JP4199796B2 - High frequency line-waveguide converter - Google Patents

Description

  The present invention converts a high-frequency line such as a strip line or a microstrip line that forms a high-frequency circuit, which is used in a microwave or millimeter wave region, into a waveguide, and connects a high-frequency circuit to an antenna or a high-frequency circuit. The present invention relates to a high-frequency line-waveguide converter that can be easily mounted on a system through a waveguide.

  In recent years, with the advent of advanced information technology, high-frequency signals used for information transmission have been studied to utilize frequencies from the microwave region of 1 to 30 GHz to the millimeter wave region of 30 to 300 GHz. Application systems using such millimeter-wave high-frequency signals have also been proposed.

  In such a high frequency system, there is a problem that the high frequency signal is attenuated in the high frequency line constituting the circuit due to the high frequency of the high frequency signal. For example, when the high-frequency line has a microstrip line structure, the dielectric loss in the dielectric substrate increases in proportion to the frequency (when the dielectric loss tangent is independent of the frequency), and the conductor loss in the line conductor is proportional to the square root of the frequency. It will be bigger. For this reason, when the frequency used in the same microstrip line is increased from 1 GHz to 10 GHz, the dielectric loss increases 10 times and the conductor loss increases approximately 3.2 times. To compensate for this loss, low noise and high There is a problem that it is necessary to frequently use expensive high-frequency components having high efficiency and high gain, and the system becomes expensive.

  It is known that a transmission loss of a high-frequency signal is small in a waveguide as compared with a high-frequency line having such a microstrip line structure. For example, the loss of the waveguide WR-28 used in the 26 GHz to 40 GHz band is about 0.005 dB / cm at 40 GHz, which is much smaller than the loss of about 1 dB / cm of the microstrip line using the alumina substrate. This is because the impedance of the waveguide is larger than that of a normal high-frequency line (generally designed at 50Ω) (designed on the order of 500Ω, which varies with the frequency), and the transmitted signal energy On the other hand, the contribution of the electric field energy transmitted through the dielectric is large, whereas air having a dielectric loss tangent of almost zero is used as the dielectric, and the waveguide that is the source of relatively small magnetic energy. This is because the current flowing through the tube wall may be small, and since the current flows in a relatively large area of the tube wall of the waveguide, the electrical resistance is reduced and the conductor loss is reduced.

  The waveguides are usually connected with screws. Therefore, attachment / detachment can be performed easily. For example, if a waveguide is used to connect the high-frequency circuit module and the antenna, each inspection is performed using each waveguide port before assembly, and a high-frequency front end can be assembled by combining non-defective products. The production 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.

  FIG. 4 is a cross-sectional view for explaining the structure of such a high-frequency front end. According to FIG. 4, the front end 60 is configured by connecting a module 61 and an antenna 62 with a waveguide member 63. Module 61 is mounted on a metal chassis 65 having a waveguide opening 64. Further, the front end 60 has a high-frequency line composed of a microstrip substrate 66 on which a microstrip line as a high-frequency line is formed, and a waveguide constituted by a waveguide opening 64 and a short-circuit termination member 67. A waveguide converter 68 is configured. A wiring board 69 on which high-frequency components are mounted is connected to the microstrip line of the microstrip board 66 by wire bonding.

  The high-frequency line-waveguide converter 68 in the front end 60 is a microstrip from the side surface of the waveguide at a position separated from the short-circuit termination surface of the short-circuit termination member 67 by a distance of 1/4 of the signal wavelength of the high-frequency signal. A probe formed on the substrate 66 (a portion in which the line conductor is extended but the ground conductor is not formed) is inserted for a length of about ¼ of the signal wavelength. This probe functions as an antenna in the waveguide, and radiates a high-frequency signal into the waveguide as an electromagnetic wave. Half of the electromagnetic wave radiated into the waveguide is directly transmitted to the lower waveguide member 63, and the other half is transmitted to the upper short-circuit termination member 67 side. The electromagnetic wave transmitted to the short-circuit termination member 67 side is totally reflected with the phase reversed at the short-circuit termination surface. The totally reflected electromagnetic wave returns to the probe portion and is synthesized with the electromagnetic wave radiated directly downward from the probe. At this time, if the distance between the probe and the short-circuit termination surface is set to 1/4 of the signal wavelength of the high-frequency signal, the optical path length of the probe-short-circuit termination surface-probe reciprocation is The phase is opposite to that of the electromagnetic wave that is ½ wavelength and is directly emitted from the probe due to the optical path difference. Eventually, the electromagnetic wave reflected from the short-circuiting end face is reversed in phase when reflected from the short-circuiting end face, and the phase is reversed due to the optical path difference, so that it is in phase with the electromagnetic wave radiated directly from the probe. Then, it is transmitted to the lower waveguide member 63.

