JP4378255B2 - Array antenna - Google Patents

Description

  The present invention relates to an array antenna that transmits and receives radio waves to, for example, a satellite, and more particularly to an array antenna having a high gain.

  An antenna using a parabolic antenna is known as an antenna that transmits and receives 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 heavy.

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

  Usually, the gain of the array antenna is determined by the distance between the element antennas and the gain of the element antennas. Therefore, in order to obtain a higher gain, it is necessary to first widen the distance between the element antennas, or secondly, arrange a metal rim or the like around the element antenna to increase the gain of the element antenna ( Non-patent document 1).

Japanese Examined Patent Publication No. 6-66573 (FIG. 1) 4-element array antenna composed of short axial mode helical antenna, Takayasu Shiokawa, Yoshio Karasawa, p1267-p1274, VOL. J65-B NO. 10 (Section J), October 1982, IEICE Transactions

  However, in the first method, the diameter of the array antenna increases as the gain increases. In an antenna that is tracked by a communication partner using the mechanical drive device disclosed in Patent Document 1, the antenna increases in weight as the antenna diameter increases, and the antenna drive device becomes complicated and expensive. is there.

  When the second method is applied to an array antenna, the position of each rim antenna serving as a wave source is different from that of the rim, so that the phase of the diffracted wave from the rim does not match, resulting in a decrease in antenna gain and a deterioration in sidelobe characteristics. There is a concern to bring about.

  The present invention has been made in consideration of such problems, and an object of the present invention is to provide an array antenna that can increase the gain without increasing the diameter of the antenna.

The array antenna of the present invention includes a plurality of element antennas and the plurality of element antennas arranged outside in a plan view, and corresponding to each of the plurality of element antennas inside in a plan view and the plurality of elements and the ground conductor plate metal wall that is at the same potential and the ground conductor in a position in equal distance from the antenna is disposed, in that it comprises the features.

  According to the present invention, the radio waves from the element antennas strike the metal wall with equal phase, and the diffracted waves from the metal wall are synthesized with equal phase. Therefore, when there is no metal wall, the radio wave radiated in the side surface direction of the antenna is combined in the broad side direction of the antenna, and the antenna gain can be improved.

  In this array antenna, when the plurality of element antennas are four element antennas provided at the vertices of a regular square, the metal wall is located at an equal distance from the center of the regular square, What is necessary is just to provide in parallel with the adjacent edge | side of an antenna.

  The plurality of element antennas can be two element antennas.

  According to the present invention, by providing the metal wall at a position equidistant from the plurality of element antennas, the gain can be increased without increasing the diameter of the array antenna.

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

  FIG. 1 is a perspective view of a circularly polarized array antenna 10 according to an embodiment of the present invention.

  FIG. 2 is a plan view of the circularly polarized array antenna 10.

  The circularly polarized array antenna 10 has a ground conductor plate 12 made of aluminum. On the ground conductor plate 12, four circularly polarized element antennas 14 and a height H, respectively, are correctly viewed in plan view. A rectangular hollow metal wall 20 is attached. The metal wall 20 with a lid may be used instead of the hollow. In the case of the metal wall 20 with a lid, for example, it can also serve as a shield for a high-frequency power supply circuit mounted inside the hollow. Each wall of the metal wall 20 is provided at an equal distance L from the opposing side surfaces of the four element antennas 14 as shown in FIG.

  As shown in FIG. 2, the four element antennas 14 are arranged on the apexes 128 of a square 130 having a side length of 0.7λ (λ is a wavelength). The frequency band used for this circularly polarized array antenna 10 is a microwave band of 300 [MHz] to 30 [GHz].

  As shown in FIGS. 1 and 2, each element antenna 14 has a configuration in which four feeding elements 18 formed on a dielectric substrate 16 are arranged.

  The feeding element 18 has a hexagonal shape as the degenerate separation element 19 by cutting off two opposing squares. Each wall of the metal wall 20 is located at an equal distance L from the adjacent degenerate separation element 19, in other words, the adjacent side of the element antenna 14.

  As a power feeding method, there are three methods described below. First, power is fed to a feed point 33 at the lower right end of each feed element 18 by a microstrip feed line (not shown). Secondly, the ground conductor plate 12 is penetrated from the back side of the ground conductor plate 12, and power is fed to the feeding point 33 using a coaxial connector or the like. Third, an opening window is opened in the ground conductor plate 12, and electromagnetic power feeding is performed from the back side.

