JP2008227720A - Transmission line connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform impedance matching at a connection part between boards by reducing transmission loss. <P>SOLUTION: In a transmission line connection structure, a pair of microstrip line boards 3a and 3b where center conductors 4a and 4b are provided on a conductive board are placed in a case 2a as a conductive base material with prescribed air gaps A and end points of the center conductors 4a, 4b between a pair of microstrip line boards 3a and 3b are connected by a line connection conductor 5 having conductivity. An air gap 6A between the pair of microstrip line boards 3a and 3b is filled with by adhesive 7 whose dielectric constant is larger than 1 in a state that the whole line connection conductors 5 is covered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission line connection structure that stabilizes the characteristic impedance of a connection portion between substrates such as a microstrip type transmission line and a coplanar type transmission line and reduces transmission loss.

  Conventionally, microwaves are used in various electronic devices such as communication / measurement / radar devices using microwave / millimeter waves such as mobile communication devices such as analog / digital mobile phones and PHS terminals, wireless LANs, and in-vehicle radar devices. An integrated circuit (MMIC: Microwave Monolithic Integrated Circuit) is used. This MMIC includes, for example, a field effect transistor (FET) formed on an insulating substrate and a transmission line for transmitting a signal.

As the transmission line, for example, a microstrip type transmission line having a conductor wire or a conductor ribbon on the surface of the insulating substrate and a ground conductor on the back surface, or a coplanar in which both the wiring and the ground conductor are formed on the surface of the insulating substrate. Type transmission lines are known. When a 50Ω transmission line is constructed, it is designed such that (L / C) ^1/2 per unit length is 50 in any minute section. However, when constructing such a 50Ω transmission line, an inductor component is generated in the wiring of each board connection part and the wiring between the board and the MMIC, and the impedance of the connection part between the boards is far from 50Ω due to this inductor component. It was difficult to match.

  The cause of this impedance mismatch is considered to be that the inductor (L) component is large, the conductor (C) component is small, or a combination thereof. For this reason, by shortening the wiring between the boards and between the board and the MMIC, increasing the number of wirings, and further increasing the dimensions of the PAD, the inductor component of the wiring is canceled, and the total impedance is 50Ω. The method to be used was used. However, when the above method is adopted, the inductor component is somewhat reduced by increasing the number of wirings. However, when the number exceeds the predetermined number, the effect is not changed, and only the low-frequency impedance can be improved. was there. As another method for solving the above problem, for example, a method disclosed in Patent Document 1 is known.

  Patent Document 1 describes a form of a microwave circuit in which microstrip line substrates are connected to each other and a form of a microwave circuit in which coplanar line substrates are connected in place of the microstrip line substrate. 9 and 10 show a configuration of a microwave circuit in which microstrip line substrates are connected to each other. 9 and 10, 101a and 101b are metal blocks, 102 is a case or chassis, 103 is a wiring such as a conductor ribbon or a conductor wire, 104a and 104b are microstrip line substrates, 105a and 105b are dielectric substrates, 106a, 106b is a strip conductor, 107 is a gap, 108a and 108b are ground conductors, and 109 is a resin adhesive such as a silicon-based adhesive.

  9 and 10, microwaves or millimeter waves can be transmitted between the microstrip line substrates without being reflected, and a predetermined gap is provided between the microstrip line substrates. Even if the microstrip line substrate expands and contracts with respect to the ambient temperature change of the wave circuit, the microstrip line substrate can be prevented from being damaged due to interference. Further, the microstrip line substrate is not required to be processed as it is in the past, and can be filled while adjusting the material and amount of the resinous adhesive, so that impedance matching can be easily adjusted and workability is improved.

  11 and 12 show the configuration of a microwave circuit in which coplanar line substrates are connected to each other. 11 and 12, 105c and 105d are dielectric substrates, 106c and 106d are strip conductors formed on the top surfaces of the dielectric substrates 105c and 105d, and 108c to 108f are ground conductors. In the figure, reference numerals 101a, 101b, 102, 103, 107 and 109 are the same as those described in FIGS.

