JP7175805B2 - Electromagnetic horn antenna and directivity control system - Google Patents

Description

The present disclosure relates to an electromagnetic horn antenna that transmits and receives electromagnetic waves, and a directivity control system that controls the directivity of electromagnetic waves. The present invention relates to an electromagnetic horn antenna and a directivity control system capable of changing directivity.

Electromagnetic horn antennas are used to transmit and receive microwaves with high directivity. The electromagnetic horn antenna has a rectangular or circular horizontal cross-section corresponding to the cross-sectional shape of the waveguide (waveguide), and the horizontal cross-sectional area gradually increases from the base side connected to the waveguide toward the tip side. It is a trumpet-shaped member that is formed so as to be large, and emits electromagnetic waves transmitted inside the waveguide into space without reflection at the open end, or receives electromagnetic waves that have traveled through the space while suppressing attenuation. is.

As such an electromagnetic horn antenna, in order to realize an electromagnetic horn antenna capable of transmitting/receiving high-frequency electromagnetic waves in the millimeter wave band with strong directivity, a fan-shaped A configuration has been proposed in which the path lengths from the center to the radio wave radiating surface are equal (see Patent Document 1).

JP-A-2005-318038

In the above-mentioned conventional electromagnetic horn antenna, a desired fan-shaped shape is accurately formed by steel plate or metal-plated plastic material, and carbon fiber cloth or ferrite material is placed inside both side walls connecting the fan-shaped surfaces to each other. The configured electromagnetic wave absorbing material is attached to improve the directivity.

However, the conventional electromagnetic horn antenna cannot change the directivity, and the conditions such as the receiving part of the electromagnetic wave transmitted from the antenna, the size of the transmission source of the electromagnetic wave received by the antenna, the distance from the antenna, the placement position etc. changes, it is possible to cope with any of the conditions, but it is impossible to always achieve the desired directivity in response to the change in conditions.

The present disclosure solves the above-described conventional problems, and provides an electromagnetic horn antenna capable of transmitting and receiving electromagnetic waves in a high frequency band of the millimeter wave band or higher by changing the directivity, and a high frequency band of the millimeter wave band or higher. It is an object of the present invention to realize a directivity control system capable of controlling directivity in transmission and reception of electromagnetic waves.

An electromagnetic horn antenna disclosed in the present application for solving the above problems is an electromagnetic horn antenna used for transmitting and receiving electromagnetic waves in a high frequency band of millimeter waves or higher, wherein a plurality of plate-like moldings have a large diameter on the opening side. a driving mechanism disposed so as to form a hollow truncated cone having a smaller diameter on the waveguide side, and capable of radially moving the end portion of each of the plate-shaped moldings on the opening side; The plate-shaped molding is characterized by being formed of an electromagnetic wave absorbing member that absorbs the electromagnetic wave.

Further, the directivity control system disclosed in the present application includes an oscillator that oscillates at a high frequency in the millimeter wave band or higher and/or a receiver that receives electromagnetic waves at a high frequency in the millimeter wave band or higher; Equipped with a waveguide connected to a receiving part, and an electromagnetic horn antenna disclosed in the present application connected to the waveguide, and directing electromagnetic waves by changing the size of the diameter of the electromagnetic horn antenna on the opening side Characterized by changing sex.

In the electromagnetic horn antenna disclosed in the present application, the cone portion of the antenna is formed by a plurality of plate-shaped molded bodies that are electromagnetic wave absorbing members, and the end of the plate-shaped molded body on the opening side can be moved in the radial direction. It has mechanism. Therefore, the diameter of the opening can be changed by the drive mechanism, and high-frequency electromagnetic waves in the millimeter wave band or higher can be transmitted and received by changing the directivity.

Further, the directivity control system disclosed in the present application includes the electromagnetic horn antenna disclosed in the present application, a waveguide, an oscillating section and/or a receiving section, and changes the opening of the plate-like molded body in the radial direction. This makes it possible to control the directivity of electromagnetic waves in a high frequency band above the millimeter wave band to be transmitted and received.

It is a figure which shows the whole structure of the directivity control system concerning this embodiment in the state in which the directivity is not narrowed down. It is a figure which shows the whole structure of the directivity control system concerning this embodiment in the state where the directivity is narrowed down. FIG. 3 is a schematic diagram for explaining a configuration example of a plate-like molded body; It is a figure explaining the shape of the electromagnetic horn antenna which simulated. FIG. 5 is a diagram showing directivity characteristics of the electromagnetic horn antenna according to the present embodiment as simulation results; FIG. 4 is an image diagram for explaining the configuration of a driving mechanism that changes the directivity of the electromagnetic horn antenna according to the present embodiment; FIG. 4 is an image diagram showing the configuration of a restricting portion that connects adjacent plate-shaped moldings of the electromagnetic horn antenna according to the present embodiment;

The electromagnetic horn antenna disclosed in the present application is an electromagnetic horn antenna used for transmitting and receiving electromagnetic waves in a high-frequency band of millimeter waves or higher, wherein a plurality of plate-shaped moldings have a large diameter on the opening side and a small diameter on the waveguide side. and a driving mechanism for radially moving an end portion of each of the plate-shaped moldings on the side of the opening, wherein the plate-shaped moldings are and an electromagnetic wave absorbing member that absorbs the electromagnetic wave.

The electromagnetic horn antenna disclosed in the present application having the above configuration changes the diameter of the opening by radially moving the end of the plate-shaped molded body formed of an electromagnetic wave absorber on the opening side by a driving mechanism. be able to. Therefore, it is possible to transmit and receive high-frequency electromagnetic waves in the millimeter wave band or higher while changing the directivity.

