4

a

of the second dielectric strip

4

was 12.7 mm, which was larger than the wavelength λ≈5 mm of high-frequency signals of 60 GHz. In this case, the first dielectric strip

2

and the second dielectric strip

4

were integrally produced by preparing molds for the strips, filling powder of cordierite ceramics into the molds and pressurizing to produce molded members, and thereafter sintering the members.

Subsequently, the top and bottom surfaces of the integrated dielectric strips

2

,

4

were interposed between the two parallel plate conductors

1

,

3

made of Cu which had a dimension of 100 mm depth×100 mm width×8 mm thickness, whereby the NRD guide S was produced.

In this experiment, the first and second dielectric strips

2

,

4

were made of ceramics having relatively high dielectric constant, so that it was possible to make the radius of curvature r relatively small. Therefore, the NRD guide S can be used as an NRD module and the invention can be implemented as, for -example, a coupler for radar modules, a transmission/reception device and the like.

On the other hand, as a comparison example, the coupler type of NRD guide S

3

as shown in

FIG. 19

was produced. The materials and the sectional shapes of the parallel plate conductors

1

,

3

and the dielectric strips

20

,

21

were to be the same as those of the above-mentioned experimental example, and the spacing L between the dielectric strip

20

and the dielectric strip

21

was optimized so that high-frequency signals of 60 GHz were divided into halves.

With regard to the NRD guide S of the invention, a transmission property of millimeter-waves (in a band of tens to hundreds GHz) measured by a network analyzer (produced by Hewlett-Packard, Network Analyzer 8757C) will be shown in FIG.

16

.

FIG. 16

shows that the NRD guide S of the invention distributed high-frequency signals having nearly equal output levels to the output port

2

b

and the output port

4

c

within a wide frequency range of about 56-62 GHz.

By using the NRD guide S of an integrated branch structure of the invention, in a use for frequency modulation FM required in radar and transmission/reception devices, it is possible to attain an excellent effect that changes of the signal strength depending on the frequency would not occur. Therefore, the invention can attain an excellent property as a module.

On the contrary, as a result of a like measurement with regard to the coupler type of NRD guide S

3

serving as a comparison example, as shown in

FIG. 20

, it was only in a rather narrow frequency range of 60-60.5 GHz that the output levels at the output port

20

b

and the output port

21

c

were almost equal.

FIG. 6

is a block diagram showing a construction of part of a radar system

101

as an embodiment of the invention. The radar system

101

comprises a millimeter-wave radar module

102

, wherein the module

102

includes an NRD guide S

6

working as a coupler.

The millimeter-wave radar module

102

as shown in

FIG. 6

adopts the FMCW (frequency modulation continuous waves) system, the operating principles of which are as follows. Signals whose voltage amplitude changes over time forming triangular waves as shown by a solid line

103

in

FIG. 7

are inputted to a MODIN terminal for inputting modulated signals of the voltage-controlled oscillating portion

21

, the output signals are frequency-modulated, and the output frequency of the voltage-controlled oscillating portion

21

is shifted as shown on the vertical axis of FIG.

7

. Then, when the output signals (radio waves) are radiated from the single transmission/reception antenna

24

as shown by an arrow

105

, reflection waves (reception waves)

106

shown by a dot line

107

in

FIG. 7

are returned with a time lag for round trip of the propagation speed of the radio waves in the case where the target

104

exists forward the transmission/reception antenna

24

as shown in FIG.

6

. At this moment, to an IFOUT terminal

108

on the output side of the mixer

82

, the frequency difference Fb (=F

2

−F

1

) between the solid line

103

and the dot line

107

in

FIG. 7

is outputted.

By an analysis of frequency components such as the output frequency of the IFOUT terminal

108

, a distance R can be given by the following expression:

Fb

=4

R·fm·Δf/c

(1)

wherein Fb=IF output frequency, R=distance, fm=modulated frequency, Δf=frequency shift width and c=light speed.

In the millimeter-wave radar

101

of FMCW system, a resolution in the direction of the target

104

needs to be about 1 m, and in order to obtain this resolution, a frequency change bandwidth of 150 MHz is required according to the following expression:

r=c

/(2

·Δf

) (2)

wherein r=distance resolution, Δf=frequency shift width and c=light speed.

