JP3613283B2 - Radio wave lens antenna device - Google Patents

Description

  The present invention relates to a radio wave lens antenna device used for satellite communication or communication between antennas.

  The Luneberg lens, known as one of radio wave lenses, is a lens made of a dielectric material that is basically a sphere, and the relative dielectric constant εr of each part substantially conforms to the following formula (1).

εr = 2− (r / a) ² ... Formula (1)
Where a: radius of the sphere
r: Distance from the center of the sphere

  The antenna device using the Luneberg lens can capture a radio wave from any direction by setting the focal point of the radio wave at an arbitrary position on the hemisphere, and can transmit the radio wave in an arbitrary direction.

  Among such Luneberg lens antenna devices, there is one having a function equivalent to a spherical lens by combining a hemispherical lens with a reflector. An outline of the apparatus is shown in FIG. In the figure, 1 is a reflector, 2 is a hemispherical Luneberg lens, and 4 is a primary radiator.

  In this type of antenna device, the distance from the lens center to the outer end of the reflecting plate 1 (the radius R of the reflecting plate) needs to be larger than the radius a of the lens 2 in order to obtain stable transmission / reception performance. The radius R of the reflector is obtained by the equation R = a / cos θ, where θ is the incident angle of the radio wave. The radius R may exceed twice a depending on the incident angle of the radio wave.

  The Luneberg lens antenna device has the advantage that it can handle radio waves from any direction by moving the primary radiator to an arbitrary position on the spherical surface of the lens. A disc concentric with the lens is considered to be placed horizontally (parallel to the ground) to take advantage of the above advantages.

  However, in this structure, since the reflecting plate projects over the entire circumference of the lens, problems such as an increase in the size of the apparatus, an increase in weight, an increase in cost, an increase in installation space, and a deterioration in handleability occur.

  Conventionally, no consideration has been given to eliminating this defect.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the size, weight, and cost of a Luneberg lens antenna device using a reflector without sacrificing the electrical performance required for the radio wave lens antenna device.

  In order to solve the above problems, in the present invention, a radio wave lens antenna apparatus for transmitting, receiving or transmitting / receiving radio waves to / from a geostationary satellite, a hemispherical Luneberg lens formed of a dielectric, and the lens A reflector that is larger than the lens diameter provided along the bisector of the sphere, and has a non-circular shape with the opposite side of the Luneberg lens removed from the direction of the geostationary satellite, and a lens held by a holder A radio wave lens antenna device comprising a primary radiator provided at a focal portion of the radio wave lens antenna device.

  The reflecting plate of this apparatus comprises a large arc edge having a diameter larger than the lens diameter concentric with the lens center, a small arc edge located near the outer periphery of the lens and facing the large arc edge, and a large arc edge. And a fan-shaped shape defined by the left and right side edges connecting the ends of the small arc edges. The shape including the fan shape can also reduce the size of the reflector. As for the shape of the reflector, the distance from the lens center to the edge (R determined by the equation R = a / cos θ) is closer to the portion where the radio wave incident angle is smaller at the edge of the large arc side based on the above-described sector shape. Ideally, the shape is notched so as to be shorter. Projecting a hemispherical lens on the reflecting surface from the opposite direction of the radio wave incident direction at the same angle as the radio wave incident angle from the communication partner at the farthest end, and removing both side edges along the projected semi-elliptical contour Become an ideal shape. In this ideal shape, when the incident angles of the radio waves from the communication partners at the extreme ends are different, the reflecting plate has an asymmetric shape (this is referred to as a modified sector here). As for the antenna device used in Japan, all existing geostationary satellites can be supported if the fan divergence angle of the fan-shaped or deformed fan-shaped reflector is 130 °.

