JP4508941B2 - Antenna device and dielectric member thereof - Google Patents

Description

  The present invention relates to an antenna device mainly used as a radar antenna.

  As a radar antenna device, a slot array type horn antenna in which a slot waveguide is provided at the base of a metal horn is generally used.

  This general horn antenna can sharpen the vertical directivity by increasing the size of the opening surface of the horn. However, if the horn opening is held at a predetermined angle and the size of the opening surface is increased, the protrusion dimension to the front of the horn inevitably increases. A powerful motor is required, which is uneconomical.

  In order to reduce the opening area of the horn antenna, it has been proposed to install a slot waveguide at the base of the horn and attach a pair of plate-like dielectrics that protrude forward in parallel to the inner surface of the horn. (See Patent Document 1).

In addition, a dielectric is shielded at the opening end of the horn provided with a slot waveguide at the base, and a protrusion projecting forward at the center position of the vertical width is formed on the dielectric. It has been proposed to have an internal / external double structure (see Patent Document 2).
JP-A-56-031205 JP-A-62-171301

  In the conventional antenna devices shown in Patent Documents 1 and 2, the opening size of the horn can be kept small and the directivity can be improved, but the protruding size of the dielectric disposed in front of the horn becomes considerably large. . By increasing the projecting dimension of the dielectric, not only the entire occupied space as the antenna device increases, but also the weight increases. Further, if the protruding dimension is large, the wind direction from the front direction is good, but it is weak to the wind blowing from the vertical direction, particularly from the lower direction. Therefore, when this antenna device is used for radar, a large and powerful motor is required for driving the turning.

  The present invention relates to a slot array type horn antenna device in which a slot waveguide is provided at the base of a metal horn, and significantly reduces the forward projecting dimension from the opening surface of the dielectric while using the dielectric. It is another object of the present invention to provide an antenna device having a sharp directivity and reduced in size and weight, and a dielectric member therefor.

The antenna device according to claim 1, wherein a slot waveguide is provided at the base of the horn, and a horn antenna provided with a metal plate having a predetermined length in the electromagnetic wave radiation direction at an upper and lower center position;
The front center position of the horn antenna is hollow with a quadrangular cross section , the vertical dimension is equivalent to one wavelength of the electromagnetic wave to be emitted, and the longitudinal dimension is equivalent to a half wavelength of the electromagnetic wave to be emitted. A main dielectric member;
An upper support dielectric member that supports the main dielectric member on the upper end portion of the horn, and a lower support dielectric member that supports the main dielectric member on the lower end portion of the horn. .

The antenna device according to claim 2 is provided with a slot waveguide at the base of the horn, and the phase plane of the electromagnetic wave at the opening surface of the horn is delayed at the vertical center position, the upper end portion, and the lower end portion, and A horn antenna that smoothly changes so as to advance between a center position and the upper end position and between the upper and lower center position and the lower end position;
A first position where the front surface of the horn antenna has a quadrangular cross section and is hollow , and the dimension of the electromagnetic wave in the vertical direction is most advanced between the vertical central position and the upper end position; A main dielectric member, which corresponds to a distance between the upper and lower center position and the second position which is most advanced between the lower end position, and whose front-rear direction dimension corresponds to a half wavelength of an electromagnetic wave to be emitted ;
An upper support dielectric member that supports the main dielectric member on the upper end portion of the horn, and a lower support dielectric member that supports the main dielectric member on the lower end portion of the horn. .

The antenna device according to claim 3 is the antenna device according to claim 1 or 2 , wherein a rhombus in cross section between the upper support dielectric member or between the upper support dielectric member and the upper side of the main dielectric member. A lower sub-dielectric that forms a rhombus in cross section between the upper sub-dielectric member forming the shape and the lower support dielectric member or between the lower support dielectric member and the lower side of the main dielectric member. And a dielectric member.

  According to the antenna device of the present invention, since each dielectric member arranged in front of the horn antenna functions as a dielectric slow wave circuit, gain improvement and sharpening of the beam pattern can be achieved, and The projecting dimension can be further shortened compared to the conventional one.

  The main dielectric member may be a hollow member having a quadrangular cross section, and can be configured as a box or a cylinder. Further, the quadrilateral cross section can be determined in consideration of the radiation characteristics of electromagnetic waves, the air resistance accompanying rotation, and the like as a rectangular shape, a trapezoidal shape, or a shape in which one side thereof is curved.