In this case as well, microwaves or millimeter waves can be transmitted without being reflected between the coplanar line substrates, and a predetermined gap is provided between the coplanar line substrates to prevent changes in the ambient temperature of the microwave circuit. Even if the coplanar line substrate expands and contracts, damage due to interference of the coplanar line substrate can be prevented. Moreover, it can be filled while adjusting the material and amount of the resin adhesive, and impedance matching can be easily adjusted to improve workability.
Japanese Patent Laid-Open No. 10-256801

  The microwave circuit in the microstrip line substrate disclosed in Patent Document 1 is filled with a resin adhesive in order to reduce the impedance between the wiring and the ground conductor (GND). However, in this configuration, a gap made of an air layer having a relative dielectric constant of 1 is interposed between the wiring and the resin adhesive. For this reason, there is a problem that the capacitance becomes the minimum with respect to the ground conductor, and as a result, impedance matching cannot be achieved. Similarly, even in a microwave circuit using a coplanar line substrate, there is a gap composed of an air layer having a relative dielectric constant of 1 between the wiring between the strip conductors and the wiring between the ground conductors. It was not consistent.

  Therefore, the present invention has been made in view of the above problems, and for example, a transmission line connection structure capable of reducing an inductor component generated at a connection portion between substrates in a microwave / millimeter wave circuit and matching with a desired impedance. Is intended to provide.

In order to achieve the above-described object, the transmission line connection structure according to claim 1 is configured such that a pair of microstrip line substrates 3a and 3b provided with central conductors 4a and 4b on a dielectric substrate are electrically connected at a predetermined interval. In the transmission line connection structure in which the end points of the central conductor between the pair of microstrip line substrates are connected by the line connection conductor 5, disposed on the conductive base material 2a,
An adhesive 7 having a relative dielectric constant greater than 1 is filled in an air gap 6A between the pair of microstrip line substrates in a state where all of the line connecting conductors 5 are covered together.

In the transmission line connection structure according to claim 2, the center conductors 4c and 4d are provided in the central portion of the upper surface of the dielectric substrate, and the ground conductors 9a, 9b, 9c and 9d are provided at predetermined intervals on both sides of the center conductor. A pair of provided coplanar line substrates 8a and 8b are arranged on the conductive substrate 2b with a predetermined interval therebetween, and the end points of the central conductor and the end points of the ground conductor between the pair of coplanar line substrates are line connecting conductors. In the transmission line connection structure connected at 5,
At least all of the line connecting conductors are collectively covered with an adhesive 7 having a relative dielectric constant greater than 1.

The transmission line connection structure according to claim 3 includes a microstrip line substrate 3c having a center conductor 4e provided on a dielectric substrate, a center conductor 4f disposed at a central portion of the upper surface of the dielectric substrate, and the center conductor. The MMIC 10 having a coplanar line structure with ground conductors 9e and 9f provided at predetermined intervals on both sides of the microstrip line substrate is disposed on the conductive substrate 2d with a predetermined interval between the central conductor of the microstrip line substrate and the MMIC. In the transmission line connection structure in which the line connection conductor 5 connects the center conductor of the MMIC and between the ground conductor of the MMIC and the conductive base material,
An adhesive 7 having a relative dielectric constant greater than 1 is filled in an air gap 6C between the microstrip line substrate and the MMIC in a state where all the line connection conductors are covered together.

  According to the transmission line connection structure of the present invention, with respect to the connection between a pair of coplanar line substrates, at least all of the line connection conductors are collectively covered with an adhesive having a relative dielectric constant greater than 1, and the pair As for the connection between the microstrip line substrates and the connection between the microstrip line substrate and the MMIC having a coplanar line structure, the air between the substrates and between the substrate and the MMIC is covered with all the line connection conductors covered together. By adopting a configuration in which the gap is filled with an adhesive having a relative dielectric constant greater than 1, it is possible to prevent all the line connecting conductors from coming into direct contact with the air and to increase the size of each line connecting conductor in a minute area. It is possible to provide a highly reliable transmission line connection structure with a capacitance and impedance matching.

  Hereinafter, the transmission line connection structures of the first to third embodiments, which are the best mode for carrying out the present invention, will be described in detail with reference to the accompanying drawings.

  1 is a plan view for explaining a first embodiment of a transmission line connection structure according to the present invention, FIG. 2 is a sectional view of the transmission line connection structure in the first embodiment, and FIG. 3 is a transmission line connection structure in the first embodiment. The figure which shows the change of the characteristic impedance which concerns on the electrical characteristic evaluation experiment with the conventional transmission line connection structure, FIG. 4 is a top view for demonstrating the 2nd form of the transmission line connection structure which concerns on this invention, FIG. FIG. 6 is a sectional view for explaining another configuration in the second embodiment, and FIG. 7 is a plan view for explaining a third embodiment of the transmission line connecting structure according to the present invention. 8 and 8 are sectional views of the transmission line connection structure in the third embodiment.

