JP3702881B2 - Dielectric line attenuator, terminator and radio equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric line attenuator, a dielectric line terminator, and a wireless device using them, which are used in a millimeter wave band or the like.
[0002]
[Prior art]
A millimeter-wave integrated circuit using a non-radiative dielectric line (hereinafter referred to as “NRD guide”) is shown in IEICE Transactions C-1 Vol.J73-CI No.3 p.87-94 1990.3 Yes.
[0003]
The NRD guide has a dielectric strip disposed between two parallel conductor planes, the dielectric strip portion is used as an electromagnetic wave propagation region, and the space sandwiched between the conductor planes on both sides thereof is used as an electromagnetic wave cutoff region. It is. In such an NRD guide, as a terminator, as shown in the above-mentioned document, a resistive film that absorbs electromagnetic waves is provided on the dielectric strip portion.
[0004]
FIG. 7 is a perspective view showing the configuration of the terminator portion. However, the upper and lower conductor plates are omitted in FIG. The dielectric strip shown in FIG. 7 is sandwiched between upper and lower conductor plates to form an electromagnetic wave propagation area. A resistive sheet and a dielectric sheet are sandwiched between two upper and lower dielectric strips. As shown in the figure, a part of the resistance sheet and the dielectric sheet are formed in a taper shape, and the impedance of the dielectric line is converted at this part, and the energy of the LSM01 mode propagating through the dielectric line is converted to the resistance sheet. So that it absorbs electromagnetic waves. Therefore, the electromagnetic wave propagating from the A direction in the figure is terminated with resistance at the terminator portion and hardly reflected in the reverse direction.
[0005]
[Problems to be solved by the invention]
Since the conventional dielectric line terminator as shown in FIG. 7 has a structure in which impedance conversion is performed with a tapered resistor sheet, a long taper length is required to obtain sufficient low reflection characteristics. Therefore, there has been a problem that the entire length of the terminator becomes long. Such a dielectric line terminator is, for example, provided at a predetermined port of a circulator to constitute an isolator as a whole, or provided at a predetermined port of a coupler to constitute a directional coupler as a whole. As a result, the entire dielectric line module using an isolator or a directional coupler increases in size. For example, providing a bend in the dielectric line so that a long terminator is placed at a predetermined position is effective for miniaturization, but the bend portion is between the LSM mode and the LSE mode. There arises a problem that mode conversion occurs and loss increases.
[0006]
In addition, if a resistive film is provided in the dielectric strip portion in the middle of the dielectric line, a dielectric line attenuator can be configured. However, in order to sufficiently suppress reflection at the resistive film portion, the resistive film As in the case of the dielectric line terminator, the pattern needs to have a long taper shape. Therefore, the same problem as described above also occurs with respect to the dielectric line attenuator.
[0007]
An object of the present invention is to provide a dielectric line attenuator, a terminator, and a radio apparatus using the same, in which the length of the dielectric line in the electromagnetic wave propagation direction is shortened to reduce the overall size.
[0008]
[Means for Solving the Problems]
A dielectric line attenuator according to the present invention comprises: a dielectric line comprising two substantially parallel conductor planes and a dielectric strip sandwiched between the conductor planes; The reflected wave suppression means for suppressing the reflected wave of the signal at the discontinuous part, and at least a part of the reflected wave suppression means, and is formed on the conductor plane. And a resistive film for attenuating a signal propagating through the dielectric line, provided along a split surface of the dielectric strip in a parallel plane. The discontinuous portions are provided at three or more locations, and the intervals between the discontinuous portions are set to odd multiples of a quarter wavelength of the different wavelengths of the reflected waves to be suppressed , and the discontinuous portions are provided. The portion is formed of a plurality of the resistor films formed as patterns that are intermittent along the extending direction of the dielectric strip.
[0009]
In this way, by attenuating the signal propagating through the dielectric line with the resistive film having the intermittent pattern, and by synthesizing the reflected wave of the signal generated at the discontinuous portion of the line impedance by the resistive film having the intermittent pattern Repress.
