JP3645724B2 - Non-radiative dielectric line - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-radiative dielectric line incorporated in, for example, a millimeter wave integrated circuit and used as a guide for a high-frequency signal, and relates to a directional coupler type that branches and couples a high-frequency signal in the middle thereof.
[0002]
[Prior art]
A basic configuration of a conventional non-radiative dielectric line S1 is shown in FIG. A non-radiative (hereinafter referred to as NRD) dielectric line S1 has parallel plate conductors 1 and 3 arranged above and below the dielectric line 2, and the interval between the parallel plate conductors 1 and 3 is λ / 2 (λ Is less than the wavelength of the high-frequency signal propagating in the space), the high-frequency signal having a wavelength larger than λ is blocked and cannot enter the space between the parallel plate conductors 1 and 3. When the dielectric line 2 is inserted between the parallel plate conductors 1 and 3, a high-frequency signal can propagate along the dielectric line 2, and the radiated wave from the high-frequency signal is blocked by the parallel plate conductors 1 and 3. Is suppressed by.
[0003]
FIG. 6 shows a conventional directional coupler type NRD dielectric line S2 to which the NRD dielectric line S1 is applied. In the NRD dielectric line S2, two dielectric lines 12 and 13 are disposed between a pair of parallel plate conductors 10 and 11, and at least one of the dielectric lines 12 and 13 is formed in a curved shape. (See JP-A-6-268446). In the figure, both dielectric lines 12 and 13 are curved, and are configured so as to be closest to each other at the center. Then, by setting the distance x between the closest portions of the dielectric lines 12 and 13 to a predetermined value, the high frequency signal input to one of the dielectric lines 12 and 13 is spatially coupled to the other, It can be output from the output end. In the figure, the upper parallel plate conductor 11 is drawn so that the inside can be seen through.
[0004]
For example, in the NRD dielectric line S2 of FIG. 6, the high frequency signal input from the input port 12a of the dielectric line 12 is spatially coupled to the dielectric line 13 at the nearest part and separated (branched). . The high frequency signals are output from the output ports 12b and 13b, respectively, and are not output from the input port 13a.
[0005]
[Problems to be solved by the invention]
However, in the conventional NRD dielectric line S2, the interval x between the closest portions has a great influence on the separation characteristics of the high-frequency signal. For example, when the dielectric lines 12 and 13 have a relative dielectric constant εr = 5, a width of 1 mm and a height of 2 mm, the interval x needs to be controlled with an accuracy of 0.1 mm or less. As described above, it is extremely difficult to install the two dielectric lines 12 and 13 between the pair of parallel plate conductors 10 and 11 with high accuracy, so that the mass productivity is lowered and the workability of the position adjustment is poor. The cost was also high.
[0006]
Further, as shown in FIG. 8, the frequency band (in the vicinity of about 60 GHz in FIG. 8) in which the signal intensities S21 and S31 output from the output ports 12b and 13b of the dielectric lines 12 and 13 substantially match each other is very narrow. There was a problem.
[0007]
Therefore, the present invention has been completed in view of the above circumstances, and its purpose is that it can separate high frequency signals at almost the same level over a wide band, and does not require special positional accuracy during assembly, so it is excellent in mass productivity and low cost. It is to be able to be manufactured with.
[0008]
[Means for Solving the Problems]
The non-radiative dielectric line of the present invention is provided with a plurality of dielectric lines having upper and lower surfaces sandwiched between parallel plate conductors having an interval of λ / 2 or less with respect to the wavelength λ of the high-frequency signal. A conductor layer is interposed between the conductor layers. The conductor layers extend in the longitudinal direction of the dielectric line, and are located on both the upper side and the lower side of the conductor layer in a completely symmetrical position or symmetrical in the vertical direction of the conductor layer. When a pair of notches is formed at a position and the distance between the parallel plate conductors is H, the width d of the notches in the direction perpendicular to the longitudinal direction of the dielectric line satisfies H / 12 to H / 3. Features.