  In addition, the main dielectric member can be supported by the support dielectric member, and the radiation characteristics of electromagnetic waves can be further improved. In addition, the upper and lower support dielectric members, the main dielectric member, and the upper and lower sub-dielectric members form a support dielectric space with a dielectric plate having a rhombus cross section. Can be further improved, and air resistance and the like accompanying rotation can be further reduced. Furthermore, since the antenna radome is composed of the dielectric slow wave circuit itself, the antenna device can be obtained at a very low cost.

  Further, according to the present invention, a small and high gain antenna device can be realized. Therefore, a relatively large antenna device such as an S band, for example, an antenna wind receiving area that serves as a resistance to prevent rotation in an environment exposed state such as a marine radar. A synergistic effect can be expected that can be reduced and the radar detection performance can be improved by increasing the gain.

  FIG. 1 is a diagram showing a configuration of a first embodiment of an antenna device according to the present invention, and shows a cross-sectional shape thereof. The antenna device of the present invention includes a horn antenna 10 and a dielectric slow wave circuit 20A composed of a dielectric provided at a front center position in the direction of electromagnetic wave radiation from the horn antenna. In FIG. 1, the horn antenna 10 and the dielectric slow wave circuit 20A are extended in the paper surface direction.

  The horn antenna 10 has a metal horn 11 and a slot waveguide 12 as a wave source provided at the base of the horn 11. An electromagnetic wave is emitted from a slot 13 provided on one surface of the slot waveguide 12. The horn 11 and the slot waveguide 12 may be the same as those in a conventional radar antenna.

  In the present invention, a metal plate 15 having a predetermined length is provided on the central axis M in the electromagnetic wave transmission direction from the slot waveguide. The thickness of the metal plate 15 is preferably as thin as possible, but is set to a thickness within a range where work accuracy, deformation prevention, and position fixing are possible. Further, the length and position of the metal plate 15 are appropriately determined according to desired phase plane characteristics at the opening surface of the horn 11. As an example, it is preferable that the horn is installed near the center of the front and back of the horn and has a length corresponding to a half wavelength of the radiated electromagnetic wave or a length shorter than that and corresponding to a quarter wavelength.

  The dielectric slow wave circuit 20A includes a hollow main dielectric member 21A having a quadrangular cross section (in this example, a rectangular shape) at the front center position of the horn antenna 10. The main dielectric member 21A has a size corresponding to one wavelength of an electromagnetic wave (eg, 3050 MHz; the same applies in the present specification) radiated in the vertical direction L1, and an electromagnetic wave radiated in the longitudinal direction. The dimension corresponding to the half wavelength is preferably set. The dielectric constant of the dielectric used for the dielectric slow wave circuit 20A is, for example, 2.8, and the material may be engineering plastic, FRP (glass fiber reinforced plastic), or the like. The dielectric slow wave circuit 20A only needs to have a quadrilateral cross section, and can be formed, for example, as a box or cylinder.

  The phase plane of the electromagnetic wave at the opening surface of the horn antenna 10 is delayed at the vertical center position and the upper end portion and the lower end portion position at the opening surface, and between the upper and lower central position and the upper end position and between the upper and lower central position and the above. It changes smoothly as it progresses between the lower end positions. The position where the phase plane of the electromagnetic wave is most advanced in the aperture plane is preferably a position corresponding to a half wavelength above and below the center position.

  In the main dielectric member 21A, the dimension L1 in the vertical direction corresponds to the position where the phase surface is most advanced in the opening surface. That is, the dimension L1 in the vertical direction is a dimension corresponding to the position where the phase plane of the electromagnetic wave on the opening surface is most advanced between the vertical center position and the upper end position of the horn 11 and between the vertical center position and the lower end position. . Further, the dimension L2 in the front-rear direction of the main dielectric member 21A is desirably a dimension corresponding to a half wavelength of the radiated electromagnetic wave in order to obtain impedance matching.

  Further, the distance L3 between the opening surface of the horn antenna 10 and the main dielectric member 21A is preferably not too close in order to suppress reflection of electromagnetic waves, for example, about a half wavelength or a little longer than that. It is preferable to adjust to a position with good matching. Further, the dimension L4 of the opening surface of the horn antenna 10 may be about two wavelengths or a little shorter than that.

