JP2005051331A - Coupling structure of microstrip line and dielectric waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coupling structure between a dielectric waveguide and a microstrip line at a low conversion loss that can easily be manufactured by multilayer technologies of prior arts and to provide a filter board or an antenna board with a coupling structure with a low conversion loss. <P>SOLUTION: The structure is used to couple the microstrip line 7 to the dielectric waveguide 6 provided with a pair of major conductor layers sandwiching a dielectric layer and formed in parallel, and two columns of a via-hole group formed to electrically connect the conductor layers at the interval of a cut-off wavelength in a signal transmission direction. Further, in the structure, a transmission via-hole 11 is extended into the dielectric waveguide 6 via an opening 14 provided to the major conductor layer of the dielectric waveguide 6 from the end of the microstrip line 7, and a conductor pattern 12 in parallel with the major conductor layers is formed to the other end of the transmission via-hole 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure for coupling a dielectric waveguide for transmitting high-frequency signals such as microwaves and millimeter waves and a microstrip line.
[0002]
[Prior art]
Conventionally, coaxial lines, waveguides, dielectric waveguides, microstrip lines, and the like are known as lines for transmitting high-frequency signals such as microwaves and millimeter waves.
Therefore, recently, a plurality of different types of lines are arranged in the wiring circuit, and a coupling technique between these lines is required, and various coupling methods have been reported.
[0003]
Among them, as a method for connecting a planar line such as a microstrip line and a waveguide, in Patent Document 1, a strip line 32 is provided in parallel to the waveguide 31 as shown in FIG. A structure has been proposed in which a conductor pillar 34 extending from an open end of the line 32 and extending through an opening 33 formed in the conductor wall of the waveguide 31 is provided. In Patent Document 2, as shown in FIG. 13B, a slot line 35 is provided on the conductor wall of the waveguide 31 instead of the conductor column 34, whereby the waveguide 31 and the strip line 32 are provided. A structure that electromagnetically couples the two has been proposed.
[0004]
[Patent Document 1]
JP-A-11-150403
[Patent Document 2]
JP-A-15-78310 [0006]
[Patent Document 3]
JP-A-10-75108 [0007]
[Patent Document 4]
Japanese Patent Laid-Open No. 15-78310
[Patent Document 5]
JP-A-11-150403
[Problems to be solved by the invention]
However, the structure of FIG. 13 is a method of connecting a strip line to a waveguide, which is accompanied by problems such as a large size, lack of design flexibility, and difficulty in processing, which are disadvantages of the waveguide. It was difficult to reduce the overall size.
[0010]
Recently, it has been proposed to form a dielectric waveguide in a multilayer circuit board by a lamination technique. For example, in Patent Document 3, a dielectric substrate is sandwiched between a pair of main conductor layers, A dielectric waveguide having sidewalls formed by via hole groups arranged in two rows connecting between conductor layers is described.
[0011]
This dielectric waveguide is a dielectric waveguide for signal transmission in a conductor wall region by surrounding four sides of a dielectric material with a pseudo conductor wall made up of a pair of main conductor layers and via-hole conductor groups. Because it can be formed with conventional ceramic or organic substrate multilayer technology, it is easier to incorporate into the system than conventional waveguides, and the size can be reduced by 1 / (εr) ^1/2 There is.
[0012]
In addition, this structure enables high-frequency signals, particularly millimeter waves having a frequency of 30 GHz or more, to transmit signals with lower loss than a planar circuit. Further, unlike a planar circuit, a power divider, coupler, and vertical signal transmission are possible. It can be realized with low loss without electromagnetic field radiation.
[0013]
However, the dielectric waveguide disposed inside such a wiring board is mainly used as a transmission line for a microwave and millimeter wave multilayer wiring board or a semiconductor package, and is connected to a semiconductor element or a high-frequency element. When considering the structure, it is desired to convert the dielectric waveguide into a microstrip line that can be easily connected to them. As a method for realizing this, the present applicant previously proposed Patent Documents 4 and 5.
[0014]
However, these structures have a problem of large reflection and high conversion loss. Patent Document 5 is a structure in which a microstrip line and a dielectric waveguide are connected via a slot line, and an electromagnetic field leaking from the slot adversely affects antenna characteristics and other circuits such as semiconductor elements. was there.