  First, a first embodiment of a transmission line connection structure according to the present invention will be described with reference to FIGS. The transmission line connection structure of the first form is a transmission line connection structure between a pair of microstrip line substrates mounted on the transmission line module 1a.

  The transmission line connection structure of the first embodiment uses a metal case 2a that also serves as a ground conductor (GND) shielded so as to block unnecessary radio waves such as high-frequency noise as a conductive base material. A pair of microstrip line substrates 3a and 3b made of a dielectric material are attached to the case 2a, which is a conductive base material, with an air gap A having a predetermined interval therebetween. A central conductor 4a for transmitting microwaves or millimeter waves is provided at the center of the upper surface of the microstrip line substrate 3a. Similarly, a central conductor 4b for transmitting microwaves or millimeter waves is also provided at the center of the upper surface of the microstrip line substrate 3b so as to face the central conductor 4a. And between the central conductors 4a and 4b provided on the pair of microstrip line substrates 3a and 3b, there are conductive line connection conductors 5 (three wires in the example of FIG. 1) such as conductor wires and conductor ribbons. It is connected.

  Further, as shown in FIG. 2, the air gap 6A portion having the width of the center conductor 4a (4b) in the air gap A covers all the line connection conductors 5 connecting the end points of the center conductors 4a and 4b together. However, the adhesive 7 is filled so as to reach the surface of the case 2a. Thereby, all the line connection conductors 5 connecting the end points of the center conductors 4a and 4b are prevented from directly touching the air. The adhesive 7 is preferably a material having a low dielectric loss and a relative dielectric constant of greater than 1. Specifically, an acrylic or epoxy ultraviolet curable adhesive that generates as little organic outgas as possible during or after curing is preferable.

  In the transmission line connection structure of the first form configured as described above, microwaves or millimeter waves input to the transmission line module 1a are transmitted from the central conductor 4a (4b) to the central conductor 4b (4a) via the line connection conductor 5. is doing.

  In the first embodiment described above, a ground conductor (not shown) serving as a reference potential point with an electric conductor is provided on the lower surface of the pair of microstrip line substrates 3a, 3b, and the pair of microstrip line substrates 3a, 3b, Even if the air gap 6A is filled with the adhesive 7 in a state where all the line connecting conductors 5 connecting the central conductors 4a and 4b provided on the upper surface of the 3b are covered, the same effect as the above-described embodiment can be obtained. .

  Moreover, in the example of FIG.1 and FIG.2, although it was set as the structure which fills the air gap 6A (a part of air gap A) with the adhesive agent 7 in the state which coat | covered all the line connection conductors 5 collectively, The adhesive 7 may be filled in the entire air gap A in a state where the connection conductors 5 are collectively covered.

  Next, a characteristic impedance evaluation experiment between the transmission line connection structure of the first embodiment described above and a transmission line connection structure between the conventional microstrip line substrates (a structure without the adhesive 7) will be described.

  In this experiment, an air gap between microstrip line substrates as a 50Ω transmission line is set to 130 μm, an ultraviolet curable adhesive is used as the adhesive 7, and three Au wires (φ20 μm) are wired to the line connecting conductor 5. Evaluated. Specifically, a central conductor of a connector (not shown) provided on the metal case 2a is connected to a central conductor 4a (4b) of the microstrip line. And using TDR (Time Domain Reflectometer), the output signal from TDR was inputted through the connector of the metal case, and the reflection characteristic with respect to the output signal was measured.

  As shown in FIG. 3, in the transmission line connection structure employing the conventional microstrip line substrate, the characteristic impedance Z = 55.1 [Ω], whereas the transmission line connection structure in the first embodiment of the present example. The characteristic impedance Z = 53.2 [Ω]. As a result, by filling the air gap between the microstrip line substrates with the adhesive 7 so as to cover all the line connection conductors 5 as in the transmission line connection structure of the first form of this example, The characteristic impedance could be further reduced compared to the conventional transmission line connection structure.