FIG. 8

is a plan view showing the simplified construction of the millimeter-wave radar module

102

mentioned before with reference to

FIGS. 6 and 7

.

FIG. 9

is a simplified plan view of another millimeter-wave radar module

102

a

which can be embodied instead of the embodiment as shown in FIG.

8

. An embodiment as shown in

FIG. 9

is similar to the embodiment as shown in

FIG. 8

, and like elements will be denoted by like reference numerals. The millimeter-wave radar modules

102

,

102

a

as shown in

FIGS. 8 and 9

comprise the voltage-controlled oscillating portion

21

.

FIG. 10

is a perspective view showing the entire construction of an example of the voltage-controlled oscillating portion

21

, and

FIG. 11

is a perspective view of a wiring board

38

included by the voltage-controlled oscillating portion

21

. The voltage-controlled oscillating portion

21

is constructed as shown in

FIGS. 10 and 11

. In these drawings, reference numeral

32

denotes a metal member such as a metal block for mounting a gun diode

33

, reference numeral

33

denotes a gun diode which is a kind of high-frequency diodes generating millimeter-waves, reference numeral

34

denotes a wiring board which is mounted on one side surface of the metal member

32

and provided with a choke-type bias supply strip

34

a

supplying bias voltage to the gun diode

33

and working as a low-pass filter for preventing high-frequency signals from leaking, reference numeral

35

denotes a band-shaped conductor such as a metal foil ribbon which connects the choke-type bias supply strip

34

a

to the upper conductor of the gun diode

33

, reference numeral

36

denotes a metal strip resonator made by disposing a resonating metal strip

36

a

to a dielectric base, and reference numerals

37

a

,

37

b

denote a dielectric strip which guides high-frequency signals of, for example, 70 GHz resonated by the metal strip resonator

36

to the outside of the voltage-controlled oscillating portion

21

.

Further, a wiring board

38

provided with a varactor diode

30

, which is a frequency-modulating diode as well as a kind of variable capacitance diodes, is mounted midway the dielectric strips

37

a

,

37

b

. A bias voltage applying direction of the varactor diode

30

is selected to be a direction

72

(electric field direction) which is perpendicular to the propagating direction

71

of high-frequency signals in the dielectric strips

37

a

,

37

b

as well as parallel to the main surfaces of the parallel plate conductors. Moreover, the bias voltage applying direction of the varactor diode

30

coincides with the electric field direction of high-frequency signals of LSM

01

mode which propagate through the dielectric strips

37

a

,

37

b

. Therefore, by electromagnetically coupling high-frequency signals and the varactor diode

30

and controlling bias voltage, it is possible to control the frequency of the high-frequency signals. In addition, reference numeral

39

denotes a dielectric plate having high dielectric constant for matching impedance of the varactor diode

30

to that of the dielectric strip

37

b.

Furthermore, as shown in

FIG. 11

, a second choke-type bias supply strip

40

is formed on one main surface of the wiring board

38

, and the beam-lead-type varactor diode

30

is mounted midway the second choke-type bias supply strip

40

. A connecting electrode

31

is formed at a junction of the second choke-type bias supply strip

40

to the varactor diode

30

.

High-frequency signals generated by the gun diode

33

are guided through the metal strip resonator

36

to the dielectric strip

37

a

. Subsequently, part of the high-frequency signals are reflected by the varactor diode

30

and returned toward the gun diode

33

. The reflection signals change according to the change of capacitance of the varactor diode

30

, and then the oscillation frequency changes.

Further, the varactor diode

30

, instead of being interposed between the first dielectric strips

37

a

,

37

b

, may be spatially electromagnetically coupled to a transmission path of high-frequency signals, or may be arranged on the transmission path of high-frequency signals. For example, the varactor diode

30

as shown in

FIG. 11

is arranged to be close to a metal strip

36

a

stripe in which resonance of high-frequency signals occurs, in a state where the bias voltage applying direction coincides with the electric field direction of the high-frequency signals. Alternatively the varactor diode

30

may be arranged to be directly close to the gun diode

33

in a state where the bias voltage applying direction coincides with the electric field direction of the high-frequency signals, or may be arranged in a choke-type bias supply strip

34

a

of the gun diode

33

.

