JP2005159768A - Branch structure of waveguide structural body and antenna substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branch structure in a compact waveguide structural body having excellent transmission characteristics and a waveguide power distributing function. <P>SOLUTION: A second waveguide structural body 1 is overlapped and arranged at the end of a first waveguide structural body 2 so that the transmission direction of high-frequency signals becomes orthogonal, and coupling windows 3 are formed on each of waveguide walls of the overlapped site. A thin portion in which the distance between the wall surface on which the coupling window 3 is formed near the portion of overlapping the first and second waveguides 1 and the wall surface opposing this is smaller than the distance of the other portion is provided, and the waveguide structural body 1 is disposed so that the center in the transmission direction of the thin portion 5 in the second waveguide is deviated from the center of the coupling window. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a branched structure of a waveguide structure for transmitting a high frequency signal such as a microwave band or a millimeter wave band.

  In recent years, researches on mobile communication and inter-vehicle radar using high-frequency signals such as microwave band and millimeter wave band have been actively promoted. In these high-frequency circuits, transmission lines for transmitting high-frequency signals are required to be small and have low transmission loss. In particular, since it is advantageous in terms of miniaturization if it can be formed on or in a substrate constituting a high-frequency circuit, conventionally, such transmission lines include strip lines, microstrip lines, coplanar lines, and dielectric waveguides. Tracks and the like have been used.

  Of these, the strip line, microstrip line, and coplanar line are composed of a dielectric substrate, a line conductor layer, and a ground (ground) conductor layer. The space around the line conductor layer and the ground conductor layer and in the dielectric substrate The electromagnetic wave of the high-frequency signal propagates through. These lines have no problem for signal transmission up to, for example, 30 GHz band, but there is a problem that transmission loss tends to occur at 30 GHz or more.

  On the other hand, a waveguide type transmission line formed by a planar conductor and a via-hole conductor as described in Patent Document 1 has a small transmission loss even in a millimeter wave band of 30 GHz or more, and in a multilayer substrate. This is advantageous in that it can be formed freely.

In addition, in a structure using a waveguide line, Patent Documents 2 and 3 describe a structure in which a waveguide line is branched into two waveguide lines in the same plane. A structure that can be branched in the direction has been proposed.
JP-A-6-53711 US Pat. No. 5,532,661 JP-A-11-112210 JP-A-12-77912

  Generally, when configuring a high-frequency circuit using a transmission line, especially when forming a feeder line of an array antenna, etc., the transmission lines are connected to each other in the wiring circuit of the transmission line, or branches are provided to distribute the power. It is necessary to control the ratio.

  However, the strip conductor, microstrip line, and coplanar line do not completely cover the line conductor layer with the ground conductor layer, so if a branch is provided in the middle of the transmission line, radiation of electromagnetic waves occurs from that branch, resulting in a large transmission loss. On the other hand, in the case of a dielectric waveguide line, it is advantageous in that transmission loss can be reduced, but a structure for distributing power using this dielectric waveguide line is as follows. So far it has not been proposed.

  Therefore, the present invention has been devised in view of the above circumstances, and an object thereof is to provide a branch structure in a waveguide structure having a waveguide power distribution function that is compact and has excellent transmission characteristics. It is intended.

  Another object of the present invention is to provide a branched structure in a waveguide structure that can be easily manufactured by a conventional multilayer technology.

  Still another object of the present invention is to provide an antenna substrate having a branch structure in a dielectric waveguide structure.

  The branching structure in the waveguide structure of the present invention is arranged such that the second waveguide structure is overlapped at the terminal portion of the first waveguide structure so that the transmission direction of the high-frequency signal is orthogonal, A coupling window is formed on each of the overlapped waveguide walls, and a wall surface formed with the coupling window in the vicinity of the overlapped portion of the first and second waveguides and a wall surface facing the wall. The thin-walled portion is provided with a space narrower than the space at the other part, and the center of the thin-walled portion in the second waveguide is shifted from the center of the coupling window. To do.

  Further, the branching structure in another dielectric waveguide structure of the present invention is such that the transmission direction of the high-frequency signal is parallel to the second waveguide structure at the terminal end of the first waveguide structure. And a wall surface in which the coupling window is formed in the vicinity of the overlapped portion of the first and second waveguides. Each of the thin-walled portions is provided with a space between the opposing wall surfaces that is narrower than that of the other portion, and the center of the thin-walled portion in the second waveguide is shifted from the center of the coupling window. It is characterized by having been arranged.

