JP2008113323A - Method for manufacturing slot antenna - Google Patents

Abstract

An object of the present invention is to suppress the generation of vertically polarized components while suppressing the mass and manufacturing cost of an antenna.
In a slot antenna, a distance along a bottom surface portion between a parallel portion of a support portion and one surface of an H surface portion of a waveguide facing the parallel portion is radiated from the slot. The amplitude of the vertically polarized wave component of the first radio wave to be adjusted is adjusted to be equal to the sum of the amplitudes of the second radio wave radiated from the bottom surface portion. The distance along the H surface portion between the bottom surface portion of the support portion 26 and the E surface where the slot is provided is such that the phase of the vertical polarization component of the first radio wave and the phase of the second radio wave are inverted. However, the second radio waves are adjusted to have the same phase. The support portion 26 supports the waveguide 12 so that no gap exists between the support portion 26 and the waveguide 12. A conductive substance is inserted between the support portion 26 and the waveguide 12.
[Selection] Figure 2

Description

  The present invention relates to antenna technology, and more particularly to a method of manufacturing a slot antenna in which a slot for radiating radio waves is provided on one of the E faces of a waveguide.

2. Description of the Related Art Conventionally, as a waveguide antenna used in radar equipment, a slot antenna having a slot on a radio wave radiation surface is known. Here, the radio wave radiated from the slot cut in the narrow wall surface of the waveguide in the slot antenna includes not only the horizontal polarization component but also the vertical polarization component. Generally, since a horizontally polarized wave component is used as a detection wave in a port monitoring radar or the like, the vertically polarized wave component becomes an extra noise component, and it is necessary to remove this component. As a technique for removing the vertical polarization component, it has been proposed to dispose a grating for suppressing the vertical polarization component in front of the slot (see, for example, Patent Document 1). In addition, it has been proposed to adjust a stub connected to a tube wall located on the side surface of the radiation surface of the slot waveguide (see, for example, Patent Document 2). Further, as a conventional method for manufacturing a slot antenna including a grating that suppresses a vertical polarization component, a method of integrally molding with plastic and depositing metal or attaching metal foil has been proposed (see, for example, Utility Model Document 1).
JP 2004-320583 A Japanese Patent Laid-Open No. 05-095222 Japanese Utility Model Publication No. 05-011020

  In general, it is desirable to manufacture an antenna so as to suppress generation of a vertically polarized component while suppressing the mass and manufacturing cost of the antenna.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of manufacturing a slot antenna that can suppress the generation of a vertically polarized component.

  In order to solve the above problems, a slot antenna according to an aspect of the present invention is a slot antenna including a waveguide having a slot for radiating a radio wave on one of the E-plane portions and a support portion for supporting the waveguide. The support portion is provided perpendicularly to each of the two parallel portions disposed opposite to each of the two H-plane portions of the waveguide at regular intervals, and one end of which is in contact with the parallel portion. The other end of the waveguide is in contact with the H-plane portion of the waveguide and the other end of each of the two bottom-surface portions and supports the other of the E-plane portions of the waveguide. A surrounding portion surrounding the portion. The distance along the bottom surface portion between the parallel portion and one surface of the H-plane portion of the waveguide facing the parallel portion is the amplitude of the vertical polarization component of the first radio wave radiated from the slot. The total amplitude of the second radio waves radiated from the bottom surface portion is adjusted to be equal, and the distance along the H surface portion between the bottom surface portion and the E surface provided with the slot is the first radio wave While the phase of the vertically polarized wave component and the second radio wave are inverted, the second radio wave is adjusted so that the phases of the second radio wave are equal to each other. The waveguide is supported so that there is no air gap between them.

  Here, “the support portion supports the waveguide so that there is no air gap between the waveguide” includes a state in which the waveguide and the support portion are attached or in close contact with each other, Moreover, the state where the space between the waveguide and the support portion is filled is included. According to this aspect, since there is no gap between the support portion and the waveguide, the impedance matching state between the waveguide and the support portion can be maintained. Therefore, adjustment for suppressing the vertical polarization component can be easily performed, and the vertical polarization component included in the radio wave generated from the choke groove can be reduced.

  A conductive substance may be inserted between the enclosing portion and the waveguide. In this case, since the waveguide and the support portion are integrally formed by filling a conductive material in the gap, current does not enter between them and the vertical polarization component is easily suppressed. Can be adjusted for.

  Another aspect of the present invention is also a slot antenna. This slot antenna is a slot antenna including a waveguide having a slot for radiating a radio wave at one of the E-plane portions and a support portion for supporting the waveguide, and the support portion includes two H portions of the waveguide. Two parallel portions arranged to face each other at a constant interval and perpendicular to each of the two parallel portions, one end touching the parallel portion and the other end touching the H-plane portion of the waveguide There are two bottom surface portions and an enclosing portion surrounding a part of the waveguide so as to contact the other end of each of the two bottom surface portions and to support the other of the E surface portions of the waveguide. A conductive substance is inserted between the enclosing portion and the waveguide. It may further include a flare portion that is in contact with the other end of the parallel portion that is not in contact with the bottom surface portion and expands in the radiation direction of the radio wave radiated from the waveguide.

