JP2001326507A - Line conversion structure, high frequency module, communication equipment and radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line conversion structure between a slot system transmission line and a waveguide, which is designed so as to be able to obtain a satisfactory conversion characteristic over a wide range and also a low VSWR characteristic even by using a dielectric substrate of a high dielectric constant, a high frequency module using the line conversion structure, communication equipment and a radar device. SOLUTION: A dielectric substrate 2 which extends from a PDTL to the almost central part of the waveguide 1 and is also parallel to two opposing faces (E faces) of the waveguide 1 is arranged at a line converting part between the PDTL being the slot system transmission line and the waveguide. The width of the dielectric substrate is symmetrical with respect to the center of the waveguide from the PDTL toward the waveguide direction and of a tapered shape which tapers off to the end, and the width of a slot 4 is also gradually expanded symmetrically with respect to the center of the waveguide from the PDTL toward the waveguide direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line conversion structure for converting a line between a slot transmission line and a waveguide, a high-frequency module including the line conversion structure, a communication device, and a radar device.

[0002]

2. Description of the Related Art Conventionally, Hoefer et al., "OPTIMAL WAVEGUIDE TO E-PL"
ANE CIRCUIT TRANSITIONS WITH BINOMINAL AND CHEBYSH
EV TRANSFORMERS "14th EuMC, Sep. 1984, pp305-310, and JP-B-7-83217.

In the prior art, a waveguide and a fin line are matched using a quarter-wave transformer. However, in a device using such a quarter-wave transformer,
There is a problem that the frequency dependence is high and the bandwidth showing good line conversion characteristics is narrow. The line conversion structure shown in FIG. FIG. 12 shows the basic configuration. (A) is a perspective view, (B) is a side view of a dielectric substrate provided in a waveguide. In this figure, 16 is a waveguide, and 14 is a dielectric substrate provided therein. A fin line slot 30 is formed on the dielectric substrate 14 by the electrodes 18 and 19. As shown by 120 and 122, the width of the slot is tapered so as to gradually increase from the fin line toward the waveguide. Further, as indicated by 126, the dielectric substrate 14 also has a tapered shape that gradually tapers over a length L1 in the waveguide direction.

[0004]

However, when the characteristics of the line conversion structure shown in FIG. 12 were calculated, the results shown in FIG. 13 were obtained. FIG. 13A shows the frequency characteristics of reflection loss using the relative dielectric constant εr of the dielectric substrate as a parameter. (B) shows the frequency characteristics of the return loss using the length L1 of the tapered portion of the dielectric substrate as a parameter. As described above, since the reflection loss increases as the relative permittivity εr of the dielectric substrate increases, it can be seen that the conversion characteristics are degraded. It can also be seen that the conversion characteristics are not significantly improved around 50 GHz even if the length L1 of the tapered portion of the dielectric substrate is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a slot system capable of obtaining good conversion characteristics over a wide band and obtaining good conversion characteristics with little reflection loss even when a dielectric substrate having a high dielectric constant is used. An object of the present invention is to provide a line conversion structure between a transmission line and a waveguide, a high-frequency module using the same, a communication device, and a radar device.

[0006]

SUMMARY OF THE INVENTION The present invention relates to, for example, a slot line and a fin line.
And a waveguide transmission line including a dielectric substrate in which a slot is formed by an electrode, such as a PDTL (planar dielectric line), and a waveguide. A line conversion part between the waveguide and the waveguide substrate, and a dielectric substrate extending from the dielectric substrate of the slot-based transmission line is disposed at a substantially central portion of the waveguide in parallel with the two opposing surfaces of the waveguide, The width of the dielectric substrate is symmetrical with respect to the approximate center of the waveguide, and is tapered toward the waveguide direction from the slot transmission line.

As described above, in the line converter, the width of the dielectric substrate is symmetrical with respect to the substantially center of the waveguide from the slot transmission line to the waveguide, and from the slot transmission line to the waveguide. By having a tapered shape,
Obtain low VSWR (voltage standing wave ratio) characteristics over a wide band. Moreover, by performing line conversion while maintaining symmetry with respect to the central axes of the waveguide and the dielectric substrate, generation of spurious modes is also suppressed.