  According to the waveguide structure branching structure of the present invention, power can be distributed at a desired power ratio by changing the impedance of the branch by adjusting the center position of the thin portion in any of the above-described configurations. That is, by disposing the center of the thin portion from the center of the coupling window, it becomes possible to adjust the impedance of each branch structure, and the thickness change of the waveguide in the branching process is small due to the presence of the thin portion. Since signal transmission proceeds smoothly, signals can be transmitted efficiently. Further, when impedance matching can be performed by changing the width of the overlapping portion of the two waveguides or by a coupling window, matching can be made more flexibly by using a thin portion. Further, by making the size of the thin portion larger than the size of the coupling window, the change in the power distribution ratio with respect to the displacement of the arrangement position of the thin portion is reduced, and the allowable amount for manufacturing deviation such as interlayer deviation can be widened. Moreover, by providing not only the thin wall portion in one waveguide but also in the other waveguide, the impedance shifted by the displacement of one thin wall portion can be matched in the thin wall portion of the other waveguide, Transmission loss can be reduced. In addition, when the waveguide thickness is large, the thickness in the Z direction at the waveguide overlap portion becomes large, and the change in thickness between the normal waveguide and the waveguide overlap portion is large, so reflection tends to occur. By providing thin portions in both waveguide portions, discontinuity in thickness can be suppressed and transmission loss can be reduced. Moreover, when forming a branch structure using a dielectric waveguide as shown below, the number of side surface through conductors can be reduced by using a thin portion, resulting in a reduction in the number of processing and a reduction in cost.

  Further, by providing the thin portion not only in one waveguide but also in the other waveguide, a change in the thickness of the waveguide is reduced, and loss of signal transmission can be reduced.

  The waveguide line includes a pair of main conductor layers sandwiching the dielectric substrate, a repetition interval of less than one half of the signal wavelength in the transmission direction of the high frequency signal, and a direction orthogonal to the transmission direction. Two rows of through-hole conductor groups for side walls formed by electrically connecting the main conductor layers with a predetermined width, and formed in parallel with the main conductor layer between the main conductor layers, The sub-conductor layers connected to each other can be easily formed in a small size in any multilayer substrate using a conventional multilayer technology.

  Further, since the dielectric substrate is made of low-temperature fired ceramics, it can be fired simultaneously using a low-resistance conductor such as silver or copper as a conductor material, which is advantageous in terms of improving high-frequency characteristics and manufacturing. In addition, the dielectric constant is higher than that of the organic substrate, the size can be reduced, the shape is not bent unlike the fluororesin, and the shape is easily maintained.

  In addition, by providing the above branch structure, it is possible to easily and easily wire in the Z direction and to obtain a highly efficient branch structure. A possible and highly efficient antenna substrate can be easily obtained.

  The waveguide line branching structure of the present invention will be described below with reference to the drawings. FIG. 1 shows a branching structure of the present invention in the case where waveguides are arranged so that the transmission directions of high-frequency signals are orthogonal to each other. 2A is a cross-sectional view taken along line AA in the branched structure of FIG. 1, and FIG. 2B is a cross-sectional view taken along line BB in the branched structure of FIG.

  According to FIGS. 1 and 2, the waveguide 1 is disposed at the end portion of the waveguide 2 so that the side walls of the waveguide are overlapped so as to be orthogonal to each other. The pipe walls are respectively formed with coupling windows 3 and are arranged so that the coupling windows coincide with each other. The center of the coupling window 3 is provided at substantially the same position as the center of the overlapping portion of the waveguides 1 and 2. Further, the shape of the coupling window 3 is a rectangle having a side parallel to the transmission direction of the waveguide 1 as a long side. The size of the coupling window 3 overlaps the waveguides 1 and 2 unless there is a problem such as strength. It is desirable to form the same size as the portion.

  1 and 2, the signal from the waveguide 2 distributes power in the direction 1a and the direction 1b in the waveguide 1, or the signals from the direction 1a and the direction 1b in the waveguide 1 are distributed. This is a branching structure that combines power and transmits signals to the waveguide 2.

  In the vicinity of the portion where the waveguide 1 and the waveguide 2 overlap, the interval a ′ between the wall surface on which the coupling window 3 is formed and the opposite waveguide wall surface facing this is larger than the interval a in other portions. Narrow thin portions 5a and 5b each having a length L in the transmission direction are formed.

