JP2009124385A - Microstrip slot antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slot antenna whose structure is simple and flexibility of a mounting position is high. <P>SOLUTION: A microstrip slot antenna 10 is achieved by a printed board where a microstrip line 2 is formed on one side of a dielectric substrate 1 and the other side is covered with a bottom board 6. On the line of the microstrip line 2, eight slots 3 are provided along a center line of the line so as to interrupt current flowing on the line at intervals of λg, thereby the microstrip slot antenna 10 functions as a slot array antenna. An impedance conversion portion 4 is provided between a portion near a feeding portion 5 of the microstrip line 2 and a portion where the slot 3 is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a slot antenna using a microstrip line.

  Conventionally, as a slot antenna using a microstrip line, there is a microstrip slot array antenna in which a feeding stripline is formed on one surface of a dielectric substrate and a conductor plate having a plurality of slots is formed on the other surface ( Patent Document 1).

In the above-described conventional microstrip slot array antenna, since the conductor plate is provided with the slot, the radio wave is radiated in both directions of the dielectric substrate, but at a position facing the surface on which the conductor plate is formed. By providing the reflector, it is possible to efficiently radiate radio waves in the direction opposite to the reflector as viewed from the dielectric substrate.
Japanese Patent No. 3002706

  However, the above-described conventional microstrip slot array antenna has a problem in that the number of components increases because the above-described reflector is required to efficiently radiate radio waves from the dielectric substrate. In addition, since the reflector as described above must be arranged at a certain distance from the dielectric substrate, the structure of the microstrip slot array antenna is complicated, and high mounting accuracy is required. There is.

  In the above-described conventional microstrip slot array antenna, when the reflector is omitted, the radio wave is radiated in both directions of the dielectric substrate, so that the radio wave cannot be radiated efficiently. Furthermore, since the directivity is disturbed by the influence of the structure located in the direction of the surface on which the conductor plate is formed when viewed from the dielectric substrate, the mounting position of the microstrip slot array antenna is restricted. There is.

  Therefore, an object of the present invention is to provide a slot antenna having a simple structure and a high degree of freedom in mounting position.

  In order to achieve the above object, the present invention adopts the following configuration. The reference numerals in parentheses show an example of the correspondence with the drawings in order to help understanding of the present invention, and do not limit the scope of the present invention.

  In the microstrip slot antenna (10, 20, 30) of the present invention, the microstrip line (2) is formed on one surface of a dielectric substrate (1), and the other surface is covered with a ground plane (6). In the printed circuit board, at least one slot (3) is provided on the microstrip line.

  A plurality of slots (3) may be provided on the microstrip line (2).

  The line width of the microstrip line (2) may be widened via the impedance converter (4).

  According to the present invention, a slot antenna having a simple structure and a high degree of freedom in mounting position can be realized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a microstrip slot antenna 10 according to an embodiment of the present invention. 2 is a cross-sectional view of the microstrip slot antenna 10 taken along the line A-B shown in FIG. In FIG. 1 or FIG. 2, 1 is a dielectric substrate, 2 is a microstrip line (conductor line), 3 is a slot, 4 is an impedance converter, 5 is a power feeder, 6 is A ground plane (grounding conductor plate).

  The microstrip slot antenna 10 is an application of a conventional microstrip line as a slot antenna. As shown in FIG. 2, the microstrip slot antenna 10 is realized by a printed circuit board in which a microstrip line 2 is formed on one surface of a dielectric substrate 1 and the other surface is covered with a ground plane 6.

  Hereinafter, the configuration of the microstrip slot antenna 10 will be described in detail with reference to FIG.

  On the line of the microstrip line 2, eight slots 3 are spaced along the center line of the line so as to block the current flowing on the line with a gap of λg (λg is a wavelength considering the influence of the dielectric). Thus, the microstrip slot antenna 10 functions as a slot array antenna. In particular, in this embodiment, each slot 3 is provided such that the angle θ between the longitudinal direction of each slot 3 and the width direction of the microstrip line 2 is 45 degrees. It functions as a slot array antenna for 45-degree polarized waves that can be used in a radar device or the like (in this case, the microstrip slot antenna 10 is used with the end portion of the power supply unit 5 of the microstrip slot antenna 10 facing down. Is assumed).

  Note that a polarization slot array antenna having a desired angle can be realized by changing the angle θ. For example, as shown in FIG. 4, a microstrip slot antenna 20 in which the angle θ between the longitudinal direction of each slot 3 and the width direction of the microstrip line 2 is 0 degree is a vertically polarized slot array antenna. Function.