[0010]
In the dielectric line attenuator according to the present invention, the interval between the discontinuous portions is set to have a relationship that is an odd multiple of approximately ¼ wavelength of the wavelength of the reflected wave to be suppressed. As a result, the reflected wave to be suppressed is canceled efficiently, and a good low reflection characteristic is obtained.
[0011]
In addition, the dielectric line attenuator of the present invention provides three or more discontinuous portions, and suppresses a plurality of reflected waves having different wavelengths between the reflected waves at the predetermined discontinuous portions. As a result, the reflected wave can be suppressed over a relatively wide band.
[0012]
Furthermore, the dielectric line attenuator of the present invention makes the dielectric constant of the substrate on which the resistive film pattern is formed higher than the dielectric constant of the dielectric strip. As a result, the wavelength shortening effect on the substrate is increased, the area occupied by the resistive film pattern is relatively reduced, and the overall size is reduced.
[0013]
The dielectric line terminator of the present invention is configured by providing the dielectric line attenuator having the above-described configuration near the end of the dielectric strip.
[0014]
Furthermore, the wireless device of the present invention is configured by providing the above-described dielectric line attenuator or terminator. For example, a millimeter wave radar module is configured by configuring a dielectric line terminator in an isolator or coupler that propagates a millimeter wave transmission / reception signal.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The configuration of the dielectric line terminator according to the first embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a main part of a dielectric line terminator. Here, 1 and 2 are conductor plates, respectively, and 3 is a dielectric strip disposed between the upper and lower conductor plates 1 and 2. Reference numeral 4 denotes a substrate on which resistance film patterns 5a and 5b are formed. The substrate 4 is also disposed between the conductor plates 1 and 2.
[0016]
As shown in the figure, a step is formed in the dielectric strip 3, and the substrate 4 is sandwiched between the dielectric strip 3 and the upper dielectric strip 3 '.
[0017]
In FIG. 1, for example, a fluorine-based resin having excellent high frequency characteristics is used for the dielectric strips 3 and 3 '. For example, a polyester resin sheet having a thickness of about 0.1 to 0.3 mm is used for the substrate 4, and a relatively high resistivity metal such as Ni—Cr or ITO (indium tin oxide) is used for the resistance film. A thin film is formed by sputtering or the like. The surface resistance value of this resistive film is about several hundred Ω □.
[0018]
2A is a top view of the portion of the substrate 4 shown in FIG. 1, and FIG. 2B is a cross section taken along a plane perpendicular to the longitudinal direction of the dielectric strip in a state where the parts shown in FIG. 1 are assembled. FIG. The conductor plates 1 and 2 are formed with grooves of a certain depth, and dielectric strips 3 and 3 'are fitted into these grooves. The lower conductor plate 1 is formed with a recess for mounting the substrate 4, and this portion holds the substrate 4 between the conductor plates 1 and 2 and between the dielectric strips 3 and 3 ′.
[0019]
As shown in FIG. 2A, the resistive film pattern 5 a on the substrate 4 is formed as a pattern that continues for a predetermined length in the longitudinal direction of the dielectric strip 3. The resistive film pattern 5b is formed as a pattern extending in a direction perpendicular to the dielectric strip 3 at a position away from the resistive film pattern 5a by a predetermined distance. The resistance film patterns 5b and 5a constitute reflected wave suppression means according to the present invention.