  And the center X with respect to the transmission direction of the thin part 5b in this 2nd waveguide and the center Y of the coupling window 3 are shifted | deviated by m. Depending on the shift width m, the lengths b1 and b2 from the wall surface 2a of the waveguide 2 in the thin portion 5b to both ends of the thin portion 5b change. According to the present invention, the shift width m and the waveguide By changing the lengths b1 and b2 of the wall surface 2a of the tube 2, the impedance in the 1a direction and the 1b direction when viewed from the coupling window 3 can be changed. This makes it possible to control the power ratio of signals transmitted in the direction 1b.

  In this branching structure, as shown in FIG. 4, the waveguide width L3 in the portion overlapping the waveguide 1 in the waveguide 2 is set to the waveguide width L2 in the other portion of the waveguide 2. It is desirable to form them differently. In this way, by controlling L, L1, L2, and L3, resonance at the coupling portion is generated, and signal transmission can be effectively performed. In the example of FIG. 4, a wide portion 2a is formed in which the width L3 of the coupling portion of the waveguide 2 is wider than the width L2 of other portions.

  For the same reason, it is possible to change the diameter at the entrance of the portion where the waveguide 1 and the waveguide 2 overlap. For example, as shown in FIG. 5, it is also possible to control the impedance by forming a narrow portion 2b having a small width at the entrance of the overlapping portion.

  The length L of the thin wall portion 5b shown in FIG. 2 is larger than the width L2 of the overlapping portion between the waveguides 1 and 2, but this is a branch structure that can distribute power even if it is small. However, it is desirable that L> L3. This is because, when L> L3, the power distribution ratio is gradual with respect to the shift amount of the thin portion 5, so that the tolerance for manufacturing deviation is large, whereas when L <L3, the power distribution ratio Since a change with respect to the shift amount becomes large, a change in characteristics due to a shift or the like tends to be large, and the characteristics may become unstable.

  On the other hand, by providing the thin portion 5a in the first waveguide 2, the impedance that is shifted when the center position of the thin layer portion 5b of the waveguide 1 is changed is matched with the thin portion 5a of the other waveguide. Thus, transmission loss can be reduced. Further, the thickness of the waveguide 1, the thickness of the overlapping portion of the waveguides 1 and 2, and the thickness of the waveguide 2 can be approximated, and the flow of the electromagnetic field becomes smoother and reflection can be reduced. Will improve.

  Further, the width L1 of the thin portion 5b is preferably longer than the length L2a of the portion where the thickness of the waveguide 2 is reduced at the overlapping portion of the waveguide 1 and the waveguide 2. If L2a is longer than L1, the distance between the upper conductor end 1c of the waveguide 1 shown in FIG. This is because it tends to cause reflection.

  Now, it has been described that the thin portion 5b is shifted with respect to the coupling window 3 in order to control the power distribution ratio. However, the thin portion 5a of the waveguide 2 is further shifted with respect to the signal transmission direction of the waveguide 2. May be. At this time, it is not necessary that the centers of the thin portions 5a and 5b are the same.

(Second Embodiment)
Next, FIGS. 6 and 7 are views showing a second branching structure of the present invention, which is a branching structure in which two waveguides are arranged so that the transmission directions of high-frequency signals are parallel to each other. Is a schematic perspective view thereof, and FIG. 7 is a cross-sectional view taken along the line CC of FIG.

  According to FIGS. 6 and 7, the waveguide 12 is disposed above the terminal end of the waveguide 13 so that the transmission directions of the waveguide 12 and the waveguide 13 are parallel to each other. A coupling window 14 is formed on the waveguide wall of each of the waveguides 12 and 13 at a length position where the end distance S is λ / 8 or more, and the coupling windows 14 are arranged to coincide with each other. . As for the shape of the coupling window 14, it is desirable that the width L5 in the signal transmission direction is shorter than the width L4 in the direction orthogonal to the signal transmission direction.

  6 and 7, the signal from the waveguide 13 distributes the power in the direction 12a and the direction 12b in the waveguide 12, or the signal from the direction 12a and the direction 12b in the waveguide 12 is the power. It is a branching structure that combines and transmits a signal to the waveguide 13.

  On the waveguide 12 side in the overlapping portion of the waveguide 12 and the waveguide 13, the distance b ′ between the wall surface on which the coupling window 14 is formed and the wall surface on the opposite side of the waveguide 12 facing the other is b. A thin portion 15b that is narrower than the interval b in the part is formed.

