JP2006303853A - High-frequency line waveguide converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency line waveguide converter with a high conversion efficiency. <P>SOLUTION: The high-frequency line waveguide converter includes a high-frequency line 1 comprising a line conductor 3 formed on the upper face of a dielectric layer 2 and a same plane grounding conductor layer 4; slots 5 formed to the same planar grounding conductor layer 4 in a way of being orthogonal to one-ends of the line conductor 3; a grounding conductor layer 9 formed to the inner layer or the lower side of the dielectric layer 2; shielding conductors 7 for surrounding the slots 5 in planar perspective view and electrically connecting the same plane grounding conductor layer 4 and the grounding conductor layer 9; and a waveguide 6 electrically connected to the grounding conductor layer 4; and if the distance between the coplanar grounding conductor layer 4 and the grounding conductor layer 9 is L, the interval between the shielding conductors 7 at both sides of the line conductor 3 and adjacent to the line conductor 3, respectively is G, and the effective wavelength of a high-frequency signal transmitted through the high frequency line 1 is λ, then equation (G+2×L)≤λ/2 holds. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention converts a high-frequency line such as a coplanar line that forms a high-frequency circuit used in a microwave or millimeter wave region into a waveguide, and connects the high-frequency circuit and the antenna or the high-frequency circuit with the waveguide. The present invention relates to a high-frequency line-waveguide converter that can easily implement and evaluate a system.

  In recent years, high-frequency signals used for information transmission have been studied to utilize frequencies from the microwave region to the millimeter wave region. For example, an inter-vehicle radar has been proposed as an application system using millimeter-wave high-frequency signals. In such a high-frequency system, there is a problem that the high-frequency signal is attenuated by a high-frequency line such as a microstrip line structure constituting the circuit due to the high frequency of the high-frequency signal.

  It is known that a transmission loss of a high-frequency signal is small in a waveguide as compared with a high-frequency line such as a microstrip line structure. For example, compared to the impedance (50Ω) of a normal high-frequency line such as a microstrip line, the impedance of the waveguide (which varies depending on the frequency but is designed on the order of about 500Ω) is large. The contribution of the electric field transmitted through the dielectric to the generated signal is large, whereas the waveguide uses air having a dielectric loss tangent of almost zero as its dielectric, The current flowing through the waveguide tube wall can be small, and since the current flows in a relatively large area of the waveguide tube wall, the electrical resistance is reduced and the conductor loss is reduced. Is due to being.

  The waveguides are usually connected with screws. Therefore, since it can be easily attached and detached, if a waveguide is used for the connection between the high-frequency circuit module and the antenna, each inspection is performed using each waveguide port before assembly, and non-defective products are combined. A high-frequency front end can be assembled, and the manufacturing yield can be increased. For these reasons, a front end using a waveguide for transmission between a high-frequency circuit module and an antenna, which often has a long transmission distance, has been conventionally used.

  Such a high-frequency front end functions as a dielectric layer, a coplanar line composed of a line conductor formed on the surface of the dielectric layer, and a coplanar ground conductor layer disposed on both sides of the dielectric layer, and an antenna formed on the tip of the coplanar line. And a waveguide connected to a position facing the slot on the back surface of the dielectric layer, and a shield conductor portion formed so as to connect the waveguide and the same-surface grounded conductor layer inside the dielectric layer. A high-frequency line-waveguide converter is proposed (see Patent Document 1 below).

  According to this converter, by setting the distance from the slot to the interface between the dielectric layer and the inside of the waveguide to be ¼ of the wavelength of the electromagnetic wave transmitted through the dielectric layer, The path difference between the reflected wave reflected at the interface between the layer and the inside of the waveguide, reflected again from the ground conductor layer on the same plane and reaching the interface, and the electromagnetic wave transmitted directly from the slot to the interface (direct wave) Since the phase is inverted when the reflected wave magnetic field is reflected at the interface between the dielectric layer and the inside of the waveguide, the direct wave and the reflected wave are in phase at the interface. Will propagate to the waveguide.