  According to this aspect, by filling a conductive material in the gap, there is no gap between the support portion and the waveguide, so that no current flows between them and the vertical polarization component is easily suppressed. You can make adjustments.

Yet another embodiment of the present invention is a method for manufacturing a slot antenna. This method includes a waveguide having a slot for radiating a radio wave at one of the E-plane portions and a support portion for supporting the waveguide, and the support portions are spaced apart from each other by two H-plane portions of the waveguide. Two parallel portions arranged opposite to each other, two bottom portions provided perpendicular to each of the two parallel portions, one end contacting the parallel portion and the other end contacting the H-plane portion of the waveguide; A manufacturing method of a slot antenna having a surrounding portion surrounding a part of a waveguide so as to contact the other end of each of two bottom surface portions and support the other of the E-plane portions of the waveguide, A step of pouring a resinous fluid into a mold manufactured so that the waveguide and the support unit are integrated; a step of cooling the poured fluid to mold the slot antenna; Step of removing the slot antenna from the formwork and radio wave radiation Comprising the step of applying a metal resin plating necessary parts in order to obtain the ability. In the method of manufacturing the slot antenna, the step of plating the slot antenna with a metallic material on the slot antenna formed by the step of forming the slot hole covers and protects the waveguide, the support portion, and the flare portion. The target casing, the waveguide, the support, and the flare are positioned in front of the radome that protects them and transmits radio waves, and the waveguide, the support, and the flare are integrated with resin. It may be molded using a mold so that metallic plating is applied only to necessary portions other than the radome. In addition, the amplitude of the vertical polarization component of the first radio wave radiated from the slot and the sum of the amplitudes of the second radio wave radiated from the bottom surface portion are equal to those of the slot antenna extracted in the extraction step. And adjusting the distance along the bottom surface portion between the parallel portion and one surface of the H-plane portion of the waveguide facing the parallel portion, so that the vertical polarization component of the first radio wave and the second radio wave Adjusting the distance along the H-plane portion between the bottom portion and the E-plane provided with the slot so that the phases of the second radio waves are equal to each other while the phases are mutually inverted. And may further be included. In addition, the slot antenna manufactured by the manufacturing method is a flare portion that is in contact with the other end of the parallel portion that is not in contact with the bottom surface portion, and extends toward the radiation direction of the radio wave radiated from the waveguide. A flare portion that opens may be included. Here, “adjusting the distance” includes performing processing so that the distance is adjusted. In this case, the vertical polarization component can be suppressed by applying a processing process for adjusting the distance to the slot antenna molded using the mold.

  According to this aspect, since the slot antenna is formed by using a mold in which the waveguide and the support portion are integrated, the waveguide and the support portion are configured integrally. Adjustment can be easily made to suppress the vertical polarization component without any current flowing in between.

  Yet another embodiment of the present invention is a slot antenna. This slot antenna is a slot antenna including a waveguide having a slot for radiating a radio wave at one of the E-plane portions and a support portion for supporting the waveguide, and the support portion includes two H portions of the waveguide. Two parallel portions arranged to face each other at a constant interval and perpendicular to each of the two parallel portions, one end touching the parallel portion and the other end touching the H-plane portion of the waveguide One of the two bottom portions, an enclosing portion that surrounds a part of the waveguide so as to contact the other end of each of the two bottom surface portions and support the other of the E-plane portions of the waveguide, and one of the parallel portions And a flare portion that expands in the radiation direction of the radio wave radiated from the waveguide. The length of the first portion along the parallel portion from the bottom surface portion to the surface where the slot is provided in the waveguide, and the parallel portion from the end of the first portion not contacting the bottom surface portion to the contact point with the flare portion The length of the second portion is adjusted so that the vertical polarization component included in the radio wave radiated from the slot antenna is reduced. According to this aspect, by adjusting the length of the first portion and the length of the second portion, it is possible to easily design a slot antenna in which the vertical polarization component is suppressed.

  A parallel portion and a waveguide facing the parallel portion so that the amplitude of the vertically polarized wave component of the first radio wave radiated from the slot is equal to the sum of the amplitudes of the second radio wave radiated from the bottom surface portion. While the distance along the bottom surface portion between one of the H-plane portions of the first radio wave is adjusted, and the phase of the vertically polarized wave component of the first radio wave and the phase of the second radio wave are mutually reversed, The distance along the H surface portion between the bottom surface portion and the E surface provided with the slot may be adjusted so that the phases of the second radio waves are equal. In this case, the vertical polarization component can be further suppressed by adjusting the distance.

  The length of the first part is shorter than the length of the second part. According to this aspect, by adjusting the length of the first portion and the length of the second portion, it is possible to easily design a slot antenna in which the vertical polarization component is suppressed. The length of the first part may be shorter than the length of the second part. In this case, the vertical polarization component can be further suppressed by adjusting the distance.

  It should be noted that any combination of the above-described constituent elements, or a conversion of the expression of the present invention between a method, an apparatus, a manufacturing method of the apparatus, etc. is also effective as an aspect of the present invention.

  According to the present invention, it is possible to manufacture a slot antenna that can suppress generation of a vertically polarized component.

