JPH036902A - Connection structure between coaxial cable and microstrip line - Google Patents

Abstract

PURPOSE:To cancel the impedance change in a section penetrating through a dielectric board with a matching stub and to obtain excellent matching by providing the matching stub to a joint of a microstrip line to which an inner conductor of the coaxial cable connects electrically. CONSTITUTION:A ground plate 2 made of a conductive metal is arranged to a rear side of a dielectric board 1 and a microstrip line 3 made of a conductive metallic thin film is arranged to the front side. Then a coaxial cable connector 5 is electrically connected to the ground plate 2 with soldering or the like and its core wire 6 is connected electrically to the microstrip line 3 with soldering or the like through a throughhole 4. A matching stub 10 is provided to a joint of the core wire 6 to which the microstrip line 3 connected electrically on the front side of the dielectric board 1. Then when the core wire 6 passing through the electric board 1 is subject to impedance change to be inductive, the matching stub 10 is formed capacitive in terms of the microwave signal to be sent to cancel the inductive component.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a connection structure between a coaxial cable and a microstrip line with excellent matching.

(Prior Art) In recent years, communication technology using microwave signals has developed rapidly. Small and lightweight microstrip lines are commonly used in circuits that process these microwave band signals. Furthermore, coaxial cables are commonly used as cables for transmitting microwave signals. Therefore, a structure is required to connect the microstrip line and coaxial cable without transmission loss.

Here, an example of a conventional connection structure between a coaxial cable and a microstrip line will be described with reference to FIGS. 1O and 11. FIG. 10 is an external perspective view of a conventional coaxial cable and microstrip line connection structure,
FIG. 11 is an enlarged cross-sectional view taken along the line A-A in FIG. 1O.

In Figures 1θ and 11, low permittivity (ε≦10
) A ground plate 2 made of a conductive metal is disposed on the back surface of a dielectric substrate l, and a microstrip line 3 made of a conductive metal thin film is disposed on one surface. A through hole 4 passing through the dielectric substrate 1 and the ground plate 2 is bored at the end of the microstrip line 3. Incidentally, it is desirable that the ground plate 2 be removed around the through hole 4 to an appropriate width. A coaxial cable connector 5 is electrically connected to the ground plate 2 by soldering or the like, and its core wire 6 passes through the through hole 4 and is electrically connected to the microstrip line 3 by soldering or the like.

In this configuration, the coaxial cable 7 can be freely connected to and separated from the microstrip line 3 via the coaxial cable connector 5.

(Problems to be Solved by the Invention) By the way, both the coaxial cable and the microstrip line 3 are designed to have an impedance of, for example, 50Ω. And coaxial cable connector 5
are also designed to have an impedance of 50Ω, so there should be no mismatch caused by these connections.

However, in reality, the section where the core wire 6 of the coaxial cable connector 5 penetrates the dielectric substrate 1 does not have a coaxial structure, and the impedance changes in this section, resulting in the impedance not being 50Ω as designed. , a problem arises in that sufficient matching cannot actually be obtained between the coaxial cable connector 5 to which the coaxial cable 7 is connected and the microstrip line 3. This is done by passing the internal conductor of the coaxial cable 7 through the dielectric substrate 1 without using the coaxial cable connector 5 to form the microstrip line 3.
The same is true even if the device is electrically connected directly to the device. Such mismatch becomes more significant as the thickness d of the dielectric substrate 1 increases.

The present invention was made to solve the problems of the conventional connection structure between a coaxial cable and a microstrip line, and based on the knowledge that impedance changes occur in the core wire or internal conductor that penetrates the dielectric substrate. It is an object of the present invention to provide a connection structure between a coaxial cable and a microstrip line in which matching can be easily obtained by providing a matching stub or matching pattern that cancels impedance changes.

(Means for Solving the Problems) In order to achieve the above object, the coaxial cable and microstrip line connection structure of the present invention connects the outer conductor of the coaxial cable to a ground plate disposed on the back surface of a dielectric substrate. the internal conductor of the coaxial cable is electrically connected to a microstrip line disposed on the surface of the dielectric substrate, and a matching stub is provided on the microstrip line at this connection part. ing.