In the electromagnetic horn antenna disclosed in the present application, it is preferable that the plate-like molded body contains magnetic iron oxide that magnetically resonates at frequencies in the millimeter wave band or higher. Since the magnetic iron oxide that magnetically resonates at frequencies above the millimeter wave band can well absorb the electromagnetic waves incident on the plate-shaped molded body, it is possible to reduce the reflection of electromagnetic waves in the electromagnetic horn antenna, resulting in high accuracy. It is possible to transmit and receive electromagnetic waves by controlling the directivity.

In this case, it is preferable that the proportion of the magnetic iron oxide contained in the plate-like molding is 5 to 50% by volume. By doing so, the electromagnetic horn antenna can be constructed from the plate-shaped molded body having electromagnetic wave absorption characteristics and sufficient brittleness as the structure of the electromagnetic horn antenna.

In addition, it is preferable that the ratio of the magnetic iron oxide in the thickness direction of the plate-shaped compact is different, and the ratio on the outer surface side is larger than the ratio on the inner surface side of the plate-shaped compact. By doing so, on the inner surface of the electromagnetic antenna, absorption of electromagnetic waves emitted from the base is reduced, and electromagnetic waves with high directivity and high intensity can be emitted, and electromagnetic noise from the outside of the antenna can be effectively absorbed. can reduce the influence of noise.

In this case, it is preferable that the plate-like molded body is configured as a laminate of a plurality of molded bodies containing the magnetic iron oxide at different ratios. By doing so, it is possible to easily form a plate-shaped molding having a different content ratio of magnetic iron oxide in the thickness direction.

Further, it is preferable that the plate-like molded body is wider on the opening side than on the waveguide side and has a thickness of 1 to 10 mm. By doing so, it is possible to ensure the electromagnetic wave absorption characteristics and rigidity of the plate-shaped molded body, and to increase the change in the size of the opening when the opening end is moved in the radial direction.

In addition, it is preferable that the electrical conductivity of the inner surface of the electromagnetic horn antenna of the plate-like molded body is 500 S/m or more.

Further, the drive mechanism includes a rotating portion arranged at an end portion of the plate-shaped molded body on the waveguide side and capable of rotating the plate-shaped molded body in a direction perpendicular to the main surface thereof; It is preferable to have a drive unit fixed to the vicinity of the waveguide-side end of the molded body for rotating the plate-shaped molded body. By doing so, it is possible to change the position of the opening of the plate-shaped molding with a simple configuration.

In addition, each of the plate-like molded bodies has a protrusion formed on the side surface thereof on the side of the opening, and a groove formed in which the protrusion of the adjacent plate-shaped molded body is slidable. is preferred. By doing so, it is possible to regulate the change in the angle of the plurality of plate-like moldings, and to change the diameter while maintaining the substantially circular state of the opening and the cross section perpendicular to the axis.

Further, the directivity control system disclosed in the present application includes an oscillator that oscillates at a high frequency in the millimeter wave band or higher and/or a receiver that receives electromagnetic waves at a high frequency in the millimeter wave band or higher; Equipped with a waveguide connected to a receiving part, and an electromagnetic horn antenna disclosed in the present application connected to the waveguide, and directing electromagnetic waves by changing the size of the diameter of the electromagnetic horn antenna on the opening side change gender.

By doing so, the directivity control system disclosed in the present application can easily and reliably control the directivity of electromagnetic waves to be transmitted and received using one electromagnetic horn antenna.

An electromagnetic horn antenna and an electromagnetic wave directivity control system disclosed in the present application will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a perspective view for explaining the overall configuration of a directivity control system according to this embodiment. FIG. 1 shows a shape in which the directivity is set weak (not narrowed).

As shown in FIG. 1 , a directivity control system 100 shown as this embodiment has an electromagnetic horn antenna 10 according to this embodiment and a base 20 .

The electromagnetic horn antenna 10 shown in FIG. 1 is formed by eight plate-like moldings 11 to 18. As a whole, the base portion 20 side has a small diameter and the opening portion 10a side opposite to the base portion 20 has a large diameter. It has a shape. More specifically, as shown in FIG. 1, in each of the plate-shaped molded bodies (11 to 18), the right side surface (the right side surface in the plate-shaped molded body 11) in the direction toward the center (the center of the truncated cone) 11a) contacts the edge of the inner surface 12b (surface on the center side) of another adjacent plate-like molded body, that is, the edge of the inner surface 12b of the plate-shaped molded body 12 on the plate-shaped molded body 11 side. are arranged as As described above, in the electromagnetic horn antenna 10 of the present embodiment, the side surface (11a) of each plate-shaped molded body (11) is the plate-shaped molding of the inner surface (12b) of the other adjacent plate-shaped molded body (12). By overlapping with the end portion on the body 11 side, the opening 10a and the shape of the cross section perpendicular to the central axis of the substantially truncated cone shape corresponding to the so-called cone portion are all substantially circular.

Since the electromagnetic horn antenna 10 according to the present embodiment is composed of a plurality of (eight in the case of the example shown in FIG. 1) plate-like moldings (11 to 18), the central axis of the substantially truncated cone shape Strictly speaking, the vertical cross section is a polygon, that is, an octagon as a whole in the case of the example shown in FIG. It has a shape that produces For this reason, it is also possible to grasp the overall shape of the electromagnetic horn antenna as a hollow "truncated pyramid" shape. However, the shape of the cone portion of the electromagnetic horn antenna according to the present embodiment, which is formed of a plurality of plate-shaped moldings, is originally a hollow truncated cone shape of the electromagnetic horn antenna. In this specification, the overall shape of the electromagnetic horn antenna is referred to as a hollow "substantially truncated cone shape" because it is a shape realized by a shaped body. Also, the shape of the opening 10a of the electromagnetic horn antenna and the shape of the cross section perpendicular to the central axis of the cone are both referred to as "substantially circular".