[0020]
As described above, the structure in which the substrate 4 on which the resistive film pattern is formed is sandwiched between the dielectric strips changes the line impedance of the dielectric line between the location where the resistive film pattern exists and the location where the resistive film pattern does not exist. Thus, the electromagnetic wave propagating through the dielectric line is reflected at the respective boundary positions of the resistive film patterns 5a and 5b. These reflected waves w1 and w2 are combined with each other, but if one wavelength on the dielectric line of the reflected wave to be suppressed is expressed by λg, the distance between the resistive film patterns 5a and 5b is approximately λg. / 4. As a result, the reflected wave w1 reflected by the end portion of the resistive film pattern 5a and the reflected waves w1 and w2 reflected by the resistive film pattern 5b are synthesized in substantially opposite phases, and these are canceled out. Actually, since the resistive film pattern 5b has a width, a reflected wave having a wavelength near λg is effectively suppressed accordingly. On the other hand, in the resistive film pattern 5a, the electromagnetic wave is absorbed by consuming the LSM01 mode electromagnetic wave propagating through the dielectric line in the resistive film.
[0021]
FIG. 3 is a diagram showing the reflection characteristics of the dielectric line terminator shown in comparison with the conventional dielectric line terminator. Here, A is the frequency characteristic of the reflection loss of the dielectric line terminator in which the conventional impedance conversion part is formed by the tapered resistive film pattern as shown in FIG. 7, and B is the impedance discontinuity part. It is the frequency characteristic of the reflection loss of the dielectric material line | wire terminator which formed the impedance conversion part by.
[0022]
Thus, according to the present invention, it can be seen that the reflection characteristic in a predetermined frequency band can be obtained with a better low reflection characteristic than that of the tapered resistance film. Moreover, since the frequency at which the reflection loss is reduced is generated by the interval between the two resistive film patterns as shown in FIG. 2A, it is good in an arbitrary frequency band by determining this interval. Reflection characteristics can be obtained.
[0023]
In the example shown above, by using a material having a high dielectric constant for the dielectric strip as the base material of the substrate 4, the physical length of the resistive films 5a-5b shown in FIG. 2 can be shortened. The body line terminator portion can be reduced in size.
[0024]
If the width of the resistive film is larger than the width of the dielectric strip, even if the positional accuracy of the resistive film pattern on the substrate 4 and the positional accuracy of the substrate 4 between the upper and lower conductor plates are relatively low, reflection loss or the like The influence on electrical characteristics can be reduced.
[0025]
The substrate 4 may be fixed by adhering to the dielectric strips 3 and 3 'or to the upper and lower conductor plates 1 and 2 in addition to being sandwiched between the upper and lower conductor plates 1 and 2. May be.
[0026]
The base material of the substrate 4 may be the same material as the dielectric strip 3. In this case, it is equivalent to a case where a resistive film is directly formed on a dielectric strip divided into upper and lower parts.
[0027]
In the example shown in FIG. 1, an example in which the end of the terminator is a short-circuited end of a dielectric line is shown. However, if the length is sufficient to absorb electromagnetic waves by the resistive film pattern 5a, The end of the line may be an open end.
[0028]
Further, in the first embodiment, the reflected wave suppression means is configured by the pattern of the resistive film, but the reflected wave at the discontinuous portion of the line impedance caused by the presence of the resistive film that attenuates the signal propagating through the dielectric line. The discontinuous part of the line impedance for suppressing the above may be constituted by a conductor film. That is, in FIGS. 1 and 2, the resistive film pattern 5b may be formed of a conductor film.
[0029]
Next, some other examples of the resistive film pattern will be described as a second embodiment with reference to FIG. 4A to 4E are plan views of the substrate portion with the upper conductor plate and the upper dielectric strip removed. In the example shown in (A), a resistive film pattern 5a extending in the longitudinal direction of the dielectric strip 3 and a direction perpendicular thereto, and a resistive film pattern 5b having a width perpendicular to the dielectric strip 3 different from 5a are provided. Forming. In this way, the portion where the width in the direction perpendicular to the dielectric strip changes becomes a discontinuous portion of the line impedance. The interval between the discontinuous portions is approximately λg / 4. With this structure, the reflected waves reflected at two places are synthesized in an antiphase relationship, and the reflected waves are suppressed. In the resistive film pattern 5a, the electromagnetic wave is absorbed by consuming the LSM01 mode electromagnetic wave propagating through the dielectric line in the resistive film.