  In order to obtain the slow wave effect of electromagnetic waves, the thickness of the dielectric of the main dielectric member 21A is preferably thicker, while the dielectric loss increases with the thickness. Therefore, the thickness of the dielectric may be 1/20 wavelength to 1/10 wavelength, and preferably 1/12 wavelength to 1/16 wavelength. In this embodiment, the thickness is 1/15 wavelength.

  In addition, although it is necessary to fix the positional relationship between the main dielectric member 21A and the horn antenna 10, as one method thereof, it is possible to fix using a polystyrene foam. Since the relative dielectric constant of polystyrene foam is almost that of air, it hardly affects the radiation characteristics of electromagnetic waves.

  The operation of the antenna device of the present invention configured as described above will be described with reference to FIG. FIG. 3 shows a phase plane of a cylindrical wave used for comparison.

  In FIG. 2, the electromagnetic wave radiated from the wave source, that is, the slot 13 of the slot waveguide 12, tends to spread in a cylindrical wave shape. In FIG. 2, since the metal plate 15 exists, the phase of the radial axis M is delayed. Also, the phase is delayed near the metal horn. As a result, the equiphase surface of the electromagnetic wave at the opening surface of the horn 11 is delayed (indicated by α) at the vertical center position (radial direction axis M) and the upper and lower end positions of the horn 11, as shown in FIG. Moreover, it smoothly changes so as to advance between the upper and lower center positions and the upper and lower end positions (indicated by β). This is the first main point of the present invention. Hereinafter, such an electromagnetic wave showing an equiphase surface is simply referred to as a quasi-plane wave for convenience. It is preferable that the dimension indicated by β-β, the phase plane of which is advanced, corresponds to the length of one wavelength.

  The independent antenna characteristics of the horn antenna 10 provided with the metal plate 15 are a gain of 10.92 dBi, a beam width of 26.36 degrees, and a side lobe level of -15.16 dB. As shown in FIG. 3, the antenna characteristics have already been improved considerably compared to that in which the electromagnetic wave is not radiated as a cylindrical wave when the metal plate 15 is not provided.

  The present invention further includes a hollow main dielectric member 21A having a quadrangular cross section (in this example, a rectangular shape) at the front center position of the horn antenna 10. This is the second main point of the present invention.

  The upper side a and the lower side b of the main dielectric member 21A act so as to delay the phase of the β point where the phase of the electromagnetic wave of the quasi-plane wave is advanced. The phase of the β point is delayed as it passes through the upper side a and the lower side b. The phase delay depends on the incident angle of the electromagnetic wave on the upper side a and the lower side b and the thickness and length of the upper side a and the lower side b. On the other hand, since the α-point electromagnetic wave is incident on the left side c and the right side d almost at right angles, the thickness of the side c and d may be small and hardly receive a delay action.

  Further, electromagnetic waves are incident on the side edges c and d almost vertically, and the electromagnetic waves concentrate on the dielectric to improve the gain. Further, the side edges c and d are separated by ½ wavelength. Therefore, impedance matching is taken.

  The antenna characteristics according to FIGS. 1 and 2 are shown in FIG. The characteristic diagram of FIG. 4 is based on an electromagnetic field analysis simulation using the FDTD method that is generally widely used and has been confirmed to be effective.

  Referring to the characteristic diagram of FIG. 4, the antenna device of the present invention has a gain of 11.94 dBi, a beam width of 26.01 degrees, and a side lobe level of -14.04 dB. This antenna characteristic is further improved as compared with the characteristic of the horn antenna 10 alone (gain 10.92 dBi, beam width 26.36 degrees, side lobe level -15.16 dB).

  As described above, according to the antenna device of the present invention, the slot waveguide 12 is provided at the base of the horn 11 of the horn antenna 10, and the metal plate 15 having a predetermined length in the electromagnetic wave radiation direction at the vertical center position of the horn 11. Or the phase plane of the electromagnetic wave at the opening surface of the horn 11 is delayed at the vertical center position, the upper end portion, and the lower end position, and advances between the vertical center position and the upper end position, and between the vertical center position and the lower end position. Change smoothly as if Then, a hollow main dielectric member 21 </ b> A having a quadrangular cross section is provided at the front center position of the horn antenna 10.

  Each dielectric member disposed in front of the horn antenna 10 functions as a dielectric slow wave circuit 20A to selectively delay an electromagnetic wave on which a specific phase plane is formed, so that gain improvement and sharpening of a beam pattern are achieved. In addition, the projecting dimension toward the front of the horn antenna can be further shortened compared to the conventional one.