  The inventors considered using a Luneberg lens antenna device using a reflector for transmitting and receiving radio waves to and from a geostationary satellite. A parabolic antenna is used for reception of BS broadcasting or the like, but this is dedicated to reception and can only deal with satellites in a specific direction. In contrast, the Luneberg lens antenna device can capture radio waves from multiple satellites by providing multiple primary radiators at the focal point of radio waves from each geostationary satellite, and increase the number of primary radiators. Thus, bidirectional communication (transmission / reception) can be performed without time difference.

  By the way, in Japan (Japan), there are currently more than 10 geostationary satellites, all of which are in the range of 110 ° to 162 ° east longitude. In this case, when a circular reflector is used, radio waves are reflected only in a limited area, and no radio waves are reflected in other areas. The present invention pays attention to this point, and removes a non-functional region where radio waves are not reflected. As a result, the reflector becomes non-circular and its size is reduced.

  The transmission / reception azimuth of radio waves varies depending on where (at which point in which region) the antenna is installed. In Yonaguni, for example, the azimuth angle for a satellite of 110 ° east longitude is 209.2 ° The azimuth angle for a satellite of 162 ° is 117.1 °, and the difference is 92.1 °. Yonaguni has a particularly large difference in azimuth angle across the country for geostationary satellites of 110 ° and 162 ° east longitude. Therefore, when the reflector is made into a symmetrical fan shape or a deformed fan shape, one side (the opening angle from the center is large) Side) is 180-171.1 = 62.9, and a double angle of 125.8 ° is required to obtain a symmetrical shape, so the fan opening angle should be set to about 130 °. For example, a reflector having the same shape can be used throughout the country.

  The size of the reflector (radius R of the large arc edge of the fan) varies depending on where the antenna is used. Suppose, for example, that 12 satellites are to be communicated, R ≧ a × 2.19 (where a is the radius of the lens), and if the radius satisfies the equation, the same size reflector is common throughout the country. Can be used.

  As described above, the radio wave lens antenna device according to the present invention removes a portion of the reflector that does not contribute to radio wave reflection and leaves only a portion corresponding to radio waves from a predetermined range of directions, so that the reflector is minimized. The size can be reduced in size, weight, and cost, leading to improved handling and reduced installation space.

  In addition, the electrical performance required for the antenna can be secured sufficiently, and it is smaller than the parabolic antenna for BS and CS broadcasting, and can receive and transmit radio waves from multiple geostationary satellites and other antennas. Is possible.

  Embodiments of the radio wave lens antenna device of the present invention will be described below with reference to FIGS.

  As shown in the figure, in this antenna device, a hemispherical Luneberg lens 2 is fixed on a reflecting plate 1, and further, a primary radiator 4 is held by a holding tool 3 provided on the reflecting plate 1 and a lens 2. It is provided near the spherical surface.

  The reflection plate 1 is formed of a metal plate having good radio wave reflectivity, a composite plate obtained by bonding a plastic plate and a metal sheet for radio wave reflection, or the like. The reflector 1 includes a large arc edge 1a having a diameter larger than the radius of the lens 2, a small arc edge 1b positioned near the outer periphery of the lens 2 and opposed to the large arc edge, and left and right straight lines connecting the ends of both arc edges. Although it has a sector shape defined by the edges 1c and 1d, it is not limited to this shape. In short, it is only necessary to be able to reflect radio waves from the communication partner and to remove as much as possible non-functional areas that do not contribute to the radio wave reflection.

  The Luneberg lens 2 is formed by laminating a dielectric hemispherical shell whose relative permittivity and diameter are gradually changed on a central hemisphere formed of a dielectric so that the whole has a multilayer structure (for example, eight layers). It is made by integrating, and the relative dielectric constant of each part approximates the value obtained by the above equation (1).

  A half-section (circular plane) of the sphere of the hemispherical Luneberg lens 2 is fixed on the reflecting surface of the reflecting plate 1 by bonding or the like. The center of the lens 2 is on the center of the radius of the large arc edge 1a of the reflecting plate 1, and is thus offset from the small arc edge 1b and attached to the reflecting plate.