(Embodiment 1)
Before describing Embodiment 1 of the present invention in detail, an outline will be described first. Embodiment 1 of the present invention relates to a slot antenna including a waveguide provided with a slot for radiating radio waves. The slot antenna is used in a harbor surveillance radar or the like, and radiates a radio wave to an object and receives a reflected radio wave to measure a distance to the object. For the measurement, a radio wave with respect to a horizontally polarized wave component among radio waves reflected from the object is used.

  Here, a waveguide provided with a slot will be described. FIG. 1A is a perspective view of the waveguide 12. The waveguide 12 is provided with a slot 18 for radiating radio waves on any surface around the waveguide. In general, the surface on which the slot 18 is provided and the surface facing the surface are referred to as the E surface. Further, among the surfaces constituting the waveguide 12 that are side surfaces of the E surface, surfaces other than the surface that the waveguide crosses (hereinafter referred to as “waveguide surface 22”) are referred to as H surfaces. In the following, of the E surfaces, the surface provided with the slot 18 is referred to as “slot surface 20”, and the E surface that is not the slot surface 20 is referred to as “opposing surface”.

  Due to its structure, the slot antenna radiates radio waves including not only horizontal polarization components but also vertical polarization components. As described above, the vertical polarization component included in the radiated radio wave becomes an extra noise component relative to the horizontal polarization component when receiving the radio wave reflected by the target object, and the horizontal polarization component. Therefore, it is necessary to remove this component.

  FIG. 1B is a front view showing a part of the slot surface 20 of the waveguide 12 shown in FIG. In the slot 18 provided in the waveguide 12, an electric field is generated as illustrated. The electric field vector generated in the slot surface 20 can be decomposed into a vertical component and a horizontal component. In other words, on the slot surface 20, a current I1 as a vertical component and a current I2 as a horizontal component are generated. Here, the current I1 as the vertical component is a current that circulates around the E plane and the H plane of the waveguide 12, and due to this, the radio wave radiated from the slot 18 includes a vertical polarization component. Become. FIG.1 (c) is sectional drawing which shows the waveguide surface 22 of the waveguide 12 of Fig.1 (a). Here, in the waveguide surface 22, the left side in the figure is the slot surface 20. As shown in the drawing, a current I1 is generated so as to circulate around the waveguide 12 and induces vertical polarization.

  Generally, in an antenna using a waveguide provided with a slot 18 (hereinafter referred to as “slot antenna”), a vertical polarization component suppression grating is installed on a radiation surface of a radio wave from the slot antenna. As a result, the vertical polarization component was suppressed. The vertical polarization component suppression grating includes a metal grating disposed in front of the slot radiation surface and arranged in the same direction as the polarization direction to be removed. The respective gratings are arranged in parallel at intervals of a length equal to or less than ½ of the radio wave propagation wavelength. This suppresses radiation of the polarization component to be removed from the radio waves radiated from the slot. However, using a vertical polarization suppression grating increases the overall mass of the antenna. In addition, since the size of the vertical polarization suppression grating greatly affects the antenna characteristics, high dimensional accuracy is required at the time of manufacture, which causes an increase in cost.

  Therefore, in the slot antenna according to the present embodiment, a groove is formed by embedding a waveguide in a part of the support portion, and a current I1 that can be generated around the waveguide with respect to the groove, By letting out the current I1 serving as the wave source of the vertical polarization component, the generation of the vertical polarization component included in the radio wave radiated from the slot is suppressed. Further, by adjusting the size of the groove, the radio wave radiated from the opening surface of the groove and the vertically polarized wave component of the radio wave radiated from the slot cancel each other. By taking such an aspect, generation | occurrence | production of a vertical polarization component can be suppressed efficiently, suppressing the mass and manufacturing cost of an antenna.

  FIG. 2A is a perspective view illustrating a configuration example of the slot antenna 100 according to the first embodiment of the present invention. The slot antenna 100 includes an antenna outer plate 10, a waveguide 12, a flare plate 14, a radome portion 16, and a support portion 26. The waveguide 12 has a rectangular parallelepiped shape in which a waveguide is formed. Further, the waveguide 12 is provided with a slot 18 on the slot surface 20 that should emit radio waves.

  The support portion 26 is a member that supports the waveguide 12 while being embedded, and is connected to the flare plate 14. The flare plate 14 expands in the direction of the radio wave radiated from the slot 18 and is connected to the antenna outer plate 10. The directivity of the radio wave radiated from the slot 18 is adjusted by adjusting the degree of expansion. The radome portion 16 is provided at the opening of the flare plate 14 and is connected to the antenna outer plate 10. The antenna outer plate 10 is an outer frame that covers the waveguide 12, the flare plate 14, the radome portion 16, and the support portion 26. The directivity of the slot antenna 100 can also be adjusted by adjusting the reflection characteristics of the radome portion 16. The radome portion 16 is illustrated so that the waveguide 12 and the flare plate 14 can be visually recognized for convenience of explanation, but the waveguide 12 and the flare plate 14 are covered when viewed from the front of the slot surface 20. It may be configured.

