JP7286726B2 - TRANSMISSION LINE CONVERSION STRUCTURE, ITS ADJUSTMENT METHOD, AND ITS MANUFACTURING METHOD - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a transmission line conversion structure between a planar transmission line and a coaxial transmission line, a method for adjusting the same, and a method for manufacturing the same.

A transmission line transition structure is used between the planar transmission line of the substrate and the coaxial transmission line used for external connection in order to propagate signals between the circuit of the substrate and the outside. Techniques for minimizing transmission loss have been proposed for transmission line conversion structures (see Patent Document 1, for example). The structure of Patent Literature 1 prevents deterioration of the transmittance due to the signal being radiated or reflected to the outside at the conversion section.

Republished WO2002/082578

The inventors discovered that when a planar transmission line and a coaxial transmission line are connected, electromagnetic waves enter the dielectric layer of the planar transmission line from the coaxial transmission line and affect transmission characteristics. It is speculated that this is caused by the intruding electromagnetic wave spatially resonating in the dielectric layer of the planar transmission line, and the spatially resonant electromagnetic wave being coupled with the signal propagating in the planar transmission line.

Accordingly, an object of the present disclosure is to prevent electromagnetic waves from entering a dielectric layer of a planar transmission line from a coaxial transmission line in a transmission line conversion structure between a planar transmission line and a coaxial transmission line.

In order to prevent electromagnetic waves from entering the dielectric layer of the planar transmission line, a via is provided on the coaxial transmission line side of the dielectric layer of the planar transmission line.

Specifically, the transmission line transformation structure of the present disclosure includes:
A planar transmission line having a signal line (11) of a microstrip transmission line, a first ground (12) and a second ground (13) as ground conductor grounds of the microstrip transmission line in this order on a substrate consisting of a plurality of layers. and a coaxial transmission line having a central conductor (31) and an outer conductor (32),
The second ground (13) is either a ground provided on the back surface of the substrate opposite to the surface on which the signal line (11) is provided, or a back surface side of the substrate from the first ground (12). is a ground provided on the layer of
the signal line (11) of the microstrip transmission line and the central conductor (31) of the coaxial transmission line are connected,
the first ground (12) and the second ground (13) of the microstrip transmission line and the outer conductor (32) of the coaxial transmission line are connected;
The first ground (12) and the second ground ( 13) is provided with a first via (10) for connecting the .

Specifically, the transmission line transformation structure of the present disclosure includes:
A signal line (21) of a coplanar transmission line and a fourth ground (22), which is a ground conductor ground of the coplanar transmission line, are provided on a substrate consisting of a plurality of layers. A planar transmission line having in order a fifth ground (23) and a sixth ground (24), which are grounds provided on any layer, and a coaxial transmission line having a central conductor (31) and an outer conductor (32) a transmission line transformation structure of
The sixth ground (24) is either the ground provided on the back surface of the substrate opposite to the surface on which the signal line (21) is provided, or the back surface side of the substrate from the fifth ground (23). It is a ground provided in that layer,
the signal line (21) of the coplanar transmission line and the central conductor (31) of the coaxial transmission line are connected,
the fourth ground (22), the fifth ground (23) and the sixth ground (24) of the coplanar transmission line are connected to the outer conductor (32) of the coaxial transmission line;
on the coaxial transmission line side of the dielectric layer (26) between the fifth ground (23) and the sixth ground (24); 24) is provided with a first via (10) connecting the .

According to the present disclosure, in a transmission line conversion structure between a planar transmission line and a coaxial transmission line, it is possible to prevent electromagnetic waves from entering the dielectric layer of the planar transmission line from the coaxial transmission line.

