JP2008219476A - Transmission line conversion part, high frequency circuit and high frequency module having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission line conversion part of a coaxial line and a microstrip line with which the coaxial line and the microstrip line formed on a multilayer dielectric substrate are converted and connected without using additional components such as substrate for mediation and in which impedance variation is reduced. <P>SOLUTION: The transmission line conversion part is constituted such that flow of ground current of the microstrip line is sequentially switched from a conductor pattern on the rear surface to the respective conductor patterns formed in a plurality of internal layers of the multilayer dielectric substrate via through holes, the ground current flown to a conductor pattern 8e flows along a ground conductor pattern 8d via the through hole 9d from the ground conductor pattern 8e and the ground current flows further and sequentially via the through holes, respectively. Thus, the transmission line conversion part is constituted so as to flow the ground current by sequentially switching the ground for every one layer and parasitic reactance per through hole is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission line conversion unit of a coaxial line and a microstrip line provided in a microwave circuit or a millimeter wave circuit. Furthermore, the present invention relates to a microwave circuit or millimeter wave circuit including such a transmission line converter, and a microwave module or millimeter wave module.

  As a conventional transmission line conversion unit between a coaxial line and a microstrip line, a configuration of a coaxial connector connection structure that connects a central conductor of a coaxial line and a strip conductor of a microstrip line in the same direction has been reported (for example, Patent Documents) 1).

  In the coaxial connector connection structure described in this document, an intermediary board composed of a double-sided board is provided between the coaxial connector and the multilayer board, and the coaxial line and the microstrip line formed on the intermediary board are connected first, By connecting with a microstrip line formed on a multilayer substrate, a coaxial connector connection structure having good reflection characteristics over a wide band is configured.

Japanese Unexamined Patent Application Publication No. 2004-281120 (FIG. 1 etc.)

  However, in the case of the coaxial connector connection structure as the transmission line conversion part of the conventional coaxial line and microstrip line as described above, it is necessary to provide an intermediary board between the coaxial connector and the multilayer board, so the number of components and the connection There was a problem that the number of parts increased and the assembly became complicated.

  The present invention has been made to solve the above-described problems. A microstrip line formed on a coaxial line and a multilayer dielectric substrate can be converted and connected without using an additional component such as an intermediary substrate. An object of the present invention is to provide a transmission line conversion unit of a coaxial line and a microstrip line in which deterioration of transmission characteristics in a wave band or a millimeter wave band is reduced. Further, it is possible to provide a microwave circuit or a millimeter wave circuit having a transmission line conversion unit of such a coaxial line and a microstrip line, and a microwave including a casing that houses such a circuit and has a coaxial connector An object is to provide a module or a millimeter wave module.

According to the present invention, the flow of the ground current of the microstrip line is switched from the conductor pattern on the back surface of the multilayer dielectric substrate to the respective conductor patterns formed on the plurality of inner layers via connection means for sequentially conducting the connection. The parasitic reactance per one connecting means to be connected is reduced.
That is, the transmission line conversion unit according to the present invention is a transmission line conversion unit of a coaxial line and a microstrip line, and is formed on the surface of the multilayer dielectric substrate, and is used for at least a conductive connection with the inner conductor of the coaxial line. A strip conductor of a microstrip line having a portion for use, a back surface of the multilayer dielectric substrate, and at least a plurality of inner layers, the distance from the connection portion of the strip conductor to a conductor forming end is the back surface of the multilayer dielectric substrate. A conductive pattern including a conductive pattern formed on the back surface of the multilayer dielectric substrate as a ground conductor that is formed so as to be sequentially expanded from the surface toward the surface and used for conductive connection with the outer conductor of the coaxial line; and A pair is provided at both side positions, and the pair or more is set to an interval of less than ½ wavelength at the operating frequency. And connection means for conducting connecting at least adjacent conductive patterns of the respective over emissions, those having a.