  FIG. 5 is a diagram showing the configuration of the second embodiment of the antenna apparatus according to the present invention. In FIG. 5, in the dielectric slow wave circuit 20B, the main dielectric member 21B has a trapezoidal cross-sectional shape, and the upper side d of the trapezoid is formed in a curved shape. The other structure is the same as that in FIG. 1, and the dimensions are the same except that it has a trapezoid and a curved side.

  In the antenna apparatus of FIG. 5, the gain is 11.85 dBi, the beam width is 26.05 degrees, and the side lobe level is -13.82 dB. As for this antenna characteristic, the characteristic of the side lobe level is slightly lowered as compared with the characteristic of the horn antenna 10 alone, but the characteristics of the gain and the beam width are improved. In FIG. 5, the main dielectric member 21B has a trapezoidal cross-sectional shape in addition to being reduced in size, and the trapezoidal right side d is formed in a curved shape. The air resistance accompanying rotation is reduced.

  FIG. 6 is a diagram showing the configuration of a third embodiment of the antenna apparatus according to the present invention. In FIG. 6, as a means for fixing the positional relationship between the main dielectric member 21C and the horn antenna 10, an upper support dielectric member 22 and a lower support dielectric member 23 are used in the dielectric slow wave circuit 20C.

  The upper support dielectric member 22 fixes the main dielectric member 21C to the upper end of the horn 11, and the lower support dielectric member 23 fixes the main dielectric member 21C to the lower end of the horn 11, The dielectric member 21C is supported by the horn antenna 10.

  The upper and lower support dielectric members 22 and 23 are provided so as to have a predetermined angle γ from the electromagnetic wave radiation direction M. This angle γ acts so that the electromagnetic wave components reflected by the upper and lower support dielectric members 22 and 23 (shown by broken lines with arrows in FIG. 6) are combined at the center position and offset each other. It is desirable to set the angle, specifically, about 45 degrees is preferable. Depending on the relationship between the opening surface dimension L4 of the horn 11 and the distance L3 between the opening surface of the horn antenna 10 and the main dielectric member 21A, the inclination of 45 degrees may be directly extended from the electromagnetic wave radiation direction. The vertical dielectric dimension L1 of the main dielectric member 21C may be crossed. In this case, just before crossing the vertical dimension L1 of the main dielectric member 21C, the direction is changed to the electromagnetic wave radiation direction M and coupled to the main dielectric member 21C as shown in FIG.

  In the antenna device of FIG. 6, the slow wave effect and reflected wave canceling effect of the upper and lower support dielectric members 22 and 23 are also obtained, and the gain is 12.06 dBi, the beam width is 25.79 degrees, and the side lobe level − 15.30 dB. The antenna characteristics are improved in gain, beam width, and side lobe characteristics as compared with the characteristics of the antenna apparatus of FIG.

  Thus, the radiation characteristics of the antenna are improved as compared with the case where there is a main dielectric member, and the structure supporting the main dielectric member, that is, the dielectric slow wave circuit 20C itself also forms a supported antenna radome. .

  FIG. 7 is a diagram showing the configuration of a fourth embodiment of the antenna apparatus according to the present invention. In FIG. 7, the dielectric slow wave circuit 20D includes an upper sub-dielectric that forms a rhombus cross section between the upper support dielectric member 22 or between the upper support dielectric member 22 and the upper side a of the main dielectric member 21D. A lower subdielectric member 25 that forms a rhombus section between the dielectric member 24 and the lower support dielectric member 23 or between the lower support dielectric member 23 and the lower side b of the main dielectric member 21D. And.

  The upper subdielectric member 24 has a portion substantially parallel to the electromagnetic wave radiation axis M and a portion substantially parallel to the upper support dielectric member 22. Accordingly, the portion substantially parallel to the upper support dielectric member 22 is provided at an angle γ (= about 45 degrees) with respect to the electromagnetic wave radiation direction M, and the distance from the upper support dielectric member 22 is approximately half a wavelength. It is set to λ / 2. Similarly, the lower subdielectric member 25 has a portion substantially parallel to the electromagnetic radiation axis M and a portion substantially parallel to the lower support dielectric member 23. Therefore, the portion substantially parallel to the lower support dielectric member 23 is provided at an angle γ (= about 45 degrees) with respect to the electromagnetic wave radiation direction M, and the distance from the lower support dielectric member 23 is approximately The half wavelength λ / 2 is set.