[0015]
Accordingly, the present invention has been devised in view of the above problems, and provides a coupling structure of a dielectric waveguide and a microstrip line that can be easily manufactured by a conventional multilayer technology and has a low conversion loss. The object is to provide a filter substrate or antenna substrate having a coupling structure with low conversion loss.
[0016]
[Means for Solving the Problems]
The coupling structure of the microstrip line and the dielectric waveguide according to the present invention includes a pair of main conductor layers formed parallel to each other with a dielectric layer interposed therebetween, and the conductor layers are electrically connected with an interval equal to or shorter than the cutoff wavelength in the signal transmission direction. A dielectric waveguide having two rows of via hole groups formed so as to be connected to each other and a microstrip line, the transmission via hole from the end of the microstrip line Extending into the dielectric waveguide through an opening provided in the main conductor layer of the dielectric waveguide, and a conductor pattern parallel to the main conductor layer is formed at the other end of the via hole for transmission. It is characterized by being formed.
[0017]
According to the present invention, the dielectric waveguide and the microstrip line can be easily connected with low conversion loss. In addition, since it can be manufactured using a multilayer technology that has been used conventionally, a highly reliable bond structure can be formed at low cost.
[0018]
In particular, the conductor pattern is a circular, elliptical or rectangular pattern. As a result, the electromagnetic field can be efficiently radiated from the transmission via hole and matched with the electromagnetic field propagation mode of the dielectric waveguide.
[0019]
Furthermore, it is desirable that the center of the conductor pattern is shifted from the center of the via hole. As a result, the electromagnetic field mode in the transmission via hole and the dielectric waveguide electromagnetic field mode can be coupled more efficiently while suppressing reflection.
[0020]
Furthermore, it is desirable to provide a matching stub at the open end of the microstrip line. Thereby, the electromagnetic field propagation mode in the microstrip line can be efficiently converted into the mode of the transmission via hole.
[0021]
The dielectric is preferably made of low-temperature fired ceramics. As a result, the conductor layer and via-hole conductor constituting the microstrip line and the dielectric waveguide can be formed of low resistance copper, gold, silver or the like, so that the loss can be further reduced.
[0022]
According to the present invention, by providing the coupling structure of the dielectric waveguide and the microstrip line on the filter substrate or the antenna substrate, the signal can be propagated with a simple and efficient structure, and the loss is reduced. The size of the substrate can be reduced.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a connection structure between a dielectric waveguide and a rectangular waveguide according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view for explaining the basic structure of a dielectric waveguide used in the present invention.
[0024]
As shown in FIG. 1, a pair of conductor layers 2 and 3 are formed so as to sandwich a dielectric substrate 1 having a predetermined thickness a, and the conductor layers 2 and 3 are at least transmission line formation positions of the dielectric substrate 1. It is formed on the upper and lower surfaces sandwiching.
[0025]
A large number of through conductors 4 such as through-hole conductors and via-hole conductors that electrically connect the conductor layers 2 and 3 are provided between the conductor layers 2 and 3.
[0026]
As shown in the figure, the two rows of through conductor groups 4 have a predetermined repetition interval c that is less than one 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) b. Thereby, an electrical side wall in the dielectric waveguide 6 is formed. In addition, the through conductor 4 is provided with an auxiliary conductor layer 5 that is electrically connected to the through conductors forming each row of the through conductor group 4 and formed in parallel with the conductor layers 2 and 3.
[0027]
In this way, by forming the auxiliary conductor layer 5 in the region surrounded by the pair of conductor layers 2 and 3 and the through conductor group 4, the side wall penetrates when viewed from the inside of the dielectric waveguide 6. The conductor group 4 and the auxiliary conductor layer 5 form a fine lattice, shields electromagnetic waves in various directions, and forms a dielectric waveguide 6 with low loss.