Further, according to the present invention, in the above-mentioned line conversion section, a slot connected to the slot of the slot-type transmission line is formed, and the width of the slot increases from the slot-type transmission line toward the waveguide. Symmetrical with respect to the approximate center of the shape. With this structure, from the slot-based transmission line to the waveguide, the entire structure including the slot-based transmission line portion is symmetrical with respect to substantially the center of the waveguide, and a low VSWR characteristic and a low spurious mode characteristic can be obtained in a wide band.

According to the present invention, the width of the dielectric substrate is kept substantially constant between the position where the width of the slot becomes the widest and the position where the width of the dielectric substrate starts to decrease. Thus, while maintaining the symmetry with respect to the central axes of the waveguide and the dielectric substrate, the width of the slot is widened and the dielectric loading in which only the dielectric portion of the dielectric substrate substantially exists in the waveguide. The length of the shaped waveguide portion is determined independently of the tapered portion of the dielectric substrate, so that the conversion characteristics can be optimized and the degree of freedom in design is improved.

Further, according to the present invention, there is provided a high-frequency module including at least two transmission lines, that is, a slot-based transmission line and a waveguide, having the above-mentioned line conversion structure.

Further, the present invention constitutes a communication device for performing communication using electromagnetic waves using the high-frequency module, or a radar device for detecting an object, measuring a distance, and measuring a relative speed, etc., by transmitting and receiving electromagnetic waves.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a line converter according to a first embodiment will be described with reference to FIGS. FIG. 1A is a perspective view of a main part. Here, the waveguide is shown by a broken line to show the inside thereof together with the waveguide. (B) is a plan view of the main part, and (C) is a view seen from the left rear end face in (A). In FIG. 1, reference numeral 1 denotes a rectangular waveguide, in which a vertical plane in the figure is an H plane parallel to a magnetic field distribution plane, and a horizontal plane perpendicular to the H plane is an E plane.
In FIG. 1A, the left rear end is PDTL, and the right front end is a waveguide as a transmission line.
2 shows a line conversion section between a waveguide and a waveguide.

Inside the waveguide 1, a dielectric substrate 2 is disposed parallel to the E-plane and substantially at the center (central height) of the waveguide. As shown in (C), electrodes 3a and 3b are formed on the upper and lower surfaces of the dielectric substrate 2 so that the slots 4a and 4b face each other. The dielectric substrate 2, the electrodes 3a and 3b, and the waveguide 1 constitute a PDTL. A region where the dielectric substrate does not exist inside the waveguide is a pure waveguide portion, and an intermediate portion between the waveguide and PDTL is a line conversion portion.

The dielectric substrate 2 extends over the section L1.
As the width goes from the middle of the line conversion part toward the waveguide,
The waveguide has a tapered shape that tapers symmetrically with respect to the approximate center of the waveguide. The slot 4 formed by the electrode 3 is a PDT.
From the end of L to a section of L3 in the middle of the line conversion portion, the taper shape is symmetrical and wide with respect to substantially the center of the waveguide toward the waveguide direction. Reference numeral 6 denotes the electrode tapered portion.

FIG. 2 shows the result of calculation of the characteristics of the line converter. (A) is a dielectric substrate 2
Frequency characteristics of return loss with the relative dielectric constant of
(B) shows the frequency characteristics of the reflection loss with the length L1 of the tapered portion of the dielectric substrate as a parameter. According to this embodiment, as shown in (A), even when the relative permittivity of the dielectric substrate is large, low VSWR characteristics can be obtained by increasing the length L1 of the tapered portion of the dielectric substrate. I understand. Further, as shown in (B), even when the relative dielectric constant of the dielectric substrate is increased, the deterioration of the conversion characteristics is smaller than in the conventional case. Such a characteristic is obtained by making the dielectric substrate and the slot symmetrical with respect to the center of the waveguide by setting a plane passing through the center axis of the dielectric substrate and the waveguide and parallel to the H plane as a symmetry plane. Even if a dielectric substrate having a high dielectric constant is used, the polarization of the electromagnetic wave from the PDTL to the waveguide does not occur (mode symmetry is maintained),
This is obtained by performing good impedance conversion. In addition, since the symmetry does not cause the electromagnetic wave to be deflected, the occurrence of spurious modes is also suppressed.