1 is a perspective view of a transmission line conversion structure according to this embodiment; FIG. FIG. 3 is a cross-sectional view of the transmission line conversion structure according to the embodiment in the signal propagation direction; It is a cross-sectional view of the transmission line conversion structure according to the present embodiment. FIG. 2 is a cross-sectional view perpendicular to the signal propagation direction of the transmission line conversion structure according to the embodiment; 1 is a perspective view of a transmission line conversion structure according to this embodiment; FIG. 1 is a perspective view of a transmission line conversion structure according to this embodiment; FIG. FIG. 3 is a cross-sectional view of the transmission line conversion structure according to the embodiment in the signal propagation direction; It is a cross-sectional view of the transmission line conversion structure according to the present embodiment. FIG. 2 is a cross-sectional view perpendicular to the signal propagation direction of the transmission line conversion structure according to the embodiment; 1 is a perspective view of a transmission line conversion structure according to this embodiment; FIG. 1 is a perspective view of a transmission line conversion structure according to this embodiment; FIG. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a simulation result of the transmission line conversion structure according to the present embodiment. It is a figure which shows the manufacturing process of the transmission-line conversion structure which concerns on this embodiment.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In addition, in this specification and the drawings, constituent elements having the same reference numerals are the same as each other.

The transmission line conversion structure according to this embodiment is a transmission line conversion structure between a planar transmission line and a coaxial transmission line. FIG. 1 is a perspective view of the transmission line conversion structure according to the present embodiment, FIG. 2 is a cross-sectional view of the transmission line in the signal propagation direction, and FIG. 3 is a cross-sectional view thereof. FIG. 4 shows a cross-sectional view perpendicular to the signal propagation direction at .

1 to 4, the planar transmission line includes a signal line 11 of a microstrip transmission line, a first ground 12 and a second ground 13 in this order on a multi-layer substrate. The first ground 12 is the ground conductor ground of the microstrip transmission line. The second ground 13 is a ground provided on the back surface of the substrate or a ground provided on any layer on the back surface side of the substrate from the first ground 12 . 1 to 3, the second ground 13 is provided on the back surface of the substrate. In FIG. 4, the second ground 13 is provided on any layer from the first ground 12 to the back side of the substrate. A dielectric layer 14 is arranged between the signal line 11 of the microstrip transmission line and the first ground 12 of the microstrip transmission line, and between the first ground 12 and the second ground 13 of the microstrip transmission line. is provided with a dielectric layer 15 .

When the second ground 13 is provided on the rear surface of the substrate, it is used for the purpose of blocking electromagnetic waves from entering the circuit of the substrate and supplying power to the circuit. When the second ground 13 is provided on any layer on the back side of the board from the first ground 12, it is used for the purpose of blocking electromagnetic induction between the layers of the board and supplying power to the circuit. be done.

1 and 4, the dielectric layer 14 between the signal line 11 of the microstrip transmission line and the first ground 12 of the microstrip transmission line and the first ground 12 and the second ground of the microstrip transmission line are shown. The dielectric layer 15 between 13 is omitted from the drawing. In FIG. 4, the dielectric layer between the second ground 13 and the third ground 16 is omitted.

1-4, the coaxial transmission line comprises a central conductor 31 , an outer conductor 32 and a coaxial dielectric 33 . A signal line 11 of a microstrip transmission line and a central conductor 31 of a coaxial transmission line are connected. The first ground 12 and second ground 13 of the microstrip transmission line and the outer conductor 32 of the coaxial transmission line are connected. Here, the term "connection" means that high-frequency connection is sufficient and physical contact is not necessarily required. Unless otherwise specified, the same applies to the following embodiments.

In FIGS. 1 to 4, the first ground 12 and the second ground 13 are connected to the coaxial transmission line side of the dielectric layer 15 between the first ground 12 and the second ground 13 . of vias 10 are installed. By providing the first via 10, it is possible to prevent electromagnetic waves propagating through the coaxial dielectric 33 of the coaxial transmission line from entering the dielectric layer 15 of the planar transmission line. If the electromagnetic wave does not enter the dielectric layer 15 of the planar transmission line, no spatial resonance will occur and the transmission characteristics will not be affected.

The first vias 10 are preferably arranged at intervals that are effective in shielding electromagnetic waves of the frequency used. For example, it is desirable that the frequency is 1/4 or less of the dielectric layer 15 of the frequency to be shielded. The via material is preferably a metal with high conductivity, such as gold, silver, copper, or aluminum. The same applies to the following embodiments.

