JP2007266836A - Aperture antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aperture antenna with an excellent transmission characteristic and a high conversion efficiency by effectively preventing absorption of an electromagnetic wave at a connection part between a high frequency line and a waveguide. <P>SOLUTION: The aperture antenna includes: the high frequency line 1 comprising a dielectric layer 2, a line conductor 3, and a ground conductor layer 4; a slot 5 formed in crossing with the line conductor 3 and electromagnetically coupled to the line conductor 3; and a plurality of shield conductors 7 for surrounding the end of the line conductor 3 and the slot 5 in plane view. A distance D1 between the shield conductors arranged in an extension direction of the line conductor 3 among the shield conductors 7 is selected narrower than a distance D2 between the other shield conductors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna used for communication and radar using microwaves and millimeter waves, and relates to an aperture antenna that has a wide band and can be thinned.

  A horn antenna using a waveguide is known as an antenna that efficiently radiates electromagnetic waves such as microwaves and millimeter waves. A horn antenna is an antenna that radiates a high-frequency signal transmitted through a waveguide into space. The inside of the waveguide has the same dielectric constant as that of space (generally, the dielectric constant of air), and its impedance is close to that of space. The electromagnetic field mode of the high-frequency signal transmitted through the waveguide is similar to the electromagnetic field mode of the high-frequency signal transmitted through the space, and the electromagnetic field mode of the high-frequency signal transmitted through the waveguide can be easily separated in the space near the horn. It is possible to change to an electromagnetic field mode of a high-frequency signal that transmits the signal. For these reasons, it is known that the horn antenna has low reflection due to impedance and mode mismatch, and is highly efficient and relatively wide in bandwidth.

  On the other hand, a circuit generally used for communication or radar using microwaves or millimeter waves is a planar circuit using a microstrip line or a coplanar line. In this case, in order to connect the circuit and the horn antenna, a converter for converting the planar circuit into the waveguide is required, and the use of the converter may cause an increase in cost and performance degradation such as reflection. A patch antenna is known as one of antennas that directly radiate electromagnetic waves from a planar circuit into space. In the patch antenna, a planar circuit having a relatively small impedance and a space having a relatively large impedance are matched using the resonance of the patch. In matching by resonance, the impedance of the resonator affects the band. In order to increase the impedance of the patch in order to widen the band, it is necessary to reduce the patch width, and the radiation efficiency decreases. Increasing the patch width to increase the radiation efficiency tends to reduce the patch impedance and narrow the band. In the design of a patch antenna, the first condition is to efficiently radiate a high-frequency signal into the space. Therefore, the band is often narrowed at the expense of the band.

In order to solve this problem, an aperture antenna using a cavity resonator having a large impedance as a resonator has been proposed. In this aperture antenna, a cavity resonator in which a dielectric is filled in a dielectric substrate forming a planar circuit is configured to realize a broadband antenna.
JP 2001-016027 A

  However, in the case of the aperture antenna, since the cavity resonator needs to be configured inside the dielectric substrate, the dielectric substrate may be thicker than the patch antenna. In particular, when a feed line such as a laminated waveguide or a microstrip line is used to feed the slot which is the primary radiator of this antenna, a dielectric layer is further provided on the slot to form the feed line. Therefore, there is a problem that the thickness of the dielectric substrate is further thicker than the thickness of the cavity resonator and the size of the device is increased.

  Therefore, the present invention has been completed in view of the above-mentioned conventional problems, and the object of the present invention is to provide a feed line without increasing the thickness of the dielectric substrate in a wide-band aperture antenna, and to radiate it. It is an object of the present invention to provide an aperture antenna having high efficiency and small variation in radiation characteristics.

  An aperture antenna according to the present invention includes a dielectric layer having first and second surfaces, and a ground that is formed on the first surface of the dielectric layer and surrounds a line conductor and an end of the line conductor. A high-frequency line composed of a conductor layer; a slot formed on the first surface of the dielectric layer so as to intersect the line conductor; and electromagnetically coupled to the line conductor; and A plurality of shield conductors which are formed inside and surround the end portions and the slots of the line conductor in a plan view, and are arranged in the extending direction of the line conductor among the plurality of shield conductors The distance between them is narrower than the distance between other shield conductors.