  At this time, in order for the probe to function as an antenna, the length inserted into the waveguide must be exactly ¼ of the signal wavelength, and it is radiated upward from the probe and reflected by the short-circuit termination surface. In order to set the phase of the electromagnetic wave thus transmitted to the same phase as the phase of the electromagnetic wave radiated downward from the probe, it is necessary to accurately set the distance between the probe and the short-circuit termination surface to ¼ of the signal wavelength. Therefore, the characteristics greatly vary depending on the position of the microstrip substrate 66 functioning as an antenna and the height of the short-circuit termination member 67.

  Since this high-frequency line-waveguide converter 68 is constructed by assembling together with the wiring board 69 on the metal chassis 65, when the conversion loss of the high-frequency line-waveguide converter increases due to the displacement of each member In addition, all of the members used were wasted, and there was a problem in assembly yield.

  In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 6-112708 discloses a dielectric substrate including a grounding conductor that functions as a short-circuit termination of a waveguide and a radiation conductor that functions as an antenna. Wave tube / plane line converters have been proposed. In JP-A-6-112708, the distance between the short-circuit end of the waveguide and the radiation conductor is set to 1/4 of the signal wavelength of the high-frequency signal. This is the same configuration as a conventionally used converter.

  However, in this configuration, the dielectric substrate that adjusts the distance between the short-circuited end of the waveguide and the radiation conductor is the same as the dielectric substrate that constitutes the microstrip line, and the thickness of this dielectric substrate is set to the signal wavelength. Therefore, the impedance adjustment of the microstrip line is performed only by the conductor width of the line conductor. Thus, in order to make the impedance of the microstrip line constant, it is necessary to widen the conductor width of the line conductor when the substrate is thick and narrow the conductor width when the substrate is thin. Therefore, depending on the signal frequency, the conductor width of the line conductor of the counterpart microstrip line to be connected is different, which causes signal reflection.

  In this converter, since the thickness of the dielectric substrate is 1/4 of the signal wavelength, the dielectric substrate is thick when the signal frequency is low, and thin when the signal frequency is high. For this reason, when the signal frequency is increased, the dielectric substrate becomes thin and the strength is weakened. For example, when the signal frequency is 76 GHz and the relative dielectric constant of the dielectric substrate is 9, the thickness of the dielectric substrate is about 0.33 mm, and the dielectric substrate may be deformed or destroyed depending on the substrate material. There is a risk of doing so.

  In this converter, the part of the radiation conductor that functions as an antenna is the part inserted into the waveguide, so the length of the part that functions as an antenna due to the positional deviation of the waveguide / planar line converter. As a result, the antenna characteristics change, and as a result, the conversion efficiency of the waveguide / planar line conversion may decrease.

  Furthermore, in order to use this converter, it is necessary to provide a recess in a part of the waveguide opening formed in the metal casing in order to prevent a short circuit of the radiation conductor. This means that a part of the part that should be the waveguide wall is missing, so that electromagnetic waves leak from this part and the conversion efficiency is lowered. . In addition, since it is essential to provide such a recess, there has been a problem that it is necessary to process the waveguide and the casing.

  The present invention has been devised in view of the above problems, and its purpose is to set the distance between the ground conductor and the radiation conductor so as to increase the conversion efficiency of the high-frequency line-waveguide conversion, and to improve the impedance of the high-frequency line. An object of the present invention is to provide a high-frequency line-waveguide converter in which the thickness of a dielectric layer can be freely set for adjustment, and no special processing is required for a waveguide opening.