FIG. 2 is a perspective view for explaining the overall configuration of the directivity control system according to this embodiment. FIG. 2 shows a shape in which directivity is strongly set (closed).

When the directivity shown in FIG. 2 is set to be strong, that is, when the electromagnetic wave is radiated with high directivity, or when the direction of the received electromagnetic wave is set narrowly, the electromagnetic horn antenna 10 The degree of overlap between the plate-shaped moldings (11 to 18) forming the is increased. That is, as is clear from the comparison between FIGS. 1 and 2, in the directivity control system 100 according to the present embodiment, the degree of overlap of the plate-shaped moldings (11 to 18) constituting the electromagnetic horn antenna 10 is changed. Thus, the directivity of the electromagnetic wave is controlled by changing the diameter of the opening 10a of the electromagnetic horn antenna.

When the directivity of electromagnetic waves is strongly narrowed, as shown in FIG. In 11, the right side surface 11a) contacts the substantially central portion of the inner surface of another adjacent plate-shaped molded body (the central position in the width direction of the plate-shaped molded body 12 among the inner surfaces 12b of the plate-shaped molded body 12). are arranged as As described above, in the electromagnetic horn antenna 10 of the present embodiment, the side surface (11a) of one plate-shaped molded body (11) is located at the central portion of the inner surface (12b) of the other adjacent plate-shaped molded body (12). By positioning, the plate-shaped molded bodies overlap each other by about half, and the diameter of the substantially circular shape of the opening 10a and the diameter of the substantially circular shape of the section perpendicular to the central axis forming the cone portion are formed. However, both are smaller than when the directivity is set weakly as shown in FIG.

In the directivity control system according to the present embodiment, a driving mechanism for changing the degree of overlap between the plate-like moldings to change the diameter of the opening will be described in detail later.

As an example, the base 20 in the directivity control system 100 according to the present embodiment shown in FIGS. The electromagnetic horn antenna 10 is arranged to protrude from an opening 21 formed in one of the pair of large surfaces 20a. As the base portion 20, in addition to the above-described substantially rectangular parallelepiped shape, a substantially fan-shaped shape having a narrower area on the base side and a wider area on the opening side can be adopted.

The small-diameter opening of the electromagnetic horn antenna 10 on the side of the base 20 has a substantially circular shape like the large-diameter opening 10a and the cross section perpendicular to the central axis of the intermediate portion, and the cross section is circular in the base 20. is connected to the end of the waveguide (waveguide) 22 on the antenna side. Although not shown, the end of the waveguide 22 opposite to the end of the waveguide 22 connected to the electromagnetic horn antenna 10 is provided with a millimeter signal transmitted by the directivity control system 100 according to the present embodiment. Either an oscillating unit that generates electromagnetic waves in a frequency band higher than the wave band, or a receiving unit that receives electromagnetic waves received by the directivity control system 100 according to the present embodiment, or both the oscillating unit and the receiving unit are arranged. be done.

As described above, in the electromagnetic wave directivity control system according to the present embodiment, the electromagnetic horn antenna according to the present embodiment can change the directivity by changing the degree of overlapping of the plate-shaped moldings forming the cone portion. The diameter of the opening of the electromagnetic horn antenna is changed by making use of the features of For example, when the directivity is strengthened and electromagnetic waves are transmitted only in a limited direction, as shown in FIG. When transmitting electromagnetic waves toward a range, as shown in FIG. Similarly, when receiving electromagnetic waves from a wide range, as shown in FIG. As shown in FIG. 2, a strong directivity is imparted by increasing the degree of overlapping of the plate-like moldings. In addition, since the plate-shaped molded body forming the cone portion of the electromagnetic horn antenna is an electromagnetic wave absorbing member that absorbs high-frequency electromagnetic waves above the millimeter wave band, unwanted reflection of electromagnetic waves on the inner surface of the electromagnetic horn antenna is suppressed. It is possible to control the directivity of electromagnetic waves with high accuracy.

[Plate shaped body]
As shown in FIGS. 1 and 2, the plate-shaped molded bodies (11 to 18) constituting the electromagnetic horn antenna 10 according to the present embodiment have a substantially rectangular main surface having a longitudinal direction and a width direction, It is an elongated thin plate-like member having a small thickness compared to the size in the longitudinal direction and the width direction.

In the electromagnetic horn antenna 10 according to the present embodiment, as an example, the electromagnetic horn antenna 10 is formed of eight plate-shaped molded bodies (11 to 18), and the eight plate-shaped molded bodies (11 to 18) are All have the same shape. Further, as shown in FIGS. 1 and 2, each plate-shaped molded body (11 to 18) is slightly wider on the opening 10a side of the electromagnetic horn antenna 10 than on the base 20 side. By doing so, the electromagnetic horn shown in FIG. The diameter of the opening 10a of the antenna 10 can be made larger. In addition, in the electromagnetic horn antenna 10 according to the present embodiment, it is not essential to form the width of the plate-shaped molded body (11 to 18) on the side of the opening 10a wider. Shaped bodies (11 to 18) can also be used.

When the electromagnetic horn antenna 10 is formed from a plurality of plate-shaped molded bodies by giving a slightly curved surface to the plate-shaped molded body so that the inside of the electromagnetic horn antenna 10 has a concave shape, the cross section perpendicular to the central axis It is possible to obtain the electromagnetic horn antenna 10 whose shape is almost circular.