  The holder 3 is preferably one that can adjust the position of the primary radiator 4. The illustrated holder 3 is provided with an arch-shaped support arm 3a straddling the lens 2, and the primary radiator 4 is attached to the support arm 3a so that the position of the primary radiator 4 can be adjusted in the arm longitudinal direction. The support arm 3a has a support shaft 3b parallel to the reflecting surface of the reflecting plate at both ends (this axis is on a line passing through the center of the lens), and the rotation of the support arm with the support shaft as a fulcrum, The primary radiator 4 is positioned at a position where the radio wave capturing efficiency is high (near the focal point) by combining the slides. Of course, the holder 3 is not limited to the one shown in the figure.

  The number of installed primary radiators 4 is not particularly limited. For example, the number may be one, and radio waves from one geostationary satellite may be received, or the number may be plural and a multi-beam antenna may be used to receive radio waves from a plurality of geostationary satellites. In addition, transmission / reception can be performed by increasing the number of primary radiators.

  The radio wave lens antenna device configured as described above can be reduced in size by removing the chain line portion in FIG. 1 of the reflector 1 that has been made circular in the past, but the reflector is small when corresponding to a plurality of geostationary satellites. If it is too long, the transmission / reception performance is significantly reduced. Therefore, the optimum shape and size of the reflector were examined. Since the shape and size vary slightly depending on the satellite used, the place where the antenna is used, and the method used, Table 1 shows a design example according to the target area and the number of target satellites. In the table, a represents the radius of the lens shown in FIG. 1, and R represents the functional part radius of the reflector. The opening angle ψ of the fan for the design examples 1 and 2 is the opening angle when the reflector is made to have a bilaterally symmetrical shape in consideration of the appearance, and the design examples 3 to 11 are the opening angles when the reflecting plate is asymmetrical to the left and right. Show.

First of all, the existing geostationary satellites in Japan.
・ BSAT-2a 110 ° East
・ JCSAT-110 East longitude 110 °
・ Super Bird D East 110 °
・ JCSAT-4A 124 ° East longitude
・ JCSAT-3 128 degrees east longitude
・ N-STARa 132 ° East
・ S-STARb 136 ° east longitude
・ Super Bird C 144 ° East
・ JCSAT-1B 150 ° East
・ JCSAT-2 East longitude 154 °
・ Super Bird A East 158 °
・ Super Bird B2 162 ° East

  The actual radius R of the reflector 1 is preferably about one wavelength longer than the value obtained by the calculation formula R = a / cos θ in order to prevent scattering of radio waves at the edge. It is desirable that the radius L of the small arc portion is also longer than the radius a of the lens 2 by about one wavelength.

  The shape of the reflector may not be a fan shape as long as the compactness is not impaired, and the radii R and L may be longer than desired values, and the fan opening angle ψ may be larger than the values in Table 1. There is no problem.

FIG. 4 explains a method for determining an ideal shape when the reflector 1 is of a nationwide type. In this figure, it is assumed that radio waves arrive from each of the directions A to E. Here, it is assumed that the incident angles θ ₁ of the radio waves from A and E are equal, and the incident angles θ ₂ of the radio waves from B and D are also equal, and θ ₁ > θ ₂ > θ ₃ (θ ₃ is from the C direction. It is assumed that the relationship of the incident angle is established.

Under this condition, when, for example, light is applied to the lens 2 at an angle θ ₁ from the direction opposite to A and E, half of the ellipse having 2R ₁ as the major axis and 2a as the minor axis is projected onto the reflecting surface. Further, when light is applied to the lens 2 at an angle θ ₂ from the opposite direction to B and D, half of the ellipse having 2R ₂ as the major axis and 2a as the minor axis is projected onto the reflecting surface, and the direction opposite to C In the projection at an angle of θ ₃ from, half of the ellipse having 2R ₃ as the major axis and 2a as the minor axis is projected. Therefore, each ellipse is connected by an envelope 5. Solid fan shape drawn in this way (element holder mounting part is required separately. Also, if the relative dielectric constant of the lens deviates from the above-mentioned equation (1), shape correction according to the deviation is necessary. Is the best form.) Depending on the installation point of the antenna, the envelope 5 may be bent in a concave shape, or the shape of the fan may be asymmetrical. When the envelope 5 bends in a concave shape, the ellipses at both ends may be connected by a straight line instead of the envelope, and in this case, the envelope is inside the straight edge, so that the reflection of radio waves is hindered. Absent.