  The center X of the thin portion 15b in the transmission direction and the center Y of the coupling window 14 are formed so as to be shifted by n1. The power ratio distributed in the 12a direction and the 12b direction of the waveguide 12 can be controlled by the shift width n1. That is, the principle of power distribution is to distribute power by making the impedance viewed from the coupling window different as in the structure shown in FIGS. 1 and 2, and the thin portion 15 b is shifted with respect to the coupling window 14. Thus, the impedance in the direction 12a and the direction 12b when viewed from the waveguide 13 is changed, whereby the power distribution ratio in the direction 12a and the direction 12b can be controlled.

  On the other hand, the provision of the thin portion 15a in the twelfth waveguide 13 makes it possible to match the impedance shifted when the center position of the thin portion 15b of the waveguide 12 is changed in the thin portion 15a of the other waveguide. Thus, transmission loss can be reduced. Further, the thickness of the waveguide 12, the thickness of the overlapping portion of the waveguides 12 and 13, and the thickness of the waveguide 13 can be approximated, and the flow of the electromagnetic field becomes smoother and reflection can be reduced. Will improve.

  The center Z of the thin portion 15a does not have to be the same as the center Y of the coupling window 14 and the center X of the thin portion 15b, and may be shifted from the center Y of the coupling window 14 by n2.

  The waveguide in the branch structure of the present invention includes a pair of main conductor layers sandwiching a dielectric substrate, a repetition interval of less than half of the signal wavelength in the transmission direction of the high-frequency signal, and orthogonal to the transmission direction. Two side wall through conductor groups formed by electrically connecting the main conductor layers with a predetermined width in a direction to be formed, and the side wall through conductors formed in parallel to the main conductor layer between the main conductor layers. The waveguide branch structure of the present invention can be obtained by using a waveguide structure configured to include a sub-conductor layer electrically connected to the group. In this case, the circuit can be reduced in size as compared with the conventional waveguide, and since complicated metal processing is unnecessary, it is easy to manufacture and suitable for mass production. Further, in the present invention, since power can be distributed while propagating signals in the Z direction, it is possible to reduce the size of a circuit constituted by a conventional dielectric waveguide.

  The case where the branch structure of the present invention is formed using a dielectric waveguide will be described below.

  FIG. 8 is a schematic perspective view for explaining a configuration example of a dielectric waveguide line used in the present invention. In FIG. 8, 16 is a dielectric layer, 17 and 18 are a pair of conductor layers sandwiching the dielectric layer 16, 19 is a repetitive interval c less than half the signal wavelength in the signal transmission direction, and the signal transmission direction. Are two rows of through conductor groups formed so as to electrically connect the pair of conductor layers 17 and 18 with a predetermined width d in a direction perpendicular to the line. Reference numeral 20 denotes an auxiliary conductor layer formed in parallel with the conductor layers 17 and 18 for electrically connecting the through conductors forming each row of the through conductor group 19, and is provided as necessary. Reference numeral 21 denotes a dielectric waveguide line formed by the pair of conductor layers 17 and 18, the through conductor group 19, and the auxiliary conductor layer 20. As described above, when the auxiliary conductor layer 20 is further formed in the region surrounded by the pair of conductor layers 17 and 18 and the through conductor group 19, when viewed from the inside of the dielectric waveguide line 21, the side wall is The through conductor group 19 and the auxiliary conductor layer 20 form a fine lattice, and shield electromagnetic waves in various directions.

  As shown in FIG. 8, a pair of conductor layers 17 and 18 are formed at a position sandwiching the dielectric layer 16 having a predetermined thickness e, and the conductor layers 17 and 18 are at least transmission line formation positions of the dielectric layer 16. It is formed on the upper and lower surfaces sandwiching. A large number of through conductors such as through-hole conductors and via-hole conductors that electrically connect the conductor layers 17 and 18 are provided, and a plurality of through conductors 19 form two rows of through conductor groups 19. .

  As shown in the figure, the two rows of through conductor groups 19 have a predetermined repetition interval c that is less than a half of the signal wavelength in the transmission direction of the high-frequency signal, that is, the line formation direction, and a predetermined direction in the direction orthogonal to the transmission direction. It is formed with a constant interval (width) d. Thereby, an electrical side wall in the dielectric waveguide line 21 is formed.

