JP2006238047A - High frequency line-waveguide converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency line-waveguide converter having an excellent transmission characteristic and high conversion efficiency by effectively preventing the adsorption of electromagnetic waves on a connection part between a high frequency line and a waveguide. <P>SOLUTION: In the high frequency line-waveguide converter provided with the high frequency line 1 comprising a line conductor 3 formed on the upper surface of a dielectric layer 2 and a same side grounding conductor layer 4, a slot 5 electromagnetically coupled with the line conductor 3, and shield conductor parts 7 arranged on the side face or inside of the dielectric layer 2 while leaving spaces from each other so as to surround one-end part of the line conductor 3 and the slot 5; a space between adjacent shield conductor parts 7 on an extended part of the line conductor 3 out of shield conductor parts 7 surrounding the slot 5 is made narrower than a space between adjacent shield conductor parts 7 on the other portions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention converts a high-frequency line such as a coplanar line forming a high-frequency circuit or a coplanar line with a ground used in a microwave or millimeter-wave region into a waveguide, and connecting the high-frequency circuit and the antenna or the high-frequency circuit. The present invention relates to a high-frequency line-waveguide converter that can easily mount and evaluate a system by performing the above-described process using a waveguide.

  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 this conventional high-frequency line-waveguide converter, a part of the electromagnetic wave of the signal transmitted through the line conductor is absorbed by the dielectric layer, and impedance mismatching is likely to occur. The transmission was hindered, and as a result, the conversion efficiency was liable to decrease.

  The present invention has been devised in view of the above problems, and its purpose is to effectively prevent the absorption of electromagnetic waves at the connection portion between the high-frequency line and the waveguide, to have excellent transmission characteristics, and high conversion efficiency. It is to provide a line-waveguide converter.

  The high-frequency line-waveguide converter of the present invention surrounds one end portion of the line conductor with the line conductor formed on the upper surface of the dielectric layer and the upper surface of the dielectric layer, and short-circuits the tip of the one end portion. A high-frequency line composed of the same-surface grounded conductor layer formed on the same-surface grounded conductor layer and a slot that is formed to be orthogonal to the one end of the line conductor and electromagnetically coupled to the line conductor; A high-frequency line-waveguide including a shield conductor portion spaced apart from each other on a side surface or inside of the dielectric layer so as to surround the one end portion and the slot of the line conductor as seen in a plan view Among the shield conductor portions surrounding the slot, the converter is adjacent to each other in the extension portion of the line conductor, and the interval between adjacent ones is narrower than the interval between adjacent portions in other portions. Characterized in that was.

  In the high-frequency line-waveguide converter according to the present invention, preferably, at least three shield conductor portions adjacent to each other in the extension portion of the line conductor are provided.

  In the high-frequency line-waveguide converter of the present invention, preferably, the length of the shield conductor portion group adjacent to the extension portion of the line conductor is 1 to 30 times the width of the line conductor.

  In the high-frequency line-waveguide converter according to the present invention, preferably, the distance between the shield conductor portions adjacent to each other in the extension portion of the line conductor is set to be twice or less the thickness of the dielectric layer.

  In the high-frequency line-waveguide converter of the present invention, among the shield conductor parts surrounding the slot, the distance between adjacent ones in the extension part of the line conductor is made narrower than the distance between adjacent ones in other parts. Therefore, it is possible to effectively prevent the electromagnetic wave from leaking through the gap between the shield conductors in the extension of the line conductor in which the electromagnetic wave of the signal transmitted through the line conductor is most easily absorbed by the dielectric layer. Therefore, a part of the electromagnetic wave of the signal transmitted through the line conductor is absorbed by the dielectric layer, and it becomes possible to suppress a rapid impedance change between the high-frequency line and the waveguide, thereby transmitting the high-frequency signal to the waveguide. Can be improved. As a result, the conversion efficiency can be increased.

  In the high-frequency line-waveguide converter of the present invention, at least three shield conductor portions adjacent to each other in the extension portion of the line conductor are provided, so that a part of the electromagnetic wave of the signal transmitted through the line conductor is absorbed by the dielectric layer. Can be prevented more effectively.