[0028]
Here, there is no particular limitation on the thickness a of the dielectric substrate 1, that is, the distance between the pair of conductor layers 2 and 3, but when used in a single mode, it is about half or twice the distance b. In the example of FIG. 1, the portions corresponding to the H surface of the dielectric waveguide 6 are formed by the conductor layers 2 and 3, and the portions corresponding to the E surface are formed by the through conductor group 4 and the auxiliary conductor layer 5. If the thickness a is about twice as large as the interval b, the portions corresponding to the E surface of the dielectric waveguide 6 are the conductor layers 2 and 3, and the portions corresponding to the H surface are the through conductor group 4 and the auxiliary conductor layer 5. Will be formed respectively.
[0029]
In addition, an electrical wall can be formed by the through conductor group 4 by setting the interval c to an interval less than half of the signal wavelength. This interval c is preferably less than a quarter of the signal wavelength.
[0030]
Since TEM waves can propagate between the pair of conductor layers 2 and 3 arranged in parallel, the distance c between the through conductors in each row of the through conductor group 4 is less than half the signal wavelength λ (λ / 2). Is larger, the electromagnetic wave leaks from between the through conductor groups 4 even if the electromagnetic wave is fed to the dielectric waveguide 6 and does not propagate along the pseudo waveguide line formed here. However, if the interval c between the through conductor groups 4 is smaller than λ / 2, an electrical side wall is formed, and the electromagnetic wave cannot propagate in the direction perpendicular to the dielectric waveguide 6. It is propagated in the signal transmission direction of the dielectric waveguide 6 while being reflected.
[0031]
As a result, according to the configuration shown in FIG. 1, a region having a cross-sectional area of a × b surrounded by the pair of conductor layers 2 and 3 and the two rows of through conductor groups 4 and the auxiliary conductor layer 5 is a dielectric. It becomes the waveguide 6.
[0032]
In the structural example shown in FIG. 1, the through conductor groups 4 are formed in two rows. However, the through conductor groups 4 are arranged in four rows or six rows, and pseudo conductor walls by the through conductor groups 4 are formed in 2 rows. By forming a triple or triple layer, leakage of electromagnetic waves from the conductor wall can be more effectively prevented.
[0033]
Such a dielectric waveguide 6 has a size of 1 / (εr) ^1/2 of a normal waveguide when the relative dielectric constant of the dielectric substrate 1 is εr. Therefore, the larger the relative dielectric constant εr is used as the material constituting the dielectric substrate 1, the waveguide size can be reduced, the high frequency circuit can be miniaturized, and the wiring can be formed at a high density. The dielectric waveguide 6 can be used as a multilayer wiring board, a package for housing semiconductor elements, or a transmission line for inter-vehicle radar.
[0034]
Note that the through conductors constituting the through conductor group 4 are arranged at a repeating interval c of less than half of the signal wavelength as described above, and this interval c is used to realize good transmission characteristics. Although it is desirable to set a constant repetition interval, the interval may be appropriately changed or several values may be combined as long as the interval is less than half the signal wavelength.
[0035]
The dielectric substrate 1 constituting the dielectric waveguide 6 is not particularly limited as long as it has a characteristic that functions as a dielectric and does not hinder the transmission of high-frequency signals. As an example of the dielectric substrate 1, ceramics can be cited from the viewpoint of accuracy when forming the substrate and ease of manufacture.
[0036]
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 according to the present invention, a paraelectric material is desirable. 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.
[0037]
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.
[0038]
Examples of such a dielectric substrate 1 include alumina ceramics, aluminum nitride ceramics, and low-temperature fired ceramics. The dielectric substrate 1 is made into a sheet shape by adding and mixing an appropriate organic solvent / solvent to the ceramic raw material powder, for example, and is formed into a sheet shape by employing a conventionally known doctor blade method or calendar roll method. By doing so, a plurality of ceramic green sheets are obtained, and thereafter, each of these ceramic green sheets is appropriately punched and laminated. Thereafter, it is manufactured by firing at an optimum firing temperature at 1500 to 1700 ° C. for alumina ceramics, 850 to 1000 ° C. for low-temperature fired ceramics, and 1600 to 1900 ° C. for aluminum nitride ceramics. .