Next, the configuration of a line converter according to a second embodiment will be described with reference to FIGS. 3A is a perspective view of a main part, and FIG. 3B is a plan view of the main part. What differs from the example shown in FIG. 1 is the shape of the dielectric substrate disposed inside the waveguide.

The dielectric substrate 2 extends over the section L1.
As the width goes from the middle of the line conversion part toward the waveguide,
The tapered shape is symmetrical and tapered with respect to the center of the waveguide. However, unlike the example shown in FIG. 1, it has a tapered shape that is bifurcated from the center to two opposing waveguide surfaces.

The slot 4 formed by the electrode 3 extends symmetrically with respect to the center of the waveguide toward the waveguide from the end of the PDTL to the section L3 in the middle of the line conversion portion so as to be wider. The tapered portion 6 is formed.

FIG. 4 shows the frequency characteristics of the return loss of the line converter portion using the relative dielectric constant of the dielectric substrate 2 as a parameter. Also according to this embodiment, the dielectric substrate and the slot are symmetric with respect to the center of the waveguide, with the plane passing through the central axis of the dielectric substrate and the waveguide and being parallel to the H plane as the symmetric plane. An electromagnetic wave is not biased from the PDTL to the waveguide, and good impedance conversion is performed. As a result, as shown in FIG. 4, even when the relative dielectric constant of the dielectric substrate is large, a lower VS is
WR characteristics are obtained.

Next, the configuration of a line converter according to a third embodiment will be described with reference to FIGS. FIG. 5 is a top view in a state where the upper surface (E surface) of the waveguide is removed.
Also in this line converter, the dielectric substrate 2 is arranged at the center height inside the waveguide. In this example, the dielectric substrate 2
Over the section of L1, the taper shape is tapered symmetrically with respect to the center of the waveguide as the width goes from the middle of the line conversion part toward the waveguide. In addition, the slot 4 formed by the electrode 3 has a tapered shape that is symmetrical and wide with respect to the center of the waveguide as it goes from the end of the PDTL to the section L3 in the middle of the line conversion section toward the waveguide. . Further, L2 sandwiched between the section of L3 and the section of L1
In the section indicated by, the dielectric substrate is present in the waveguide as it is, so the section indicated by L2 acts as a dielectric-loaded waveguide. Therefore, line conversion is performed in the order of (PDTL)-(dielectric loaded waveguide)-(waveguide).

FIG. 6 shows that the relative permittivity εr is as high as 24,
Shows the frequency characteristics of the return loss with L2 as a parameter under conditions as short as 4.5 mm. Thus, L
By setting 2 to 6 mm, the frequency range showing the low VSWR characteristic becomes wider when L2 = 0, that is, as compared with the case of the structure shown in FIG. This is because the dielectric-loaded waveguide portion is lengthened, so that the (waveguide)-(dielectric-loaded waveguide) converter and (dielectric-loaded waveguide)-(PDTL) This is because interference with the conversion unit in ()) is reduced.

FIG. 7 is a diagram showing a configuration of a line converter according to a fourth embodiment. As in the case of the third embodiment, the width of the dielectric substrate 2 is tapered symmetrically with respect to the center of the waveguide as it goes from the middle of the line conversion part toward the waveguide over the section L1. And a tapered shape. However, unlike the example shown in FIG. 5, it has a tapered shape that is bifurcated from the center to two opposing waveguide surfaces. Even with such a structure, characteristics similar to those of the third embodiment can be obtained.

In each of the embodiments described above, examples have been described in which line conversion between PDTL and waveguide is performed. However, various transmission lines as shown in the sectional view of FIG. be able to. That is, FIG.
In the example shown in FIG. 1, the electrode 3 is provided on one surface of the dielectric substrate 1 to form a slot 4, and this is provided inside the waveguide 1, thereby forming a single-sided slot fin line. When the line conversion between the fin line and the waveguide is performed, the same configuration as that described in each embodiment can be adopted except that the electrode 3 is formed only on one surface of the dielectric substrate. That is, the end of the dielectric substrate in the line conversion portion may be tapered, the electrode 3 may be tapered, and the width of the slot 4 may be gradually increased.