That is, the dielectric layer interposed between the slot and the waveguide and having a thickness set to ¼ of the wavelength of the electromagnetic wave functions as a matching unit between the slot and the waveguide having different impedances. Become.
JP 2004-32321 A

  However, in the conventional high-frequency line-waveguide converter, the shield conductor portion arranged so as to surround the slot needs to avoid the line conductor, and due to the interval, the transmission mode of the slot becomes unstable, As a result, there is a problem in that the reflection loss increases and the conversion efficiency deteriorates.

  The present invention has been devised in view of the above problems, and an object thereof is to provide a high-frequency line-waveguide converter having high conversion efficiency.

  The high-frequency line-waveguide converter of the present invention includes a line conductor formed on an upper surface of a dielectric layer and a coplanar ground conductor layer formed so as to surround one end portion of the line conductor on the upper surface of the dielectric layer. A high-frequency line comprising: a slot formed on the same-surface ground conductor layer so as to be orthogonal to the one end of the line conductor and electromagnetically coupled to the line conductor; and an inner layer or a lower surface of the dielectric layer A frame-like ground conductor layer that is formed in a plan view and surrounds the slot; and a shield conductor portion that surrounds the slot in a plan view and electrically connects the same-surface ground conductor layer and the ground conductor layer; A high-frequency line-waveguide converter comprising a waveguide disposed on a lower surface side of a dielectric layer so as to face the slot and electrically connected to the ground conductor layer, Ground contact L is the distance between the layer and the ground conductor layer, G is the distance between the shield conductor portions provided on both sides of the line conductor and adjacent to the line conductor, and is further transmitted by the high-frequency line. When the effective wavelength of the high-frequency signal is λ, (G + 2 × L) ≦ λ / 2.

  In the high-frequency line-waveguide converter of the present invention, the distance between the coplanar ground conductor layer and the ground conductor layer is L, and the shield conductor portions provided on both sides of the line conductor adjacent to the line conductor are respectively When the interval is G and the effective wavelength of the high-frequency signal transmitted through the high-frequency line is λ, (G + 2 × L) ≦ λ / 2 is satisfied. The electric potential can be made the same, and the electric characteristics of the high-frequency line and the slot can be stabilized. As a result, reflection loss can be suppressed and conversion efficiency can be greatly improved.

  That is, when the line conductor is inserted into the slot, the slot is cut off, and in the cut off part, the same-surface ground conductor layers on both sides of the line conductor are one shield conductor part having a length L, They are electrically connected via a ground conductor layer having a length of G located between shield conductor portions disposed on both sides of the line conductor and the other shield conductor portion having a length of L. Therefore, L + G + L, that is, (G + 2 × L), which is the total distance, is equal to or less than λ / 2 of the effective wavelength λ of the high-frequency signal transmitted through the high-frequency line. Can be made substantially the same potential, and the electrical characteristics of the slot can be stabilized.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing an example of an embodiment of a high-frequency line-waveguide converter of the present invention, where (a) is a plan view, and (b) is a high-frequency line-waveguide converter of (a). It is sectional drawing in the A-AA line. In FIG. 1, 1 is a high-frequency line, 2 is a dielectric layer, 3 is a line conductor, 4 is a ground conductor layer on the same plane, 5 is a slot formed in the ground conductor layer 4 on the same plane, 6 is a waveguide, The shield conductor portion 9 is a ground conductor layer.

  In these examples of the high-frequency line-waveguide converter of the present invention, the dielectric layer 2, the line conductor 3 disposed on the upper surface of the dielectric layer 2, and the same surface so as to surround one end of the line conductor 3. A coplanar line serving as the high-frequency line 1 is formed by the coplanar ground conductor layer 4 disposed on (the upper surface of the dielectric layer 2). In addition, a slot 5 formed so as to be orthogonal to one end of the line conductor 3 is disposed in the same grounded conductor layer 4 on the upper surface of the dielectric layer 2 and is electromagnetically coupled to one end of the high-frequency line 1. ing. Thus, the high-frequency signal transmitted to the high-frequency line 1 is arranged to extend downward from the slot 5 on the lower surface side of the dielectric layer 2 with the opening facing the one end of the line conductor 3 and the slot 5. It is radiated as electromagnetic waves into the waveguide 6 formed.