The plate-shaped moldings (11 to 18) are magnetic particles containing ferritic magnetic iron oxide (powder) such as strontium ferrite, hexagonal ferrite, and epsilon iron oxide dispersed in a non-conductive organic material binder. It is constructed by molding paint into a predetermined shape.

As the magnetic iron oxide powder, ferritic magnetic iron oxide powder such as strontium ferrite, hexagonal ferrite, and epsilon iron oxide can be used favorably. In particular, epsilon iron oxide has a high coercive force and is excellent in absorbing electromagnetic waves. ing. These ferritic magnetic iron oxides have different gyromagnetic constants depending on the type of magnetic material, and the electromagnetic waves that can be absorbed differ depending on the gyromagnetic constants. For example, strontium ferrite is preferable as a material that absorbs electromagnetic waves in the range of 10 to 140 GHz, and epsilon iron oxide is preferably used as a material that absorbs electromagnetic waves in the range of 30 to 300 GHz. Thus, the ferritic magnetic iron oxide can be appropriately selected according to the required absorption band. Furthermore, by mixing two or more of these different ferritic magnetic iron oxides, it is possible to widen the frequency band of electromagnetic waves to be absorbed.

Various resin materials such as epoxy-based resins, polyester-based resins, polyurethane-based resins, acrylic-based resins, phenol-based resins, and melamine-based resins can be used as binders constituting the plate-shaped moldings (11 to 18). . In selecting the resin material, the plate-shaped moldings (11 to 18) should be sufficiently adapted to the change in shape (for example, the change between the state shown in FIG. 1 and the state shown in FIG. 2) accompanying directivity control. It must have the strength to withstand. For this reason, it is preferable to use a thermosetting resin material, and a thermoplastic resin material that does not soften under temperature conditions within the operating range can also be used. On the other hand, it is not preferable to use a rubber-based resin material that has a large elasticity and causes a change in the overall shape during normal use.

All of the ferrite-based magnetic iron oxide powders contained in the plate-shaped moldings (11 to 18) undergo magnetic resonance at frequencies in the millimeter wave band or higher, and emit electromagnetic waves incident on the plate-shaped moldings (11 to 18). It can be converted into heat and absorbed. Further, by forming the plate-shaped moldings (11-18) by molding a magnetic paint containing magnetic iron oxide in a resin binder, the plate-shaped moldings (11-18) can be shaped and sized. can be easily determined.

The amount of magnetic iron oxide contained in the thickness direction, that is, the content per unit volume of the plate-shaped moldings (11 to 18) used for the horn antenna according to the present embodiment can be varied. . In this case, it is preferable to reduce the magnetic iron oxide content on the inner surface side of the plate-shaped compacts (11 to 18) and increase the magnetic iron carbide content on the outer surface side.

FIG. 5 is a schematic diagram for explaining the state of the plate-shaped compacts with different contents of magnetic iron oxide in the thickness direction. 5(a), 5(b), and 5(c), the shades of colors in the figures correspond to the shades of the magnetic iron oxide content.

FIG. 5(a) shows that in one plate-shaped molding 110 (each of the plate-shaped moldings 11 to 18), the content of magnetic iron oxide in the portion arranged on the outer surface side is arranged on the inner surface side. It shows a state in which the content of magnetic iron oxide is larger than that of the magnetic iron oxide. In addition, FIG. 5(b) shows that the plate-shaped molded bodies 120 (each of the plate-shaped molded bodies 11 to 18) is composed of a member 121 having a large content of magnetic oxide and a member 122 having a small content of magnetic iron oxide. It shows a state in which it is configured as a two-layer laminate. Furthermore, FIG. 5(c) shows that the plate-shaped molded bodies 130 (each of the plate-shaped molded bodies 11 to 18) is a member 131 having a large content of magnetic oxide and a member 132 having an intermediate content of magnetic iron oxide. and a member 133 having a small magnetic iron oxide content.

As in the configuration example illustrated in FIG. 3, by reducing the content of magnetic iron oxide on the inner surface side of the plate-shaped molded body, the absorption of electromagnetic waves emitted from the base is reduced, and electromagnetic waves with high directivity and high intensity can be generated. can take out. In addition, by increasing the content of magnetic iron oxide on the outer surface side of the plate-shaped molded body, electromagnetic wave noise from the outside can be absorbed by the outer surface, which has a large amount of magnetic iron oxide, thereby reducing the influence of noise. can be made

When providing a distribution in the magnetic iron oxide content in the thickness direction of the plate-like molded body as shown in FIG. In the case of the example shown in FIG. 1, it is preferable to apply to all the eight plate-like moldings 11 to 18 . However, for example, by adopting magnetic iron oxide having different magnetic iron oxide densities in the thickness direction for half of the four plate-shaped molded bodies, it is possible to improve the directivity of the electromagnetic waves to be radiated and eliminate the external magnetic field as described above. It is not always necessary to use the plate-shaped molded bodies illustrated in FIG.

Further, the electrical conductivity of the electromagnetic horn antenna formed by the plate-shaped moldings (11 to 18) is preferably 500 S/m or more, more preferably 5000 S/m or more. With this range, the electromagnetic waves emitted from the waveguide are reflected by the plate-shaped molded body, so that the directivity of the electromagnetic waves can be further enhanced. Even if the upper limit of the conductivity is increased to 1×10 ⁵ S/m or more, the effect is saturated, so the upper limit is preferably about 1×10 ⁵ S/m. If the electrical conductivity is less than 500 S/m, the effect of reflecting electromagnetic waves on the surface of the plate-shaped molded body is reduced, and the directivity of electromagnetic waves is reduced.