  The high-frequency line-waveguide converter of the present invention is disposed on the first dielectric layer, the line conductor disposed on the upper surface of the first dielectric layer, and the lower surface of the first dielectric layer. A high-frequency line-waveguide converter for converting a high-frequency line including a ground conductor into a waveguide, the opening of the ground conductor facing one end of the line conductor, and the first A second dielectric layer stacked under the dielectric layer, a radiation conductor disposed on the lower surface of the second dielectric layer so as to face one end of the line conductor, and the opening of the ground conductor. A connection conductor that passes through the first and second dielectric layers and electrically connects the one end of the line conductor and the radiation conductor; and the second dielectric layer of the connection conductor A shield disposed on the side or inside of the second dielectric layer so as to surround the penetrating portion and the radiation conductor It has and a body portion, the shield conductor portion and being provided so as to be located inside the opening of the waveguide.

  In the high-frequency line-waveguide converter according to the present invention, preferably, the shield conductor portion is composed of a plurality of shield through conductors arranged inside the second dielectric layer.

  In the high-frequency line-waveguide converter of the present invention, preferably, the thickness of the second dielectric layer is approximately ¼ of the wavelength of the signal transmitted through the high-frequency line.

  In the high-frequency line-waveguide converter of the present invention, preferably, the connection conductor is connected to a position shifted from the center of the radiation conductor.

  According to the high-frequency line-waveguide converter of the present invention, the thickness of the dielectric layer constituting the high-frequency line is adjusted by the thickness of the first dielectric layer, and the radiation conductor is formed by the second dielectric layer. It is possible to adjust the distance to the ground conductor that functions as a short-circuit termination of the waveguide, and as a result, the thickness of the second dielectric layer is increased to increase the conversion efficiency of the high-frequency line-waveguide conversion. The impedance can be adjusted by freely selecting the thickness of the dielectric layer constituting the high-frequency line regardless of the signal frequency, while setting the thickness to a certain thickness (for example, approximately ¼ of the signal wavelength of the high-frequency signal). Therefore, the width of the line conductor can be matched with the width of the line conductor of the external high-frequency line, and signal reflection at the connection portion can be reduced. Even when the signal frequency is increased (the signal wavelength is shortened) and the thickness of the second dielectric layer is reduced in order to increase the conversion efficiency of the high-frequency line-waveguide conversion, Since the thickness is the total thickness of the first dielectric layer and the second dielectric layer, the entire thickness of the transducer does not become extremely thin, and a decrease in strength can be suppressed.

  Further, according to the high-frequency line-waveguide converter of the present invention, when the shield conductor portion is composed of a plurality of shield through conductors arranged inside the second dielectric layer, the high-frequency line-waveguide converter is used. These shield through conductors can be formed at the same time as the connecting conductor when the device is manufactured, and the high-frequency line-waveguide converter can be easily manufactured. In addition, since the shape of the region surrounded by the shield through conductor of the second dielectric layer can be arbitrarily designed, for example, unnecessary resonance occurs in the region surrounded by the shield through conductor of the second dielectric layer. In this case, it is possible to shift the unnecessary resonance out of the band of signal conversion by adjusting the arrangement of the shield conductor portion.

  Further, according to the high-frequency line-waveguide converter of the present invention, when the thickness of the second dielectric layer is approximately 1/4 of the wavelength of the signal transmitted by the high-frequency line, the radiation conductor and the ground conductor And the optical path length until the electromagnetic wave radiated from the radiation conductor to the ground conductor side is totally reflected by the ground conductor and returns to the radiation conductor is approximately ½ of the signal wavelength. Therefore, the phase is reversed, combined with the phase inversion when the total reflection is made on the ground conductor side, and in phase with the electromagnetic wave radiated directly from the radiating conductor to the waveguide side. The signal is efficiently transmitted to the waveguide.