  The length of each slot 3 may not be uniform. For example, as shown in FIG. 3, the length of the slot 3 may be increased as the distance from the power feeding unit 5 increases. By changing the length of the slot 3 individually, the excitation distribution of the entire slot array antenna can be changed to obtain a desired excitation distribution.

  Note that the number of slots 3 is not limited to eight, and may be one or an arbitrary number of two or more. The interval between the slots 3 is preferably λg, but is not strictly limited to λg.

  The line width of the microstrip line 2 in the portion where the slot 3 is provided is wider than the line width in the vicinity of the power feeding unit 5 so that the slot 3 can be disposed inside (that is, the line of the microstrip line 2). The width is configured to be larger than the length of the slot 3 in the width direction of the microstrip line 2). When the line width of the microstrip line 2 changes, the characteristic impedance of the microstrip line 2 changes as shown in FIG. Therefore, for impedance matching, the impedance converter 4 is provided between the portion near the power feeder 5 and the portion where the slot 3 is provided. In the present embodiment, as shown in FIG. 6, a quarter wavelength line is inserted between the portion near the power feeding portion 5 and the portion where the slot 3 is provided as the impedance conversion portion 4. The line width of this ¼ wavelength line is a characteristic obtained by Z2 = √ (Z1 · Z3), where Z1 is the characteristic impedance in the vicinity of the power feeding portion 5 and Z3 is the characteristic impedance in the portion where the slot 3 is provided. The line width corresponds to the impedance Z2. For example, when it is desired to widen the line width from 2.9 mm (characteristic impedance of this line portion is 50Ω) to 12.0 mm (characteristic impedance of this line portion is 18Ω), 6.2 mm (characteristic impedance of this line portion is It is only necessary to insert a quarter wavelength line having a line width of 30Ω.

  In the present embodiment, a quarter wavelength line is used as the impedance conversion unit 4, but the impedance conversion unit 4 may be realized using any other means.

  The end of the microstrip line 2 (the end opposite to the power feeding unit 5) is preferably opened at a position away from the slot 3 closest to this end by λg / 4. As another preferred example, like the microstrip slot antenna 30 shown in FIG. 7, the end of the microstrip line 2 (the end opposite to the feeding unit 5) is λg from the slot 3 closest to this end. It may be short-circuited at a position separated by / 2.

  8 and 9 show the directivity characteristics of the microstrip slot antenna 10. As is apparent from these drawings, according to the microstrip slot antenna 10 of the present embodiment, since the base plate 6 is not provided with a slot, the emission of radio waves to the rear (base plate 6 side) is suppressed, and the front ( Radio waves are efficiently radiated to the microstrip line 2 side).

  As described above, according to the microstrip slot antenna 10 of the present embodiment, radio waves can be efficiently transmitted forward (on the microstrip line 2 side) without providing a reflector unlike the conventional microstrip slot array antenna described above. Can be radiated. In addition, since the surface of the dielectric substrate 1 opposite to the surface on which the microstrip line 2 is formed is covered with the ground plane 6, it is positioned in the direction of the surface on which the ground plane 6 is formed when viewed from the dielectric substrate 1. The directivity is not disturbed by the influence of the structure to be performed, and the mounting position of the microstrip slot antenna 10 is not restricted. Further, since the microstrip slot antenna 10 of the present embodiment can be realized with a printed circuit board, it is easy to manufacture.

  Since the microstrip slot antenna of the present invention has a simple structure and a high degree of freedom in mounting position, it is useful as an antenna device for an arbitrary communication system such as an antenna device for in-vehicle equipment.

The perspective view of the microstrip slot antenna of one Embodiment of this invention Sectional drawing of the microstrip slot antenna of one Embodiment of this invention The front view of the microstrip slot antenna of one Embodiment of this invention Front view of a modified microstrip slot antenna Diagram showing the relationship between line width and characteristic impedance of microstrip line Diagram showing details of impedance converter Front view of a modified microstrip slot antenna The figure which shows the directivity of the microstrip slot antenna of one Embodiment of this invention The other figure which shows the directivity of the microstrip slot antenna of one Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Microstrip line 3 Slot 4 Impedance conversion part 5 Feeding part 6 Ground plane 10, 20, 30 Microstrip slot antenna

Claims (3)

  A microstrip slot, wherein a microstrip line is formed on one surface of a dielectric substrate and the other surface is covered with a ground plate, and at least one slot is provided on the microstrip line. antenna.   The microstrip slot antenna according to claim 1, wherein a plurality of slots are provided on the microstrip line.   The microstrip slot antenna according to claim 1 or 2, wherein a line width of the microstrip line is widened through an impedance converter.

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