It should be noted that the electrical conductivity within the preferred range described above may be applied to the entire thickness direction of the plate-like molding, or may be applied only to the inner surface of the electromagnetic horn antenna. When the electrical conductivity of the entire thickness direction of the plate-like molding is to be within a preferable range, the binder can be mixed with carbon black or metal particles, and the plate-like molding having the desired electrical conductivity can be formed by adjusting the mixed amount. . When the inner surface of the plate-shaped molded body has a predetermined conductivity, a conductive film may be formed on the surface of the plate-shaped molded body with a composition in which carbon black or metal particles are mixed with a binder, or vapor deposition or sputtering may be used. It is also possible to form a conductive film on the surface by a vacuum method such as ion plating.

Here, one example of the method for producing the plate-shaped moldings (11 to 18) will be described.

In order to produce the plate-like moldings (11 to 18) as described above, a magnetic paint is first produced.

For example, when epsilon iron oxide is used as the magnetic iron oxide powder, the magnetic paint is obtained by obtaining a kneaded product of epsilon iron oxide powder, a phosphoric acid compound as a dispersant, and an epoxy resin as a resin binder. It is prepared by filtering through a filter after dilution and dispersion.

The kneaded product is obtained by kneading with a pressurized batch type kneader or by other methods. Further, the kneaded material can be dispersed as a dispersion using, for example, a sand mill filled with beads such as zirconia. At this time, a cross-linking agent can be blended as necessary.

The magnetic paint thus obtained is coated on a releasable support, such as a polyethylene terephthalate (PET) sheet having a predetermined thickness that has been subjected to a release treatment with a silicone coat, using a table coater or bar coater. apply.

Thereafter, the magnetic paint in a wet state is dried at 80° C., and further calendered at a predetermined temperature using a calendering device to form plate-like moldings (11 to 18) having a predetermined shape and size on a support. can be formed.

As another method for producing the plate-like moldings (11 to 18), an extrusion molding method can be used.

When the extrusion molding method is used, for example, magnetic iron oxide powder, a binder, and, if necessary, a dispersant, an antioxidant, etc., are first blended in advance, and these blended materials are extruded from a resin supply port of an extruder to produce plasticity. It can be fed into a cylinder and plasticized and melted by a screw arranged in the cylinder. As an extruder, a normal extruder equipped with a plastic cylinder, a die provided at the tip of the plastic cylinder, a screw rotatably disposed in the plastic cylinder, and a drive mechanism for driving the screw A molding machine can be used.

The molten material plasticized by the band heater of the extruder is sent forward by the rotation of the screw and extruded from the tip in the form of a sheet. The extruded material is pulverized by a pelletizer to produce resin pellets. This pellet becomes a masterbatch in which magnetic iron oxide powder as an electromagnetic wave absorbing material is dispersed in a resin.

Subsequently, the obtained resin pellets are put into the plasticizing cylinder from the inlet of the injection molding machine, plasticized and melted by the screw, and then injected into the mold connected to the tip of the injection molding machine. Mold into shape. In this case, another resin may be mixed with the resin pellets and charged into the plasticizing cylinder through the inlet.

When forming the plate-shaped moldings (11 to 18), when magnetic paint is applied to change the content of magnetic iron oxide contained in a unit volume in the thickness direction, the content of magnetic iron oxide varies. Paints are prepared, and each magnetic paint is laminated in order of the content so that the content of magnetic iron oxide on the outer surface side of the plate-like molding is greater than that on the inner surface side. In this case, each coating may be laminated at the same time, or each layer may be separately formed and then attached with an adhesive or adhesive tape. In the case of simultaneous lamination, pellets having different amounts of magnetic iron oxide can be prepared in advance using an extruder, and plate-shaped compacts having different contents of magnetic iron oxide can be prepared by two-color molding.

Furthermore, as a method of producing the plate-shaped moldings (11 to 18), a method of producing a magnetic compound containing a magnetic iron oxide powder and a binder, molding it to a predetermined thickness, and cross-linking it is used. can also

In this case, first, a magnetic compound is produced. A magnetic compound can be obtained by kneading a magnetic iron oxide powder, a binder, and, if necessary, a dispersant. The kneaded material is obtained, for example, by kneading with a pressurized batch kneader. At this time, a cross-linking agent can be blended as necessary.

The resulting magnetic compound is crosslinked and molded into a predetermined shape at a temperature of 150° C. using, for example, a hydraulic press. After that, secondary cross-linking treatment is performed at a temperature of 170° C. in a constant temperature bath. In this manner, the plate-shaped moldings (11 to 18) having a predetermined shape can be produced.

The plate-shaped moldings (11 to 18) having a predetermined shape produced as described above are peeled off from the support, and a plurality of plate-shaped moldings (11 to 18) are attached with a drive mechanism, which will be described later. An electromagnetic horn antenna composed of plate-shaped moldings (11 to 18) having a predetermined shape can be produced.

The size of the plate-shaped molding formed in this manner can be, for example, 60 mm in the longitudinal direction and 20 to 30 mm in width. As shown in FIGS. 1 and 2, when the width of the plate-like molded body is variable in the longitudinal direction, the width of the wide opening side is 10 to 50% of the width of the narrow base side. % is preferable. As an example, the width on the base side may be 20 mm and the width on the opening side may be 25 mm (125% of the width on the base side, ie 25% wider).

It is preferable to determine the thickness of the plate-shaped molded body in consideration of the electromagnetic wave absorption capability of the plate-shaped molded body.

Table 1 below shows the case where strontium ferrite (SrFe ₁₂ O ₁₉ ) is used as the magnetic iron oxide powder contained in the plate-shaped molding, and the relative magnetic permeability (χ _s O) is 0.08, damping The constant (a) is 4.00E-02, the real part of the dielectric constant is 7, and the imaginary part is 0.5. The result of the simulation of the absorption characteristics of the electromagnetic wave by the plate-like molded body is expressed in dB.