  Further, according to the high-frequency line-waveguide converter of the present invention, when the connection conductor is connected at a position shifted from the center of the radiation conductor, a difference occurs in the length of the radiation conductor divided by the connection conductor. Because the electromagnetic wave radiated from the longer part of the radiation conductor is stronger than the electromagnetic wave radiated from the shorter part, high-frequency signals can be radiated into the waveguide as electromagnetic waves according to the difference. The signal can be efficiently transmitted to the waveguide.

  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 according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along the line A-AA. FIG. 2 is a similar view showing another example of the embodiment of the high-frequency line-waveguide converter of the present invention, where (a) is a plan view and (b) is a cross-sectional view along the line B-BB. is there. 1 and 2, 1 is a microstrip line as a high-frequency line, 2 is a first dielectric layer, 3 is a line conductor, 4 is a ground conductor, 5 is an opening formed in the ground conductor 4, and 6 is The second dielectric layer, 7 is a waveguide, 8 is a radiation conductor, 9 is a connection conductor, and 10 is a shield conductor.

  In the examples of the high-frequency line-waveguide converter of the present invention, the first dielectric layer 2, the line conductor 3 disposed on the upper surface of the first dielectric layer 2, and the first dielectric layer A microstrip line 1 as a high-frequency line is formed by the ground conductor 4 disposed on the lower surface of 2. A second dielectric layer 6 is laminated under the first dielectric layer 2 and the ground conductor 4, and a radiation conductor 8 is disposed on the lower surface of the second dielectric layer 6. Is electrically connected to one end of the line conductor 3 by a connection conductor 9 passing through an opening 5 formed in the ground conductor 4. As a result, the high-frequency signal transmitted to the line conductor 3 is radiated from the radiation conductor 8 into the waveguide 7 arranged as an electromagnetic wave so as to extend below the radiation conductor 8. The portion of the connecting conductor 9 that penetrates the second dielectric layer 6 and the radiating conductor 8 are arranged on the side surface or the inside of the second dielectric layer 6 so as to surround them, and are connected to the ground conductor 4 and the waveguide 7. It is shielded by the shield conductor 10 that is electrically connected, and prevents the electromagnetic wave radiated from the radiation conductor 8 to the ground conductor 4 side and the reflected wave of the electromagnetic wave from the ground conductor 4 from leaking, and the conversion efficiency is improved. Prevents the decline. The waveguide 7 is arranged and connected so that the radiation conductor 8 is disposed in the opening.

  By adopting such a structure, the thickness of the dielectric layer constituting the microstrip line 1 which is a high-frequency line and the distance between the radiation conductor 8 and the ground conductor 4 are respectively set to the thickness of the first dielectric layer 2. Since it can be adjusted independently depending on the thickness of the second dielectric layer 6, the impedance adjustment of the microstrip line 1 is facilitated, and the conductor width of the line conductor 3 is adjusted to a width suitable for connection to the external high-frequency line. At the same time, the distance between the radiation conductor 8 and the ground conductor 4 can be adjusted so as to increase the conversion efficiency of the high-frequency line-waveguide conversion.

  Further, when the signal frequency is high (the signal wavelength is short), even if the thickness of the second dielectric layer 6 is reduced in order to increase the efficiency of the high-frequency line-waveguide conversion, the total thickness of the converter Since the thickness is the total thickness of the first dielectric layer 2 and the second dielectric layer 6, the entire thickness of the converter is not extremely reduced, and a decrease in strength can be suppressed. .

  Further, since the entire radiation conductor 8 is disposed in the opening of the waveguide 7, it functions as an antenna even if the high-frequency line-waveguide converter is displaced relative to the waveguide 7. The length of the portion of the radiating conductor 8 is constant, and the characteristics are not deteriorated. Further, since the line conductor 3 and the radiation conductor 8 can be connected without providing a cut or the like in the opening of the waveguide 7, leakage of electromagnetic waves from the cut in the opening of the waveguide 7 is possible. There is no reduction in conversion efficiency due to such electromagnetic wave leakage.