  FIG. 2B is a front view of the waveguide surface 22 of the slot antenna 100 of FIG. As illustrated, the support portion 26 has a concave cross section parallel to the waveguide surface 22 of the waveguide 12 as indicated by a broken line. Further, in the support portion 26, a part of the waveguide 12 is embedded from a facing surface into a part of the bottom surface including the bottom side in the recess of the concave cross section. Here, the “bottom surface” is a surface parallel to the slot surface 20 and a surface in a recess in the concave cross section of the support portion 26.

  Two grooves 24 are formed between the support portion 26 and the waveguide 12. The groove 24 has a bottom surface of the support portion 26 and two surfaces of the waveguide 12 in contact with the bottom surface at right angles, that is, an H surface and both of the support portions 26 facing the two H surfaces. It is formed with wall surfaces. As described above, by providing the groove 24 so as to be in contact with the H surface of the waveguide 12, the current flowing around the waveguide 12 can be released as shown in FIG. As a result, the current flowing around the waveguide 12 serving as the wave source of the vertically polarized component is reduced, and the vertically polarized component contained in the radio wave radiated from the slot surface 20 can be suppressed.

  FIG. 3 is a first front view showing the waveguide surface 22 of the waveguide 12 in the slot antenna 100 of FIG. As shown in the figure, the waveguide 12 is embedded in the concave cross section of the support portion 26 so that two grooves 24 are formed between the waveguide 12 and the support portion 26. By taking such an embodiment, the current I1 flowing around the waveguide 12 as shown in FIG. 1C changes direction at the place where the H surface and the support portion 26 are in contact with each other, and is transmitted through the groove 24. It flows like.

  Here, the distance between the bottom surface and the slot surface 20, that is, the depth dimension of the H surface portion of the cross section of the groove 24 is defined as d. By making the depth dimension d narrower than the wavelength, for example, about 1/6 to 1/4 wavelength, a cutoff effect is exerted on the horizontal polarization component. Therefore, the groove 24 does not affect the horizontally polarized wave component. As for the horizontally polarized wave, as shown in the figure, a radio wave is excited by a current flowing into the groove 24 and the groove 24 itself functions as a horn antenna. Therefore, the directivity in the vertical direction of the antenna is a superposition of the radio wave radiated from the horn antenna and the radio wave radiated from the slot opening surface. By adjusting the width w and depth dimension d of the groove 24 so that these two radio waves have the same amplitude and opposite phase, it becomes possible to suppress the vertical polarization component. Specifically, the adjustment of the amplitude of the radiation from the groove 24 can be performed by adjusting the width w of the groove 24, and the adjustment of the phase can be performed by adjusting the depth dimension d of the groove 24. It becomes. Here, the width w of the groove 24 refers to the distance between the two H planes of the waveguide 12 and the wall surface of the support portion 26 facing each H plane. The depth d of the groove 24 refers to the distance between the bottom surface of the support portion 26 and the slot surface 20.

  FIG. 4 is a second front view showing the waveguide surface 22 of the waveguide 12 in the slot antenna 100 of FIG.

In FIG. 4, the vertical polarization component E ₁ is radiated from the slot surface 20. Further, the vertically polarized components E _2A and E _2B are radiated from the bottom surface of the support portion 26, that is, the opening surfaces of the two grooves 24. Here, as described above, the vertical polarization component is suppressed by adjusting the depth dimension d and the width w of the groove 24 so that the vertical polarization components of the radio wave radiated from the waveguide 12 cancel each other. it can. In other words, in FIG. 4, vertical polarization components can be suppressed by making E ₁ , E _2A and E _2B a relationship of the following equations and canceling each other. Note that Am {X} represents a function that outputs the amplitude component of X. Ph {Y} indicates a function that outputs a phase component of Y.
Am {E ₁ } = Am {E _2A } + Am {E _2B } Expression (1)
Ph {E ₁ } = − Ph {E _2A } = − Ph {E _2B } (2)

Here, each component of E _{1 on} the left side of the equations (1) and (2) is determined by the characteristics of the radio wave radiated from the waveguide 12. Therefore, the expressions (1) and (2) may be satisfied by adjusting each of E _2A and E _{2B on} the right side. Here, the amplitudes of E _2A and E _2B depend on the amount of current flowing through the bottom surface of the support portion 26. The amount of current depends on the widths wA and wB of the groove 24. Therefore, it is only necessary to satisfy the expression (1) by adjusting the widths wA and wB. The phases of E _2A and E _2B depend on the depth dimension d of the groove 24. Therefore, the equation (2) may be satisfied by adjusting the depth dimension d.

  Since it is difficult to analytically derive the adjustment method of the widths wA, wB and the depth dimension d satisfying the expressions (1) and (2), the widths wA, wB and the depth dimension d are the slots shown in FIG. It is necessary to determine the effect of suppressing the vertical polarization component in the antenna 100 while experimenting.