If the plate-shaped molded body can attenuate the electromagnetic wave incident from the surface to about 1/10 or less (the electromagnetic wave absorption amount is about 10 dB), the reflection of the electromagnetic wave on the inner surface of the electromagnetic horn antenna can be sufficiently reduced. , the precision of the directivity of the electromagnetic waves radiated from the electromagnetic horn antenna or incident on the electromagnetic horn antenna can be sufficiently improved. From the simulation results in Table 1 above, when the thickness of the plate-shaped molded body is 1 mm or more and the content of the magnetic iron oxide powder is 5% by volume or more, the electromagnetic wave absorption characteristic of the plate-shaped molded body is 10 dB or more. It can be seen that this is sufficient to reduce the reflection of electromagnetic waves on the inner surface and improve the accuracy of directivity.

As is clear from Table 1 above, the greater the thickness of the plate-like molded body, the better the electromagnetic wave absorption characteristics. However, as shown in FIGS. 1 and 2, in the electromagnetic horn antenna according to the present embodiment, the end portions of the plate-shaped moldings are arranged so as to overlap the adjacent plate-shaped moldings. If the thickness is large, the step of the overlapped portion becomes large, deviating from the ideal circular cross-sectional shape of the cone portion formed by the plate-like molded body, and directivity accuracy is lowered. In addition, if the thickness of the plate-shaped molded body is large, the mechanism for changing the overlapping state of the plate-shaped molded bodies to change the diameter of the cone portion of the electromagnetic horn antenna becomes larger, resulting in high cost. As a result, it becomes difficult to accurately control the shape change of the cone portion. Therefore, it is preferable to set the thickness of the plate-like molding to 10 mm or less.

Further, from Table 1, it can be seen that the higher the content of the magnetic iron oxide powder contained in the plate-shaped molded body, the better the electromagnetic wave absorption characteristics of the plate-shaped molded body. However, if the content of the magnetic iron oxide powder is too high, the effect of dispersing the magnetic iron oxide powder by the binder will be reduced, making the plate-like molded body brittle, and the force exerted when the shape of the cone will change, or from external forces. Cracks and chipping of the plate-shaped molded body are likely to occur due to the impact of the metal. From this point of view, the content of the magnetic iron oxide powder is preferably 50% by volume or less as long as the brittleness of the plate-like molding does not decrease excessively.

The inventors evaluated the directivity of electromagnetic waves by simulation using the plate-like molding disclosed in the present application.

FIG. 4 shows the shape of the electromagnetic horn antenna used in the simulation.

In the simulation, 13% by volume of strontium ferrite was contained as magnetic iron oxide powder in the resin, and calculation was performed using a plate-shaped body having an inner surface conductivity of 70000 S/m and a thickness of 1.0 mm. As for the shape of the electromagnetic horn antenna, as shown in FIG. 4, the long side (W) of the opening was 30.0 mm, the short side (H) was 22.8 mm, and the length (L) was 59.6 mm. Further, the plate-like molding used had a magnetic permeability of .mu.'=1.06 and .mu.''=0.16, and a dielectric constant of .epsilon.r'=0.83 and .epsilon.r''=0.05.

Using these conditions, the electromagnetic field analysis software ANSYS HFSS (manufactured by ANSYS JAPAN Co., Ltd.) was used to simulate the anisotropy of the electromagnetic wave with a frequency of 75 GHz output from the waveguide to the electromagnetic horn antenna. .

FIG. 5 shows the results of the simulation.

FIG. 5(a) is a diagram showing the intensity of the electromagnetic wave in the cross section of the XZ plane shown in FIG. FIG. 5(b) is a diagram showing the intensity of electromagnetic waves in the XY plane cross section shown in FIG.

From the results shown in FIGS. 5(a) and 5(b), it was confirmed that the electromagnetic horn antenna using the plate-shaped molding of the present application has strong anisotropy in the electromagnetic wave emission direction (X direction). .

[Driving mechanism]
Next, in the electromagnetic horn antenna 10 according to the present embodiment, a driving mechanism for controlling the directivity by changing the degree of overlap of the plate-like moldings forming the cone will be described.

FIG. 6 is an image diagram showing a configuration example of a drive mechanism for changing the shape of the electromagnetic horn antenna according to this embodiment. FIG. 6 shows a state in which the plate-like molding is viewed from the side.

As shown in FIG. 6, in the electromagnetic horn antenna 10 according to the present embodiment, a rotation portion as a driving mechanism is provided at each end portion of the plate-shaped molded bodies (11 to 18) forming the cone portion on the waveguide 22 side. 30 and a driving part 40 are formed.

The rotating part 30 is a member that allows each plate-shaped molded body (11 to 18) to rotate in a direction perpendicular to its main surface (the inner surface 12b of the plate-shaped molded body 12 in FIGS. 1 and 2). , hold the respective plate-shaped moldings (11 to 18) in a state in which the end portion on the side of the opening 10a can be moved in the radial direction of the opening 10a. Specifically, as shown in FIG. 6, the rotating portion 30 of the electromagnetic horn antenna 10 according to the present embodiment is a rotating portion arranged in parallel with the main surface 12b of the plate-shaped molded body (12 is illustrated in FIG. 6). This is a so-called hinge mechanism composed of a shaft 31 , a holding portion 32 that holds the plate-like molding 12 so as to be rotatable around the rotation shaft 31 , and a support portion 33 that supports the rotation shaft 31 . By arranging this rotating portion 30 at the waveguide 22 side end portion of the plate-shaped molded bodies (11 to 18), the plate-shaped molded body 12 has almost the position 12c of the waveguide 22 side end portion of the inner surface 12b. Without change, that is, in a state in which the waveguide 22 and the electromagnetic horn antenna 10 are substantially connected, the position of the end on the opening 10a side is changed in the radial direction of the opening 10a, that is, the waveguide The inclination angle α of the plate-like molding 12 with respect to the plane A of the open end of 22 can be changed.