  Next, a second embodiment of the transmission line connection structure according to the present invention will be described with reference to FIGS. The transmission line connection structure of a 2nd form is a transmission line connection structure between a pair of coplanar line board | substrates (Coplanar Waveguide: CPW) mounted in the transmission line module 1b. In the second embodiment described below, the same components as those in the first embodiment described above will be described with the same reference numerals.

  As shown in FIG. 4 or 5, the transmission line connection structure of the second form conducts a metal case 2 b that also serves as a ground conductor (GND) shielded so as to block unnecessary radio waves such as high-frequency noise. It is used as a base material. A pair of coplanar line substrates 8a and 8b made of a dielectric material are fixedly attached to the case 2b, which is a conductive base material, with an air gap B at a predetermined interval. A central conductor 4c for transmitting microwaves or millimeter waves is provided at the center of the upper surface of the coplanar line substrate 8a. In addition, ground conductors 9a and 9b are provided on both sides of the center conductor 4c with a predetermined interval. Similarly, a central conductor 4d for transmitting microwaves or millimeter waves is also provided at the central portion of the upper surface of the coplanar line substrate 8b so as to face the central conductor 4c. The ground conductors 9c and 9d are also provided on both sides of the central conductor 4d so as to face the ground conductors 9a and 9b with a predetermined interval. Between the end points of the central conductors 4c and 4d provided on the upper surfaces of the pair of coplanar line substrates 8a and 8b and between the end points of the ground conductors 9a and 9c and the end points of the 9b and 9d, for example, a conductor wire or a conductor ribbon These are connected by line connecting conductors 5 having conductivity such as 5 (in the example of FIG. 4, 5 wires).

  Further, as shown in FIG. 5, all line connections for connecting the end points of the central conductors 4c and 4d provided on the upper surface of the pair of coplanar line substrates 8a and 8b and the end points of the ground conductors 9a, 9b, 9c and 9d are connected. An adhesive 7 is filled so as to cover the conductors 5 together. This prevents all the line connection conductors 5 connecting the end points of the center conductors 4c and 4d and the end points of the ground conductors 9a, 9b, 9c and 9d from directly touching the air. As described above, the adhesive 7 is preferably made of a material having a low dielectric loss and a relative dielectric constant of greater than 1, and specifically, an acrylic or epoxy ultraviolet curable adhesive can be used.

  In the transmission line connection structure of the second form configured as described above, the microwave or the millimeter wave input to the transmission line module 1b is transmitted from the central conductor 4c (4d) to the central conductor via the line connection conductor 5 as in the first form. 4d (4c).

  By the way, as a coplanar line, in addition to the ground conductors 9a, 9b, 9c and 9d in the second embodiment, a grounded coplanar line substrate 8c in which a metal case 2c as a conductive base material also serves as a ground conductor (GND). , 8d (grounded CPW) is also known. In this configuration, since the radio waves from the central conductors 4c and 4d reach not only the ground conductors 9a, 9b, 9c and 9d but also the case 2c, the adhesive 7 is applied to all the line connecting conductors 5 as shown in FIG. In addition, the adhesive 7 is filled into the air gap 6B between the pair of grounded coplanar line substrates 8c and 8d so as to cover the surface of the case 2c.

  Similar to the first embodiment, the coplanar line substrates 8a and 8b are provided with a ground conductor (not shown) serving as a reference potential point on the lower surface of the electric conductor, or the grounded coplanar line substrates 8c and 8d. The bottom surface is provided with a ground conductor (not shown) serving as a reference potential point with an electric conductor, and the adhesive 7 is filled in the air gap 6B or the entire air gap B with all the line connection conductors 5 covered together. Even so, the same effect as the above-described embodiment can be obtained.

  Next, a third embodiment of the transmission line connection structure according to the present invention will be described with reference to FIGS. The transmission line connection structure of the third form is a transmission line connection structure between a microstrip line substrate mounted on the transmission line module 1d and a microwave integrated circuit (hereinafter referred to as MMIC) having a coplanar line structure. In the third embodiment described below, the same components as those in the first embodiment and the second embodiment described above will be described with the same reference numerals.

  As shown in FIG. 7 and FIG. 8, the transmission line connection structure in the third embodiment is made of a conductive metal case 2d that also serves as ground (GND) shielded so as to block unnecessary radio waves such as high-frequency noise. It is used as a base material. A microstrip line substrate 3c made of a dielectric having a central conductor 4e at the central portion of the upper surface is fixedly attached on the case 2d forming the conductive base material.