Then, the outer conductor of the coaxial cable is electrically connected to a 7-rank member made of conductive metal, the flange member is electrically connected to the ground plate, and the inner conductor of the coaxial cable is passed through the dielectric substrate. Alternatively, the microstrip connector may be electrically connected directly to the microstrip connector.

Further, a portion of the dielectric substrate is removed, the outer conductor of the coaxial cable is fixed to the front side of the removed portion using a holding fitting for electrical connection, and the inner conductor is arranged on the edge of the removed portion. The microstrip line may be electrically connected to the microstrip line.

In addition, first and second dielectric substrates are stacked with a ground plate in between, a portion of the first dielectric substrate is removed to expose the ground plate, and the exposed ground plate is used to connect the coaxial cable to the outside of the coaxial cable. conductors are electrically connected, the internal conductor of the coaxial cable is passed through the second dielectric substrate and electrically connected to a matching pattern provided on the surface of the second dielectric substrate, and the matching the microstrip conductor pattern disposed on the surface of the first dielectric substrate is electrically connected to the conductive pin passing through the first and second dielectric substrates and the ground plate. You can also do that.

(Function) Since a matching stub is provided at the connection part of the microstrip line where the internal conductor of the coaxial cable is electrically connected, the matching stub can cancel out impedance changes in the section that passes through the dielectric substrate. Consistency is obtained.

If the outer conductor of the coaxial cable is connected to the ground plate via a flange member made of conductive metal, and the inner conductor is electrically connected directly to the microstrip line, there is no need for a coaxial cable connector, and the structure is easy.

Furthermore, if the outer conductor of the coaxial cable is fixed to the ground plate using a holding fitting, the structure is even simpler, and the coaxial cable can be arranged parallel to the surface of the dielectric substrate.

In addition, the first and second dielectric substrates are stacked with a ground plate in between, and the coaxial cable is connected to the first dielectric substrate via the matching pattern arranged on the surface of the second dielectric substrate. If connecting to a microstrip line provided on the surface, the coaxial cable and microstrip cable can be placed on the same side of the dielectric substrate, and a microstrip condenser etc. can be placed on the surface of part 2 of the dielectric substrate. Coaxial cables can be easily disposed of when

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an external perspective view of a first embodiment of the coaxial cable and microstrip line connection structure of the present invention, and FIG. 2 is an enlarged cross-sectional view taken along the line B--B in FIG. 1. In FIGS. 1 and 2, the same or equivalent members as in FIGS. 1O and 11 are given the same reference numerals, and redundant explanation will be omitted.

1 and 2, the difference from the conventional type shown in FIG. 1θ and FIG.
The matching stub 1O is provided at the connection portion where the is electrically connected. For example, if the core wire 6 passing through the dielectric substrate 1 changes in impedance and becomes inductive, the matching stub IO is formed capacitively with the microwave signal to be transmitted so as to cancel the inductance component.

In the multi-hook configuration, even if an impedance change occurs in the core wire 6 passing through the dielectric substrate 1, 1. The matching stub IO allows impedance adjustment, and matching between the microstrip line 3 and the coaxial cable 7 (or the coaxial cable connector 5) can be easily obtained. Furthermore, the coaxial cable connector 5 allows the coaxial cable 7 to be easily connected and separated.

3 and 4 show a second embodiment of the coaxial cable and microstrip line connection structure of the present invention,
FIG. 3 is an external perspective view of the second embodiment, and FIG. 4 is a
FIG. 4 is an enlarged cross-sectional view taken along the line CC in FIG. 3; In FIGS. 3 and 4, the same or equivalent members as in FIGS. 1 and 2 are given the same reference numerals and redundant explanations will be omitted.