[0030]
In the example shown in FIG. 4B, a resistive film pattern 5c is further formed in addition to the resistive film patterns 5a and 5b. Here the distance between the ends of the resistive film pattern 5a and the central portion of the resistive film pattern 5b is approximately λg _2/4, resisting film pattern 5b, the distance between the central portion of 5c approximately λg _1/4. These λg ₁ and λg ₂ are two different wavelengths of the reflected wave to be suppressed. With such a structure, it is possible to effectively suppress reflected waves for the _two wavelengths λg ₁ and λg ₂ . In addition, since the resistive film patterns 5b and 5c actually have a width in the traveling direction of the electromagnetic wave propagating through the dielectric line, the frequency at which the reflection loss is suppressed also has a width.
[0031]
In the example shown in FIG. 4C, the resistance film patterns 5a, 5b, and 5c are further increased by one portion where the width in the direction perpendicular to the dielectric strip is different from that shown in FIG. Is forming. Here resistive film pattern 5b electromagnetic wave propagation direction of length approximately lambda] g _2/4 of, and the electromagnetic wave propagation direction of the length of the resistive film pattern 5c was approximately λg _1/4. With this structure, the reflected wave is effectively suppressed in the vicinity of the _two wavelengths λg ₁ and λg ₂ .
[0032]
In the example shown in FIG. 4D, the resistive film pattern 5b extending perpendicularly to the longitudinal direction of the dielectric strip is formed, and the end of the resistive film pattern 5a is connected to the longitudinal direction of the dielectric strip. It is tilted. Here is the distance between the ends of the resistive film pattern 5a and the central portion of the resistive film pattern 5b is approximately λg ₁ / 4~λg _2/4. These λg ₁ and λg ₂ are two different wavelengths of the reflected wave to be suppressed.
With such a structure, it is possible to effectively suppress the reflected wave for the wavelengths λg _{1 to} λg ₂ . In addition, since the resistive film pattern 5b actually has a width in the traveling direction of the electromagnetic wave propagating through the dielectric line, the frequency at which the reflection loss is suppressed further has a width. As a result, a continuous low reflection loss characteristic can be obtained over a predetermined frequency range.
[0033]
In the example shown in FIG. 4E, the end portion of the resistive film pattern 5a is inclined with respect to the longitudinal direction of the dielectric strip and the resistive film pattern 5b extends in the inclined direction with respect to the longitudinal direction of the dielectric strip. Is forming. With this structure, the distance between the reflection point at the end of the resistance film pattern 5a and the two reflection points of the resistance film pattern 5b becomes a continuous region having a width. As a result, a continuous low reflection loss characteristic can be obtained over a predetermined frequency range.
[0034]
Next, two configurations of the dielectric line attenuator according to the third embodiment will be described with reference to FIG. FIGS. 5A and 5B are plan views with the upper conductor plate and the upper dielectric strip portion removed, respectively. In the example shown in FIG. 5A, the resistance film patterns indicated by 5a, 5b, and 5c are formed on the upper surface of the substrate 4. Here, the resistive film pattern 5a spreads in the longitudinal direction of the dielectric strip 3 and the direction perpendicular thereto, and is combined with the electromagnetic wave of the LSM01 mode, which is the propagation mode of the dielectric line, to be attenuated. The distance between the resistive film patterns 5a and 5b and the distance between 5a and 5c are approximately λg / 4. As a result, the reflected wave at one end of the resistive film pattern 5a cancels out the reflected wave at the resistive film pattern 5b, and similarly, the reflected wave at the other end of the resistive film pattern 5a and the resistive film pattern 5c part. This cancels out the reflected wave at. Therefore, when the electromagnetic wave propagates from the port #A to the port #B direction, or conversely, when the electromagnetic wave propagates from the port #B to the port #A direction, the reflected wave in the reverse direction is suppressed and the electromagnetic wave is detected. Attenuates by a fixed amount.