  According to the present invention, the transmission characteristics in the microwave band or millimeter wave band can be converted and connected without using additional components such as an intermediary board between the microstrip line formed on the coaxial line and the multilayer dielectric substrate. It is possible to realize a transmission line conversion section of a coaxial line and a microstrip line with reduced noise.

  In the following embodiments, a microwave circuit (or a millimeter wave circuit) having a transmission line conversion unit between a coaxial line and a microstrip line is housed in a casing, and a coaxial connector corresponding to the coaxial line is connected to the microstrip line. FIG. 1 and FIG. 2 (cross-sectional view of FIG. 1), and FIG. 3 and FIG. 4 (cross-sectional view of FIG. ) Of the transmission line converter of the coaxial line and the microstrip line of the present invention, a microwave circuit (or millimeter wave circuit) having such a transmission line converter, and such a circuit. An embodiment of a microwave module (or a millimeter-wave module) including a housing having a coaxial connector and a coaxial connector will be described.

Embodiment 1 FIG.
With reference to FIG. 1 and FIG. 2, the transmission line conversion part of the coaxial line and the microstrip line concerning Embodiment 1 of this invention is demonstrated. 1 is a top view, and FIG. 2 is a cross-sectional view showing a cross section AA ′ in FIG.
In the figure, 1 is a housing, 2 is a coaxial connector, 3 is a multilayer dielectric substrate, and 4 is a connector mounting hole provided in a side wall of the housing 1. A central conductor 5 of the coaxial connector 2 is inserted into the connector mounting hole 4 via an insulator 6.
Here, the main part when the conversion part of a coaxial line and a microstrip line is arrange | positioned at one corner of the housing | casing 1 which accommodates a microwave circuit is shown. A strip conductor 7 of a microstrip line is formed on the surface of the multilayer dielectric substrate 3, and the central conductor 5 of the coaxial connector 2 corresponding to the inner conductor of the coaxial line is directly connected to the connection portion at the end of the strip conductor 7. It is connected to the. Conductor patterns 8a, 8b, 8c, and 8d that function as ground conductors of the microstrip line are formed on the inner layer of the multilayer dielectric substrate 3, and conductors that function as ground conductors of the microstrip line are formed on the back surface of the multilayer dielectric substrate 3. A pattern 8e is provided. The outer conductor (flange) of the coaxial connector 2 corresponding to the outer conductor of the coaxial line is conductively connected to the conductor pattern 8e via the housing 1.
Further, the distance from the connection portion of the strip conductor 7 to the coated conductor forming end of each conductor pattern 8a, 8b, 8c, 8d, 8e is gradually increased from the conductor pattern 8e on the back surface of the multilayer dielectric substrate 3 toward the surface. The microstrip line composed of the strip conductor 7 and the respective conductor patterns 8a, 8b, 8c, 8d, and 8e due to the difference in the position in the extending direction of the strip conductor 7 The microstrip lines have different intervals from the conductor.

Further, through-holes 9a, 9b, 9c, and 9d that form pairs as conductive means for conductively connecting at least adjacent conductive patterns of the conductive patterns 8a, 8b, 8c, 8d, and 8e are formed along the strip conductor 7 respectively. It is provided on both sides. The through hole 9a connects the conductor pattern 8a and the conductor pattern 8b, the through hole 9b connects the conductor pattern 8b and the conductor pattern 8c, the through hole 9c connects the conductor pattern 8c and the conductor pattern 8d, and the through hole 9d. Are a pair of through holes connecting the conductor pattern 8d and the conductor pattern 8e. Further, the distance between each pair of through holes 9a, 9b, 9c, 9d and the distance between adjacently arranged through holes in the extending direction of the strip conductor 7 are also within the multilayer dielectric substrate 3 at the frequency used. Theoretically, it is desirable to provide it so as to be less than half of the wavelength at. In this way, by setting the interval between the through holes to be an interval of less than ½ wavelength at the operating frequency, it is possible to prevent the propagation of the waveguide mode propagating by the pseudo waveguide composed of the conductor pattern and the through hole. .
1 and FIG. 2 exemplify the case where the through holes 9a, 9b, 9c, 9d provided as a pair are arranged on both sides at the same interval with respect to the strip conductor pattern 7, but the interval for each through hole is illustrated. May be different.
When actually manufacturing the transmission line conversion section, as shown in FIG. 2, the through holes 9a, 9b, 9c, 9d are formed through the multilayer dielectric substrate 3 from the front surface to the back surface. In this case, the interval between at least a pair of through holes may be set to be less than ½ wavelength at the used frequency.