The material of the choke-type bias supply strip

34

a

and the band-shaped conductor

35

of the voltage-controlled oscillating portion

21

as shown in

FIGS. 10 and 11

is Cu, Al, Au, Ag, W, Ti, Ni, Cr, Pd, Pt or the like, and specifically, Cu and Ag are preferable because they exhibit a preferable electric conductivity, low losses and high oscillation outputs.

Further, the band-shaped conductor

35

is electromagnetically coupled to the metal member

32

to keep a specific spacing from the surface of the metal member

32

, and bridged between the choke-type bias supply strip

34

a

and the gun diode device

33

. That is to say, one end of the band-shaped conductor

35

is soldered to one end of the choke-type bias supply strip

34

a

and the other end of the band-shaped conductor

35

is soldered to the upper conductor of the gun diode device

33

, whereby the band-shaped conductor

35

excluding the junctions is suspended in midair.

Since the metal member

32

also establishes a ground for the gun diode device

33

, it only needs to be a metal conductor, the material of which is not restricted as long as the metal member is a metal (including alloy) conductor. Therefore, the metal member is made of brass (Cu—Zn alloy), Al, Cu, SUS (stainless steel), Ag, Au, Pt or the like. Further, the metal member

32

may be: (a) a metal block entirely made of metal; (b) an insulation base such as ceramics or plastic, the surface of which is entirely or partly metal plated; or (c) an insulation base, the surface of which is entirely or partly coated with a conductive resin material or the like.

Further, it is preferable that the material of the dielectric strips

37

a

,

37

b

is a sinter whose major constituent is a Mg—Al—Si composite oxide such as cordierite (2MgO.2Al

2

O

3

.5SiO

2

) ceramics, or may be alumina (Al

2

O

3

) ceramics, glass ceramics or the like. These materials exhibit low losses in a high-frequency band. Specifically, with a sinter whose major constituent is a Mg—Al—Si composite oxide, it is possible to produce a dielectric strip which exhibits low losses in a high-frequency band.

In the invention, it is preferable that the dielectric strip is made of a sinter whose major constituent is a Mg—Al—Si composite oxide, more specifically, cordierite ceramics or the like. It is preferable that the dielectric constant of the sinter mentioned above is about 4.5-8. The reason for limiting the dielectric constant to this range is that in the case where the dielectric constant is less than 4.5, electromagnetic waves of the LSM mode in a propagation mode are largely converted to the LSE mode. On the other hand, in the case where the dielectric constant is more than 8, it is necessary to make the width of the dielectric strip considerably narrow for using in the frequency of 50 GHz or more, so that processing the strip is difficult, the accuracy of shape is degraded and a problem regarding strength occurs.

Further, it is preferable to use, as the material of the dielectric strip, ceramics whose major constituent is a Mg—Al—Si composite oxide with the value of Q of 1000 or more in the use frequency of 50-90 GHz. This material attains a sufficient low-loss property as a dielectric strip used in 50-90 GHz included in a millimeter-wave band recently.

It is preferable that the composition and the composition ratio of the dielectric strip satisfy a mole ratio composition expression of xMgO.yAl

2

O

3

.zSiO

2

, wherein x=10-40 mole %, y=10-40 mole %, z=20-80 mole % and x+y+z=100 mole %.

The reason for limiting the composition ratio of the major constituent of ceramics (dielectric porcelain composite), which is a material of the dielectric strip of the invention, to the above-mentioned range is as follows. A subscript x denoting mole % of MgO is limited to 10-40 mole %, because a preferable sinter cannot be obtained in the case of less than 10 mole %, whereas the dielectric constant gets high in the case of more than 40 mole %. In specific, the subscript x is preferably 15-35 mole % in view of selecting the value of Q in 60 GHz to be 2000 or more.

Further, a subscript y denoting mole % of Al

2

O

3

is limited to 10-40 mole %, because a preferable sinter cannot be obtained in the case where the amount y of Al

2

O

3

is less than 10 mole %, whereas the dielectric constant gets high in the case of more than 40 mole %. The subscript y denoting the amount of Al

2

O

3

is preferably 17-35 mole % in view of selecting the value of Q in 60 GHz to be 2000 or more.