The first via 10 need not be placed on the entire coaxial transmission line side of the substrate. It may be installed at least in the portion where the dielectric layer 15 and the coaxial dielectric 33 overlap. For example, as shown in FIG. 4, when the second ground 13 is a ground provided in any layer on the back side of the substrate from the first ground 12, the first via 10 is connected to the first ground. 12 and the second ground 13 may be connected. At least, if the first via 10 is provided in the portion where the dielectric layer 15 and the coaxial dielectric 33 overlap, the electromagnetic wave propagating through the coaxial dielectric 33 of the coaxial transmission line will not enter the dielectric layer 15 of the planar transmission line. can be prevented. If the electromagnetic wave does not enter the dielectric layer 15 of the planar transmission line, no spatial resonance will occur and the transmission characteristics will not be affected. In addition, when a third ground 16 is provided on the back surface of the substrate opposite to the surface on which the signal line is provided, the first ground 12, the second ground 13 and the third ground 16 are respectively connected to the first ground. may be connected through vias 10 of

The planar transmission line may further include a second via connecting between the first ground 12 and the second ground 13 . FIG. 5 shows a perspective view of a transmission line conversion structure between a planar transmission line and a coaxial transmission line further including a second via in addition to the transmission line conversion structure of FIG. The second via 17 in FIG. 5 is arranged along the signal propagation direction of the dielectric layer 15 between the first ground 12 and the second ground 13, connect between

FIG. 11 shows a structure in which the microstrip transmission line has an eighth ground on the same plane as the signal line 11, in contrast to the transmission line conversion structure of FIG. A second via 17 shown in FIG. 11 connects the eighth ground 18 , the first ground 12 and the second ground 13 . In FIGS. 5 and 11, the second ground 13 is provided on the back surface of the substrate, but may be provided on any layer on the back surface side of the substrate from the first ground 12 . Providing the first via 10 for such a planar transmission line is effective in preventing electromagnetic waves from entering the dielectric layer 15 of the planar transmission line from the coaxial transmission line.

The transmission line conversion structure according to this embodiment is a transmission line conversion structure between a planar transmission line and a coaxial transmission line. FIG. 6 is a perspective view of the transmission line conversion structure according to the present embodiment, FIG. 7 is a cross-sectional view of the transmission line in the signal propagation direction, and FIG. 8 is a cross-sectional view thereof. FIG. 9 shows a cross-sectional view perpendicular to the signal propagation direction at .

6 to 9, the planar transmission line includes a signal line 21 and a fourth ground 22, a fifth ground 23 and a sixth ground 24 of a coplanar transmission line on a multi-layer substrate in this order. The fourth ground 22 is the ground conductor ground of the coplanar transmission line. The fifth ground 23 is a ground provided in any layer from the fourth ground 22 to the back side of the substrate. The sixth ground 24 is a ground provided on the back surface of the substrate or a ground provided on any layer on the back surface side of the substrate from the fifth ground 23 . 6 to 8, the sixth ground 24 is provided on the back surface of the substrate. In FIG. 9, the sixth ground 24 is provided on any layer from the fifth ground 23 to the back side of the substrate. A dielectric layer 25 is arranged between the coplanar transmission line and the fifth ground 23 , and a dielectric layer 26 is arranged between the fifth ground 23 and the sixth ground 24 . The fourth ground 22 may be arranged on one side or both sides of the signal line 21 . The provision of the fifth ground 23 facilitates the design of transmission characteristics and can be expected to improve the transmission characteristics.

When the sixth ground 24 is provided on the rear surface of the substrate, it is used for the purpose of preventing electromagnetic waves from entering the circuit of the substrate and supplying power to the circuit. When the sixth ground 24 is provided on any layer from the fifth ground to the back side of the board, it is used for the purpose of blocking electromagnetic induction between the layers of the board and supplying power to the circuit. be.

6 and 9, the dielectric layer 25 between the coplanar transmission line and the fifth ground 23 and the dielectric layer 26 between the fifth ground 23 and the sixth ground 24 are omitted. ing. In FIG. 9, the dielectric layer between the sixth ground 24 and the seventh ground 28 is omitted.

6-9, the coaxial transmission line comprises a central conductor 31 , an outer conductor 32 and a coaxial dielectric 33 . A signal line 21 of the coplanar transmission line and a central conductor 31 of the coaxial transmission line are connected. The fourth ground 22, fifth ground 23 and sixth ground 24 of the coplanar transmission line are connected to the outer conductor 32 of the coaxial transmission line.