Next, the operation of the transmission line conversion unit of the first embodiment will be described.
The high frequency signal input to the coaxial connector 2 propagates to the strip conductor pattern 7 through the center conductor 5. On the other hand, the ground current corresponding to the high-frequency signal flows from the outer conductor of the coaxial connector 2 to the conductor pattern 8e provided as a ground conductor on the back surface of the dielectric substrate 3 via the housing 1. The ground current flowing through the conductor pattern 8e flows from the conductor pattern 8e through the through hole 9d to the conductor pattern 8d, and further through the through hole 9c to the conductor pattern 8c, and through the through hole 9b to the conductor pattern 8b. Adjacent to the conductor pattern 8a through the hole 9a, the conductor pattern 8e on the back surface of the multilayer dielectric substrate 3 having the maximum distance from the strip conductor 7 of the microstrip line is gradually reduced from the strip conductor 7 to the adjacent conductor pattern 8a. A ground current sequentially flows through the arranged conductor patterns through the through holes.

  Here, with respect to the ground of the microstrip line, a parasitic reactance occurs in a portion where the ground is switched to a conductor pattern provided in a different layer through a through hole. As described above, the transmission line according to the first embodiment is used. In the conversion unit, the ground current is configured such that the conductor patterns are provided in different steps of the multilayer dielectric substrate 3 in a staircase pattern, and the ground current is switched by sequentially switching the ground layer by layer. The parasitic reactance per location can be reduced.

  In order to obtain better characteristics, the width of the strip conductor 7 is changed. That is, as the position in the extending direction of the strip conductor 7 is further away from the connection portion of the strip conductor 7 to which the central conductor 5 of the coaxial connector 2 is connected, the dielectric material is separated from the strip conductor 7 on the surface of the dielectric substrate 3. Although the distance to the back surface of the substrate 3 or the conductor pattern on the inner layer is narrowed, the width of the strip conductor 7 corresponds to the coated conductor forming end of each conductor pattern 8a, 8b, 8c, 8d according to the change. Since the width of the strip conductor 7 is reduced as the distance from the connecting portion of the strip conductor 7 is changed at the surface position of the multilayer dielectric substrate 3, the microstrip line is formed by reducing the distance from the strip conductor 7 to the conductor pattern. And the impedance of the microstrip line by reducing the width of the strip conductor 7. Temperature acts to cancel, it is possible to reduce the change in impedance as a microstrip line.

As described above, according to the transmission line conversion unit of the coaxial line and the microstrip line according to the first embodiment, the multilayer dielectric in which the outer conductor of the coaxial line is provided at the widest distance from the strip conductor of the microstrip line. Conductive connection is made with the conductor pattern on the back surface of the substrate 3, and the distance between the strip conductor 7 and each conductor pattern formed on the inner layer of the multilayer dielectric substrate 3 that becomes the ground conductor in the extending direction of the strip conductor 7 is sequentially changed. Since the microstrip line is configured and the ground current of the microstrip line is made to flow by switching the conductor pattern, the parasitic reactance can be reduced and the change in impedance as the microstrip line can be reduced.
Furthermore, by changing the width of the strip conductor 7 of the microstrip line, the change in impedance due to the change in the distance from the strip conductor 7 to the conductor pattern can be reduced, and the change in impedance as the microstrip line can be further reduced. .
Therefore, according to the transmission line conversion part of the coaxial line and the microstrip line in the first embodiment, the width and length of the strip conductor pattern 7, the conductor patterns 8b, 8c, 8d, and 8e and the through holes 9a, 9b, and 9c. , 9d can be easily adjusted by adjusting the arrangement.