  On the metal case 2d, the MMIC 10 is fixedly attached with an air gap C of a predetermined interval so as to be close to the microstrip line substrate 3c. This MMIC 10 has a coplanar line structure in which a central conductor 4f for transmitting microwaves or millimeter waves is provided at the center of the upper surface, and ground conductors 9e and 9f are provided on both sides of the central conductor 4f with a predetermined interval therebetween. is there. The central conductor 4e provided on the microstrip line substrate 3c and the central conductor 4f of the MMIC 10 are connected by a conductive line connecting conductor 5 such as a conductor wire or a conductor ribbon. Similarly, the line connection conductor 5 connects between the case 2d and the ground conductors 9e, 9f provided in the MMIC 10 as well.

  Further, as shown in FIG. 8, the air gap 6C (a part of the air gap C) between the microstrip line substrate 3c and the MMIC 10 includes the MMIC 10 and the case 2d between the microstrip line substrate 3c and the MMIC 10. The adhesive 7 is filled so as to cover the surface of the case 2d in a state in which all the line connection conductors 5 connecting them are collectively covered. Thereby, all the line connection conductors 5 connected between the microstrip line substrate 3c and the MMIC 10 and between the MMIC 10 and the case 2d are prevented from directly touching the air. As described above, the adhesive 7 is preferably made of a material having a small dielectric loss and a relative dielectric constant larger than 1. In particular, in the connection between the microstrip line substrate 3c and the MMIC 10, if an organic solvent component remains in the adhesive 7 to be used, the organic outgas may damage the internal circuit of the MMIC 10. Therefore, it is preferable to use an ultraviolet curable adhesive that generates less outgas.

  In the transmission line connection structure of the third form configured as described above, the microwave or the millimeter wave input to the transmission line module 1d is transmitted from the center conductor 4e (4f) to the line connection conductor 5 similarly to the first form and the second form. Is transmitted to the central conductor 4f (4e).

  In the above-described third embodiment, the microstrip line substrate 3c and the MMIC 10 are provided with a ground conductor (not shown) serving as a reference potential point on the lower surface of the electrical conductor, and connected between the microstrip line substrate 3c and the MMIC 10. Even if all the line connecting conductors 5 covered are covered together and the adhesive 7 is filled in the air gap 6C or the entire air gap C between the microstrip line substrate 3c and the MMIC 10, the same as the above-described embodiment An effect is obtained.

  Further, in the example of FIGS. 7 and 8, the air gap 6C (a part of the air gap C) is filled with the adhesive 7 in a state where all the line connection conductors 5 are covered together, The entire air gap C may be filled with the adhesive 7 in a state where the connection conductors 5 are collectively covered.

  Thus, the transmission line connection structure of the first embodiment described above has a pair of microstrip line substrates 3a in a state where all the line connection conductors 5 connected between the pair of microstrip line substrates 3a and 3b are covered together. , 3b is filled with an adhesive 7 in the air gap 6A.

  As a result, all the line connecting conductors 5 are collectively covered with the adhesive 7 to prevent all the line connecting conductors 5 from directly touching the air, and to add a larger minute capacity to each minute section of the line connecting conductor 5. As a result, impedance mismatch caused by the air layer existing between the case 2a and the line connecting conductor 5 can be prevented.

  In addition, the transmission line connection structure of the second form is formed by filling the adhesive 7 so as to cover all the line connection conductors 5 connected between the coplanar line substrates 8a and 8b together, thereby connecting all the lines. Since the conductor 5 can have a larger minute capacity for each minute section of the line connecting conductor 5 without directly touching the air, it is generated by an air layer existing between the case 2b and the line connecting conductor 5 as in the first embodiment. Impedance mismatch can be prevented.

  Furthermore, even when the grounded coplanar line substrates 8c and 8d which are other configurations of the second form are adopted, all the line connection conductors 5 connected between the grounded coplanar line substrates 8c and 8d are collected together. By filling the air gap 6B between the pair of grounded coplanar line substrates 8c and 8d with the adhesive 7 in a covered state, all the line connecting conductors 5 are prevented from being directly exposed to air, and the line connecting conductors 5 Since a large minute capacity can be added to each minute section, the same effect as in the above embodiment can be obtained.