FIG. 5A and FIG. 5B are graphs showing experimental results of the effect of suppressing the vertical polarization component in the slot antenna 100 of FIG. The horizontal axis indicates the depth dimension d of the groove 24. The vertical axis indicates the attenuation amount of the vertical polarization component. FIG. 5A is a graph showing the attenuation characteristic of the vertical polarization component when the width w of the groove 24 is set to 4 mm to 6 mm. FIG. 5B is a graph showing the attenuation characteristic of the vertical polarization component when the width w is set to 6.5 mm to 8.5 mm. Here, the frequency of the radio wave used was approximately 9 GHz. Here, in order to simplify the design conditions, the width w is set to have the following relationship between wA and wB described above.
w = wA = wB (3)

The purpose of this experiment is to obtain a combination of the width w and the depth dimension d so that the attenuation amount of the vertical polarization component is 30 dB or more from the experimental results shown in FIGS. 5 (a) and 5 (b). Then, as shown in the figure, in order to attenuate the amount of attenuation of the vertical polarization component by 30 dB or more, it is generally desirable to adjust the width w and the depth dimension d so as to have the following combinations.
(D, w) = (5.5 mm, 7 mm) (4)
(D, w) = (5.7 mm, 6.5 mm) (5)
(D, w) = (5.75 mm, 6 mm) Expression (6)
(D, w) = (6 mm, 5.5 mm) (7)
(D, w) = (6.25 mm, 5 mm) (8)
(D, w) = (6.5 mm, 4.5 mm) (9)
(D, w) = (6.75 mm, 4 mm) (10)

  According to the present embodiment, a groove 24 is formed between the waveguide 12 and the support portion 26, and by adjusting the size of the groove 24, generation of vertical polarization components is achieved while suppressing the mass and manufacturing cost of the antenna. Can be efficiently suppressed. By providing the groove 24, the current generated around the waveguide can be released to the groove. Since the current component serving as the wave source of the vertical polarization component can be released, the vertical polarization component included in the radio wave radiated from the slot can be reduced. Further, the amplitude characteristic of the radio wave characteristics of the second radio waves radiated from the two grooves depends on the distance between both wall surfaces and the surface of the waveguide facing the respective wall surfaces. By adjusting the amplitude characteristic of the second radio wave. Moreover, since the phase characteristic of the radio wave characteristics of the second radio wave depends on the distance between the bottom surface and the surface provided with the slot, the phase characteristic of the second radio wave can be adjusted by adjusting this distance. . Further, by adjusting the amplitude and phase of the second radio wave so as to cancel the vertical polarization component of the first radio wave, the vertical polarization component of the first radio wave can be suppressed.

  Further, the design can be facilitated by adjusting the width between the both wall surfaces of the support portion 26 and the surface of the waveguide facing each wall surface to the same width w. Further, by adjusting the mutual relationship between the width w of the groove 24 and the depth dimension d of the choke groove 24, the vertical polarization component can be efficiently suppressed.

(Embodiment 2)
The second embodiment of the present invention relates to a slot antenna as in the first embodiment. In addition, about the structure which is common in Embodiment 1 mentioned above, the same code | symbol is attached | subjected and description is simplified. The slot antenna according to the second embodiment has the same configuration as that shown in FIGS.

  As illustrated in FIG. 2B, in the slot antenna according to the second embodiment, two grooves 24 are formed between the support portion 26 and the waveguide 12. The groove 24 has a bottom surface of the support portion 26 and two surfaces of the waveguide 12 in contact with the bottom surface at right angles, that is, an H surface and both of the support portions 26 facing the two H surfaces. It is formed with wall surfaces. As described above, by providing the groove 24 so as to be in contact with the H surface of the waveguide 12, the current flowing around the waveguide 12 can be released as shown in FIG. As a result, the current flowing around the waveguide 12 serving as the wave source of the vertically polarized component is reduced, and the vertically polarized component contained in the radio wave radiated from the slot surface 20 can be suppressed.

  In the second embodiment, out of the current flowing around the waveguide 12 serving as the wave source of the reduced vertical polarization component, both wall surfaces of the bottom surface of the support portion 26 of the groove 24 face each wall surface. By adjusting the distance between the H plane of the waveguide 12, current is prevented from flowing inside the groove 24. Therefore, the vertical polarization component included in the radio wave radiated from the waveguide 12 can be further suppressed.

  FIG. 6 is a front view showing the waveguide surface of the waveguide in the slot antenna according to the second embodiment of the present invention.

  Here, the distance between the bottom surface and the slot surface 20, that is, the depth dimension of the H surface portion of the cross section of the groove 24 is defined as d. By setting the depth dimension d to ¼ of the wavelength of the radio wave, the impedance at the opening surface of the groove becomes infinite. Then, a current that flows on the slot surface 20 and can be a wave source of a vertically polarized component does not flow into the inside of the groove, and does not flow into the outside of the groove. In other words, the groove 24 has a function as a choke by setting the depth dimension d to ¼ of the wavelength λ of the radio wave. That is, a current that can be a wave source of a vertically polarized component exists only in the slot surface 20, and the vertically polarized component included in the radio wave radiated from the waveguide 12 can be further suppressed.

  Hereinafter, modifications of the slot antenna shown in the first embodiment and the second embodiment will be described. The following modifications also include the characteristics of the slot antenna described so far. That is, by forming a groove 24 as a choke between the waveguide 12 and the support portion 26 and adjusting the size of the groove 24, the generation of vertical polarization components can be efficiently performed while suppressing the mass and manufacturing cost of the antenna. Can be suppressed. Therefore, below, the description regarding the above characteristics is abbreviate | omitted and characteristics other than those characteristics are demonstrated.