  In the high-frequency line-waveguide converter of the present invention, the length of the shield conductor part group adjacent in the extension part of the line conductor is set to 1 to 30 times the width of the line conductor. A part of the electromagnetic wave can be more effectively prevented from being absorbed by the dielectric layer, and cracks can be effectively prevented from being generated by a stress due to a difference in thermal expansion between the dielectric layer and the shield conductor.

  In the high-frequency line-waveguide converter according to the present invention, the distance between adjacent shield conductors in the extension of the line conductor is set to be twice or less the thickness of the dielectric layer. It is possible to more effectively prevent a part of the material from being absorbed by the dielectric layer.

  Next, the first invention in the present invention will be described in detail based on the attached material. FIG. 1A is a plan view showing an example of an embodiment of a high-frequency line-waveguide converter according to the present invention, and FIG. 1B is a diagram of A of the high-frequency line-waveguide converter of FIG. FIG. 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, 8 is a lower ground conductor layer, 9 is an upper ground conductor layer, and 10 is a second dielectric layer, which form a high-frequency line-waveguide converter.

  The high-frequency line 1 is formed in a coplanar line shape by a line conductor 3 formed on the upper surface of the dielectric layer 2 and a coplanar ground conductor layer 4 formed so as to surround the line conductor 3. Further, a slot 5 is provided 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 line conductor 3. Thereby, the high frequency signal transmitted to the high frequency line 1 is radiated from the slot 5 as an electromagnetic wave into the waveguide 6 arranged to extend downward.

  In addition, the dielectric layer 2 is shielded by a shield conductor portion 7 made of a side conductor formed on the side surface of the dielectric layer 2 or a through conductor disposed inside the dielectric layer 2 as shown in FIG. The electromagnetic wave radiated from the slot 5 into the dielectric layer 2 is prevented from leaking, and the conversion efficiency is prevented from being lowered.

  In the present invention, among the shield conductor portions 7 surrounding the slot 5, the interval between the adjacent portions in the extension portion of the line conductor 3 is made narrower than the interval between the adjacent portions in other portions. This effectively prevents the electromagnetic wave from leaking through the gap between the shield conductors 7 in the extension of the line conductor 3 where the electromagnetic wave of the signal transmitted through the line conductor 3 is most easily absorbed by the dielectric layer 2. be able to. Therefore, a part of the electromagnetic wave of the signal transmitted through the line conductor 3 is absorbed by the dielectric layer 2, and it is possible to suppress a rapid impedance change between the high-frequency line 1 and the waveguide 6 and to guide the high-frequency signal. The transmission to the tube 6 can be improved. As a result, the conversion efficiency can be increased.

  Preferably, at least three shield conductor portions 7 adjacent to each other in the extension portion of the line conductor 3 are provided. Thereby, it is possible to more effectively prevent the electromagnetic wave of the signal transmitted through the line conductor 3 from passing through the gap between the shield conductor portions 7.

  Preferably, the length of the group of shield conductor portions 7 adjacent to each other in the extension portion of the line conductor is 1 to 30 times the width of the line conductor 3. If it is less than 1 time, the effect of effectively preventing the electromagnetic wave of the signal transmitted through the line conductor 3 from passing through the gap between the shield conductor portions 7 tends to be small. On the other hand, if it exceeds 30 times, the wall thickness between the shield conductor portions 7 becomes thin, the stress due to the difference in thermal expansion between the shield conductor portion 7 and the dielectric layer 2 increases, and a crack occurs in the dielectric layer 2. It becomes easy.

  Further, it is preferable that the interval between the shield conductor portions 7 adjacent to each other in the extended portion of the line conductor 3 is set to be twice or less the thickness of the dielectric layer 2. If it is larger than twice, part of the electromagnetic wave of the signal transmitted through the line conductor 3 leaks to the dielectric layer 2 and is absorbed, and the impedance becomes mismatched between the high-frequency line 1 and the slot, resulting in a high frequency It becomes easy to inhibit transmission of the signal to the waveguide.