In Figures IJ3 and 4, a hole is bored in the center of the flange member 11 made of conductive metal, and the outer conductor 12 of the coaxial cable 7 passes through this hole.
An electrical connection is made by soldering, etc. This flange member 11 is electrically connected to the ground plate 2 by soldering, screwing, or the like. Further, the internal conductor 13 of the coaxial cable 7 passes through the through hole 4 of the dielectric substrate 1 and is directly electrically connected to the microstrip line 3 by soldering or the like. A matching stub 10 is provided at the connection portion of the microstrip line 3.

This configuration does not require the coaxial cable connector 5 as in the embodiment shown in FIGS. The impedance is as stable as in the case where it is used, making it suitable for production. Furthermore, matching can be easily achieved using the matching stub IO.

5 to 7 show a third embodiment of the coaxial cable and microstrip line connection structure of the present invention,
FIG. 5 is a plan view of the third embodiment, FIG. 6 is a sectional view taken along the line D-D in FIG. 5, and FIG. 7 is a sectional view taken along the line E-E in FIG. h45. It is.

In FIGS. 5 to 7, a portion of the dielectric substrate 1 is removed at the periphery of the laminated member of the dielectric substrate 1 and the ground plate 2. As shown in FIG. Then, the outer conductor 12 of the coaxial cable 7 from which the insulation coating has been removed at the tip is pressed onto the ground plate 2 by the press fitting 21 on the front side of the removed portion 20, thereby being electrically connected and fixed. Furthermore, the internal conductor 13 exposed at the tip is electrically connected to the microstrip line 3 by soldering. Note that a matching stub lO is provided at the connection portion of the microstrip line 3. Further, the presser metal fitting 21 is fixed to the ground plate 2 with screws or the like.

In such a configuration, an impedance change occurs until the inner conductor 13 exposed from the outer conductor 12 is connected to the microstrip line 3, but matching is achieved by the matching stub 10. Furthermore, the structure is simple and can be constructed at extremely low cost.

Furthermore, the coaxial cable 7 is arranged parallel to the surface of the dielectric substrate 1, which is advantageous for making the device thinner.

8 and 9 show a fourth embodiment of the coaxial cable and microstrip line connection structure of the present invention,
FIG. 8 is an external perspective view of the fourth embodiment, and FIG. 9 is an enlarged cross-sectional view taken along line FF in FIG.

In FIGS. 8 and 9, the first and 'J42 dielectric substrates 30, 31 are stacked with the ground plate 2 in between. Then, a portion of the first dielectric substrate 30 is removed to expose the ground plate 2, and the ground plate 2 and the second
A through hole 4 is bored through the dielectric substrate 31 . Further, a coaxial cable connector 5 is electrically connected to the ground plate 2 of the removal part 32 by soldering or the like, and a core wire 6 is made of a conductive metal thin film disposed on the surface of the second dielectric substrate 31. Electrical connection is made to the matching pattern 33 by soldering or the like.

Furthermore, microstrip lines 34 and 34 are arranged on the surface of the first dielectric substrate 30. Then, through holes 35, 35 are bored through the ground plate 2, the first and second dielectric substrates 30.31, the matching layer pattern 33, and the microstrip lines 34.34, and conductive pins made of conductive metal are formed. 36 and 38 are inserted into the through holes 35 and 35, and both ends thereof are electrically connected to the matching pattern 33 and the microstrip lines 34 and 34 by soldering.

In such a configuration, for example, a microstrip resonator or the like (not shown) is disposed on the surface of the second dielectric substrate 31, and a microstrip resonator or the like is disposed on the surface of the first dielectric substrate 30. Microstrip lines 34, 34 for power supply are provided. The coaxial cable 7 can then be provided on the same side of the microstrip line 34, 34 and the dielectric substrate. Moreover, the matching pattern 33
Accordingly, the coaxial cable 7 can be easily aligned with the microstrip line 34, 34.

(Effects of the Invention) Since the coaxial cable and microstrip line connection structure of the present invention is configured as described above, the following effects can be achieved.

In the coaxial cable and microstrip line connection structure according to the first aspect, the matching stub cancels impedance changes in the section passing through the dielectric substrate, and matching can be easily achieved. Therefore, microwaves can be transmitted between the microstrip line and the coaxial cable without being attenuated.