[0039]
Further, the pair of conductor layers 2 and 3 are formed of, for example, an oxide such as alumina, silica, or magnesia suitable for metal powder such as tungsten or molybdenum when the dielectric substrate 1 is made of ceramics such as alumina or aluminum nitride. Printed on the ceramic green sheet so that at least the transmission line is completely covered by a thick film printing method using an organic solvent / solvent added and mixed into a paste, and then fired at a high temperature of about 1600 ° C. And a thickness of 10 to 15 μm or more.
[0040]
In the case of low-temperature fired ceramics, the metal powder is preferably at least one selected from the group consisting of copper, gold, and silver. The thickness of the conductor layers 2 and 3 is generally 5 to 50 μm.
[0041]
The through conductors constituting the through conductor group 4 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 that of the conductor layers 2 and 3 in a through hole produced by punching a ceramic green sheet, and then firing the same simultaneously with the dielectric substrate 1. The through conductor has a diameter of 50 to 300 μm.
[0042]
The dielectric substrate 1 is not limited to the above ceramics, and a resin substrate can also be used. For example, known resin substrates such as fluororesin substrates and glass-epoxy substrates can be used. Via-hole conductors and through-hole conductors can be formed by plating or metal powder paste embedding, and a dielectric waveguide can be formed in the same manner as the ceramic substrate except that a heat-curing process is performed instead of a baking process.
[0043]
2 and 3 show an example of a dielectric waveguide and a microstrip line according to the present invention. FIG. 2 is a perspective view, and FIG. 3 is an xx cross-sectional view of FIG. The microstrip line 7 formed on the dielectric layer 1 c is connected to a dielectric waveguide 6 composed of the through conductor group 4 and the upper and lower ground main conductor layers 8 and 9. In FIG. 2, the penetrating conductor group 4 and the auxiliary conductor layer 5 forming the side surface of the dielectric waveguide are omitted, and the dielectric waveguide 6 is drawn as a box.
[0044]
In the connection structure of the present invention, the open end 7a of the microstrip line 7 passes through the opening 14 (the portion where no conductor is formed) formed in the main conductor layer 8 of the dielectric waveguide 6 to transmit the signal. A via hole 11 extends in the dielectric waveguide 6.
[0045]
A conductor pattern 12 parallel to the main conductor layers 8 and 9 is formed at the other end portion of the transmission via hole 11 extending in the dielectric waveguide 6.
[0046]
The conductor pattern 12 provided at the end portion of the transmission via hole 11 is necessary for effectively transmitting a signal into the dielectric waveguide 6, thereby making it possible to perform electromagnetic field matching and reduce reflection. Here, the position where the transmission via hole 11 is formed, particularly the distance from the termination conductor 10 of the dielectric waveguide 6 and the length of the transmission via hole 11 are the signal frequency, the dielectric waveguide shape, the dielectric thickness, the leading It is appropriately adjusted according to the shape of the hole 14 formed in the body pattern, and can be easily optimized by simulation or the like.
[0047]
Further, as shown in the plan view of FIG. 4, the conductor pattern 12 may be any one of (a) a circle, (b) an ellipse, and (c) a rectangle. This is desirable for improving the electromagnetic field matching with the signal propagation mode in the body waveguide.
[0048]
Furthermore, by shifting the center of the conductor pattern 12 from the center of the transmission via hole 11 as shown in FIG. 5, electromagnetic field matching becomes easier, reflection can be reduced, and signal transmission can be performed with low loss. In particular, it is desirable to shift the center of the conductor pattern 12 from the center of the transmission via hole 11 in the direction opposite to the end of the waveguide.
[0049]
Also, as shown in FIG. 6, by forming a stub 15 at the open end of the microstrip line 7, impedance matching can be achieved and signal transmission loss can be reduced. In particular, the stub length is desirably λ / 2 or less with respect to the signal wavelength λ.
[0050]
In addition, the above-described connection structure of the dielectric waveguide of the present invention and the microstrip line is preferably manufactured using low-temperature fired ceramics. Low-temperature fired ceramics can use copper, gold, and silver, which have high electrical conductivity, as a conductor, so there is an advantage that conductor loss can be reduced, and the dielectric constant is high and the structure is compact compared to general organic substrates. There are also benefits. Furthermore, from the viewpoint of reliability, unlike the organic substrate, the steam resistance is high, so that high reliability can be obtained.