Also, the dielectric constant of the dielectric substrate is set such that the electromagnetic wave of a plane wave of a predetermined frequency propagates in the region where the slots on both surfaces of the dielectric substrate face each other while being totally reflected by the upper slot and the lower slot. It is not limited to the PDTL in which the ratio and the thickness are set, but is simply a double-sided fin line in which two slots 4a and 4b formed by electrodes 3a and 3b are arranged on the upper and lower surfaces of the dielectric substrate 2 as shown in FIG. The same can be applied.

In the example shown in FIG. 2C, the electrode 3 is provided only on one surface of the dielectric substrate 2 to form the slot 4, and the conductor plates 7a and 7b are arranged above and below at a predetermined interval. Make up the line. In the example shown in (D), the electrodes 3a, 3b are provided on both surfaces of the dielectric substrate 2 to form slots 4a, 4b, and the conductor plates 7a, 7b are arranged above and below at a predetermined interval. Make up the line. When the line conversion between the slot line and the waveguide is performed, the upper and lower conductor plates 7a and 7b are connected to the E-plane of the waveguide, respectively, and the dielectric substrate 2 is connected to the line converter at the line converter. Slots 4 are arranged inside a waveguide having an E-plane and an H-plane, and the dielectric substrate in the line conversion section is tapered as shown in each embodiment, and the electrode 3 is also tapered. May be formed so that the width gradually increases from the slot line toward the waveguide.

Next, a configuration example of the high-frequency module will be described with reference to FIG. In FIG. 9, ANT is a transmitting / receiving antenna, DPX is a duplexer, BPFa and BPFb are band-pass filters, AMPa and AMPb are amplifier circuits, MIXa and MIXb are mixers, OS
C is an oscillator, and SYN is a frequency synthesizer.

MIXa mixes the intermediate frequency signal IF with the signal output from SYN, and BPFa allows only the transmission frequency band of the mixed output signal from MIXa to pass,
AMPa amplifies the power and transmits it from ANT via DPX. AMPb amplifies the reception signal output from DPX, and BPFb allows only the reception frequency band of the signal to pass. MIXb mixes the frequency signal output from the SYN with the received signal to produce an intermediate frequency signal IF.
Is output.

Here, since the DPX is directly connected to the antenna, a waveguide is used for the transmission line of the DPX and its input / output unit. Slot transmission lines are used for transmission lines of other circuit portions in consideration of miniaturization and ease of mounting components. Therefore, the line conversion structure shown in FIGS. 1 to 8 is applied to the connection between DPX and AMPa and AMPb.

FIG. 10 is a block diagram showing the configuration of the communication device. Here, a circuit having the structure shown in FIG. 9 is used for the high-frequency module, and a circuit for transmitting and receiving signals and processing signals for transmission signals and reception signals using the high-frequency module is provided as a signal processing circuit. With this overall configuration, wireless communication of analog signals or digital data in the microwave band or millimeter wave band is performed.

FIG. 11 is a block diagram showing the configuration of the millimeter wave radar module. Here, VCO is a voltage controlled oscillator, ISO is an isolator, CPL is a directional coupler,
MIX is a mixer. The oscillation signal of the VCO is transmitted from the transmitting antenna via the isolator ISO and the directional coupler CPL. When the reflected wave from the object is received by the receiving antenna, the mixer MIX mixes the received signal with the local signal from the directional coupler CPL to produce an intermediate frequency signal IF.
Is output. A control circuit for controlling the millimeter wave radar module detects the distance to the object and the relative speed from the VCO modulation signal and the IF signal.

In FIG. 11, the transmission lines of the circuit part for processing the VCO and IF signals are PDTL, ISO, CPL,
The transmission line of the MIX portion is a waveguide. Therefore, P
A line conversion structure having the structure shown in FIGS. 1 to 8 is formed between the DTL and the waveguide.

[0032]

According to the present invention, since a quarter-wave transformer is not used, a low VSWR characteristic can be obtained over a wide band. In addition, since the dielectric substrate has a symmetric shape with respect to the center of the waveguide from the slot transmission line to the waveguide, and has a tapered shape from the slot transmission line to the waveguide, the VSWR (voltage is low) over a wide band. Standing wave ratio) characteristics can be obtained. Moreover, since line conversion is performed while maintaining symmetry with respect to the central axes of the waveguide and the dielectric substrate, generation of spurious modes is suppressed.