(Embodiment 3)
FIG. 7 is a diagram schematically illustrating a configuration example of the slot antenna 100 according to the third embodiment. The slot antenna 100 includes a waveguide 12, a flare plate 14, and a support portion 26. The support portion 26 includes a parallel portion connected to the flare plate 14, a bottom surface portion connected to the parallel portion, and a surrounding portion connected to the bottom surface portion. The parallel portions are opposed to the two H-plane portions of the waveguide 12 at regular intervals. The bottom surface portion is provided perpendicular to each of the two parallel portions, one end is in contact with the parallel portion, and the other end is in contact with the H surface portion of the waveguide 12. The enclosing portion is in contact with the other end of each of the two bottom surface portions, and surrounds a part of the waveguide 12 so as to support the other of the E surface portions of the waveguide 12. The slot antenna 100 fixes the waveguide 12 by fitting the waveguide 12 to the support portion 26. Here, a gap exists between the waveguide 12 and the surrounding portion of the support portion 26 as shown by the broken line 30. When a current leaking from the waveguide 12 flows into the gap, the radio wave radiated from the waveguide 12 or the radio wave generated from the choke groove 24 may be affected. In such a case, since the impedance matching state between the waveguide 12 and the support portion 26 is lost, the vertical polarization component included in the radio wave generated by the waveguide 12 and the choke increases. Therefore, in the first modification, the generation of the vertical polarization component is suppressed by designing the waveguide 12 and the support portion 26 so that the gap indicated by the broken line 30 does not exist. The waveguide 12 and the support portion 26 may be attached to each other. Here, “attachment” includes a state in which two surfaces are connected by a force acting on an interface. Thereby, the performance deterioration by presence of a clearance gap can be suppressed.

  In the present embodiment, in order to prevent the gap indicated by the broken line 30 from being present, for example, the waveguide 12 and the support portion 26 are integrally molded so as not to have a gap.

By integrally molding the waveguide 12 and the support portion 26, the above-described performance deterioration can be prevented. In order to integrally mold the waveguide 12 and the support portion 26, for example, the waveguide 12 and the support portion 26 may be manufactured by the following procedure.
(I) A mold for molding the slot antenna 100 in which no gap exists between the waveguide 12 and the support portion 26 is manufactured. If the formwork has already been manufactured, (i) can be omitted unless a design change occurs.
(Ii) Pour fluid into the manufactured formwork.
(Iii) The slot antenna 100 is molded by cooling the fluid.
(Iv) Take out the molded slot antenna 100 from the mold.

  FIG. 8 shows a cross-sectional view of a mold 36 for manufacturing the slot antenna 100 of FIG. In the mold 36, the cavity 38 is a cavity part, and in the step (ii), fluid such as liquefied copper or aluminum is poured into this part. The cavity 38 includes a waveguide portion 42 and a support portion 44. The waveguide portion 42 and the support portion 44 correspond to the waveguide 12 and the support portion 26 in the slot antenna 100 to be molded, respectively. As shown in the figure, there is no gap as shown in FIG. 7 between the waveguide portion 42 and the support portion 44, and the current generated on the slot surface 20 does not flow, so that the above-mentioned performance deterioration occurs. Can be prevented. In addition, the fluid substance poured in (ii) may have conductivity, or may not have conductivity.

Here, in (ii), when a non-conductive fluid such as resin is poured into the mold 36, the following procedure may be added after the manufacturing steps (i) to (iv) described above. Good.
(V) In the extracted slot antenna 100, a slot hole for radiating radio waves is formed in the E-plane portion of the waveguide 12. The slot hole may be formed by cutting the slot portion from the extracted slot antenna 100. In the step (i), when manufacturing a formwork in which slot holes are already formed, this step can be simplified.
(Vi) Depth dimension d and width w are derived by simulation or the like, and fine processing is performed on slot antenna 100. In the step (i), when manufacturing a mold in which the depth dimension d and the width w are already taken into consideration, this step can be omitted.
(Vii) The slot antenna 100 in which the slot hole is formed is plated using a metallic substance. The plating process is also performed inside the waveguide of the slot antenna 100. Here, the plating process includes vapor deposition, spraying, or application.

  Thus, the weight can be reduced by manufacturing the slot antenna 100 using a resin or the like. Further, the processing in (vi) can be easily realized, and the design cost can be reduced. In addition, since the processing is easy, the processing accuracy can be increased and good characteristics can be realized.

  FIG. 9 is a diagram illustrating the effect of the second embodiment. The vertical axis represents the normalized gain, and the horizontal axis represents the phase distribution of the radio wave radiated from the waveguide 12. In FIG. 9, the case where there is no gap, that is, the case of the first modification is indicated by a solid line, and the case where there is a gap is indicated by a broken line.

  In general, in the design of the slot antenna 100, the phase characteristics required for the radiated radio wave are required to be about 25 to 30 dB or more in gain difference between the main lobe in the range of ± 2 degrees and the other phases. However, when there is a gap, a shoulder 46 indicated by a broken line is generated at a position around 25 to 30 dB. However, by using the slot antenna 100 shown in the first modification, the shoulder 46 is reduced as shown in the figure. Even when the slot antenna 100 shown in the first modified example is used, although there is some distortion, the distortion occurs at −30 dB or less, so there is no problem.