[0051]
Further, the connection structure of the dielectric waveguide and the microstrip line of the present invention described in detail above can be built in an antenna substrate as shown in FIG. In the antenna substrate 21, a line made of a dielectric waveguide 23 is built in a dielectric substrate 22, and a radiation slot 25 is formed in the main conductor layer 24 of the dielectric line 23. When power is supplied to the radiation slot 25, the connection structure of the present invention is applied when power is supplied from the microstrip line 7 to the dielectric line 23. As a result, power can be supplied from the microstrip line 7 to the radiation slot 25 via the dielectric waveguide 23, and the versatility of the power supply method can be increased and an antenna substrate with less loss can be produced. In FIG. 7, power is supplied from the microstrip line 7 on the lower surface of the dielectric waveguide 23. FIG. 7 shows a slot antenna in which the radiation slot 25 is provided in the main conductor layer 24 on one side of the dielectric waveguide 23. However, the antenna type is not limited to this, and one of the feed lines is not limited to this. Any antenna substrate such as a patch antenna using a radiating patch may be used as long as the antenna substrate uses a dielectric waveguide for the part and needs to be connected to the microstrip line.
[0052]
Further, as shown in FIG. 8, even if the connection structure of the dielectric waveguide 32 and the microstrip line 33 of the present invention is built in the filter substrate 31, a low-loss filter can be obtained. In the filter of FIG. 8, a resonator 34 is formed by providing a portion where the interval between via-hole conductors forming the side wall of the dielectric waveguide 32 is narrowed to form a filter. According to the invention, the connection structure of the invention is used to input or output signals to this filter. Note that the filter circuit in the filter substrate is not limited to that shown in FIG. 8, and any filter circuit using a strip line or the like may be used.
[0053]
【Example】
As an example, the transmission characteristics of the structure shown in FIGS. A dielectric waveguide 6, a microstrip line 7, and a conversion structure connecting them were formed using a dielectric having εr = 4.9. A via conductor forming the through conductor group 4 has a diameter of 0.2 mm, a via pitch b of 1.5 mm, c of 0.52 mm, a dielectric waveguide thickness a of 0.5 mm, and a transmission via hole 11 from the end face of the waveguide. The transmission via 11 is a circle having a diameter of 0.15 mm, the opening 14 is a circle having a diameter of 0.3 mm, and the conductor pattern 12 is a circle having a diameter of 0.5 mm. The width of the microstrip line is 0.16 mm, and the thickness of the dielectric layer 1c forming the microstrip line is 0.1 mm. In this structure, the center of the conductor pattern 12 is the same as the center of the transmission via 11.
[0054]
FIG. 9 shows S parameters from 50 GHz to 90 GHz. The solid line is S21 and the broken line is S11. As can be seen, signal transmission is possible with the lowest loss in the vicinity of 64 GHz.
[0055]
For comparison, a connection structure was formed with exactly the same dimensions except that no conductor pattern was formed as shown in FIG. 13A, and transmission characteristics were similarly evaluated.
The results are shown in FIG.
[0056]
FIG. 11 shows the results when the conductor pattern 12 is shifted by 0.1 mm in the direction opposite to the waveguide end face 10 by 0.1 mm. As can be seen, S11 is improved, and the band where S11 <−10 dB is widened from 16.4 GHz to 19.8 GHz.
[0057]
FIG. 12 shows a structure for 77 GHz. The diameter of the transmission via is 0.1 mm and the conductor pattern 12 is a circle having a diameter of 0.4 mm. From the center of the conductor pattern 12 to the center of the via conductor forming the waveguide end face. And the conductor pattern 12 was formed at a position shifted from the center of the transmission via hole by 0.05 mm in the direction opposite to the end face of the waveguide. As can be seen from this result, S21 is approximately 0 dB at 70 GHz to 84 GHz, and S11 is also −20 dB or less.