  Further, the dielectric layer 2 is shielded by a shield conductor portion 7 disposed inside or on the side surface of the dielectric layer 2 so as to surround one end of the line conductor 3 and the slot 5 as shown in the example of FIG. Thus, the electromagnetic wave radiated from the slot 5 to the dielectric layer 2 and the electromagnetic wave reflected at the boundary between the dielectric layer 2 and the waveguide 6 are prevented from leaking and the conversion efficiency is prevented from being lowered. .

  In addition, the high-frequency line 1 and the slot 5 are formed in the same plane, and as a result, the relative positional relationship between the two is less likely to vary, and the length of the stub that is the protruding portion of the high-frequency line 1 with respect to the slot 5 Therefore, the variation in electromagnetic coupling characteristics can be reduced.

  In the high-frequency line-waveguide converter of the present invention, the distance between the same-surface ground conductor layer 4 and the ground conductor layer 9 is L, and the line conductor 3 is provided on both sides adjacent to the line conductor 3. When the interval between the shield conductor portions 7 is G and the effective wavelength of the high-frequency signal transmitted through the high-frequency line 1 is λ, (G + 2 × L) ≦ λ / 2. Thereby, the same-surface grounding conductor layer 4 on both sides of the line conductor 3 can be set to substantially the same potential, and the electrical characteristics of the high-frequency line 1 and the slot 5 can be stabilized. As a result, reflection loss can be suppressed and conversion efficiency can be greatly improved.

  That is, when the line conductor 3 is inserted into the slot 5, the slot 5 is cut off, and in this cut-off portion, the same-surface ground conductor layers 4 on both sides of the line conductor 3 have one length L. Through the ground conductor layer 9 having a length of G located between the shield conductor portions 7 disposed on both sides of the line conductor 3 and the other shield conductor portion 7 having a length of L. It is connected to the. Therefore, by setting L + G + L that is the total distance, that is, (G + 2 × L), to be equal to or less than λ / 2 of the effective wavelength λ of the high-frequency signal transmitted through the high-frequency line 1, the same plane ground conductors on both sides of the line conductor 3 are used. The layers 4 can have substantially the same potential, and the electrical characteristics of the slot 5 can be stabilized.

  As a dielectric material for forming the dielectric layer 2, ceramic material mainly composed of aluminum oxide, aluminum nitride, silicon nitride, mullite, glass, or glass formed by firing a mixture of glass and ceramic filler Ceramic materials, epoxy resins, polyimide resins, organic resin materials such as fluorine resins such as tetrafluoroethylene resin, and organic resin-ceramic (including glass) composite materials are used.

  As a conductor material for forming the shield conductor portion 7 composed of the line conductor 3, the same-surface ground conductor layer 4, the through conductor, etc., metallization mainly composed of tungsten, molybdenum, gold, silver, copper or the like, or gold, silver, A metal foil or the like mainly composed of copper, aluminum or the like is used.

  In particular, when the high-frequency line-waveguide converter is built in a wiring board on which high-frequency components are mounted, the dielectric material forming the dielectric layer 2 has a small dielectric loss tangent and can be hermetically sealed. It is desirable to be. A particularly desirable dielectric material includes at least one inorganic material selected from the group of aluminum oxide, aluminum nitride, and glass ceramic material. Such a hard material is preferable in terms of improving the reliability of the mounted high-frequency component because the dielectric loss tangent is small and the mounted high-frequency component can be hermetically sealed. In this case, it is desirable to use a metallized conductor that can be fired simultaneously with the dielectric material as the conductor material in terms of hermetic sealing and productivity.

  The high-frequency line-waveguide converter of the present invention is manufactured as follows. For example, when an aluminum oxide sintered body is used as a dielectric material, first, an appropriate organic solvent or solvent is added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide to form a slurry. This is formed into a sheet shape by a conventionally known doctor blade method or calendar roll method to produce a ceramic green sheet. Further, a metallized paste is prepared by adding and mixing an appropriate organic solvent and solvent to a raw material powder such as a high melting point metal such as tungsten or molybdenum, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide or the like.