  In addition, from each feed point 33 of each feed element 18, the feed lines are sequentially gathered as one feed port through the feed lines whose phases are shifted by 90 °, thereby feeding power. At the mouth, the current flowing through the feeding element 18 can be synthesized in phase.

  In the circularly polarized array antenna configured as described above, power is fed from a feed point 33 formed in the vicinity of one side of the feed element 18 having the degeneracy separation element 19 obtained by cutting off two square corners. Currents based on the two wave sources flow in a direction in which the separation element 19 faces and in a direction perpendicular thereto, and the element antenna 14 operates corresponding to circular polarization. At this time, by appropriately selecting the distance L and the height H of the metal wall 20 at an equal distance L from each element antenna 14, the radio wave from each element antenna 14 hits the metal wall 20 in an equal phase. The diffracted waves from the metal wall 20 are synthesized in equiphase by the feed element 18. For this reason, when the metal wall 20 is not present, the radio wave radiated in the side surface direction (the direction along the ground conductor plate 12) of the power feeding element 18 is combined in the broad side direction of the element antenna 14, and thus the antenna gain. Can be high.

  In FIG. 3, there is a metal wall 20, the distance L from the feeding element 18 is L = 0.1 × λ0, and the heights H are H = 0.08λ0, H = 0.13λ0, and H = 0, respectively. .18 is an actually measured characteristic diagram showing the relationship between the normalized frequency and antenna gain [dBi] in the case of 18λ0.

  Note that λ0 is a wavelength when the normalized frequency is “1”, and in this embodiment, λ0 = 188 [cm] (frequency is 1.592 [GHz]).

  As can be seen from FIG. 3, when the metal wall 20 is present, the antenna gain [dBi] is increased at least over the entire range of the normalized frequency 0.95 to 1.05, compared to the case without the metal wall 20. I understand that.

The present invention is not limited to the above-described embodiment. As shown in FIG. 4, two element antennas 114 each having a feeding element 118 disposed on a dielectric substrate 116 and the two element antennas 114 are used. A metal wall 120 having a height H disposed at a position at an equal distance L and a ground conductor plate 112 on which two element antennas 114 are disposed are provided. It goes without saying that various configurations can be adopted based on the description of this specification, such as the array antenna 110 that feeds power to 133. In the case of FIG. 4 as well, as shown in FIG. 5, the feeding method is a method of using the array antenna 110A that feeds power from the feeding terminal 136 to the feeding end 133 through the microstrip line 134, or although not shown in FIG. Needless to say, a method of opening an opening window in the ground conductor plate 112 of the example and electromagnetically feeding from the back side can be adopted.
In any embodiment, the metal walls 20 and 120 are electrically connected to the ground conductor plate 116 (ground conductor), and the metal walls 20 and 120 are at the same potential as the ground conductor.

1 is a perspective view of an array antenna according to an embodiment of the present invention. It is a top view of the array antenna of the example of FIG. It is a characteristic view of the antenna gain with and without the metal wall with respect to the normalized frequency. It is a perspective view of the array antenna which concerns on other embodiment. It is explanatory drawing of the other electric power feeding method of the array antenna of the example of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 110, 110A ... Array antenna 12, 112 ... Ground conductor plates 14, 114 ... Element antenna 16 ... Dielectric substrate 18 ... Feeding element 19 ... Degenerate separation element 20, 120 ... Metal wall 33 ... Feeding point

Claims (3)

A plurality of element antennas;
The plurality of element antennas are arranged outside in a plan view, and are in the same potential as the ground conductor at a position corresponding to each of the plurality of element antennas and in the same distance from the plurality of element antennas in a plan view A ground conductor plate on which the arranged metal wall is disposed ;
An array antenna comprising: The array antenna according to claim 1, wherein
When the plurality of element antennas are four element antennas provided at the vertices of a regular square, the metal wall is located at an equal distance from the center of the regular square, and the element antennas An array antenna characterized by being provided so as to be parallel to adjacent sides. The array antenna according to claim 1, wherein
The array antenna, wherein the plurality of element antennas are two element antennas.

Images