[0035]
In the example shown in FIG. 5B, resistance film patterns indicated by 5a, 5b, and 5c are formed on the upper surface of the substrate 4. Here, the resistive film pattern 5a spreads in the longitudinal direction of the dielectric strip 3 and the direction perpendicular thereto, and is combined with the electromagnetic wave of the LSM01 mode, which is the propagation mode of the dielectric line, to be attenuated. The resistive film patterns 5b and 5c are formed as patterns extending by approximately λg / 4 in the direction of the dielectric strip 3 with the width in the direction perpendicular to the dielectric strip different from 5a. As a result, the reflected wave at one end of the resistive film pattern 5a and the reflected wave at the end of the resistive film pattern 5b cancel each other, and similarly, the reflected wave and the resistive film pattern at the other end of the resistive film pattern 5a. The reflected wave at the end of 5c cancels out. Therefore, when the electromagnetic wave propagates from the port #A to the port #B direction, or conversely, when the electromagnetic wave propagates from the port #B to the port #A direction, the reflected wave in the reverse direction is suppressed and the electromagnetic wave is detected. Attenuates by a fixed amount.
[0036]
In each of the first and second embodiments, the example of the dielectric line terminator is shown. However, the substrate 4 on which the resistive film pattern 5 is formed is the same as the example shown in the third embodiment. In addition, it is configured as a dielectric line attenuator that attenuates the electromagnetic wave propagating through the dielectric line by a predetermined amount between the input and output ports by providing it at a predetermined position in the middle of the dielectric line (between the input and output ports). Can do. As a result, the dielectric line attenuator also has a wide frequency range in which low reflection loss characteristics can be obtained by providing discontinuous portions of the line impedance at a plurality of locations, as shown in FIGS. Can be given. In addition, as shown in FIGS. 4D and 4E, the end of the resistive film pattern is inclined with respect to the longitudinal direction of the dielectric strip so that the frequency range in which low reflection loss characteristics can be obtained can be widened. it can.
[0037]
Next, the configuration of a wireless device according to the fourth embodiment will be described with reference to FIG. FIG. 6 is a block diagram of the millimeter wave radar module. Here, the VCO is a voltage controlled oscillator using a variable reactance element such as a Gunn diode oscillator and a varactor diode, and oscillates a millimeter wave signal corresponding to the modulation signal. The circulator A and the terminator A transmit the output signal of the VCO in the coupler direction, and the reflected wave returning in the VCO direction is absorbed by the terminator A. The circulator A and the terminator A constitute an isolator. The coupler propagates the signal from the circulator A as the transmission signal Tx in the direction of the circulator B and extracts a part thereof as the local signal Lo. The terminator B absorbs the reflected wave returning from the circulator B in the coupler direction. The coupler and the terminator B constitute a directional coupler. Circulator B propagates transmission signal Tx to the antenna and propagates reception signal Rx from the antenna to the mixer. The mixer mixes the received signal Rx and the local signal Lo and outputs the beat signal as an intermediate frequency signal IF. As the terminator A and terminator B shown in FIG. 6, the dielectric line terminator shown in the first or second embodiment is used.
[0038]
In each of the embodiments, an example is shown in which the upper and lower conductor plates are applied to a dielectric line of a type in which a groove for fitting a dielectric strip is formed. The same applies to dielectric lines of the same type.
[0039]
Furthermore, in each of the embodiments, a structure is shown in which a step is provided in a part of the dielectric strip, a substrate is disposed in that part, and the substrate is sandwiched between the dielectric strip that fills the step part and the step. However, the dielectric strip may be divided into upper and lower parts in the longitudinal direction of the dielectric strip, and a substrate on which a resistive film pattern is formed may be disposed therebetween.