Further, the transmission line conversion unit of the coaxial line and the microstrip line is configured as described above, and the transmission line conversion unit is formed by forming the transmission line conversion unit on the multilayer dielectric substrate on which the microwave circuit is formed. A microwave circuit having the same can be manufactured.
Furthermore, as shown in FIGS. 1 and 2, the microwave module can be manufactured by housing such a microwave circuit in a housing and providing a coaxial connector.
In the case of a microwave module, the transmission line converter and the microwave circuit may be formed on separate substrates and housed in a housing.
Also, a millimeter wave module can be manufactured by forming a transmission line conversion section on a dielectric substrate, forming a millimeter wave circuit on a separate substrate such as a GaAs substrate and storing it in a housing, and providing a coaxial connector.

  FIGS. 1 and 2 show the case where the central conductor of the coaxial connector is brought into direct contact with the connection portion of the strip conductor pattern to conduct electricity. However, a gold ribbon, solder, conductive adhesive or the like is interposed between the two. It may be used for conducting connection.

As described above, the transmission line conversion unit according to the first embodiment of the present invention does not require a separate part such as an intermediary substrate as in the conventional example. It is suitable for the production of a microwave circuit formed together with a circuit.
Furthermore, it is also suitable for manufacturing a millimeter wave circuit having a transmission line converter formed on a multilayer dielectric substrate and a transmission line converter formed by combining another circuit on another substrate such as a GaAs substrate if necessary. Yes.

Embodiment 2. FIG.
With reference to FIG. 3 and FIG. 4, the transmission line conversion part of the coaxial line and microstrip line concerning Embodiment 2 of this invention is demonstrated. 3 is a top view, and FIG. 4 is a cross-sectional view showing a cross section AA ′ in FIG.
The difference between the second embodiment and the first embodiment is that, in the transmission line conversion portion between the coaxial line and the microstrip line according to the second embodiment, the connection portion of the strip conductor 7 on the inner layer of the multilayer dielectric substrate 3 is different. An island-like conductor 10 is formed below, and a configuration in which the conductor pattern 8e formed on the back surface of the multilayer dielectric substrate 3 is conductively connected by through holes 11 provided on both sides of the central conductor 5 of the coaxial connector 2 is added. ing.
3 and 4 show the case where the island-like conductors 10 are provided in all the inner layers of the dielectric substrate 3, the structure may be provided only in some inner layers.
Other configurations are the same as those in FIGS. 1 and 2 of the first embodiment.

Next, the operation of the transmission line converter of the second embodiment will be described.
In the second embodiment, since the formed island-shaped conductor 10 is disposed under the portion of the center conductor 5 of the coaxial connector 2 that protrudes from the insulator 6, a capacitance is provided between the center conductor 5 and the island-shaped conductor 10. Occurs. Since the island-like conductor 10 is conductively connected to the conductor pattern 8e on the back surface of the dielectric substrate 3 through the through hole 11, this capacitance becomes a capacitance with respect to the ground, and the portion protruding from the insulator 6 of the center conductor 5 has. It acts to cancel out the inductance.
Therefore, it is possible to reduce the influence of the parasitic inductance caused by the central conductor 5 of the coaxial connector 2 corresponding to the inner conductor of the coaxial line, which is unavoidable in the production of the transmission line conversion portion of the coaxial line and the microstrip line.