  In addition, the transmission line connection structure of the third form is provided between the microstrip line substrate 3c and the MMIC 10 with all the line connection conductors 5 connected between the microstrip line substrate 3c and the MMIC 10 covered together. Adhesive 7 is filled in the air gap 6C. As a result, it is possible to prevent all the line connecting conductors 5 from directly contacting the air, and to attach a larger minute capacity to each minute section of the line connecting conductor 5, so that the case is the same as in the first and second embodiments. Impedance mismatch caused by the air layer existing between 2d and the line connecting conductor 5 can be prevented.

  As mentioned above, although the best form in this invention was demonstrated, this invention is not limited with the description and drawing by this form. That is, it is a matter of course that all other forms, examples, operation techniques, and the like made by those skilled in the art based on this form are included in the scope of the present invention.

It is a top view for demonstrating the 1st form of the transmission line connection structure which concerns on this invention. It is sectional drawing of the transmission line connection structure in the 1st form of FIG. It is a figure which shows the change of the characteristic impedance which concerns on the electrical-characteristic evaluation experiment of the transmission line connection structure in a 1st form, and the conventional transmission line connection structure. It is a top view for demonstrating the 2nd form of the transmission line connection structure which concerns on this invention. It is sectional drawing of the transmission line connection structure in the 2nd form of FIG. It is sectional drawing for demonstrating the other structure in a 2nd form. It is a top view for demonstrating the 3rd form of the transmission line connection structure which concerns on this invention. It is sectional drawing of the transmission line connection structure in the 3rd form of FIG. 10 is a plan view for explaining a connection structure between microstrip line substrates disclosed in Patent Document 1. FIG. FIG. 10 is a cross-sectional view of a connection structure between the microstrip line substrates of FIG. 9. 10 is a plan view for explaining a connection structure between coplanar line substrates disclosed in Patent Document 1. FIG. It is sectional drawing of the connection structure between the coplanar line | wire boards of FIG.

Explanation of symbols

1a to 1d Transmission line module 2a to 2d Case (conductive base)
3a to 3c Microstrip line substrate 4a to 4f Center conductor 5 Line connection conductor A to C, 6A to 6C Air gap 7 Adhesive 8a, 8b Coplanar line substrate 8c, 8d Grounded coplanar line substrate 9a to 9f Ground conductor 10 MMIC

Claims (3)

A pair of microstrip line substrates (3a, 3b) provided with central conductors (4a, 4b) on a dielectric substrate are arranged on a conductive substrate (2a) with a predetermined interval therebetween, and the pair of microstrip lines In the transmission line connection structure in which the end points of the central conductor between the substrates are connected by the line connection conductor (5),
An adhesive (7) having a relative dielectric constant greater than 1 is filled in an air gap (6A) between the pair of microstrip line substrates in a state where all of the line connection conductors (5) are covered together. Transmission line connection structure. A pair of coplanar lines in which a center conductor (4c, 4d) is provided at the center of the upper surface of the dielectric substrate, and ground conductors (9a, 9b, 9c, 9d) are provided at predetermined intervals on both sides of the center conductor. A board | substrate (8a, 8b) is arrange | positioned on a conductive base material (2b) at predetermined intervals, and the end points of the central conductor between the pair of coplanar line substrates and the end points of the ground conductor are line connecting conductors (5). In the transmission line connection structure connected at
A transmission line connection structure characterized in that at least all of the line connection conductors are collectively covered with an adhesive (7) having a relative dielectric constant greater than 1. A microstrip line substrate (3c) provided with a central conductor (4e) on a dielectric substrate, and a central conductor (4f) disposed at a central portion of the upper surface of the dielectric substrate, and at predetermined intervals on both sides of the central conductor. And an MMIC (10) having a coplanar line structure provided with grounding conductors (9e, 9f) with a predetermined interval disposed on the conductive substrate (2d), and a central conductor of the microstrip line substrate, In the transmission line connection structure in which the center conductor of the MMIC and the ground conductor of the MMIC and the conductive base material are connected by a line connection conductor (5),
An adhesive (7) having a relative dielectric constant greater than 1 is filled in an air gap (6C) between the microstrip line substrate and the MMIC in a state where all the line connection conductors are covered together. Transmission line connection structure.

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