Further, according to the present invention, in the line converter, the width of the slot connected to the slot of the slot-based transmission line becomes larger with respect to the center of the waveguide as going from the slot-based transmission line toward the waveguide. Since the shape is symmetrical and wide, the entire area including the slot-type transmission line and the slot-type transmission line is symmetrical with respect to the approximate center of the waveguide, so that the VSWR characteristic and the spurious response are low over a wide band. Modal characteristics are obtained.

Further, according to the present invention, by keeping the width of the dielectric substrate substantially constant between the position where the width of the slot becomes the widest and the position where the width of the dielectric substrate starts to become narrower, While maintaining the symmetry with respect to the central axis of the waveguide and the dielectric substrate, the length of the dielectric-loaded waveguide portion where only the dielectric portion of the dielectric substrate is present in the waveguide, It can be determined independently of the tapered shape portion of the body substrate, so that the conversion characteristics can be optimized and the degree of freedom in design can be improved. Moreover, the interference between the (slot transmission line)-(dielectric loaded waveguide) line converter and the (dielectric loaded waveguide)-(waveguide) line converter is reduced. , The frequency range showing the low VSWR characteristic is widened.

Further, according to the present invention, since at least two transmission lines of the slot type transmission line and the waveguide are provided, and the conversion part of both transmission lines performs line conversion with low VSWR and low insertion loss. Thus, a high-frequency module utilizing the characteristics of the slot transmission line and the waveguide can be constructed.

Further, according to the present invention, a communication device or a radar device having high efficiency and excellent high-frequency characteristics can be configured using a high-frequency module in which line conversion is performed with low VSWR and low insertion loss.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a line converter according to a first embodiment.

FIG. 2 is a diagram showing characteristics of the line converter.

FIG. 3 is a diagram showing a configuration of a line converter according to a second embodiment.

FIG. 4 is a diagram showing characteristics of the line converter.

FIG. 5 is a diagram showing a configuration of a line converter according to a third embodiment.

FIG. 6 is a diagram showing characteristics of the line converter.

FIG. 7 is a diagram showing a configuration of a line converter according to a fourth embodiment.

FIG. 8 is a sectional view showing some configuration examples of a slot transmission line.

FIG. 9 is a block diagram illustrating a configuration of a high-frequency module.

FIG. 10 is a block diagram illustrating a configuration of a communication device.

FIG. 11 is a block diagram illustrating a configuration of a radar device.

FIG. 12 is a diagram showing a conventional line conversion structure.

FIG. 13 is a diagram showing a characteristic example of the line converter.

[Explanation of symbols]

 Reference Signs List 1-waveguide 2-dielectric substrate 3-electrode 4-slot 5-tapered portion of dielectric substrate 6-tapered portion of electrode 7-conductor plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoya Sonoda 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Stock Company Murata Manufacturing Co., Ltd. (72) Inventor Kiyoshi Kanagawa 2-26-10 Tenjin, Nagaokakyo-city, Kyoto Stock Murata Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. A line conversion structure between a slot-based transmission line including a dielectric substrate provided with electrodes so as to form slots at predetermined intervals, and a waveguide, wherein the slot-based transmission line and the waveguide are connected to each other. And a dielectric substrate extending from the dielectric substrate of the slot-type transmission line and disposed substantially parallel to the two opposing surfaces of the waveguide and substantially at the center of the waveguide. A line conversion structure in which a substrate has a shape that tapers symmetrically with respect to substantially the center of the waveguide as going from the slot-based transmission line toward the waveguide. 2. In the line converter, a slot is formed to be connected to a slot of the slot-based transmission line, and the slot is formed such that the more the slot is directed toward the waveguide from the slot-based transmission line, the substantially the center of the waveguide. The line conversion structure according to claim 1, wherein the line conversion structure has a shape that is symmetrical and wide. 3. The width of the dielectric substrate between the position where the width of the slot is the widest and the position where the width of the dielectric substrate starts to be reduced is kept substantially constant.
3. The line conversion structure according to item 1. 4. A high-frequency module comprising the line conversion structure according to claim 1. 5. A communication device using the high-frequency module according to claim 4. 6. A radar device using the high-frequency module according to claim 4.