The driving unit 40 is arranged near the waveguide 22 side end of each of the plate-shaped moldings (11 to 18), and moves the opening 10a side end of the plate-shaped moldings (11 to 18) to the opening 10a. It is a member that moves in the radial direction of the As shown in FIG. 6 as an example, the driving section 40 includes a connecting portion 41 connected to the outer side surface 12d of the plate-like molded body 12, and a connecting portion 41 connected to the connecting portion 41 to move the plate-shaped molded body 12 to the main surfaces (12b, 12d). 12d), and a power mechanism (not shown) moves the rod 42 in the direction of the white arrows a or b in FIG. is rotated around the rotating shaft 42 of the rotating portion 40 to change the inclination angle α.

In this manner, in the electromagnetic horn antenna 10 according to the present embodiment, the plate-shaped moldings (11 to 18) are rotated around the rotation shaft 32 by the force applied by the drive unit 40, and a plurality of plate-shaped moldings are formed. By changing the diameter of the opening 10a formed by the moldings (11 to 18), it is possible to switch between the weak directivity state shown in FIG. 1 and the strong directivity state shown in FIG. .

As shown in FIG. 6, the rotating portion 30 and the driving portion 40 are arranged on the outer surface (12d) side of the plate-like molding (12 in FIG. 6). In the electromagnetic horn antenna 10 according to this embodiment, since the inner surface (12b) of the plate-shaped moldings (11 to 18) forms the cone portion of the electromagnetic horn antenna 10, if a protrusion is present on the inner surface (12b), the electromagnetic horn This is to avoid the disturbance of the electromagnetic wave inside the antenna 10 and the inability to control the directivity accurately.

Next, in the electromagnetic horn antenna 10 according to the present embodiment, a mechanism for smoothly changing the inclination angles (α in FIG. 6) of the plate-shaped moldings (11 to 18) as a whole will be described.

FIG. 7 is an image diagram showing the configuration of a restricting portion that connects the plate-like moldings of the electromagnetic horn antenna according to the present embodiment and restricts a change in shape.

In the electromagnetic horn antenna 10 according to this embodiment, each plate-shaped molded body (11 to 18) is connected at a position near the opening 10a, and the diameter of the opening 10a is increased by the movement of the plate-shaped molded body (11 to 18). It has a regulating portion 50 that smoothly changes the . More specifically, as shown in FIG. 7, in the electromagnetic horn antenna 10 according to the present embodiment, the restricting portion 50 is positioned on the right side of the center axis of one plate-shaped molded body (plate-shaped molded body 11 as an example). A protrusion 51 is formed on the side surface (11a) to protrude sideways, and the inner surface 12b of another plate-shaped molded body (12) arranged adjacent to the right side of this plate-shaped molded body (11) has a , a groove portion 52 formed so that the projection portion 51 of the plate-shaped molded body 11 can slide inside thereof.

As shown in FIG. 7, protrusions 51 formed on the side surfaces of the respective plate-shaped molded bodies (11 to 18) are grooves 52 formed on the inner surfaces of adjacent plate-shaped molded bodies (11 to 18). By providing the regulating portion 50 that slides inside, when the plate-shaped moldings (11 to 18) receive a force toward the central axis side or the opposite side by the driving portion 40 of the driving mechanism described above, respectively can be prevented from moving apart. In addition, since the regulating portion 50 is formed on the opening 10a side of the plate-shaped moldings (11 to 18), the openings of the plate-shaped moldings (11 to 18) are connected by the regulating portion 50. A force acts in the circumferential direction. As a result, the plurality of plate-shaped moldings (11-18) move while maintaining the same angle α with respect to the plane A formed by the opening of the waveguide 22, and the plate-shaped moldings (11-18) ), the size of the diameter can be changed while maintaining the substantially circular shape formed in the cross section perpendicular to the opening 10a and the central axis.

In the above-described embodiment, an example is shown in which the drive unit that applies force to all the plate-shaped molded bodies is attached to all eight plate-shaped molded bodies. If the angle α of the moldings is well interlocked, it is not necessary to attach the drive to all the plate-shaped moldings. Half of the plate-like molded bodies (four in the case of the above embodiment), or less than half of the plate-shaped molded bodies, may be provided with drive mechanisms. On the other hand, in the case where all the plate-like moldings are provided with driving portions, and if the change in the angle of the plate-like moldings by the respective driving portions can be unified and controlled, there is no need to provide the regulating portion. However, in the electromagnetic horn antenna shown in this embodiment, the restricting portion is not an essential component.

In order to change the angle of the plate-shaped molded body, either an electric means such as a motor or a mechanical means such as turning a dial or a handle is adopted as a power mechanism for applying force to the rod of the drive section. can also

As described above, the electromagnetic horn antenna and the electromagnetic wave directivity control system disclosed in the present application are formed by a plurality of plate-shaped moldings formed of electromagnetic wave absorbing members for a high frequency band above the millimeter wave band. is configured, it is possible to reduce unwanted reflection of electromagnetic waves on the inner surface of the electromagnetic horn antenna and to accurately control the directivity of the transmitted and received electromagnetic waves. In addition, since the plurality of plate-shaped moldings constituting the electromagnetic horn antenna have a driving mechanism for moving the end on the side of the opening in the radial direction of the opening, the diameter of the opening can be changed, Directivity can be easily controlled.