  FIG. 5 is a specific example of a horizontally-symmetrical reflector that is designed on the basis of the above-mentioned concept. In the figure, the alternate long and short dash line is the most northeastern point of Japan, and the dotted line is the symmetrical reflector shape determined corresponding to all existing geostationary satellites at the southwestern point. If the two figures are overlapped to form a solid-line reflector 1 that includes both figures, this can be used as a common reflector anywhere in Japan. The shape of the reflector at the most northeastern point is the right half of the shape of the right half with respect to line C in FIG. 6, and the shape of the reflector at the southwestern point is on the left with reference to line C in FIG. It almost coincides with the half-shape made symmetrical.

  Note that the ideal shape of the regional reflector varies depending on the number and position of geostationary satellites to be captured and the place where the antenna is used. Examples thereof are shown in FIGS.

  If several figures obtained for each specific area are overlapped as shown in FIG. 6 and a solid line shape including all the overlapping figures based on the same idea as in FIG. The idea is the same in other regions). Further, for example, if the shape of the reflector for Hokkaido in FIG. 6 and the shape of the reflector for Tohoku in FIG. . The regional and multi-region reflectors can also be formed into a symmetrical reflector with good appearance by inverting the half of the large figure with the line C as a reference and replacing it with the small figure. it can. The concept of shape determination is the same in other regions, and in this way, wasteful parts are eliminated and downsizing is achieved.

The top view which shows embodiment of the antenna apparatus of this invention Side view of the antenna device Perspective view of the antenna device Illustration of how to determine reflector shape The figure which shows the best shape of a nation-compatible reflector The figure which shows an area correspondence type reflector The figure which shows an area correspondence type reflector The figure which shows an area correspondence type reflector The figure which shows an area correspondence type reflector The figure which shows an area correspondence type reflector (A) Side view of a Luneberg antenna device having a circular reflector, (b) Plan view

Explanation of symbols

1 reflector 1a large arc edge 1b small arc edge 1c, 1d linear edge 2 hemispherical Luneberg lens 3 holder 4 primary radiator R radius of large arc edge of reflector a radius of sphere L small of reflector Arc edge radius ψ Fan opening angle

Claims (5)

  A radio wave lens antenna apparatus for transmitting, receiving, or transmitting / receiving radio waves to / from a geostationary satellite, comprising a hemispherical Luneberg lens formed of a dielectric and a lens diameter provided along a bisector of the lens sphere A reflector that is a non-circular shape with the opposite side of the Luneberg lens removed from the direction of the geostationary satellite, and a primary radiator that is held by a holder and provided at the focal point of the lens. A radio wave lens antenna device characterized by.   The reflector has a large arc edge larger than the lens diameter concentric with the lens center, a small arc edge located near the outer periphery of the lens and facing the large arc edge, and the ends of the large arc edge and the small arc edge. The radio wave lens antenna device according to claim 1, wherein the radio wave lens antenna device has a sector shape defined by left and right side edges to be connected or a shape including the sector shape.   The reflector is formed in a shape in which the edge on the large arc side is notched so that the distance from the center of the lens to the edge becomes shorter as the angle of incidence of the radio wave becomes smaller, based on the sector shape described in claim 2. 1. The radio wave lens antenna device according to 1.   The radio wave lens antenna device according to claim 2 or 3, wherein the reflector is asymmetric.   The radio wave lens antenna device according to claim 2 or 3, wherein the reflector is symmetrical, and the fan has a spread angle of 130 ° or less.

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