  The upper and lower support dielectric members 22 and 23, the main dielectric member 21D, and the upper and lower subdielectric members 24 and 25 form two support dielectric spaces 26 having a rhombus cross section formed by a dielectric plate. , 27 are formed.

  The main dielectric member 21D and the support dielectric spaces 26 and 27 having a rhombus cross section are premised on that a quasi-plane wave electromagnetic wave is incident on the main dielectric member 21D. Near electromagnetic wave surface is incident. Therefore, the dimensions of the support dielectric spaces 26 and 27, specifically, the installation positions and sizes of the upper and lower subdielectric members 24 and 25 are adjusted so as to obtain desired antenna characteristics.

  In the antenna device of FIG. 7, due to the slow wave effect of the main dielectric member 21D and the support dielectric spaces 26 and 27 having a rhombus section, the gain is 12.37 dBi and the beam width is 25 as shown in the characteristic diagram of FIG. .06 degrees, side lobe level -16.97 dB, and the characteristics of gain, beam width, and side lobe are further improved even when compared with those with supporting dielectric members 22 and 23 in FIG. Yes.

  Thus, the support dielectric space 26 made of a dielectric plate having a rhombus cross section is formed by the upper and lower support dielectric members 22 and 23, the main dielectric member 21D, and the upper and lower sub dielectric members 24 and 25. 27, the radiation characteristics of electromagnetic waves can be further improved, and the air resistance and the like accompanying rotation can be further reduced.

  In addition, since a small and high gain antenna device can be realized, it is possible to reduce a wind receiving area that is a resistance that hinders rotation in an environmentally exposed state such as an S-band antenna device, for example, a marine radar. It is possible to obtain a synergistic effect that the radar detection performance can be improved by increasing the gain.

  In addition, ribs 28 and 29 are provided in the supporting dielectric spaces 26 and 27 of the dielectric slow wave circuit 20D of FIG.

  In order to produce the dielectric slow wave circuit 20D, that is, the antenna radome with the supporting dielectric spaces 26 and 27 at a low cost, it may be produced by extrusion using a radome material such as engineering plastic as a dielectric. In general, extrusion molding has a high cost as an initial investment, but there is an advantage that a unit price is lowered as a result when a large amount of extruded product is produced.

  However, the extrusion manufacturing method has extrusion molding conditions, such as temperature, humidity, extrusion pressure, extrusion temperature, cooling temperature, etc., and these are difficult to control, and are the know-how of the manufacturing company. Among these conditions, the control of the extrusion pressure is closely related to the shape of the extrusion molded product, and in order to change the extrusion pressure, it may be necessary to change an expensive extrusion mold.

  In order to avoid this, a rib for adjusting the extrusion pressure, which is not in the originally desired molded product, may be added. Since this rib is determined by the extrusion manufacturing company, the user often cannot specify its position and size. The radome with the supporting dielectric space shown in FIG. 7 is an example in which a rib having a thickness of 1 mm is determined.

  The antenna characteristics when these ribs having a thickness of 1 mm are provided at various rib positions in the support dielectric spaces 26 and 27, including the case where the ribs 28 and 29 in FIG. As a result of the calculation, it was confirmed that the antenna characteristics remained slight even when the rib was provided at any position. Therefore, the position is not limited to the position of the ribs 28 and 29 in FIG.

  As an example of the use of the rib, extrusion molding is given as an example. However, not only the extrusion molding but also a rib is provided for the purpose of reinforcing the rigidity, the change in the antenna characteristics is also slight.

  FIG. 9 is a diagram showing the configuration of a fifth embodiment of the antenna apparatus according to the present invention, and shows a cross-sectional shape thereof. The antenna device of FIG. 9 includes a horn antenna 10A and a dielectric slow wave circuit 20A composed of a dielectric provided at a front center position in the direction of electromagnetic wave radiation from the horn antenna. In FIG. 9, the horn antenna 10A and the dielectric slow wave circuit 20A are also extended in the paper surface direction.

  The dielectric slow wave circuit 20A may be basically the same as that shown in FIG. Also, the dielectric slow wave circuit 20A can have the same structure as that shown in the embodiments of FIGS.

  The horn antenna 10A has a metal horn 11A and a slot waveguide 12 as a wave source provided at the base of the horn 11A. An electromagnetic wave is emitted from a slot 13 provided on one surface of the slot waveguide 12.