  A frame-like lower ground conductor layer 8 is disposed on the lower surface of the dielectric layer 2 so as to surround the slot 5 in a plan view. The same-surface ground conductor layer 4 and the lower ground conductor layer 8 are connected to the connection conductor 7. Connected with.

  Preferably, a second dielectric layer 10 having a frame-like upper ground conductor layer 9 formed on the upper main surface is brazed to the lower ground conductor layer 8 with an Au—Sn brazing material or the like. It is preferable that the opening of the ground conductor layer 9 and the opening of the lower ground conductor layer 8 face each other.

  By adopting such a structure, the second dielectric layer 10 in contact with the inside of the waveguide 6 having the strongest magnetic field of the TM mode, which is a resonance mode generated in the dielectric layer, and the high-frequency line 1 are formed. Since the dielectric layer 2 formed can be separated by the upper ground conductor layer 9 and the lower ground conductor layer 8, the TE mode and the TM mode, which are the electromagnetic field modes for transmitting the high frequency line 1, are coupled to each other. It is possible to effectively prevent the signal energy transmitting 1 from shifting to the TM mode. As a result, it is possible to effectively prevent signal reflection due to resonance and perform good signal conversion from the high-frequency line 1 to the waveguide 6.

  Examples of the dielectric material forming the dielectric layer 2 and the second dielectric layer 10 include ceramic materials mainly composed of aluminum oxide, aluminum nitride, silicon nitride, mullite, glass, and a mixture of glass and ceramic filler. Used are glass ceramic materials formed by firing, organic resin materials such as epoxy resins, polyimide resins, fluororesins such as tetrafluoroethylene resin, and organic resin-ceramic (including glass) composite materials. It is done.

  As the conductor material for forming the line conductor 3, the same-surface ground conductor layer 4, the shield conductor portion 7 such as the through conductor, the lower ground conductor layer 8, and the upper ground conductor layer 9, tungsten, molybdenum, gold, silver, copper, etc. Metallization having a main component or metal foil having gold, silver, copper, aluminum or the like as a main component 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 tangent is small as a dielectric material for forming the dielectric layer 2 and the second dielectric layer 10, And it is desirable that airtight sealing is possible. Examples of such a dielectric material include ceramics and glass ceramic materials such as an aluminum oxide sintered body and an aluminum nitride sintered body. 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 capable of co-firing with a dielectric material as the conductor material in order to improve 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 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 solvent and solvent to a raw material powder such as refractory metal such as tungsten or molybdenum, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide or the like.

  Next, a through hole for forming the shield conductor portion 7 which is a through conductor is formed in the ceramic green sheet to be the dielectric layer 2 and the second dielectric layer 10 by, for example, a punching method. A metallized paste is embedded in the through hole, and then the metallized paste is printed in the shape of the line conductor 3, the same-surface ground conductor layer 4, the lower ground conductor layer 8, and the upper ground conductor layer 9. Further, when the dielectric layer 2 and the second dielectric layer 10 have a laminated structure of a plurality of dielectric layers, similarly, a ceramic green sheet printed with a metallized paste or embedded in a through hole is laminated, You may pressurize and pressure-bond.

  Then, the ceramic green sheets to be the dielectric layer 2 and the second dielectric layer 10 are fired at a high temperature (about 1600 ° C.). Furthermore, if necessary, the surface of the conductor exposed on the upper and lower surfaces, such as the line conductor 3, the same-surface ground conductor layer 4, the lower ground conductor layer 8, the upper ground conductor layer 9, and the like, for example, nickel plating and gold plating Adhere.

  Thereafter, the lower ground conductor layer 8 of the dielectric layer 2 and the upper ground conductor layer 9 of the second dielectric layer 10 are brazed, and the second dielectric layer 10 is attached to the outer periphery of the lower ground conductor layer 8. By connecting the waveguides 6 so as to surround them, a high-frequency line-waveguide converter is completed.

  The shield conductor portion 7 of the present invention is disposed on the side surface or inside of the dielectric layer 2 so as to surround the slot 5 and electrically connects the same-surface ground conductor layer 4 and the lower ground conductor layer 8.