Therefore, an electromagnetic horn antenna capable of changing the strength of directivity can be realized with a simple configuration at a low cost. For this reason, for example, by adopting it in the transmitter and/or receiver of an in-vehicle radar, the directivity can be changed according to the spread of the electromagnetic wave to be transmitted and the change in the position of the source of the electromagnetic wave to be received. can be used successfully for new applications of

In the above embodiment, the number of plate-shaped molded bodies constituting the electromagnetic horn antenna is exemplified as eight, but it goes without saying that the number of plate-shaped molded bodies constituting the electromagnetic horn antenna is not limited. The number of plate-like moldings can be appropriately selected within an allowable range from the viewpoints of forming an electromagnetic horn antenna that can be understood to have a substantially truncated cone shape as a whole and not making the configuration too complicated.

Further, in the above-described embodiment, the plate-shaped molded body of the electromagnetic horn antenna overlaps with the inner surface of another adjacent plate-shaped molded body so that the end on the right side toward the center is in contact with each other. It is needless to say that there is no problem even if the formed body overlaps with the inner surface of another adjacent plate-shaped molded body so that the left end toward the center of the molded body is in contact with the inner surface. In addition, if the plate-like moldings are arranged in a state where there is almost no gap between them, and electromagnetic waves do not leak from the gaps and do not cause unwanted scattering or reflection of electromagnetic waves in the electromagnetic horn antenna, then the adjacent plates should be separated from each other. There is no problem even if the shaped bodies are arranged in a state in which they do not overlap each other.

Furthermore, the thickness of the molded body, particularly the thickness in the direction toward the opening of the electromagnetic horn antenna, does not have to be constant. It can also be designed to be thinner from the base side toward the opening side as much as possible.

Further, in the above-described embodiment, an example was shown in which the members of the rotating portion and the driving portion constituting the driving mechanism are directly provided on the outer surface of the plate-like molded body. It is possible to adopt other configurations that can change the angle of the plate-like molded body in a desired state, such as using a metal plate provided with a rotating portion and a driving portion mounted on at least the outer surface of the end portion. can.

Furthermore, in the above-described embodiment, the configuration in which the plate-like molded body includes magnetic iron oxide that magnetically resonates has been described. It is also possible to use other materials such as carbon, carbon fiber, etc., which can satisfactorily absorb such electromagnetic waves.

The electromagnetic horn antenna and electromagnetic wave directivity control system disclosed in the present application can control the directivity in transmitting and receiving electromagnetic waves in a high frequency band above the millimeter wave band, so various transmitters and receivers using high frequency electromagnetic waves It can be suitably used for

Reference Signs List 10 electromagnetic horn antenna 10a opening 11 to 18 plate-like molded body 30 rotating portion (driving mechanism)
40 drive unit (driving mechanism)
100 directional control system

Claims (10)

An electromagnetic horn antenna used for transmitting and receiving electromagnetic waves in a high frequency band of millimeter waves or higher,
A plurality of plate-shaped moldings are arranged to form a hollow truncated cone shape with a large diameter on the opening side and a small diameter on the waveguide side,
a driving mechanism for moving the end of each plate-like molded body on the side of the opening in the radial direction of the opening;
An electromagnetic horn antenna, wherein the plate-like molded body is formed of an electromagnetic wave absorbing member that absorbs the electromagnetic wave. 2. The electromagnetic horn antenna according to claim 1, wherein said plate-like molded body contains magnetic iron oxide that magnetically resonates at frequencies above the millimeter wave band. 3. The electromagnetic horn antenna according to claim 2, wherein the magnetic iron oxide contained in the plate-like molding has a ratio of 5 to 50% by volume. 4. The electromagnetic horn antenna according to claim 3, wherein the ratio of said magnetic iron oxide in the thickness direction of said plate-shaped compact is different, and the ratio on the outer surface side is greater than the ratio on the inner surface side of said plate-shaped compact. 5. The electromagnetic horn antenna according to claim 3 or 4, wherein said plate-shaped molded body is constructed as a laminate of a plurality of molded bodies containing different proportions of said magnetic iron oxide. 6. The electromagnetic horn antenna according to any one of claims 1 to 5, wherein said plate-shaped molded body is wider on said opening side than on said waveguide side, and has a thickness of 1 to 10 mm. 7. The electromagnetic horn antenna according to any one of claims 1 to 6, wherein the electrical conductivity of the inner surface of said electromagnetic horn antenna of said plate-like molding is 500 S/m or more. The drive mechanism is arranged at the waveguide-side end of the plate-like molded body, and holds the plate-shaped molded body so as to be rotatable in a direction perpendicular to the main surface thereof. 8. The drive unit according to any one of claims 1 to 7, further comprising a driving unit fixed to the vicinity of the waveguide-side end of the molded body and applying a force to the plate-shaped molded body in a direction perpendicular to its main surface. The electromagnetic horn antenna described in 1. Each of the plate-shaped moldings has a projection formed on the side surface on the opening side of each of the plate-shaped moldings, and a groove formed so that the projections of the other plate-shaped moldings adjacent to the inner surface are slidable, The electromagnetic horn antenna according to claim 8. An oscillator that oscillates at a high frequency in the millimeter wave band or higher, and/or a receiver that receives electromagnetic waves at a high frequency in the millimeter wave band or higher, a waveguide connected to the oscillator or the receiver, and the guide. An electromagnetic horn antenna according to any one of claims 1 to 9 connected to a wave path,
A directivity control system, wherein the directivity of electromagnetic waves is changed by changing the size of the diameter of the electromagnetic horn antenna on the opening side.

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