  The dielectric material for forming the first dielectric layer 2 and the second dielectric layer 6 is a ceramic material, glass, or glass and ceramic filler mainly composed of aluminum oxide, aluminum nitride, silicon nitride, mullite, etc. Glass ceramic materials, epoxy resins, polyimide resins, organic resin materials such as fluororesins such as tetrafluoroethylene resin, and organic resin-ceramic (including glass) composites Materials etc. are used.

  As a conductor material for forming the shield conductor portion 10 by the line conductor 3, the ground conductor 4, the radiation conductor 8, the connection conductor 9 and the through conductor, etc., metallization mainly composed of tungsten, molybdenum, gold, silver, copper, etc. A metal foil mainly composed of gold, silver, 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 for forming the first dielectric layer 2 and the second dielectric layer 6 is dielectric. It is desirable that the tangent is small and hermetic sealing is possible. Particularly desirable dielectric materials include 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 / 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 / solvent to a raw powder such as refractory metal such as tungsten or molybdenum, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide. Next, a through hole for forming the connecting conductor 9 and a through conductor as the shield conductor portion 10 in FIG. 2 is formed in the ceramic green sheet by, for example, a punching method, and a metallized paste is applied to the through hole by, for example, a printing method. Subsequently, the metallized paste is printed in the shape of the line conductor 3, the ground conductor 4 and the radiation conductor 8. The ceramic green sheets on which these conductors are printed are stacked, 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 and the radiation conductor 8.

  The shield conductor portion 10 is disposed on the side or inside of the second dielectric layer 6 so as to surround the portion of the connecting conductor 9 that penetrates the second dielectric layer 6 and the radiation conductor 8, and is electrically connected to the ground conductor 4. Connected and grounded.

  The example shown in FIG. 1 shows the case where the shield conductor portion 10 is formed on the side surface of the second dielectric layer 6, and the tube wall at the end of the waveguide 7 also serves as the shield conductor portion 10. However, the shield conductor portion 10 in this case may be a metallized layer formed on the side surface of the second dielectric layer 6, and the metallized layer on the side surface at that time is electrically connected to the waveguide 7. What is necessary is just to form. In this case, the waveguide 7 may be connected to the metallization layer on the side surface by positioning the opening of the waveguide 7 on the lower surface of the second dielectric layer 6, but suppressing leakage of electromagnetic waves as much as possible. For this purpose, it is desirable to install the waveguide 7 so that the lower surface of the second dielectric layer 6 is located inside the opening of the waveguide 7 as shown in FIG. In addition, the metallized layer is formed on the side surface of the second dielectric layer 6 in the above-described manufacturing method, after the ceramic green sheet is pressure-bonded, the portion of the side surface of the laminate that becomes the second dielectric layer 6 is formed. A method of applying the metallized paste by printing, a method of polishing the side surface of the second dielectric layer 6 after firing, etc., and then applying and baking the metallized paste on the side surface may be employed.

  As shown in FIG. 2, the shield conductor portion 10 may be constituted by a plurality of shield through conductors arranged inside the second dielectric layer 6. In the example shown in FIG. 2, the plurality of shield through conductors are arranged in the second dielectric layer 6 so as to surround the radiation conductor 8 and the connection conductor 9 to form a shield conductor portion 10. At this time, it is desirable that the shield through conductor is disposed so as to be located inside the opening of the waveguide 7 so that unnecessary resonance does not occur. When the shield conductor portion 10 is formed of a plurality of shield through conductors in this way, it can be formed simultaneously with the connection conductor 9 in the second dielectric layer 6 at the time of production. The step of separately forming the side surface of the second dielectric layer 6 can be omitted, and the outer shape of the second dielectric layer 6 enters the opening of the waveguide 7 as in the example shown in FIG. There is no need to match the shape, and a high-frequency line-waveguide converter can be easily manufactured. Further, since the shape of the region surrounded by the shield conductor portion 10 of the second dielectric layer 6 can be arbitrarily designed, for example, in the region surrounded by the shield conductor portion 10 of the second dielectric layer 6 When unnecessary resonance occurs, the arrangement of the shield conductor portion 10 can be adjusted to shift the unnecessary resonance out of the signal conversion band.