6 to 9, a first ground connecting the fifth ground 23 and the sixth ground 24 to the coaxial transmission line side of the dielectric layer 26 between the fifth ground 23 and the sixth ground 24 is provided. of vias 10 are installed. By providing the first via 10, it is possible to prevent electromagnetic waves propagating through the coaxial dielectric 33 of the coaxial transmission line from entering the dielectric layer 26 of the planar transmission line. If the electromagnetic wave does not enter the dielectric layer 26 of the planar transmission line, no spatial resonance will occur and the transmission characteristics will not be affected.

The first via 10 need not be placed on the entire coaxial transmission line side of the substrate. It may be installed at least in the portion where the dielectric layer 26 and the coaxial dielectric 33 overlap. For example, as shown in FIG. 9, when the sixth ground 24 is a ground provided in any layer from the fifth ground 23 to the back side of the substrate, the first via 10 is connected to the fifth ground 23 and the sixth ground 24 may be connected. At least, if the dielectric layer 26 and the coaxial dielectric 33 are installed at the overlapping portion, it is possible to prevent the electromagnetic wave propagating through the coaxial dielectric 33 of the coaxial transmission line from entering the dielectric layer 26 of the planar transmission line. If the electromagnetic wave does not enter the dielectric layer 26 of the planar transmission line, no spatial resonance will occur and the transmission characteristics will not be affected. In addition, when a seventh ground 28 is further provided on the back surface of the substrate opposite to the surface on which the signal line is provided, the fifth ground 23, the sixth ground 24, and the seventh ground 28 each connect the first via 10. may be connected via

The planar transmission line may further comprise a second via 17 connecting between the fifth ground 23 and the sixth ground 24 . FIG. 10 shows a perspective view of a transmission line conversion structure between a planar transmission line and a coaxial transmission line having a second via in addition to the transmission line conversion structure of FIG. The second via 17 in FIG. 10 is arranged along the signal propagation direction of the dielectric layer 26 between the fifth ground 23 and the sixth ground 24, and the fifth ground 23 and the sixth ground 24. connect between In FIG. 10 , the second via 17 may connect the fourth ground, the fifth ground 23 and the sixth ground 24 . In FIG. 10, the sixth ground 24 is provided on the back surface of the substrate, but may be provided on any layer from the fifth ground 23 on the back surface side of the substrate. Providing the first via 10 for such a planar transmission line is effective in preventing electromagnetic waves from entering the dielectric layer 26 of the planar transmission line from the coaxial transmission line.

In this embodiment, the coaxial transmission line is described as a coaxial cable, but it may be a connector with a coaxial structure in which the metal shell constitutes the outer conductor.

Although the coaxial transmission line is connected to the planar transmission line in FIG. 11, the transmission characteristics were simulated when the coaxial transmission line, the planar transmission line, and the coaxial transmission line were cascade-connected. A conventional structure, that is, a transmission line conversion structure without the first via 10 (FIG. 12A) is used for each transmission line conversion structure from a coaxial transmission line to a planar transmission line and from a planar transmission line to a coaxial transmission line. FIG. 12(B) shows the simulation result of the application. Transmission line transition structures from coaxial transmission line to planar transmission line and from planar transmission line to coaxial transmission line (FIG. 13(A)), that is, a first via on the coaxial transmission line side of the dielectric layer 15 FIG. 13B shows the simulation result when the structure in which 10 is installed is applied.

In the conventional transmission line conversion structure, as shown in FIG. 12(B), a drop in pass characteristics due to a resonance phenomenon appears at many frequencies above 70 GHz. In the transmission line conversion structure of the present embodiment, as shown in FIG. 13(B), the drops at many frequencies shown in FIG. 12(B) could be eliminated. However, a large dip in pass characteristics appeared at a frequency of 76 GHz. Therefore, a method for adjusting the frequency of the large drop in the pass characteristic, that is, the resonance frequency was investigated.

FIG. 14A shows a structure and its simulation results when the thickness between the first ground 12 and the second ground 13 is reduced by 0.1 mm with respect to the transmission line conversion structure shown in FIG. ) and FIG. 14(B). It can be seen that when the thickness between the first ground 12 and the second ground 13 is reduced, the resonance frequency shifts to a high range of 84 GHz.

