JP2006094356A - Array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small array antenna of a new configuration having a simple structure and improved performance. <P>SOLUTION: A regular pentagon-arranged array antenna 10 has a new structure in which five element antennas 16 which are each arranged on each of vertices of a regular pentagon are provided on a base conductor plate 14. The array antenna 10 has a simple structure compared to a triangle-arranged array antenna in a conventional technique in which seven element antennas are arranged in triangle, and a cost can be reduced. The array antenna 10 can increase an antenna gain [dBi], compared to the seven element triangle-arranged array antenna. In the array antenna 10, a distance d[λ] is set at d=0.3-0.6 where the relation between the distance d[λ]from a center O and the dimension D[λ] of the base conductor plate 14 is D=äd+αλ}×2, where a wavelength is λ and a unfixed constant is α. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an array antenna that transmits or receives radio waves of 300 [MHz] to 30 [GHz], and particularly relates to an array antenna having a novel structure that is small and highly efficient.

  An antenna using a parabolic antenna is known as an antenna that transmits and receives microwave radio waves to and from a satellite or the like (see Patent Document 1).

  This antenna is required to be small and light because it is covered with a so-called radar dome and attached to the mast of a ship.

  However, since the parabolic antenna requires a reflecting mirror and a primary radiator, it is large in shape and weight.

  Therefore, it is conceivable to use an array antenna instead of the parabolic antenna.

  FIG. 5 shows a schematic configuration of the array antenna 2 according to the prior art. The array antenna 2 has a configuration in which seven element antennas 6 are arranged on a circular ground conductor plate 4 via a dielectric. The element antenna 6 has a so-called triangular structure in which the regular hexagon 7 is arranged at the apex and the center of the regular hexagon 7 (the center of the circular ground conductor plate 4) O.

Japanese Examined Patent Publication No. 6-66573 (FIG. 1)

  In general, in the array antenna 2 in which a plurality of element antennas 6 are arranged on the ground conductor plate 4, the triangular arrangement in which the element antennas 6 are arranged on the vertices of a regular triangle obtained by dividing the regular hexagon 7 shown in FIG. It is believed that this is the way in which the efficiency is obtained. The reason is that all the element intervals are the same, and therefore the minimum distance between the elements is the maximum.

  By the way, for example, an antenna mounted on a moving body such as a ship needs to be oriented in the direction of the satellite. Therefore, the ground conductor plate having the maximum area constituting the movable part is as small as possible. Is preferred.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an array antenna having a novel configuration with a simple structure, a small size, and improved performance.

  The array antenna according to the present invention includes five element antennas and a ground conductor plate in which the five element antennas are arranged at the apexes of a regular pentagon.

  In the array antenna having a novel configuration in which five element antennas arranged at the apexes of a regular pentagon are provided on the ground conductor plate, the structure is smaller than the array antenna in which the seven element antennas according to the prior art are arranged in a triangle. Since it becomes easy, cost can be reduced. In general, the gain of the array antenna is determined by the gain of the element antenna and the gain by the arrangement method. The antenna gain of the array antenna having a novel configuration in which the element antennas are arranged at the apex of the regular pentagon according to the present invention is the prior art. It has been found that the number of element antennas is larger than that of, for example, an array antenna with seven arrays.

  Specifically, when the ground conductor plate is circular and the diameter is D, the wavelength d is λ, the indefinite constant is α, the distance d [λ] from the center of the regular pentagon to the apex, and the diameter D [λ] Is D = {d + αλ} × 2, a five-element regular pentagonal vertex array antenna (also referred to as a regular pentagonal array antenna) where the distance d [λ] is d = 0.3 to 0.6. ) Can increase the antenna gain [dBi] as compared to the array antenna 2 (see FIG. 5) in which seven element antennas are arranged in a triangle.

  Here, the value of the indefinite constant α is, for example, α = (De / 2) × 1.3 to (De / 2), assuming a circle whose diameter De is the length of the longest part of the element antenna to be used. A value between x1.5 can be determined.

  The regular pentagonal array antenna in which the element antennas according to the present invention are arranged at the apexes of a regular pentagon has a simple structure, a small size, and improved performance.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the drawings to be referred to below, the same reference numerals are assigned to the components corresponding to those shown in FIG. 5 and the detailed description thereof is omitted.

  FIG. 1 shows a planar configuration of an array antenna 10 according to an embodiment of the present invention.

  The array antenna 10 has a circular ground conductor plate 14 and five element antennas 16 disposed on the ground conductor plate 14 via a dielectric layer. This array antenna (also referred to as a regular pentagonal array antenna) 10 can be manufactured by, for example, a double-sided printed wiring board.

  The five element antennas 16 are arranged at the apexes of a regular pentagon 18 having a side length of 2d × cos 54 ° and a distance d from the center O.