  The gap between the shield through conductors (indicated by G in FIG. 2) is preferably less than ¼ of the signal wavelength. This is because the electromagnetic wave is less likely to leak from the gap between the shielding through conductors by setting it to less than ¼ of the signal wavelength, so that the shielding effect can be enhanced.

  The shield through conductor constituting the shield conductor portion 10 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.

  In order to increase the conversion efficiency of the high-frequency line-waveguide conversion, the second dielectric layer 6 has a thickness (indicated by H in FIG. 1) of the signal wavelength transmitted by the microstrip line 1. It is preferable to set to 1/4. When the thickness of the second dielectric layer 6 is set to approximately ¼ of the signal wavelength, the distance between the radiation conductor 8 and the ground conductor 4 becomes approximately ¼ of the signal wavelength. Since the optical path length until the electromagnetic wave radiated to is totally reflected by the ground conductor 4 and returns to the radiation conductor 8 is approximately ½ of the signal wavelength, the phase is reversed when returning to the ground conductor 4. Combined with the phase inversion due to total reflection at, the phase is the same as that of the electromagnetic wave directly radiated from the radiation conductor 8 to the waveguide 7, and these are combined with each other to efficiently transmit the signal to the waveguide 7. The Rukoto.

  The thickness of the second dielectric layer 6 can be adjusted by adjusting the thickness of the ceramic green sheet that becomes the second dielectric layer 6 after firing in the above-described manufacturing method. In this case, the thickness may be adjusted by the thickness of one ceramic green sheet, or may be adjusted by laminating a plurality of ceramic green sheets.

  The connection conductor 9 may be connected to a position shifted from the center of the radiation conductor 8, for example, a position shifted in the transmission direction of the high-frequency line 1. Thereby, as shown in FIG. 1, the radiation conductor 8 is divided into a long portion 8 a and a short portion 8 b by the connecting conductor 9. Since the long and short portions 8a and 8b of the radiating conductor 8 extend in opposite directions from the connection point of the connection conductor 9, the long and short portions 8a and 8b of the radiating conductor 8 are directed from the connection point. The phases of the electromagnetic waves radiated by transmitting the signals are reversed because the signal transmission directions are opposite to each other. In this way, the electromagnetic waves having opposite phases cancel each other, and the intensity of the radiated electromagnetic waves corresponds to the lengths of these long portions and short portions 8a and 8b of the radiating conductor 8, so that the radiating conductor 8 is long. An electromagnetic wave having an intensity corresponding to the difference between the length of the portion 8 a and the length of the short portion 8 b of the radiation conductor 8 is radiated to the waveguide 7. Therefore, when the connection conductor 9 is connected to a position shifted from the center of the radiating conductor 8, the electromagnetic wave radiated from the long portion 8a of the radiating conductor 8 is stronger than the electromagnetic wave radiated from the short portion 8b of the radiating conductor 8. Thus, electromagnetic waves are radiated into the waveguide 7 by the difference, so that the conversion from the high frequency line 1 to the waveguide 7 becomes possible. Further, when the connection conductor 9 is connected to the end of the radiation conductor 8 and the radiation conductor 8 extends only in one direction from the connection point, the length of the long portion 8a of the radiation conductor 8 and the radiation conductor 8 are increased. Since the difference with the length of the short portion 8b is maximized and the structure with the highest conversion efficiency is obtained, it is more preferable. On the other hand, when the connecting conductor 9 is connected to the center of the radiating conductor 8 and the long portion 8a and the short portion 8b have the same length, the electromagnetic waves having the same intensity and opposite phase cancel each other out in the radiating conductor 8. It may be difficult to efficiently radiate electromagnetic waves into the waveguide 7.

  The opening 5 formed in the ground conductor 4 is provided at a position facing one end of the line conductor 3 so that the connection conductor 9 and the ground conductor 4 are electrically insulated. The size of the opening 5 is such that the gap between the connection conductor 9 and the ground conductor 4 is equal to or greater than the thickness of the first dielectric layer 2 on which the microstrip line 1 is formed, and is equal to or less than ¼ of the signal wavelength. Something like that. If the gap between the connection conductor 9 and the ground conductor 4 is smaller than the thickness of the first dielectric layer 2, impedance mismatch between the connection conductor 9 and the microstrip line 1 is likely to occur. This is because if the gap with the ground conductor 4 is larger than ¼ of the signal wavelength, electromagnetic waves are likely to leak from the gap.