[0040]
In each of the embodiments described above, the reflected wave suppression means is configured by the pattern of the resistance film or the pattern of the resistance film and the conductor film, but the presence of the resistance film that attenuates the signal propagating through the dielectric line. The line impedance discontinuity for suppressing the reflected wave at the generated line impedance discontinuity may be formed regardless of the pattern of the resistive film or conductor film on the substrate. For example, it is possible to adopt a structure in which the cross-sectional shape of the dielectric strip is changed at a portion to be a discontinuous portion, the dielectric constant of the dielectric strip is changed, or a gap is formed in the longitudinal direction of the dielectric strip. . Alternatively, the end of the substrate may be used as a discontinuous portion of the line impedance of the dielectric line by making the relative permittivity of the substrate on which the resistance film is formed different from the relative permittivity of the dielectric strip.
[0041]
【The invention's effect】
According to the first aspect of the present invention, the reflected wave at the discontinuous portion of the line impedance caused by the presence of the resistive film that attenuates the signal propagating through the dielectric line is suppressed by the reflected wave suppressing means. The signal is attenuated by low reflection at a short distance in the signal propagation direction of the body line. Furthermore, the attenuation of the signal propagating through the dielectric line and the suppression of the reflected wave can be simultaneously performed by the resistive film pattern, so that the entire structure is not complicated and the manufacture is facilitated. Further, the reflected wave to be suppressed is canceled out efficiently, and a good low reflection characteristic for a predetermined wavelength can be obtained. In addition, the reflected wave can be suppressed over a relatively wide band.
[0044]
According to the second aspect of the present invention, the wavelength shortening effect on the substrate is increased, the area occupied by the resistive film pattern can be relatively reduced, and the overall size can be reduced.
[0045]
According to the third aspect of the present invention, the distance in the signal propagation direction can be shortened, and a small dielectric line terminator can be configured as a whole.
[0046]
According to the fourth aspect of the present invention, for example, a radio apparatus using a dielectric line as a transmission line, such as a millimeter wave radar module, can be easily downsized.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of a dielectric line terminator according to a first embodiment. FIG. 2 is a plan view and a sectional view of a main part of the dielectric line terminator. The figure which shows the frequency characteristic of the reflection loss of a line terminator. FIG. 4 is a top view of the principal part of the dielectric line terminator which concerns on 2nd Embodiment. FIG. 5 is the dielectric line attenuator which concerns on 3rd Embodiment. FIG. 6 is a block diagram of a millimeter wave radar module according to a fourth embodiment. FIG. 7 is a perspective view showing the configuration of a conventional dielectric line terminator.
1, 2-conductor plate 3, 3'-dielectric strip 4-substrate 5-resistive film pattern

Claims (4)

In a dielectric line comprising two substantially parallel conductor planes and a dielectric strip sandwiched between the conductor planes,
Reflected wave suppressing means for changing the line impedance of the dielectric line at a plurality of discontinuous portions and suppressing a reflected wave of a signal at the discontinuous portions;
A signal propagating through the dielectric line, which constitutes at least a part of the reflected wave suppressing means and is provided along a division surface of the dielectric strip in a plane substantially parallel to the conductor plane. A resistive film to attenuate,
The plurality of discontinuous portions are a plurality of the resistive films formed as a pattern that is intermittent along the extending direction of the dielectric strip,
The discontinuous portions are provided at three or more locations, and the interval between the discontinuous portions is set to an odd multiple of a quarter wavelength of a different wavelength of the reflected wave to be suppressed , and each of the plurality of resistance films A dielectric line attenuator characterized in that the reflected waves at the discontinuous portion are suppressed by synthesizing the generated reflected waves. 2. The dielectric line attenuator according to claim 1 , wherein a dielectric constant of a substrate on which the resistive film pattern is formed is higher than a dielectric constant of the dielectric strip. A dielectric line terminator comprising the dielectric line attenuator according to claim 1 or 2 provided near an end of the dielectric strip. Wireless device having a dielectric line termination device according to the dielectric waveguide attenuator or claim 3 according to any one of claims 1 or 2.

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