As described above, according to the transmission line conversion unit according to the second embodiment, the portion protruding from the insulator 6 of the central conductor 5 of the coaxial connector 2 by providing the island-shaped conductor 10 that is conductively connected to the conductor pattern 8e. The effect of inductance can be reduced, and impedance matching at the transmission line converter is facilitated.
In other words, it is possible to ease the placement accuracy of the conductive connection between the inner conductor of the coaxial line and the strip conductor of the microstrip line, and the central conductor of the coaxial connector is brought into direct contact with the strip conductor pattern. Even when connecting using a conductive adhesive or the like, there is an effect that impedance matching at the transmission line conversion section becomes easy.
Moreover, since the transmission line conversion part which has such an effect is realizable, it is suitable for manufacture of the microwave circuit which formed the transmission line conversion part and the other circuit together in the multilayer dielectric substrate. Furthermore, it is also suitable for manufacturing a millimeter wave circuit having a transmission line converter formed on a multilayer dielectric substrate and a transmission line converter formed by combining another circuit on another substrate such as a GaAs substrate.
In addition, the microwave circuit or millimeter wave circuit having such a transmission line conversion unit, and the microwave module or millimeter wave module including such a circuit and a casing having a coaxial connector are easily manufactured. There is an effect that good characteristics can be realized.

  In the above description, the direction in which the signal is transmitted from the coaxial line to the microstrip line has been described. However, the transmission line conversion unit is generally reversible, and according to the transmission line conversion unit according to the present invention, the signal is microscopic. The same effect can be obtained in the direction of transmission from the strip line to the coaxial line for the reason described above.

It is a top view which shows the structure of the transmission line conversion part of the coaxial line and microstrip line concerning Embodiment 1 of this invention. It is sectional drawing which shows the A-A 'cross section in FIG. It is a top view which shows the structure of the transmission line conversion part of the coaxial line concerning Embodiment 2 of this invention, and a microstrip line. It is sectional drawing which shows the A-A 'cross section in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Case, 2 Coaxial connector, 3 Multilayer dielectric board, 4 Connector mounting hole, 5 Center conductor, 6 Insulator, 7 Strip conductor, 8a, 8b, 8c, 8d, 8e Conductor pattern, 9a, 9b, 9c, 9d Through hole, 10 island conductor, 11 through hole.

Claims (7)

A transmission line conversion unit for a coaxial line and a microstrip line, formed on the surface of the multilayer dielectric substrate, and having a connection portion for providing a conductive connection with at least the inner conductor of the coaxial line, and a strip conductor of the microstrip line, Each of the back surface of the multilayer dielectric substrate and at least the plurality of inner layers is formed such that a distance from the connection portion of the strip conductor to a conductor forming end is sequentially increased from the back surface to the surface of the multilayer dielectric substrate, and at least A conductor pattern including a conductor pattern formed on the back surface of the multilayer dielectric substrate as a ground conductor for conducting connection with the outer conductor of the coaxial line, and a pair of both sides of the strip conductor are provided. One or more pairs are at intervals of less than ½ wavelength at the operating frequency, and at least adjacent conductor patterns of each of the conductor patterns. Transmission line converter unit, characterized in that it comprises a connection means for conducting connecting over down together, the. 2. The transmission line conversion unit according to claim 1, wherein the conductor pattern is formed on an inner layer of the multilayer dielectric substrate below the connection portion, separately from the conductor pattern, and formed on the back surface of the multilayer dielectric substrate. A transmission line converter comprising an island-like conductor that is conductively connected to the transmission line. 3. The transmission line converter according to claim 1, wherein the width of the strip conductor is at least a surface of the multilayer dielectric substrate corresponding to a position where the coated conductor is formed on each of the conductor patterns formed on the inner layer of the multilayer dielectric substrate. A transmission line conversion section that changes in position and narrows the width of the strip conductor as it is separated from the connection site. A microwave circuit having the transmission line conversion unit according to claim 1. A millimeter wave circuit having the transmission line converter according to claim 1, 2 or 3. A housing having a coaxial connector, wherein the microwave circuit according to claim 4 is housed, an inner conductor is conductively connected to the connection portion, and an outer conductor is conductively connected to a conductor pattern formed on a back surface of the multilayer dielectric substrate. A microwave module with a body. A housing having a coaxial connector that houses the millimeter wave circuit according to claim 5, wherein an inner conductor is conductively connected to the connection portion, and an outer conductor is conductively connected to a conductor pattern formed on a back surface of the multilayer dielectric substrate. Millimeter wave module with body.

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