  The shape of the waveguide 7 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. Depending on the frequency of the high-frequency signal, a rectangular waveguide that is miniaturized within a range in which a higher-order mode does not occur may be used in order to reduce the size and weight of the system. A circular waveguide may be used.

  The waveguide 7 is made of metal, and the inner wall of the tube is preferably 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 7 is attached to the high-frequency line-waveguide converter by joining with a brazing material or fastening with a screw.

  In order to attach the waveguide 7 to the high-frequency line-waveguide converter by joining with a brazing material, a waveguide to which a waveguide connecting conductor electrically connected to the ground conductor 4 and the shield conductor 10 is attached. It is good to form according to the opening of the tube 7. For example, as shown in FIG. 2, a waveguide connecting conductor 11 made of a metallized layer connected to a shield conductor portion 10 made of a shielding through conductor is formed on the lower surface of the second dielectric layer 6. Good. Similarly, when the shield conductor 10 is a metallized layer formed on the side surface of the second dielectric layer 6, the second dielectric is connected to the metallized layer as the side shield conductor 10. A waveguide connecting conductor 11 made of a metallized layer may be formed on the lower surface of the layer 6. If such a waveguide connecting conductor 11 is formed, the waveguide 7 and the shield conductor portion 10 and the ground conductor 4 when the waveguide 7 is attached to the high-frequency line-waveguide converter are connected. Since electrical connection becomes more reliable, it is preferable in that a highly reliable high-frequency line-waveguide converter can be configured.

  In the example shown in FIG. 1, a portion of the ground conductor 4 exposed on the surface of the first dielectric layer 2 around the second dielectric layer 6 functions as a waveguide connecting conductor. It has become.

  The waveguide connecting conductor 11 is simultaneously formed by printing a metallized paste on the shape of the waveguide connecting conductor 11 in the above-described manufacturing method, similarly to the formation of the line conductor 3, the ground conductor 4 and the radiation conductor 8. What is necessary is just to form. Furthermore, as with the conductor exposed on the surface of the line conductor 3 and the radiation conductor 8, etc., when nickel plating and gold plating are applied to the surface, the brazing material wettability in the case of joining with the brazing material is improved. It becomes more preferable.

  It should be noted that the present invention is not limited to the embodiments described above, and various modifications may be made without departing from the spirit of the present invention.

  For example, FIGS. 1 and 2 show an example in which the high-frequency line has a microstrip line structure, but the first dielectric is provided so that a certain gap is provided on both sides of the line conductor 3 and the impedance becomes a predetermined value. Even when a coplanar line structure is formed by forming a coplanar line conductor on the upper surface of the layer 2, a dielectric layer is further laminated on the first dielectric layer 2, and the upper surface of the dielectric layer is formed. A top plate ground conductor layer may be formed so as to face the ground conductor 4 on the bottom surface of the first dielectric layer 2 so as to cover the line conductor 3 to form a triplate line structure. The positional relationship among the dielectric layer 2, the line conductor 3, the ground conductor 4, the opening 5, the second dielectric layer 6, the waveguide 7, the radiation conductor 8, and the connection conductor 9 is as shown in FIG. The same effect can be acquired by making it the same.

  Next, in order to confirm the effect of the high-frequency line-waveguide converter of the present invention, the following experiment was conducted.

  First, an evaluation as shown in FIG. 3 is performed using a ceramic green sheet of alumina ceramics having a dielectric loss tangent of 0.0006 at 10 GHz after firing and a metallized paste for tungsten metallization by a normal green sheet lamination technique and a co-firing technique. A substrate was produced. 3A is a top view of the evaluation substrate, FIG. 3B is a cross-sectional view taken along line C-CC in FIG. 3A, and FIG. 3C is a bottom view.