[0058]
【The invention's effect】
As described in detail above, the present invention makes it possible to match the electromagnetic field by forming a conductor pattern at the end of a via hole for transmission from a microstrip line to a dielectric waveguide. The body waveguide can be connected. Further, by shifting the conductor pattern 12 from the center of the transmission via 11, the electromagnetic field can be more matched and loss can be reduced. Also, forming a stub at the end of the microstrip line is effective for electromagnetic field matching, and conversion can be performed with low loss.
[0059]
In addition, by using a low-temperature fired ceramic for the dielectric substrate, it is possible to use a silver or copper conductor layer having a high conductivity, so that the electrical characteristics can be improved.
[0060]
Furthermore, according to the connection structure between the dielectric waveguide and the microstrip line of the present invention, a transmission via hole is extended from the microstrip line into the dielectric waveguide, and the other end of the transmission via hole is connected to the dielectric waveguide. Since electromagnetic field matching can be obtained by inserting the dielectric waveguide into the dielectric waveguide and forming a conductor pattern parallel to the main conductor layer at the end thereof, a low-loss antenna substrate and filter substrate can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view illustrating an example of a dielectric waveguide used in the present invention.
FIG. 2 is an assembly diagram of an example of an embodiment of a connection structure between a dielectric waveguide and a microstrip line according to the present invention.
FIG. 3 is a sectional view taken along line xx of FIG.
FIG. 4 is a plan view of another example of an embodiment of a connection structure between a dielectric waveguide and a microstrip line according to the present invention.
FIG. 5 is a plan view of still another example of an embodiment of a connection structure between a dielectric waveguide and a microstrip line according to the present invention.
FIG. 6 is a plan view of still another example of the embodiment of the connection structure between the dielectric waveguide and the microstrip line according to the present invention.
FIG. 7 is a perspective view showing an example of an embodiment of an antenna substrate incorporating a connection structure between a dielectric waveguide and a microstrip line according to the present invention.
FIG. 8 is a perspective view showing an example of an embodiment of a filter substrate having a built-in connection structure between a dielectric waveguide and a microstrip line according to the present invention.
FIG. 9 is a diagram illustrating transmission characteristics of an example of a connection structure according to the present invention.
FIG. 10 is a diagram showing transmission characteristics of a conventional connection structure.
FIG. 11 is a diagram illustrating transmission characteristics of an example of a connection structure according to the present invention.
FIG. 12 is a diagram illustrating transmission characteristics of still another example of the present invention.
FIG. 13 is a diagram illustrating transmission characteristics of an example of a conventional connection structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dielectric 2 and 3 Main conductor layer 4 Via-hole group 5 Subconductor layer 6 Dielectric waveguide 7 Microstrip line 8, 9 Main conductor layer 10 Dielectric waveguide side end conductor 11 Transmission via hole 12 Conductor pattern 13 Ground Pattern 14 Opening 15 Stub

Claims (8)

A pair of main conductor layers formed in parallel with a dielectric layer in between, and two rows of via hole groups formed so as to electrically connect the conductor layers at intervals equal to or shorter than the cutoff wavelength in the signal transmission direction. A structure for coupling a dielectric waveguide and a microstrip line, wherein a transmission via hole is opened from an end of the microstrip line through an opening provided in a main conductor layer of the dielectric waveguide, A dielectric waveguide and a microstrip line extending in the dielectric waveguide and having a conductor pattern parallel to the main conductor layer at the other end of the transmission via hole Bonding structure. 2. The dielectric waveguide / microstrip line coupling structure according to claim 1, wherein the conductor pattern is a circular or elliptical pattern. 2. The dielectric waveguide / microstrip line coupling structure according to claim 1, wherein the conductor pattern is a square pattern. 4. The coupling structure of a dielectric waveguide and a microstrip line according to claim 2, wherein the center of the conductor pattern is deviated from the center of the transmission via hole. 5. The dielectric waveguide / microstrip line coupling structure according to claim 1, wherein a matching stub is provided at an open end of the microstrip line. 5. The dielectric waveguide / microstrip line coupling structure according to claim 2, wherein the dielectric is made of low-temperature fired ceramics. 6. A filter substrate comprising a coupling structure of a dielectric waveguide according to claim 1 and a microstrip line. 6. An antenna substrate comprising the dielectric waveguide and microstrip line coupling structure according to claim 1.

Images