  Next, a through hole for forming a through conductor as the shield conductor portion 7 is formed in the ceramic green sheet by, for example, a punching method, and a metallized paste is embedded in the through hole by, for example, a printing method. The metallized paste is printed in the shape of the same-surface grounded conductor layer 4 having the slots 5. When the dielectric layer 2 has a laminated structure of a plurality of dielectric layers, ceramic green sheets embedded and printed with these conductors are laminated, pressed and pressed, and fired at a high temperature (about 1600 ° C.). Furthermore, nickel plating and gold plating are applied to the surface of the conductor exposed on the surface of the line conductor 3, the same-surface ground conductor layer 4, and the like.

  The shield conductor portion 7 is disposed on the side surface or inside of the dielectric layer 2 so as to surround one end portion of the line conductor 3 and the slot 5, and is electrically connected to the same-surface ground conductor layer 4 and grounded.

  The shield through conductor constituting the shield conductor portion 7 may be a so-called through-hole conductor in which a conductor layer is attached to the inner wall of the through-hole, or a so-called via conductor in which the inside of the through-hole is filled with a conductor. It may be. Further, the shield conductor portion 7 may be a side conductor or castellation conductor formed on the side surface of the dielectric layer 2.

  Further, as shown in FIG. 1, the ground conductor layer 9 may be formed in a frame shape so as to surround the slot 5 in a plan view through the inner layer of the dielectric layer 2, or may be formed on the lower surface of the dielectric layer 2. It may be formed in a frame shape so as to surround the slot 5 as seen through.

  The shape of the waveguide 6 is not particularly limited. For example, when a WR series standardized as a rectangular waveguide is used, a variety of measurement calibration kits are available, so that various characteristics can be easily evaluated. In order to reduce the size and weight of the system in accordance with the frequency of the high-frequency signal, a rectangular waveguide that is miniaturized within a range in which the waveguide is not cut off may be used. A circular waveguide may be used.

  The waveguide 6 is made of metal, and the inner wall of the tube may be covered with a noble metal such as gold or silver in order to reduce conductor loss due to current or prevent corrosion. Alternatively, the resin may be molded into a necessary waveguide shape, and the inner wall of the tube may be covered with a noble metal such as gold or silver as in the case of metal. The waveguide 6 is attached to the high-frequency line-waveguide converter by joining with a brazing material or fastening with a screw.

  When the ground conductor layer 9 is formed on the lower surface of the dielectric layer 2, the waveguide 6 is joined to the ground conductor layer 9 via a conductive joining material such as a brazing material. When the ground conductor layer 9 is formed in the inner layer of the dielectric layer 2 as shown in FIG. 1, in order to attach the waveguide 6 to the high-frequency line-waveguide converter by bonding with a brazing material, A waveguide connecting conductor 10 electrically connected to the conductor layer 9 may be formed in accordance with the opening of the waveguide 6 to be attached. For example, as shown in FIG. 1, a shield conductor 7 'electrically connected to the installation conductor layer 9 is formed in the lower layer of the dielectric layer 2, and the shield conductor 7' is electrically connected. A waveguide connecting conductor 10 made of a metallized layer is preferably formed. If such a waveguide connecting conductor 10 is formed, the electrical connection between the waveguide 6 and the ground conductor layer 9 when the waveguide 6 is attached to the high-frequency line-waveguide converter is reduced. Since it becomes more reliable, it is preferable in that a highly reliable high-frequency line-waveguide converter can be configured.

  The waveguide connecting conductor 10 is simultaneously formed by printing metallized paste on the shape of the waveguide connecting conductor 10 in the above-described manufacturing method, similarly to the formation of the line conductor 3 and the same-surface grounded conductor layer 4. do it. Further, like the conductor exposed on the surface of the line conductor 3 and the same-surface ground conductor layer 4 and the like, when nickel plating and gold plating are applied to the surface, the wettability of the brazing material in the case of joining with the brazing material is increased. Since it improves, it becomes more preferable.

  Similarly to the shield conductor portion 7 described above, the shield conductor 7 ′ is made of a through conductor, a through-hole conductor, a side conductor, a castellation conductor, and the like, and can be manufactured by the same method as the shield conductor portion 7.