[0009]
According to the above configuration, the present invention has a simplified structure that does not require high-accuracy position adjustment, so that no special position accuracy is required at the time of assembly, and as a result, it is excellent in mass productivity and can be manufactured at low cost. In addition, the high-frequency signal can be separated at substantially the same level over a wide band.
[0010]
In addition, since the dielectric line of the present invention is installed via the conductor layer, a so-called image NRD guide is formed in which a high-frequency signal is not radiated and leaked from the conductor layer to the adjacent dielectric line. Therefore, the plurality of dielectric lines are completely cut off by the conductor layer, which is equivalent to installing them spatially apart so as not to couple high-frequency signals. That is, the non-radiative dielectric line of the present invention has an effect that a plurality of dielectric lines can be arranged in a very compact manner and is very small.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An NRD dielectric line S of the present invention is shown in FIGS. In FIG. 1, 20 and 21 are parallel plate conductors that sandwich the dielectric lines 22 and 23 from above and below, 24 is a conductor layer interposed between the close side surfaces of the dielectric lines 22 and 23, and 25 a and 25 b are dielectrics. These are notches (slits) extending in the longitudinal direction A of the lines 22 and 23 and formed on both the upper and lower sides of the conductor layer.
[0012]
In the present invention, the dielectric lines 22 and 23 are preferably made of a low-loss organic resin material such as Teflon, an organic-inorganic composite material, cordierite, alumina, glass ceramics or other low dielectric constant ceramic material. Is easy to process with low loss and suitable for mass production.
[0013]
The parallel plate conductors 20 and 21 have a conductive plate such as Cu, Al, Fe, SUS (stainless steel), Ag, Au, or Pt, or a conductive layer thereof on the surface in terms of high electrical conductivity and workability. A formed insulating plate may be used. The conductor layer 24 may be formed by subjecting the surface of an insulating plate such as a conductive plate such as Cu, Al, Ag, W, or Mo, a plastic plate, a glass plate, or a ceramic plate to metallization, plating, etc. The conductors 20 and 21 may be erected.
[0014]
The NRD dielectric line S of the present invention can be manufactured as follows when the dielectric lines 22 and 23 are made of a ceramic material. Each of the molded bodies of the dielectric lines 22 and 23 molded to a predetermined size is manufactured, and a metal paste is printed and applied so that the notches 25a and 25b are formed on the side surfaces of one of these molded bodies. The thin metal foil or metal plate in which the notches 25a and 25b are formed is sandwiched and laminated between two molded bodies, and then they are integrally sintered.
[0015]
Moreover, when the dielectric lines 22 and 23 are organic resin materials and organic-inorganic composite materials, they can be manufactured by a known press molding method, injection molding method, print coating method, or the like.
[0016]
As shown in FIG. 2, the notches 25a and 25b provided in the conductor layer 24 of the present invention extend along the longitudinal direction A of the dielectric lines 22 and 23 and are formed on both the upper and lower sides of the conductor layer 24. The high frequency signals propagating through the dielectric lines 22 and 23 are electromagnetically coupled, preferably by using a pair of substantially symmetrical ones in the vertical direction. The positions where the notches 25a and 25b are provided may be anywhere in the length direction of the dielectric lines 22 and 23, the upper notch 25a is at the upper end of the conductor layer 24, and the lower notch 25b is the conductor layer. It is good to form symmetrically in the up-down direction in the lower end part of 24. This strengthens the electromagnetic coupling between the dielectric lines 22 and 23 via the notches 25a and 25b, and suppresses the generation of leakage waves from the dielectric lines 22 and 23 to the parallel plate conductors 20 and 21. Because it can.
[0017]
A plurality of pairs of notches 25a and 25b can be provided in the longitudinal direction A, but a pair is sufficient for separating high-frequency signals.