  Here, there is no particular limitation on the thickness e of the dielectric layer 1, that is, the distance between the pair of conductor layers 17 and 18, but about half or twice the distance d when used in a single mode. In the example of FIG. 8, the portions corresponding to the H surface of the dielectric waveguide line 21 are formed by the conductor layers 17 and 18, and the portions corresponding to the E surface are formed by the through conductor group 19 and the auxiliary conductor layer 20, respectively. . Further, if the thickness e is about twice as large as the distance d, the portions corresponding to the E surface of the dielectric waveguide 21 are the conductor layers 17 and 18, and the portions corresponding to the H surface are the through conductor group 19 and the auxiliary conductor layer. 20 respectively.

  In addition, an electrical wall can be formed by the through conductor group 19 by setting the distance d to be less than one half of the signal wavelength. The interval c is preferably less than a quarter of the signal wavelength in order to prevent leakage of electromagnetic waves. Since TEM waves can propagate between the pair of conductor layers 17 and 18 arranged in parallel, the distance c between the through conductors in each row of the through conductor group 19 is less than half the signal wavelength λ (λ / 2). If it is larger, even if electromagnetic waves are fed to the dielectric waveguide 21, the electromagnetic waves leak from between the through conductor groups 19 and do not propagate along the pseudo waveguide formed here. However, if the distance c between the through conductor groups 19 is smaller than λ / 2, an electric side wall is formed, and the electromagnetic wave cannot propagate in the direction perpendicular to the dielectric waveguide line 21. The light is propagated in the signal transmission direction of the dielectric waveguide 21 while being reflected.

  As a result, according to the configuration shown in FIG. 8, the region having a cross-sectional area of d × e surrounded by the pair of conductor layers 17 and 18 and the two rows of through conductor groups 19 and the auxiliary conductor layer 20 is a dielectric. It becomes the waveguide line 21.

  In the embodiment shown in FIG. 8, the through conductor groups 19 are formed in one row on each side of the waveguide. However, the through conductor groups 19 are arranged in two or more rows on one side, By forming the conductor wall in a double or triple manner, leakage of electromagnetic waves from the conductor wall can be more effectively prevented.

According to the dielectric waveguide line 21 as described above, the transmission line is a dielectric waveguide. Therefore, when the dielectric constant of the dielectric substrate 16 is εr, the waveguide size is that of a normal waveguide. The size is 1 / (εr) ^1/2 . Therefore, the waveguide size can be reduced as the relative dielectric constant εr of the material constituting the dielectric substrate 16 is increased, and the high-frequency circuit can be reduced in size.

  Note that the through conductors constituting the through conductor group 19 are arranged at a repetition interval c of less than half of the signal wavelength as described above, and this interval c is constant in order to realize good transmission characteristics. However, as long as the interval is less than half the signal wavelength, it may be changed as appropriate or some values may be combined.

  The dielectric substrate 16 constituting the dielectric waveguide line 21 is not particularly limited as long as it has a characteristic that functions as a dielectric and does not hinder the transmission of a high-frequency signal. The dielectric substrate 16 is preferably made of ceramics from the viewpoint of accuracy in forming the line and ease of manufacture.

  As such ceramics, ceramics having various relative dielectric constants have been known so far, but in order to transmit a high frequency signal by the dielectric waveguide line according to the present invention, it is desirable to be a paraelectric material. . This is because ferroelectric ceramics generally have a large dielectric loss and a large transmission loss in the high frequency region. Accordingly, the relative dielectric constant εr of the dielectric substrate 1 is suitably about 4 to 100.

  In general, since the line width of a wiring layer formed in a multilayer wiring board, a semiconductor element storage package, or an inter-vehicle radar is at most about 1 mm, a material having a relative dielectric constant of 100 is used, and the upper part is an H plane, that is, a magnetic field. Is used so as to have an electromagnetic field distribution that wraps parallel to the upper surface, the minimum frequency that can be used is calculated as 15 GHz, and can also be used in the microwave band region.

  Examples of the dielectric substrate 16 include low-temperature fired ceramics such as alumina ceramics, aluminum nitride ceramics, and glass ceramics. The dielectric substrate 16 is formed into a slurry shape by adding and mixing an appropriate organic solvent and solvent to the ceramic raw material powder, and this is formed into a sheet shape by employing a conventionally known doctor blade method, calendar roll method or the like. To obtain a plurality of ceramic green sheets, and after that, each of these ceramic green sheets is appropriately punched and laminated, and in the case of alumina ceramics, 1500 to 1700 ° C., in the case of low-temperature fired ceramics Is manufactured by firing at a temperature of 850 to 1000 ° C., and in the case of aluminum nitride ceramics at a temperature of 1600 to 1900 ° C.