A subscript z denoting mole % of SiO

2

is limited to 20-80 mole %, because the dielectric constant gets high in the case where the subscript z is less than 20 mole %, whereas a preferable sinter cannot be obtained and the value of Q is lowered in the case of more than 80 mole%. The subscript z denoting the amount of SiO

2

is preferably 30-65 mole % in view of selecting the value of Q in 60 GHz to be 2000 or more.

The subscripts x, y, z denoting mole % of MgO, Al

2

O

3

, SiO

2

can be specified in an analysis method such as the EPMA (electron probe micro analysis) method or the XRD (X-ray diffraction) method.

Further, regarding ceramics (dielectric porcelain composite) for the dielectric strip of the invention, the major crystal phase thereof is cordierite (2MgO.2Al

2

O

3

.5SiO

2

). As other crystal phases, mullite (3Al

2

O

3

.2SiO

2

), spinel (MgO.Al

2

O

3

), protoenstatite {a kind of steatite whose major constituent is magnesium metasilicate (MgO.SiO

2

)}, crinoenstatite {a kind of steatite whose major constituent is magnesium metasilicate (MgO.SiO

2

)}, forsterite (2MgO.SiO

2

), cristobalite {a kind of silicate (SiO

2

) }, tridymite {a kind of silicate (SiO

2

) }, sapphirine (a kind of silicate of Mg, Al) and the like are often deposited. The deposition phase is different depending on the composition. Dielectric porcelain composite of the invention may have a crystal phase of cordierite alone.

Dielectric porcelain composite for the dielectric strip of the invention is produced in the following manner. As powders of raw material, MgCO

3

powder, Al

2

O

3

powder and SiO

2

powder are used, for example. These powders are measured and wet mixed in the specific proportions, and then dried. The mixture is presintered at 1100-1300° C. in the air and crushed into powder. The obtained powder, to which a proper amount of resin binder is added, is molded, and the molded member is sintered at 1300-1450° C. in the air, whereby dielectric porcelain composite can be obtained.

The respective elements Mg, Al, Si contained in the powders of raw material may be an inorganic compound such as oxide, carbonate or acetate, or an organic compound such as organic metal. They can be anything that can become oxide by sintering.

The major constituent of dielectric porcelain composite of the invention is Mg—Al—Si composite oxide, and in a range not to impair the property that the value of Q at 50-90 GHz is 1000 or more, impurities of crush ball or powder of raw material other than the above-mentioned elements may be mixed in, and other constituents may be contained in order to control a sintering temperature range and enhance a mechanical property. For example, such constituents are rare-earth element compound, oxide such as Ba, Sr, Ca, Ni, Co, In, Ga or Ti, and non-oxide such as nitride like silicon nitride. A single constituent may be contained, or a plurality of constituents may be contained.

Referring to

FIG. 8

again, a millimeter-wave radar module

102

includes a high-frequency diode

33

, first dielectric strips

37

a

,

37

b

, a voltage-controlled oscillating portion

21

, a second dielectric strip

75

, a circulator

76

, a third dielectric strip

77

, a fourth dielectric strip

81

, a mixer

82

, and a pair of conductor plates

84

,

85

.

The high-frequency diode

33

outputs high-frequency signals of millimeter-wave band. One end of the first dielectric strips

37

b

(

37

a

) are connected to the high-frequency diode

33

, and the first dielectric strips

37

a

,

37

b

propagate high-frequency signals outputted by the high-frequency diode

33

. A variable capacitance diode

30

is interposed midway in a transmitting direction

71

of the first dielectric strips

37

a

,

37

b

, the variable capacitance diode

30

outputs transmission millimeter-wave signals, which are the high-frequency signals frequency-modulated by modulated waves obtained by periodically controlling bias voltage of a variable capacitance diode

30

placed so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals. The second dielectric strip

75

is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the variable capacitance diode

30

in the direction

71

for transmitting the transmission millimeter-wave signals of the first dielectric strips