  The shield conductor 7 only needs to be able to electrically connect the same-surface ground conductor layer 4 and the lower ground conductor layer 8, and various means such as a side conductor and a through conductor are used. For example, a conductor deposited on the side surface of the dielectric layer 2, a so-called castellation conductor in which a conductor layer is deposited on the inner wall of the notch on the side surface of the dielectric layer 2, or a conductor layer is coated on the inner wall of the through hole. Examples include so-called through-hole conductors attached, and so-called via conductors in which the insides of the through holes are filled with a conductor.

  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 can be composed of a metal or a dielectric having a metal layer formed on the inner surface. For example, the waveguide 6 can be formed into a tubular shape or a dielectric such as ceramics or resin is required. In this case, the inner surface is coated with a metal after being molded. The inner surface of the waveguide 6 may be covered with a noble metal such as gold or silver in order to reduce conductor loss due to current or prevent corrosion. The waveguide 6 is attached to the lower ground conductor layer 8 by joining with a brazing material, tightening with a screw or the like, and the waveguide 6 and the lower ground conductor layer 8 are electrically connected.

  In order to attach the waveguide 6 to the lower ground conductor layer 8 with the brazing material, the lower connection conductor layer electrically connected to the same-surface ground conductor layer 4 and the shield conductor portion 7 is attached to the waveguide 6. It is good to form it according to the opening. For example, as shown in FIG. 1, a lower ground conductor layer 8 made of a metallized layer connected to a shield conductor portion 7 made of a shield through conductor may be formed on the lower surface of the dielectric layer 2. If such a lower ground conductor layer 8 is formed, the waveguide 6, the shield conductor portion 7 and the coplanar ground conductor layer 4 when the waveguide 6 is attached to the high-frequency line-waveguide converter, Therefore, it is preferable in that a highly reliable high-frequency line-waveguide converter can be configured.

  The thickness of the second dielectric layer 10 is preferably not more than ½ times the wavelength of the signal transmitted through the high-frequency line 1. As a result, the light is radiated from the slot 5 and reflected at the interface between the lower main surface of the second dielectric layer 10 and the inside of the waveguide 6, reflected again by the upper ground conductor layer 9, and again reflected by the second dielectric. The reflected wave returning to the interface between the lower main surface of the layer 10 and the inside of the waveguide 6, and directly from the slot 5 to the interface between the lower main surface of the second dielectric layer 10 and the inside of the waveguide 6 The transmitted direct wave can be in phase, and the reflected wave and the direct wave are intensified, so that the conversion efficiency from the high-frequency line 1 to the waveguide 6 can be further increased.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High frequency line 2 ... Dielectric layer 3 ... Line conductor 4 ... Same surface grounding conductor layer 5 ... Slot 6 ... Conduction Wave tube 7: Shield conductor

Claims (4)

A high-frequency line comprising a line conductor formed on the upper surface of a dielectric layer and a coplanar grounded conductor layer formed so as to surround one end of the line conductor on the upper surface of the dielectric layer and to short-circuit the tip of the one end And a slot that is formed in the same plane ground conductor layer so as to be orthogonal to the one end of the line conductor and electromagnetically coupled to the line conductor, and the one end of the line conductor and the slot in a plan view A high-frequency line-waveguide converter comprising shield conductor portions spaced apart from each other on the side or inside of the dielectric layer so as to surround the slot, wherein the shield conductor surrounds the slot Among the sections, the interval between the adjacent portions in the extension portion of the line conductor is made narrower than the interval between adjacent portions in other portions. Converter. 2. The high-frequency line-waveguide converter according to claim 1, wherein at least three shield conductor portions adjacent to each other in the extension portion of the line conductor are provided. 3. The high-frequency line-waveguide conversion according to claim 1, wherein the length of the shield conductor portion group adjacent to the extension portion of the line conductor is 1 to 30 times the width of the line conductor. vessel. 4. The high-frequency line-conductor according to claim 1, wherein an interval between adjacent shield conductor portions in the extension portion of the line conductor is set to be not more than twice the thickness of the dielectric layer. 5. Wave tube converter.

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