  FIG. 10 is a diagram illustrating an example of the manufacturing process of the first modification. The formwork used for this process shall be manufactured beforehand. First, a fluid is poured into the mold 36 (S10). Next, the formwork into which the fluid is poured is cooled (S12). Next, the solidified slot antenna is taken out from the cooled mold (S14). Here, when the fluid substance poured in the casting process of S10 is a substance having conductivity (Y in S16), the process is terminated. On the other hand, when the fluid material poured in the casting process of S10 is a substance having no electrical conductivity (N of S16), the slot antenna taken out in the process of S14 is plated (S18). The process is terminated. In addition, when the formwork used for this process does not have a slot hole, you may add the process of forming a slot hole after the process of S14.

(Modification)
Hereinafter, modifications of the slot antenna shown in the first embodiment, the second embodiment, and the third embodiment will be described.
In the modified example, in addition to the adjustment of the depth dimension d and the width w described in the first or second embodiment, the design flexibility can be improved while suppressing the vertical polarization component by adding a new design parameter. Indicates.

  FIG. 11 is a diagram illustrating a configuration example of the slot antenna 100 according to the modification. The slot antenna 100 includes a waveguide 12, a support portion 26, a first parallel portion 48 a and a second parallel portion 48 b represented by a parallel portion 48, and the flare plate 14. Here, each of the first parallel portion 48a and the second parallel portion 48b has a length of (d1 + d2) as illustrated. d1 represents a distance along the H plane from the bottom surface portion of the support portion 26 to the slot surface 20 of the waveguide 12, and d2 represents a distance parallel to the H plane from the end of d1 to the flare plate 14.

  d1 is designed on the order of millimeters according to the previous embodiment. However, when manufacturing the slot antenna 100, a design error may occur. Therefore, even if d1 and w are adjusted, the vertical polarization component may not be suppressed depending on the design error. In general, even if molding is performed with high accuracy, a design error of around ± 0.4 mm from the target value exists.

  Here, since the portion having the length of d2 forms a parallel plate with the facing portion, a waveguide (Parallel Plate Waveguide) is formed from one to the other. Then, the radio wave radiated from the slot antenna 100 is shaped by the waveguide, and the vertical polarization component changes according to the length of d2. In other words, the vertical polarization component can be adjusted by adjusting d2. Therefore, in the third modified example, not only d1 and w targeted for adjustment in the above-described embodiment, but also the length of d2 is adjusted. Thereby, the slot antenna 100 with reduced vertical polarization components can be easily manufactured.

  FIG. 12 is a diagram illustrating an example of the effect of suppressing the vertical polarization component of the slot antenna 100 according to the modification. The vertical axis indicates the amplitude intensity (Cross-Polarization Level) of the cross-polarization component that is the vertical polarization component. The horizontal axis indicates the length of d1. Further, the amplitude intensity of the cross polarization component when d2 is 0 mm is indicated by a solid line. The amplitude intensity of the cross polarization component when d2 = 12 mm is indicated by a broken line.

  In the illustrated example, when d2 is 0 mm and 12 mm, the minimum value of the amplitude intensity of both cross polarization components is almost the same. However, paying attention to the width of d1 where the amplitude intensity satisfies −35 dB, when d2 is 0 mm, it is approximately ± 0.1 mm with respect to the minimum amplitude value, whereas when d2 is 12 mm, it is generally ± 0. 4 mm. As shown in the figure, this width increases as the amplitude intensity increases.

  The width described above indicates the amount of tolerance in the design. This will be specifically described. Here, it is assumed that the required suppression amount of the cross polarization component is −35 dB. In general, the design is designed so that the cross-polarized wave component is minimized. Therefore, when d2 is set to 0 mm, d1 is designed to be 6.25 mm. Further, when d2 is set to 12 mm, d1 is designed to be 5.25 mm. However, as described above, there are many cases where the design involves an error, and a tolerance of ± 0.1 mm when d2 is set to 0 mm is expected to be extremely difficult for those skilled in the art in designing. The However, when d2 is set to 12 mm, an error of about ± 0.4 mm is allowed, so that a desired suppression amount can be easily obtained. In other words, by adjusting the length of d2, the allowable design error amount for d1 can be increased, so that the slot antenna 100 that can suppress the cross polarization component included in the radiated radio wave can be easily designed. Become.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the third embodiment, the waveguide 12 and the support portion 26 have been described as being molded using a mold so as to be integrated. However, the present invention is not limited to this. For example, the mold may be molded using a mold in which the waveguide 12, the support portion 26, and the flare plate 14 are integrated. Alternatively, the waveguide 12, the support portion 26, the flare plate 14, and the radome portion 16 may be molded using a mold that includes the casing portion 51 or the united frame. In these cases, the design and manufacturing period can be shortened.

FIG. 13A illustrates a slot antenna in which the radome 16, the casing 51, the waveguide 12, the support 26, and the flare plate 14 are molded using a mold in the third embodiment. It is sectional drawing of the 1st structural example.
FIG. 13B shows a second configuration example according to the third embodiment of the slot antenna in which the radome portion 16, the waveguide 12, the support portion 26, and the flare plate 14 are molded using a mold so as to be integrated. In this configuration example, the interior is covered with the radome portion 16 and also serves as a housing.
In both figures, the metallic plating portion 52 of the integrally molded slot antenna indicated by the solid line portion is subjected to metallic plating, and the metallic plating unnecessary portion 53 of the integrally molded slot antenna indicated by the broken line portion is metallic plated. Do not apply. The portion not subjected to metallic plating operates as a radome, radiates radio waves, and protects the inside.