  The element antenna 16 is circular in this embodiment, and its radius is 0.18λ (λ is a wavelength). The diameter of the circle having a radius of 0.18λ shown in FIG. 1 is the longest part of the element antenna to be used (for example, the element antenna is square) when the element antenna 16 has a shape other than a circle such as a square. If there is a circle with the diameter De as the length of the diagonal line, it is expressed as Da = 2 × α × λ. α is an indefinite constant and takes a value between (De / 2) × 1.3 and (De / 2) × 1.5.

  In this example of FIG. 1, when the diameter of the circular ground conductor plate 14 is D [λ], the wavelength is λ, and the apex of the regular pentagon 18 from the center of the regular pentagon 18 (circular center of the ground conductor plate 14) O. The relationship between the distance d [λ] and the diameter D [λ] is D = {d + 0.25λ)} × 2.

  When the distance Da / 2 (radius with respect to the diameter Da) from the apex of the regular pentagon 18 to the periphery of the ground conductor plate 14 is expressed as Da / 2 = αλ where an indefinite constant is α, this equation is generally expressed as D = {D + (Da / 2)} × 2 = {d + αλ} × 2.

  Here, assuming that the element antenna 16 having a diameter De [λ] of De = 0.36λ is used, α = (0.36 / 2) × 1.4≈0.25.

  Here, as a power feeding method for the element antenna 16, first, power is fed by a microstrip feeding line. Second, power is supplied to the element antenna 16 through the ground conductor plate 14 from the back side of the ground conductor plate 14. Thirdly, it is possible to select one of the methods of opening an opening window in the ground conductor plate 14 and supplying electromagnetic power from the back surface.

  The table shown in FIG. 2 shows the distance d [λ] from the center O of the regular pentagonal array antenna 10 having the novel configuration shown in FIG. 1 and the array antenna 2 according to the related art having the triangular array shown in FIG. The calculated value of the antenna gain [dBi] when the element spacing (equal to the distance from the center O) d [λ] and the diameter D [λ] [mm] of the ground conductor plates 4 and 14 is changed is shown. Yes.

  FIG. 3 is a characteristic diagram showing a change in antenna gain [dBi] with respect to the diameter D [mm] of the antenna ground conductor plate in which the values in the table of FIG. 2 are plotted. The frequency used in this embodiment is 1.592 [GHz] (wavelength λ is λ = 188 [cm]).

  For example, when the distance / element spacing d [λ] is d = 0.3 and α = 0.25, the diameter D [λ] of the ground conductor plates 4 and 14 is D = (0.3λ + 0.25λ). ) × 2 = 1.1λ, and the diameter D [mm] is D = 1.1 × 188 [cm] ≈206 [mm].

  As can be seen from FIGS. 2 and 3, the regular pentagonal array antenna 10 having a distance d [λ] of d = 0.3 to 0.6 is an array antenna 2 in which seven element antennas are arranged in a triangle. In comparison, the antenna gain [dBi] can be increased. That is, in the region where the distance d is d = 0.3 to 0.6, the regular pentagonal array antenna 10 is a small array antenna having a high antenna gain [dBi] compared to the triangular array antenna 2.

  Since the structure is simple even when the distance d exceeds d = 0.6, the cost including the feeding structure can be reduced, and if the antenna gain is sufficient, the regular pentagonal array antenna 10 is used. By doing so, the cost can be reduced.

  The regular pentagonal array antenna 10 is not limited to the circular shape of the element antenna 16, but is square or the array antenna 10A of the helical antenna 20 (see FIG. 4, the radius of the helical antenna is 0.18λ). Furthermore, the element antenna can be used as either a circularly polarized antenna or a linearly polarized antenna such as a dipole antenna or a crossed dipole antenna.

  The use frequency band of the regular pentagon array antennas 10 and 10A is about 300 [MHz] to 30 [GHz].

It is a top view of the regular pentagon array array antenna which concerns on this embodiment. It is a table | surface figure which compares the gain of a regular pentagon array antenna and a triangular array antenna. It is the characteristic comparison figure which plotted the value of the table | surface figure of FIG. It is a perspective view of the regular pentagon array array antenna whose element antenna is a helical antenna. It is a top view of the triangular array antenna which concerns on a prior art.

Explanation of symbols

2, 10, 10A ... Array antenna 4, 14 ... Ground conductor plates 6, 16 ... Element antenna 7 ... Regular hexagon 18 ... Regular pentagon 20 ... Helical antenna

Claims (2)

5 element antennas,
An array antenna comprising the five element antennas and a ground conductor plate arranged at the apexes of a regular pentagon. The array antenna according to claim 1, wherein
When the ground conductor plate is circular and the diameter is D, the wavelength is λ, the indefinite constant is α, and the relationship between the distance d [λ] from the center of the regular pentagon to the apex and the diameter D [λ] is , D = {d + (αλ)} × 2, the distance d [λ] is d = 0.3 to 0.6.

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