[0018]
Further, the length of the notches 25a and 25b in the longitudinal direction A depends on the frequency of the high frequency signal, the relative dielectric constant of the dielectric lines 22 and 23, the width of the dielectric lines 22 and 23, the distance between the parallel plate conductors 20 and 21, and the like. For example, when the frequency is 77 GHz, the relative dielectric constant is 4.8, the width of the dielectric lines 22 and 23 is 0.4 mm, and the interval between the parallel plate conductors 20 and 21 is 1.8 mm, for example, a high-frequency signal is output. In order to obtain a 3 dB directional coupler separated in half, the length in the longitudinal direction A of the notches 25a and 25b is preferably 2.4 to 2.44 mm. If it is out of the range, a 3 dB directional coupler cannot be constructed. In this way, by controlling the length of the notches 25a and 25b in the longitudinal direction A, the strength of coupling between the dielectric lines 22 and 23 can be adjusted, and for example, a 10 dB directional coupler can be configured. .
[0019]
Further, the width d of the notches 25a and 25b in the direction (vertical direction) perpendicular to the longitudinal direction A is set to H / 12 to H / 3 with respect to the interval H between the parallel plate conductors 20 and 21 . If it is smaller than H / 12, the coupling between the dielectric lines 22 and 23 is weak, and if it is larger than H / 3, the reflected wave to the input port 22a becomes large. For example, in the case of the 3 dB directional coupler, it is preferable to set it to 0.18 to 0.22 mm.
[0020]
Furthermore, it is preferable to provide a pair of notches 25a and 25b at positions that are completely symmetrical in the direction perpendicular to the longitudinal direction A, as shown in FIG. However, since the dielectric lines 22 and 23 constitute an image NRD guide, the dielectric lines 22 and 23 have a characteristic that a leakage wave is hardly generated. As a result, the notches 25a and 25b are perpendicular to the longitudinal direction A as shown in FIG. Even if it is provided at a position that overlaps at least about 70% in the direction (overlap, where B in FIG. 3 overlaps), substantially the same effect as when a pair is provided at a completely symmetrical position (FIG. 2) can be obtained. That is, the notches 25a and 25b can be provided in a substantially symmetrical position instead of a completely symmetrical position in the vertical direction.
[0021]
Such an NRD dielectric line S functions similarly to that of FIG. For example, a high-frequency signal input from the input port 22a of the dielectric line 22 is electromagnetically coupled to the dielectric line 23 side through the notches 25a and 25b and separated. And it outputs from the output ports 22b and 23b, respectively, and does not output from the input port 23a.
[0022]
The NRD dielectric line S of the present invention may be an NRD dielectric line Sa provided with three dielectric lines 22, 23 and 26 as shown in FIG. In this case, for example, a high frequency signal input from the input port 23a can be functioned to be output from the output ports 22b, 23b, and 26b. Therefore, in the present invention, three or more dielectric lines may be provided. In the figure, 26 is a dielectric line, 27 is a conductor layer, and 28a and 28b are notches.
[0023]
The NRD dielectric line S of the present invention is used for an automobile millimeter wave radar or the like. For example, a millimeter wave is guided by the dielectric line 22 to irradiate obstacles around the automobile and other automobiles. Then, the reflected wave is received by the dielectric line 23 and combined with the high frequency signal separated from the dielectric line 22 side to obtain a beat signal. By analyzing the beat signal, the obstacles and other automobiles are analyzed. Distances, their moving speeds, moving directions, etc. are obtained. The NRD dielectric line S of the present invention can be applied to any high-frequency circuit that uses a high-frequency signal in the range of several tens to several hundreds of GHz.
[0024]
Thus, the present invention can separate high-frequency signals at almost the same level over a wide band and does not require special positional accuracy at the time of assembly. Therefore, the present invention has the effect of being excellent in mass productivity and capable of being manufactured at low cost.
[0025]
In addition, this invention is not limited to said embodiment, A various change does not interfere in the range which does not deviate from the summary of this invention.
[0026]
【Example】
Examples of the present invention will be described below.
[0027]
(Example)
The NRD dielectric line S shown in FIGS. 1 and 2 was produced by the following steps [1] to [5].
[0028]
[1] A rectangular 2 having a dielectric constant of 4.8 and a dielectric loss of 2.7 × 10 ⁻⁴ (measurement frequency of 77 GHz) and a cross section of 0.4 mm in width and 1.8 mm in height. Two dielectric lines 22 and 23 were produced.
[0029]
[2] A conductor layer 24 was formed on one side surface (bonded surface) of the dielectric lines 22 and 23 by Cu plating.