In the connection structure between a coaxial cable and a microstrip line according to claim 2, an expensive coaxial cable connector is not required, and although the structure is simple, the impedance is as stable as that using a coaxial cable connector. It is easy to obtain matching and is suitable for mass production.

Furthermore, in the connection structure of a coaxial cable and a microstrip line according to claim 3, the structure is even simpler, and the coaxial cable can be arranged parallel to the surface of the dielectric substrate, which is advantageous for making the device thinner. It is.

In addition, in the connection structure of a coaxial cable and a microstrip line according to claim 4, the coaxial cable can be disposed on the side of the dielectric substrate where the microstrip line is disposed, and the microstrip resonance can be caused on the other surface. There is no need to route the coaxial cable on the microstrip resonator side when installing equipment, etc., making it easier to dispose of the coaxial cable.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a first embodiment of the coaxial cable and microstrip line connection structure of the present invention;
FIG. 2 is an enlarged cross-sectional view taken along the line B-B in FIG.
Figure 5 is an external perspective view of the second embodiment of the coaxial cable and microstrip line connection structure of the present invention;
The figures are an enlarged cross-sectional view taken along the line CC in FIG. 3, FIG. 5 is a plan view of a third embodiment of the coaxial cable and microstrip line connection structure of the present invention, and FIG. is a sectional view taken along line D-D in FIG. 5, and FIG. 7 is a cross-sectional view taken along line E in FIG.
8 is an external perspective view of the fourth embodiment of the coaxial cable and microstrip line connection structure of the present invention, and FIG. F
FIG. 10 is an enlarged cross-sectional view taken along arrows, FIG. 1O is an external perspective view of a conventional coaxial cable and microstrip line connection structure, and FIG. 11 is an enlarged cross-sectional view taken along line A-A of FIG. 1O. . 1.30.31: Dielectric substrate, 2 Nigerland plate, 3.
34: Microstrip line, 4.35: Through hole, 5: Coaxial cable connector, 6: Core wire, 7: Coaxial cable. lO: alignment stub, 11: flange member, 12:
Outer conductor, 13: Inner conductor, 20.32: Removal part, 21: Holding metal fitting, 33: Matching pattern,
36: Conduction pin. Figure 1

Claims (4)

[Claims] (1) The outer conductor of the coaxial cable is electrically connected to the ground plate arranged on the back surface of the dielectric substrate, and the inner conductor of the coaxial cable is electrically connected to the microstrip line arranged on the surface of the dielectric substrate. A connection structure for a coaxial cable and a microstrip line, characterized in that the coaxial cable and the microstrip line are connected to each other, and a matching stub is provided on the microstrip line at this connection part. (2) In the coaxial cable and microstrip line connection structure according to claim 1, the outer conductor of the coaxial cable is electrically connected to a flange member made of a conductive metal, and the flange member is electrically connected to the ground plate. The coaxial cable and microstrip line connection structure is further characterized in that the internal conductor of the coaxial cable is electrically connected directly to the microstrip line by passing through the dielectric substrate. (3) In the coaxial cable and microstrip line connection structure according to claim 1, a portion of the dielectric substrate is removed, and the outer conductor of the coaxial cable is electrically connected to the front side of the removed portion using a holding fitting. A connection structure for a coaxial cable and a microstrip line, characterized in that the inner conductor is electrically connected to the microstrip line disposed at the edge of the removed portion. (4) First and second dielectric substrates are stacked with a ground plate in between, a portion of the first dielectric substrate is removed to expose the ground plate, and a coaxial cable is connected to the exposed ground plate. an outer conductor is electrically connected, an inner conductor of the coaxial cable is passed through the second dielectric substrate and electrically connected to a matching pattern disposed on a surface of the second dielectric substrate; A matching pattern and a microstrip line disposed on the surface of the first dielectric substrate are electrically connected via a conductive pin passing through the first and second dielectric substrates and the ground plate. A connection structure for coaxial cables and microstrip lines.