Among these, it is desirable that the dielectric substrate 16 is manufactured using low-temperature fired ceramics. Low-temperature fired ceramics have the advantage that copper or silver with high conductivity can be used as a conductor, so that the conductor loss can be reduced, and the advantage is that the dielectric constant is high and the structure can be made compact compared to general organic substrates. There is also. Further, from the viewpoint of reliability, unlike the organic substrate, the steam resistance is high, so that high reliability can be obtained. Examples of the low-temperature fired ceramics are obtained by mixing and firing glass components such as borosilicate glass and alkaline earth-containing glass and ceramic powders such as Al ₂ O ₃ , SiO ₂ , ZnO, and MgO.

  Further, the pair of conductor layers 17 and 18 are, for example, when the dielectric substrate 16 is made of alumina ceramics, oxides such as alumina, silica, and magnesia, organic solvents and solvents suitable for metal powders such as tungsten and molybdenum. Is added on and mixed to form a paste, and is printed on a ceramic green sheet so as to completely cover at least the transmission line by a thick film printing method, and then fired at a high temperature of about 1600 ° C. It is formed to be 15 μm or more.

  As the metal powder, copper, silver and gold are suitable for low-temperature fired ceramics, and tungsten and molybdenum are suitable for aluminum nitride ceramics. The thickness of the conductor layers 17 and 18 is generally about 5 to 50 μm.

  The through conductors constituting the through conductor group 19 may be formed of, for example, a via hole conductor or a through hole conductor. The cross-sectional shape may be a polygon that is easy to manufacture, or a polygon such as a rectangle or a rhombus. These through conductors are formed, for example, by embedding a metal paste similar to the conductor layers 17 and 18 in a through hole produced by punching a ceramic green sheet, and then firing simultaneously with the dielectric substrate 16. The through conductor has a diameter of 50 to 300 μm.

  Next, FIG. 9 shows an example of an embodiment of the waveguide branching structure of the present invention of FIG. 1 using such a dielectric waveguide line.

  Here, the waveguide 1 ′ and the waveguide 2 ′ are composed of the through conductor group 19, the sub conductor layer 20, and the conductor layers 17, 18, and have a coupling window 3 ′ at the joint portion. A thin portion 5 ′ is formed in the vicinity of the portion. The basic waveguide arrangement and thin wall configuration in FIG. 9 are the same as in FIG. 1, and the center of the thin wall portion 5 ′ is different from the center of the coupling window 3 ′, thereby realizing power distribution at a constant ratio. doing. Here, the upper main conductor layer 4 ′ of the waveguide 1 is notched in the thin portion 5 b ′. However, since the upper portion of the thin portion 5 b ′ is sealed with the conductor layer 4 ″, the conductor layer 4 ′ does not need to be cut out at the thin portion 5 b ′.

  Further, the waveguide branching structure of the present invention of FIG. 6 in which two dielectric waveguides are arranged so as to be parallel to each other in the transmission direction of the high-frequency signal is not shown here, but can be realized as in FIG. .

  Further, as shown in FIG. 10, the connection structure of the two waveguide lines of the present invention described in detail above may be incorporated in an antenna substrate 22 made of a multilayer wiring substrate. In the antenna substrate 22, it is necessary to change the radiation ratio of each antenna element 23 in order to reduce the side lobe, for example, in order to make the beam shape a desired shape. For this reason, the feed line to each antenna element 23 is required. When a waveguide is used as 24, the beam shape can be easily designed by using the power distribution structure of the present invention. 10 shows the slot antenna 25 in which a notch is provided in the conductor layer on one side of the dielectric waveguide, but there is no problem even if a patch antenna that feeds power through the slot or via conductor is used. It does not depend on the antenna configuration.