  After firing, the surface of each metallized layer on the upper and lower surfaces of the evaluation substrate was plated with nickel and gold. Here, the high-frequency line-waveguide converter in the evaluation board was designed with the corresponding waveguide set to WR-10 for W band (75 GHz to 110 GHz) and 76 GHz as the center frequency. The evaluation board is a shield conductor portion comprising the first dielectric layer 2, the line conductor 3, the ground conductor 4, the second dielectric layer 6, the radiation conductor 8, the connection conductor 9 and the shield through conductor shown in FIG. 10 includes two high-frequency line-waveguide converters of the present invention, one on each of the left and right sides of the figure, and these two converters include both line conductors 3 and ground conductors 4. Each has an integrated structure. The integrated line conductor 3 and ground conductor 4 together with the dielectric layer 2 constitute a connecting microstrip line 50. The distance between the left and right high-frequency line-waveguide converters was 20 mm so that the measurement waveguides could be connected to each. Thus, this evaluation board has a configuration in which two high-frequency line-waveguide converters are connected by a connecting microstrip line 50 having a length of 20 mm.

  Next, the waveguide opening of the measurement waveguide is aligned with the waveguide connection conductor 11 of each high-frequency line-waveguide converter of this evaluation board, and is tightened with a screw to be connected. The insertion loss in the range of 75 GHz to 110 GHz was measured by a method of inputting a signal from the tube and measuring the signal output from the other waveguide. From this result and the loss of the connection microstrip line 50 measured separately, the conversion loss of the high-frequency line-waveguide converter was estimated.

  As a result, the conversion loss at 76 GHz was about 1 dB, and it was confirmed that the conversion loss was sufficiently small for producing a practical high-frequency module. Moreover, since the band when the conversion loss is 1.5 dB is 75 GHz to 85 GHz, 10% or more is obtained as a ratio band with respect to the design center frequency of 76 GHz, and the frequency characteristic is a relatively wide band. Was also confirmed.

(A) is a top view which shows an example of embodiment of the high frequency line-waveguide converter of this invention, (b) is the sectional view on the AA line of (a). (A) is a top view which shows the other example of embodiment of the high frequency line-waveguide converter of this invention, (b) is the sectional view on the B-BB line of (a). (A) which shows the evaluation board | substrate of the high frequency line-waveguide converter of this invention is a top view, (b) is the CC sectional view taken on the line of (a), (c) is a bottom view. It is sectional drawing which shows the example of the conventional high frequency track-waveguide converter.

Explanation of symbols

1 ... Microstrip line (high frequency line)
2... First dielectric layer 3... Line conductor 4... Ground conductor 5... Opening 6. .... Waveguide 8 ... Radiation conductor 9 ... Connection conductor
10 ... Shield conductor
50 ・ ・ ・ ・ ・ Microstrip line for connection

Claims (4)

  A high-frequency line comprising a first dielectric layer, a line conductor disposed on the upper surface of the first dielectric layer, and a ground conductor disposed on the lower surface of the first dielectric layer is guided. A high-frequency line-waveguide converter for converting into a tube, wherein an opening portion of the ground conductor facing the one end of the line conductor and a second layer laminated under the first dielectric layer A dielectric layer; a radiation conductor disposed on the lower surface of the second dielectric layer so as to face one end of the line conductor; and the first and second dielectric layers passing through the opening of the ground conductor A connection conductor that electrically connects the one end of the line conductor and the radiation conductor, and a portion that penetrates the second dielectric layer of the connection conductor and the radiation conductor so as to surround the radiation conductor. A shield conductor disposed on the side or inside of the dielectric layer, and the shield Body section high-frequency line, characterized in that it is provided so as to be located inside the opening of the waveguide - waveguide converter.   2. The high-frequency line-waveguide converter according to claim 1, wherein the shield conductor portion is composed of a plurality of shield through conductors arranged inside the second dielectric layer.   The high-frequency line-waveguide converter according to claim 1 or 2, wherein the thickness of the second dielectric layer is approximately ¼ of the wavelength of a signal transmitted by the high-frequency line. .   4. The high-frequency line-waveguide converter according to claim 1, wherein the connection conductor is connected to a position shifted from a center of the radiation conductor. 5.

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