  The aperture antenna of the present invention is characterized in that at least three shield conductors are provided in the extending direction of the line conductor.

  In the aperture antenna of the present invention, the width of the shield conductor forming region in the extending direction of the line conductor is 1 to 30 times the width of the line conductor.

  The aperture antenna of the present invention is characterized in that an interval between the shield conductors arranged in the extending direction of the line conductor is not more than twice the thickness of the dielectric layer.

  The aperture antenna according to the present invention is a signal transmitted through a line conductor because the distance between the shield conductors arranged in the extending direction of the line conductor is smaller than the distance between the other shield conductors among the plurality of shield conductors. The leakage of the electromagnetic wave in the region in the extension direction of the line conductor that is most easily absorbed by the dielectric layer can be reduced. Therefore, a part of the electromagnetic wave of the signal transmitted through the line conductor is absorbed by the dielectric layer, and it is possible to suppress a rapid impedance change between the high frequency line and the waveguide, and to the waveguide of the high frequency signal. Can be transmitted well. As a result, the conversion efficiency can be increased.

  In the aperture antenna of the present invention, at least three shield conductors are provided in the extending direction of the line conductor, so that a part of the electromagnetic wave of the signal transmitted through the line conductor is absorbed by the dielectric layer. Can be reduced.

  The aperture antenna according to the present invention is an electromagnetic wave of a signal transmitted through a line conductor because the width of the shield conductor forming region in the extending direction of the line conductor is 1 to 30 times the width of the line conductor. It is possible to reduce the absorption of the portion by the dielectric layer, and it is possible to reduce the possibility of cracks in the dielectric layer due to the stress due to the difference in thermal expansion between the dielectric layer and the shield conductor.

  In the aperture antenna of the present invention, the distance between the shield conductors arranged in the extending direction of the line conductor is not more than twice the thickness of the dielectric layer, so that the electromagnetic wave of the signal transmitted through the line conductor can be reduced. It is possible to reduce that part of the material is 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 the aperture antenna of the present invention, and FIG. 1B is a cross-sectional view taken along the line A-A ′ of the aperture antenna of FIG. In FIG. 1, 1 is a high-frequency line, 2 is a dielectric layer, 3 is a line conductor, 4 is a coplanar ground conductor layer, 5 is a slot formed in a first ground conductor layer (coplanar ground conductor layer) 4, 7 is a shield conductor, 8 is a lower ground conductor layer, 9 is an upper ground conductor layer, and 10 is a second dielectric layer, which form an aperture antenna.

  The high-frequency line 1 is formed in a coplanar line shape by a line conductor 3 formed on the first surface (upper surface) 2 a of the dielectric layer 2 and a coplanar ground conductor layer 4 formed so as to surround the line conductor 3. Has been. 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. As a result, the high-frequency signal transmitted to the high-frequency line 1 is radiated downward from the slot 5 as an electromagnetic wave.

  The dielectric layer 2 is shielded by a shield conductor 7 formed 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. 5 prevents the electromagnetic wave radiated into the dielectric layer 2 from leaking out and prevents the conversion efficiency from decreasing.

  In the present invention, among the shield conductors 7 surrounding the slot 5, the interval D1 between adjacent ones in the extension direction region of the line conductor 3 is narrower than the interval D2 between adjacent ones in other regions. Thereby, the leakage of the electromagnetic wave can be reduced in the region in the extending direction 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. Therefore, the conversion efficiency can be increased.

  Preferably, at least three shield conductors 7 adjacent to each other in the extension direction region 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 conductors 7.

  Preferably, the length of the group of shield conductors 7 adjacent to each other in the extension direction 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 conductors 7 tends to be small. On the other hand, if it exceeds 30 times, the wall thickness between the shield conductors 7 becomes thin, the stress due to the thermal expansion difference between the shield conductor 7 and the dielectric layer 2 becomes large, and the dielectric layer 2 is likely to crack. .

  Further, it is preferable that the interval between the shield conductors 7 adjacent to each other in the extending direction region of the line conductor 3 is set to be not more than twice 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.