[0030]
[3] By applying a resist and etching it, the notches 25a and 25b having a width of 0.2 mm in the vertical direction and a length of 2.42 mm are in contact with the upper and lower edges (edges) of the conductor layer 24. Formed in parallel.
[0031]
[4] Two dielectric lines 22 and 23 were bonded together with an adhesive via the conductor layer 24 and integrated.
[0032]
[5] The upper and lower surfaces of the integrated dielectric lines 22 and 23 are sandwiched between two parallel plate conductors 20 and 21 made of Cu, which are 100 mm long × 100 mm wide × 8 mm thick. Was made.
[0033]
With respect to this NRD dielectric line S, the result of measuring the transmission characteristics of the high-frequency signal with a network analyzer is shown in FIG. In the figure, S11 is a reflection loss at the input port 22a, S21 is an insertion loss at the output port 22b, S31 is an insertion loss at the output port 23b, and S41 is an insertion loss at the input port 23a. As shown in the figure, it can be seen that the frequency range in which S21 and S31 have substantially the same loss and are separated in half (-3 dB) covers a wide band of about 72 GHz to about 82 GHz.
[0034]
【The invention's effect】
The present invention provides a plurality of dielectric lines sandwiching upper and lower surfaces between parallel plate conductors, a conductor layer is interposed between these dielectric lines, and the conductor layer extends in the longitudinal direction of the dielectric line and By forming notches on both the upper and lower sides of the conductor layer, it becomes a simplified structure that does not require high-accuracy position adjustment, which eliminates the need for exceptional positional accuracy during assembly, resulting in high productivity. It can be manufactured at an excellent low cost. Moreover, it has the effect that a high frequency signal can be separated at substantially the same level over a wide band.
[0035]
In addition, the dielectric line of the present invention forms an image NRD guide, and the plurality of dielectric lines are completely cut off by the conductor layer, so that the plurality of dielectric lines can be arranged extremely compactly and extremely compact. It also has the effect of becoming.
[Brief description of the drawings]
FIG. 1 is a partially transparent perspective view of an NRD dielectric line S of the present invention.
2 is an enlarged cross-sectional view of notches 25a and 25b in the NRD dielectric line S of FIG.
3 is an enlarged cross-sectional view of the notches 25a and 25b when the notches 25a and 25b partially overlap in the NRD dielectric line S of FIG.
FIG. 4 is a partially transparent perspective view of an NRD dielectric line Sa having three dielectric lines according to the present invention.
FIG. 5 is a partially cutaway perspective view of a conventional NRD dielectric line S1.
FIG. 6 is a partially transparent perspective view of a conventional NRD dielectric line S2.
FIG. 7 is a graph obtained by measuring transmission characteristics of a high frequency signal for the NRD dielectric line S of the present invention.
FIG. 8 is a graph obtained by measuring transmission characteristics of a high frequency signal for a conventional NRD dielectric line S2.
[Explanation of symbols]
1: Lower parallel plate conductor 2: Dielectric line 3: Upper parallel plate conductor 10: Lower parallel plate conductor 11: Upper parallel plate conductor 12: Dielectric line 12a: Input port 12b: Output port 13: Dielectric line 13a: Input port 13b: Output port 20: Lower parallel plate conductor 21: Upper parallel plate conductor 22: Dielectric line 22a: Input port 22b: Output port 23: Dielectric line 23a: Input port 23b: Output port 24: conductor layer 25a: notch 25b: notch

Claims (1)

A plurality of dielectric lines sandwiching upper and lower surfaces are provided between parallel plate conductors whose interval is λ / 2 or less with respect to the wavelength λ of the high frequency signal, and a conductor layer is interposed between the dielectric lines, The conductor layer extends in the longitudinal direction of the dielectric line and forms a pair of notches on both the upper and lower sides of the conductor layer at a position that is completely symmetric or symmetrical in the vertical direction of the conductor layer, A nonradiative dielectric line characterized in that a width d in a direction perpendicular to the longitudinal direction of the dielectric line satisfies H / 12 to H / 3, where H is an interval between parallel plate conductors .

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