  In order to evaluate the high frequency characteristics of the waveguide branch structure of the present invention, S parameters were simulated. The type used was a type in which the two waveguide structures shown in FIGS. 4 and 9 are stacked so that the transmission directions of the high-frequency signals are orthogonal to each other, and the waveguide is formed of a dielectric waveguide. Shape. The dielectric substrate 16 was made of glass ceramics having a relative dielectric constant εr of 4.9, and the through conductors were formed with vias having a diameter of 0.2 mm. The interval width between the two rows of through conductor groups 19, that is, the waveguide widths L1 and L2, is the distance between the via centers, L1 = 1.6 mm for the waveguide 1 and L2 = 1.79 mm for the waveguide 2. However, in the overlapping part of the waveguides 1 and 2, the width L3 of the waveguide 2 is set to 2.21 mm. The thicknesses of the waveguides 1 and 2 are both 0.6 mm, the thickness of the thin portion in the waveguide 1 is 0.3 mm, and the thickness of the thin portion of the waveguide 2 is also 0.3 mm. The size L of the thin portion 5b on the waveguide 1 side is 1.369 mm, and the size L2a of the thin portion 5a on the waveguide 2 side is 1.38 mm. The misalignment m of the thin portion 5b with respect to the opening window 3 was 0.14 mm. The size of the opening window 3 was 2.006 mm on the side parallel to the waveguide 1 and 1.386 mm on the orthogonal side. The results are shown in FIGS. In the figure, the solid line is S11, the broken line is S21, and the dotted line is S31. From the results of FIGS. 11 and 12, it can be seen that S21 is approximately −4.8 dB and S31 is approximately −1.8 dB while the reflection is suppressed.

It is a schematic perspective view for demonstrating an example of 1st invention of the branched structure of the waveguide of this invention. It is a schematic sectional drawing of the AA in FIG. It is a schematic sectional drawing of the BB line in FIG. It is a schematic perspective view for demonstrating another example of the waveguide branch structure of this invention. It is a schematic perspective view for demonstrating another example of the waveguide branch structure of this invention. It is a schematic perspective view for demonstrating an example of 2nd invention of the waveguide branch structure of this invention. It is CC sectional schematic sectional drawing of FIG. It is a schematic perspective view for demonstrating the basic structure of a dielectric waveguide line. FIG. 9 is a schematic transparent perspective view when the dielectric waveguide of FIG. 8 is applied to the branch structure of FIG. 1. It is a general | schematic see-through | perspective perspective view in case the branch structure of this invention is used for an antenna board | substrate. It is a transmission characteristic figure in simulation in an example. It is a transmission characteristic figure in simulation in an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 2nd waveguide 1a ... One port of the waveguide 1
1b... Another port of the waveguide 1
2... First waveguide 3... Coupling window 4... Upper main conductor 5... Thin portion 6. Waveguide 13... Waveguide 14... Coupling window 15... Thin portion 16... Dielectric substrates 17 and 18. .... Subconductor layer 21 ... Dielectric waveguide

Claims (5)

The second waveguide structure is placed on the terminal end of the first waveguide structure so that the transmission direction of the high-frequency signal is perpendicular to each other, and a coupling window is formed on each of the waveguide walls of the overlapped portion. A thin-walled portion that is formed and has a space between the wall surface in which the coupling window is formed in the vicinity of the overlapped portion of the first and second waveguides and a wall surface facing the wall, which is narrower than the space at other portions. And a branch structure of the waveguide structure, wherein a center of the thin-walled portion in the second waveguide is shifted from a center of the coupling window. A second waveguide structure is placed on the terminal portion of the first waveguide structure so that the transmission direction of the high-frequency signal is parallel, and a coupling window is formed on each waveguide wall of the overlapped portion. A thin wall in which the interval between the wall surface in which the coupling window is formed in the vicinity of the overlapped portion of the first and second waveguides and the wall surface facing this is narrower than the interval in other portions A branching structure of a waveguide structure, wherein a portion is provided, and a center in a transmission direction of the thin portion in the second waveguide is shifted from a center of the coupling window. The waveguide structure has a pair of main conductor layers sandwiching a dielectric substrate and a predetermined interval in a direction orthogonal to the transmission direction at a repetition interval of less than half of the signal wavelength in the transmission direction of the high-frequency signal. And two rows of through conductor groups for side walls formed by electrically connecting the main conductor layers with the width of the main conductor layers, and formed in parallel with the main conductor layers between the main conductor layers. The branch structure of the waveguide structure according to claim 1, further comprising: a sub-conductor layer connected to the waveguide. The branched structure of the waveguide structure according to any one of claims 1 to 3, wherein the dielectric substrate is made of low-temperature fired ceramics. An antenna substrate comprising the branch structure according to claim 1.

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