  Further, a frame-like lower ground conductor layer 8 formed so as to surround the slot 5 in plan view is disposed on the second surface (lower surface) 2b of the dielectric layer 2, and the same-surface ground conductor layer 4 and the lower ground conductor are disposed. The conductor layers 8 are connected by connecting conductors 7.

  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 having the strongest magnetic field of the TM mode, which is a resonance mode generated in the dielectric layer, and the dielectric layer 2 on which the high-frequency line 1 is formed are connected to the upper ground. Since it can be separated by the conductor layer 9 and the lower ground conductor layer 8, the TE mode, which is an electromagnetic field mode for transmitting the high-frequency line 1, and the TM mode are combined and the signal energy transmitted through the high-frequency line 1 is changed to the TM mode. It is possible to effectively prevent migration. 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 second dielectric layer 10.

  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.

  The conductor material for forming the line conductor 3, the same-surface ground conductor layer 4, the shield conductor 7 such as the through conductor, the lower ground conductor layer 8, and the upper ground conductor layer 9 is mainly tungsten, molybdenum, gold, silver, copper or the like. Metallized as a component, or a metal foil mainly composed of gold, silver, copper, aluminum or the like is used.

  In particular, when the aperture antenna is built in a wiring board on which high-frequency components are mounted, the dielectric material for forming the dielectric layer 2 and the second dielectric layer 10 is small in dielectric loss tangent and hermetically sealed. It is desirable to be 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 aperture antenna 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 a shield conductor 7 as 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. The metallized paste is embedded in the holes, 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. In addition, 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 to complete the aperture antenna.

  The shield conductor 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 that are attached, and so-called via conductors in which the insides of the through-holes are filled with a conductor.

  In order to attach to the lower ground conductor layer 8 by the brazing material, the lower connection conductor layer 8 electrically connected to the same-surface ground conductor layer 4 and the shield conductor 7 is formed in the opening of the upper ground conductor layer 9 to be attached. It is good to form together. For example, as shown in FIG. 1, when a lower ground conductor layer 8 made of a metallized layer connected to a shield conductor 7 made of a shielding through conductor is formed on the lower surface of the dielectric layer 2, the conductor portion 7 Further, since the electrical connection with the grounded conductor layer 4 is more reliable, it is preferable in that a highly reliable aperture antenna 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 by the lower main surface of the second dielectric layer 10, reflected again by the upper ground conductor layer 9, and returned to the lower main surface of the second dielectric layer 10 again. The reflected wave and the direct wave transmitted directly from the slot 5 to the lower main surface of the second dielectric layer 10 can be in phase, and the reflected wave and the direct wave are intensified so that the high frequency The conversion efficiency from the line 1 to the dielectric layer 2 can be further increased.

(A) is a top view which shows the example of embodiment of the aperture antenna of this invention, (b) is sectional drawing in the A-A 'line | wire of the aperture antenna of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High frequency line 2 ... Dielectric layer 3 ... Line conductor 4 ... Same surface grounding conductor layer 5 ... Slot 7 ... Shield Conductor 8... Lower ground conductor layer 9... Upper ground conductor layer 10... Second dielectric layer

Claims (4)

A dielectric layer having first and second surfaces;
A high-frequency line formed on the first surface of the dielectric layer, comprising a line conductor and a grounding conductor layer surrounding an end of the line conductor;
A slot that is formed on the first surface of the dielectric layer so as to intersect the line conductor, and is electromagnetically coupled to the line conductor;
A plurality of shield conductors that are formed inside the dielectric layer and surround the end portions of the line conductor and the slot in a plan view,
Of the plurality of shield conductors, an aperture antenna in which an interval between shield conductors arranged in an extending direction of the line conductor is narrower than an interval between other shield conductors. The aperture antenna according to claim 1, wherein at least three shield conductors are provided in an extending direction of the line conductor. The aperture antenna according to claim 1 or 2, wherein a width of the shield conductor forming region in the extending direction of the line conductor is 1 to 30 times the width of the line conductor. The opening surface according to any one of claims 1 to 3, wherein an interval between the shield conductors arranged in the extending direction of the line conductor is not more than twice the thickness of the dielectric layer. antenna.

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