Next, the second ground 13 is a ground provided on any layer from the first ground 12 to the back side of the board, and the third ground 16 is the back side of the board opposite to the side where the signal line is present. A structure (FIG. 15(A)) provided in and connected by a first via was studied. A simulation result is shown in FIG. The thickness between the first ground 12 and the second ground 13 is the same as the structure of FIG. 14(A). From FIGS. 14B and 15B, regardless of the presence or absence of the third ground 16, if the thickness between the first ground 12 and the second ground 13 is the same, the resonance It can be seen that the frequency does not change.

Furthermore, for the structure of FIG. 13(A), the thickness between the first ground 12 and the second ground 13 is 0.2 mm (FIG. 16(A)) and 0.4 mm (FIG. 17(A) )) only thinned. The respective simulation results are shown in FIGS. 16(B) and 17(B). The resonance frequency shifts according to the thickness between the first ground 12 and the second ground 13 .

From these results, since the resonant frequency depends on the thickness between the first ground 12 and the second ground 13, changing the thickness between the first ground 12 and the second ground 13 Thereby, the resonance frequency of the planar transmission line can be set. In other words, a substrate having a thickness between the first ground 12 and the second ground 13 such that the resonance frequency is equal to or higher than the operating frequency is selected, and the dielectric layer 15 of the planar transmission line and the coaxial dielectric layer of the coaxial transmission line are selected. By providing the first via 10 between the body 33 and the microstrip transmission line shown in FIGS.

The same applies to the coplanar transmission lines shown in FIGS. 6 to 10. FIG. Since the resonance frequency depends on the thickness between the fifth ground 23 and the sixth ground 24, by changing the thickness between the fifth ground 23 and the sixth ground 24, the planar transmission line The resonance frequency of can be adjusted. In other words, a substrate having a thickness between the fifth ground 23 and the sixth ground 24 is selected so that the resonant frequency is equal to or higher than the operating frequency, and the dielectric layer 26 of the planar transmission line and the coaxial dielectric layer of the coaxial transmission line are selected. If the first via 10 is provided between the body 33, the pass characteristics within the working band of the coplanar transmission lines shown in FIGS. 6 to 10 can be flattened.

FIG. 18 shows each step of a method of manufacturing a transmission line conversion structure that adjusts the resonance frequency of a microstrip transmission line so that no resonance frequency occurs within the operating band. Manufacture of a transmission line conversion structure using microstrip transmission lines is started (S10). In the manufacturing data creation step (S11), the relationship between the thickness and the resonance frequency (FIGS. 12 to 17) between the first ground 12 and the second ground 13 of the microstrip transmission line is obtained. In the substrate selection step (S12), a substrate having a thickness between the first ground 12 and the second ground 13 at which the resonant frequency is equal to or higher than the operating frequency is selected. In the via formation step (S13), a first via and a second via are formed in the selected substrate. In the pattern forming step (S14), patterns are formed on the substrate on which the first vias and the second vias are formed. In the contour processing step (S15), the substrate on which the pattern is formed is separated, and the contour of the microstrip transmission line is processed. In the connecting step (S16), the microstrip transmission line whose outer shape is processed and the coaxial transmission line are connected. A transmission line conversion structure is completed (S17).

The same applies to a method of manufacturing a transmission line conversion structure that adjusts the resonance frequency of a coplanar transmission line so that no resonance frequency occurs within the operating band. However, in the manufacturing data creation step (S11), the relationship between the thickness and the resonance frequency (FIGS. 12 to 17) between the fifth ground 23 and the sixth ground 24 of the microstrip transmission line is acquired, and the substrate In the selection step (S12), a substrate having a thickness between the fifth ground 23 and the sixth ground 24 at which the resonant frequency is equal to or higher than the operating frequency is selected.

As described above, the transmission line conversion structure of the present disclosure can achieve flat pass characteristics within the operating band.

The present disclosure can be applied to the information and communications industry.