  In this embodiment, a first metal plate 15-1 having a predetermined length is provided on the central axis M in the electromagnetic wave transmission direction from the slot waveguide, and between the central axis and the upper end side of the horn 11A. The second metal plate 15-2 is provided in the electromagnetic wave transmission direction, and the third metal plate 15-3 is provided in the electromagnetic wave transmission direction between the central axis and the lower end side of the horn 11A. The thickness of these metal plates 15-1 to 15-3 is preferably as thin as possible, but is set to a thickness within a range in which work accuracy, deformation prevention, and position fixing are possible. Further, the lengths and positions of the metal plates 15-1 to 15-3 are appropriately determined according to desired phase plane characteristics on the opening surface of the horn 11A.

  The phase plane of the electromagnetic wave at the opening surface of the horn antenna 10A is smooth so as to be delayed at the positions where the metal plates 15-1 to 15-3 exist, the upper end portion, and the lower end portion, and advance at their respective intermediate points. To change. The phase plane of the electromagnetic wave at the opening surface of the horn antenna 10A in FIG. 9 is closer to a plane wave than the phase surface of the electromagnetic wave at the opening surface of the horn antenna 10 in FIG. This phase plane is adjusted by the dielectric slow wave circuit 20A (that is, the main dielectric member 21A) to obtain a phase plane closer to a plane wave.

  The dielectric slow wave circuit 20A may be removed and only the horn antenna 10 of FIG. 1 or the horn antenna 10A of FIG. Even in this case, the antenna device can be used as a small antenna device with improved antenna characteristics to some extent.

The figure which shows the structure of 1st Example of the antenna apparatus which concerns on this invention. The figure explaining the effect | action of the antenna apparatus of this invention The figure which shows the phase surface of a cylindrical wave for contrast with the quasi-plane wave of this invention The figure which shows the antenna characteristic by FIG. The figure which shows the structure of 2nd Example of the antenna apparatus which concerns on this invention. The figure which shows the structure of 3rd Example of the antenna apparatus which concerns on this invention. The figure which shows the structure of 4th Example of the antenna device which concerns on this invention. The figure which shows the antenna characteristic by FIG. The figure which shows the structure of 5th Example of the antenna device which concerns on this invention.

Explanation of symbols

10, 10A Horn antenna 11, 11A Horn 12 Slot waveguide 13 Slot 15, 15-1 to 15-3 Metal plates 20A, 20B, 20C, 20D Dielectric slow wave circuits 21A, 21B, 21C, 21D Main dielectric member 22, 23 Support dielectric members 24, 25 Subdielectric members 26, 27 Support dielectric spaces 28, 29 Ribs

Claims (3)

A slot waveguide is provided at the base of the horn, and a horn antenna provided with a metal plate having a predetermined length in the electromagnetic wave radiation direction at the upper and lower center position;
The front center position of the horn antenna is hollow with a quadrangular cross section , the vertical dimension is equivalent to one wavelength of the electromagnetic wave to be emitted, and the longitudinal dimension is equivalent to a half wavelength of the electromagnetic wave to be emitted. A main dielectric member;
An upper support dielectric member that supports the main dielectric member on the upper end portion of the horn, and a lower support dielectric member that supports the main dielectric member on the lower end portion of the horn. , Antenna device. A slot waveguide is provided at the base of the horn, and the phase plane of the electromagnetic wave at the opening surface of the horn is delayed in the vertical center position, the upper end portion, and the lower end portion, and between the vertical center position and the upper end position. And a horn antenna that smoothly changes so as to proceed between the vertical center position and the lower end position,
A first position where the front surface of the horn antenna has a quadrangular cross section and is hollow , and a vertical dimension of the electromagnetic wave phase plane at the opening surface is most advanced between the vertical center position and the upper end position; A main dielectric member, which corresponds to a distance between the upper and lower center position and the second position which is most advanced between the lower end position, and whose front-rear direction dimension corresponds to a half wavelength of an electromagnetic wave to be emitted ;
An upper support dielectric member that supports the main dielectric member on the upper end portion of the horn, and a lower support dielectric member that supports the main dielectric member on the lower end portion of the horn. , Antenna device. An upper sub-dielectric member that forms a rhombus cross section between the upper support dielectric member or between the upper support dielectric member and the upper side of the main dielectric member; and the lower support dielectric member The lower subdielectric member which forms a rhombus cross section between the lower support dielectric member and the lower side of the main dielectric member, or the lower subdielectric member according to claim 1 or 2 . Antenna device.

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