37

a

,

37

b

. Here, the straight portion

37

b

1

may be formed like an arc having a radius of curvature r, and the second dielectric strip

75

may be linearly joined to the arc-shaped portion. The circulator

76

has an input end

78

, an input/output end

79

and an output end

80

, and is connected to the other end of the first dielectric strip

37

b

at the input end

78

. The circulator

76

outputs transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and outputs reception signals inputted into the input/output end

79

to the output end

80

. The third dielectric strip

77

is connected to the input/output end

79

of the circulator

76

. One end of the fourth dielectric strip

81

is connected to the output end

80

of the circulator

76

. The mixer

82

connects the second dielectric strip

75

and the fourth dielectric strip

81

to generate intermediate frequency signals of respective signals transmitted to the second and fourth dielectric strips

75

,

81

. A pair of conductor plates

84

,

85

are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in which spacing are disposed the high-frequency diode

33

, the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

81

, the voltage-controlled oscillating portion

21

, the circulator

76

and the mixer

82

.

In this millimeter-wave radar module

102

of

FIG. 8

, the mixer

82

has a construction of electromagnetically coupling an arc-shaped portion

87

midway in a transmitting direction

86

of the second dielectric strip

75

to a straight portion

89

midway in a transmitting direction

88

of the fourth dielectric strip

81

, so as to be in close proximity to each other. In this construction, the straight portion

89

may be formed like an arc. Further, the arc-shaped portion

87

may be formed straight, and the straight portion

89

may be formed like an arc.

Although the millimeter-wave radar module

102

a

in

FIG. 9

is similar to the millimeter-wave radar module

102

of

FIG. 8

, in particular, in this millimeter-wave radar module

102

a

of

FIG. 9

, the mixer

82

has a construction of tangentially joining, to a straight portion

91

of the fourth dielectric strip

81

, the second dielectric strip

75

along an arc-shaped portion

92

having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals. In this construction, the straight portion

91

may be formed like an arc having a radius of curvature r, and the second dielectric strip

75

may be linearly joined to the arc-shaped portion.

FIG. 12

is a block diagram showing the entire construction of millimeter-wave radar of another embodiment of the invention. This embodiment is similar to the above-mentioned embodiment, and corresponding portions are designated by the same reference characters. This millimeter-wave radar comprises a millimeter-wave radar module

102

b.

FIG. 13

is a simplified plan view showing a specific construction of the millimeter-wave radar module

102

b

as shown in FIG.

12

. This millimeter-wave radar module

102

b

includes the voltage-controlled oscillating portion

21

mentioned before with reference to

FIGS. 10 and 11

. This millimeter-wave radar module

102

b

includes a high-frequency diode

33

, first dielectric strips

37

a

,

37

b

, a voltage-controlled oscillating portion

21

, a second dielectric strip

75

, a circulator

76

, a third dielectric strip

77

, a terminator

112

, a fourth dielectric strip

114

, a mixer

82

, and a pair of conductor plates

84

,

85

. In

FIG. 13

, reference numeral

113

denotes a fifth dielectric strip, which has the terminator

112

at an end thereof opposite to the output end

80

.

The high-frequency diode

33

outputs high-frequency signals of millimeter-wave band. One end of the first dielectric strips

37

b

(

37

a

) are connected to the high-frequency diode

33

, and the first dielectric strips

37

a

,

37

b

propagate high-frequency signals outputted by the high-frequency diode

33

. A variable capacitance diode

30

is interposed midway in a transmitting direction

71

of the first dielectric strips

37

a

,

37

b

, the variable capacitance diode

30

outputs transmission millimeter-wave signals, which are the high-frequency signals frequency-modulated by modulated waves obtained by periodically controlling bias voltage of a variable capacitance diode

30

placed so that a bias voltage applying direction

72

coincides with an electric field direction of the high-frequency signals. The second dielectric strip

75

is joined, along an arc having a radius of curvature r not less than the wavelength λ of the transmission millimeter-wave signals, to a straight portion

37

b

1

of the first dielectric strip

37

b

on the downstream side from the voltage-controlled oscillating portion

21

in the direction

71

for transmitting the transmission millimeter-wave signals of the first dielectric strips