  It should be understood by those skilled in the art that the above-described first and second embodiments and the first to third modifications can be combined with each other. For example, when the first and second embodiments are combined, the depth dimension d is set to ¼ of the wavelength, and the width w to be combined with the depth dimension d may be obtained by experiments or the like. This aspect can further suppress the vertical polarization component. In addition, when combining the first modification example or the second modification example with the third modification example, the slot antenna 100 is designed so as not to create a gap between the waveguide 12 and the support portion 26. By adjusting the lengths of the first parallel portion 48a and the second parallel portion 48b shown in FIG. 11, the slot antenna 100 with reduced vertical polarization components can be easily designed.

  It should be noted that combinations other than those described above are possible, and it goes without saying that the respective modes can be combined and the effects can be superimposed.

FIG. 1A is a perspective view illustrating a configuration example of a waveguide. FIG. 1B is a cross-sectional view showing a part of the slot surface of the waveguide of FIG. FIG.1 (c) is sectional drawing which shows the waveguide surface of the waveguide of Fig.1 (a). FIG. 2A is a perspective view illustrating a configuration example of the slot antenna according to the first embodiment of the present invention. FIG. 2B is a front view of the waveguide surface of the slot antenna of FIG. FIG. 3 is a first front view showing a waveguide surface of a waveguide in the slot antenna of FIG. FIG. 3 is a second front view showing a waveguide surface of a waveguide in the slot antenna of FIG. FIG. 5A and FIG. 5B are graphs showing experimental results of the effect of suppressing the vertical polarization component in the slot antenna of FIG. It is a front view which shows the waveguide surface of the waveguide in the slot antenna concerning Embodiment 2 of this invention. It is a figure which shows typically the structural example of the slot antenna concerning a 1st modification. FIG. 8 is a cross-sectional view of a mold for manufacturing the slot antenna of FIG. 7. It is a figure which shows the effect of a 1st modification. It is a figure which shows the example of the manufacturing process of a 1st modification. It is a figure which shows the structural example of the slot antenna concerning a 3rd modification. It is a figure which shows the example of a suppression effect of the vertical polarization component of the slot antenna concerning a 3rd modification. FIG. 13A shows a first configuration example according to the third embodiment of the slot antenna in which the radome portion, the casing portion, the waveguide, the support portion, and the flare plate are molded using a mold so as to be integrated. It is sectional drawing. FIG. 13B is a cross-sectional view of a second configuration example of a slot antenna formed by using a mold so that the radome, the waveguide, the support, and the flare plate are integrated in the third embodiment. .

Explanation of symbols

10 antenna outer plate, 12 waveguide, 14 flare plate, 16 radome portion, 18 slot, 20 slot surface, 22 waveguide surface, 24 groove, 26 support portion, 30 broken line, 36 mold, 38 cavity, 42 waveguide Portion, 44 support portion, 46 shoulder, 48 parallel portion, 48a first parallel portion, 48b second parallel portion, 51 housing portion, 52 metal plating location of integrally molded slot antenna, 53 of integrally molded slot antenna 100-slot antenna where metal plating is unnecessary.

Claims (3)

A waveguide having a slot for radiating a radio wave at one of the E-plane portions; two parallel portions disposed opposite to each of the two H-plane portions of the waveguide at regular intervals; and the two parallel portions Each of the bottom surfaces of the waveguide, one end of which is in contact with the parallel portion and the other end of which is in contact with the H-plane portion of the waveguide, and the other end of each of the two bottom portions. A slot antenna manufacturing method comprising: a support portion having a surrounding portion surrounding a part of the waveguide so as to support the other of the E-plane portions,
Pouring a fluid resin into a mold made so that the waveguide and the support are integrated;
Cooling the poured resin and molding the slot antenna;
Removing the molded slot antenna;
Of the slot antenna extracted by the step of extracting the slot antenna, a step of forming a slot hole to radiate radio waves in a portion corresponding to the E surface of the waveguide;
Plating the slot antenna formed by the step of forming the slot hole with a metallic substance;
A method for manufacturing a slot antenna, comprising:


The slot antenna manufactured by the manufacturing method is a flare portion that is in contact with the other end of the parallel portion that is not in contact with the bottom surface portion, and expands in the radiation direction of the radio wave radiated from the waveguide. The slot antenna manufacturing method according to claim 1, further comprising a flare portion.

The step of plating the slot antenna formed by the step of forming the slot hole with a metallic substance includes a housing part for the purpose of covering and protecting the waveguide, the support part, and the flare part, A mold is used so that the waveguide, the support portion, and the flare portion are positioned in front of the radome portion that protects and transmits radio waves, and the waveguide, the support portion, and the flare portion are integrated with resin. 3. The method for manufacturing a slot antenna according to claim 1, wherein the metallic plating is applied only to a necessary part other than the radome part.