  Examples of the high-frequency line-waveguide converter of the present invention will be described below.

  First, a line conductor 3 and a coplanar ground conductor layer having a characteristic impedance of 50Ω as a high-frequency line 1 on the upper surface of a dielectric layer 2 made of alumina ceramic having a relative dielectric constant of 8.6 and having a thickness of 1.9 mm. 4 was formed. Further, the ground conductor layer 9 and the shield conductor portion 7 for connecting the same-surface ground conductor layer 4 and the ground conductor layer 9 were formed inside the dielectric layer 2.

  Further, a slot 5 having a length in the line direction of the line conductor 3 of 0.1 mm and a length in the direction perpendicular to the line conductor 3 of 3.1 mm is formed in the same plane ground conductor layer 4 so as to be orthogonal to the line conductor 3. Formed.

  Note that G + 2 × L, where G is the distance between the shield conductor portions 7 with the line conductor 3 interposed therebetween, and L is the distance between the ground conductor layer 4 and the ground conductor layer (the length of the shield conductor portion 7). Was changed to 3.20, 2.66, 2.12 and 1.60 mm.

  Here, the waveguide 6 to be connected was set to WR-42 (18 GHz to 26.5 GHz), and a high frequency three-dimensional structure simulator (HFSS manufactured by Ansoft) was used to design 24 GHz as a center frequency.

  As a result, it was confirmed that in 2.12 and 1.60 mm corresponding to λ / 2 or less, a reflection loss S11 ≦ −15 dB and a practical reflection loss can be obtained in manufacturing a high-frequency module.

  Note that the present invention is not limited to the above-described embodiments and examples, and various modifications may be made without departing from the scope of the present invention.

  For example, FIG. 1 shows an example in which the high-frequency line 1 has a coplanar line structure, but a dielectric layer is further laminated on the dielectric layer 2 so that the line conductor 3 is covered on the upper surface of the dielectric layer. A coplanar line structure with a ground provided with an upper surface ground conductor layer may be used. In this case as well, the dielectric layer 2, the line conductor 3, the coplanar ground conductor layer 4, the slot 5, the waveguide 6, the shield conductor portion 7, the ground By making the positional relationship of the conductor layer 9 the same as in the example shown in FIG. 1, the same effect can be obtained.

  FIG. 1 shows an example in which the shield conductor portion 7 is a plurality of through conductors. However, the dielectric layer 2 is reduced to form a conductor layer on the side surface, or the waveguide 6 is replaced with a high-frequency line-waveguide. The waveguide 6 may be used as a shield conductor portion by extending to the converter side.

(A) is a top view which shows an example of embodiment of the high frequency line-waveguide converter of this invention, (b) is in the A-AA line of the high frequency line-waveguide converter of (a). It is sectional drawing.

Explanation of symbols

1: High-frequency line 2: Dielectric layer 3: Line conductor 4: Coplanar ground conductor layer 5: Slot 6: Waveguide 7: Shield conductor 9: Ground conductor layer

Claims (1)

A line conductor formed on the upper surface of the dielectric layer, a high-frequency line including a coplanar ground conductor layer formed so as to surround one end portion of the line conductor on the upper surface of the dielectric layer, and the coplanar ground conductor layer A slot formed perpendicular to the one end of the line conductor and electromagnetically coupled to the line conductor, and a frame shape formed on the inner layer or the lower surface of the dielectric layer and surrounding the slot as seen through a plane. A ground conductor layer, a shield conductor portion that surrounds the slot in a plan view and electrically connects the same ground conductor layer and the ground conductor layer, and an opening on the lower surface side of the dielectric layer is opposed to the slot A high-frequency line-to-waveguide converter comprising a waveguide electrically disposed and connected to the ground conductor layer, wherein the high-frequency line-waveguide converter is provided between the coplanar ground conductor layer and the ground conductor layer. Distance to L When the distance between the shield conductor portions provided on both sides of the line conductor adjacent to the line conductor is G and the effective wavelength of the high-frequency signal transmitted through the high-frequency line is λ, (G + 2 × L) A high-frequency line-waveguide converter characterized in that ≦ λ / 2.

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