37

a

,

37

b

. Here, the straight portion

37

b

1

may be formed like an arc having a radius of curvature r, and the second dielectric strip

75

may be linearly joined to the arc-shaped portion. The circulator

76

has an input end

78

, an input/output end

79

and an output end

80

, and is connected to the other end of the first dielectric strip

37

b

at the input end

78

. The circulator

76

outputs transmission millimeter-wave signals inputted into the input end

78

to the input/output end

79

, and outputs reception signals inputted into the input/output end

79

to the output end

80

. The third dielectric strip

77

is connected to the input/output end

79

of the circulator

76

. The terminator

112

is connected to the output end

80

of the circulator

76

. The fourth dielectric strip

114

guides the received millimeter-wave signals. The mixer

82

connects the second dielectric strip

75

and the fourth dielectric strip

114

to generate intermediate frequency signals of respective signals transmitted to the second and fourth dielectric strips

75

,

114

. A pair of conductor plates

84

,

85

are placed in parallel at a spacing equal to or less than one half of the wavelength λ of the millimeter-wave signals, in a spacing between the conductor plates

84

,

85

, the high-frequency diode

33

, the first to fourth dielectric strips

37

a

,

37

b

;

75

,

77

,

114

, the voltage-controlled oscillating portion

21

, the circulator

76

and the mixer

82

are disposed.

To the third dielectric strip

77

is connected a transmission antenna

121

which transmits millimeter-waves

105

toward the target

104

. Reflected waves

106

from the target

104

are received by a reception antenna

122

. An output of the reception antenna

122

is supplied to the fourth dielectric strip

114

. The millimeter-wave radar module

102

b

may includes the transmission antenna

121

and reception antenna

122

.

Intermediate frequency signals from the mixer

82

is supplied through the fourth dielectric strip

114

to an amplifier

124

to be amplified and thereafter is supplied to a frequency measuring circuit

125

to measure the frequency Fb. The other constitutions and operations are the same as those in the foregoing embodiment.

In the millimeter-wave radar module

102

b

of

FIG. 13

, the mixer

82

has a construction of electromagnetically coupling an arc-shaped portion

115

midway in a transmitting direction

86

of the second dielectric strip

75

to a straight portion

116

midway in a transmitting direction

88

of the fourth dielectric strip

114

, so as to be in close proximity to each other.

In this construction, the straight portion

116

may be formed like an arc. Further, the arc-shaped portion

115

may be formed straight, and the straight portion

116

may be formed like an arc.

FIG. 14

is a simplified plan view showing a millimeter-wave radar module

102

c

of another embodiment of the invention. Although the millimeter-wave radar module

102

c

in

FIG. 14

is similar to the millimeter-wave radar module

102

b

of

FIG. 13

, in particular, in this millimeter-wave radar module

102

c

of

FIG. 14

, the mixer

82

has a construction of tangentially joining, to a straight portion

118

of the fourth dielectric strip

114

, the second dielectric strip

75

along an arc-shaped portion

119

having a radius of curvature r not less than the wavelength λ of the received millimeter-wave signals.

In this construction, the straight portion

118

may be formed like an arc having a radius of curvature r, and the second dielectric strip

75

may be linearly joined to the arc-shaped portion.

The nonreflective terminator

112

disposed at one end of the fifth dielectric strip

113

as shown in

FIGS. 13 and 14

has the following structure. As shown in

FIG. 15

, the fifth dielectric strip

113

is divided into substantially equal two portions in a direction parallel to the parallel plate conductors (horizontal direction), and to a divided surface of one end of the fifth dielectric strip

113

is applied a NiCr resistance film

112

a

or conductive resin coating film containing conductive particulates such as carbon. Additionally the NiCr resistance film

112

a

or conductive coating film may be formed also on side and end surfaces of the terminator

112

.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.

Number	Date	Country
0-767507	Apr 1997	EP
2-217114	Oct 1989	GB
6-174824	Jun 1994	JP
8-8621	Jan 1996	JP
244442	Oct 1969	RU

Junction structure of dielectric strip nonradiative dielectric waveguide and millimeter-wave transmitting/receiving apparatus

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

US Referenced Citations (1)

Foreign Referenced Citations (5)