10: first via 11: signal line 12: first ground 13: second ground 14: dielectric layer 15: dielectric layer 16: third ground 17: second via 18: eighth ground 21: signal line 22: fourth ground 23: fifth ground 24: sixth ground 25: dielectric layer 26: dielectric layer 28: seventh ground 31: center conductor 32: outer conductor 33: coaxial dielectric body

Claims (10)

A planar transmission line having a signal line (11) of a microstrip transmission line, a first ground (12) and a second ground (13) as ground conductor grounds of the microstrip transmission line in this order on a substrate consisting of a plurality of layers. and a coaxial transmission line having a central conductor (31) and an outer conductor (32),
The second ground (13) is either a ground provided on the back surface of the substrate opposite to the surface on which the signal line (11) is provided, or a back surface side of the substrate from the first ground (12). is a ground provided on the layer of
the signal line (11) of the microstrip transmission line and the central conductor (31) of the coaxial transmission line are connected,
the first ground (12) and the second ground (13) of the microstrip transmission line and the outer conductor (32) of the coaxial transmission line are connected;
The first ground (12) and the second ground ( 13) is provided with a first via (10) connecting the
Along the signal propagation direction of the dielectric layer (15) between the first ground (12) and the second ground (13), the first ground (12) and the second ground (13) ), characterized in that it comprises a second via (17) connecting between the . wherein the second ground (13) is a ground provided in any layer from the first ground (12) to the rear surface side of the substrate;
2. The transmission line transformation structure according to claim 1, further comprising a third ground (16) provided on the back surface of said substrate opposite to the surface on which said signal line is located. A signal line (21) of a coplanar transmission line and a fourth ground (22), which is a ground conductor ground of the coplanar transmission line, are provided on a substrate consisting of a plurality of layers. A planar transmission line having in order a fifth ground (23) and a sixth ground (24), which are grounds provided on any layer, and a coaxial transmission line having a central conductor (31) and an outer conductor (32) a transmission line transformation structure of
The sixth ground (24) is either the ground provided on the back surface of the substrate opposite to the surface on which the signal line (21) is provided, or the back surface side of the substrate from the fifth ground (23). It is a ground provided in that layer,
the signal line (21) of the coplanar transmission line and the central conductor (31) of the coaxial transmission line are connected,
the fourth ground (22), the fifth ground (23) and the sixth ground (24) of the coplanar transmission line are connected to the outer conductor (32) of the coaxial transmission line;
on the coaxial transmission line side of the dielectric layer (26) between the fifth ground (23) and the sixth ground (24); 24), characterized in that a first via (10) is provided to connect the . wherein the sixth ground (24) is a ground provided in any layer from the fifth ground (23) to the rear surface side of the substrate;
4. The transmission line transformation structure according to claim 3 , further comprising a seventh ground (28) provided on the back surface of the substrate opposite to the surface on which the signal line is located. Along the signal propagation direction of the dielectric layer (26) between the fifth ground (23) and the sixth ground (24), the fifth ground (23) and the sixth ground (24) 5. The transmission line transformer structure according to claim 3 or 4 , further comprising a second via (17) connecting between . 6. The transmission line conversion structure according to any one of claims 1 to 5 , wherein the transmission line conversion structure is set so that the resonance frequency of the planar transmission line does not occur within the operating band. A method for tuning a transmission line transformation structure according to claim 1 or 2 , wherein by varying the thickness between the first ground (12) and the second ground (13), the plane An adjustment method for adjusting the resonance frequency of a transmission line. A method for manufacturing the transmission line conversion structure according to claim 1 or 2 ,
Acquiring the relationship between the thickness between the first ground (12) and the second ground (13) and the resonance frequency of the planar transmission line,
Selecting the planar transmission line that does not generate a resonance frequency within the operating band,
A method of manufacturing a transmission line conversion structure for forming the first via and pattern in the selected planar transmission line. A method for tuning a transmission line transformation structure according to any one of claims 3 to 5, wherein by varying the thickness between the fifth ground (23) and the sixth ground (24), An adjustment method for adjusting the resonance frequency of the planar transmission line. A method for manufacturing a transmission line conversion structure according to any one of claims 3 to 5 ,
Acquiring the relationship between the thickness between the fifth ground (23) and the sixth ground (24) and the resonance frequency of the planar transmission line,
Selecting the planar transmission line that does not generate a resonance frequency within the operating band,
A method of manufacturing a transmission line conversion structure for forming the first via and pattern in the selected planar transmission line.

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