JP4541595B2 - Microstrip antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microstrip antenna, and more particularly to improvement of orthogonal directivity of a microstrip antenna that radiates linearly polarized waves.
[0002]
[Prior art]
A microstrip antenna called a patch antenna is used as a PHS base station antenna or a wireless LAN antenna. FIG. 5 shows a schematic diagram of such a microstrip antenna. 11 is a ground conductor, 12 is a radiating conductor, and has two types of linearly polarized waves having a horizontal polarization feed point 13a and a vertical polarization feed point 13b. Can be sent and received.
[0003]
[Problems to be solved by the invention]
However, the linearly polarized wave radiated from the microstrip antenna shown in FIG. 5 has a different directivity in the direction orthogonal to the directivity in the same direction as the electric field. As shown in FIG. The half-value angle was a different value. Therefore, there is a difference between the transmission / reception area for horizontal polarization and the transmission / reception area for vertical polarization. This is not a desirable characteristic because, for example, the sensitivity differs between when the PHS mobile phone is used upright and when it is used sideways. Therefore, for example, changing the aspect ratio of the ground conductor to expand the width and aligning the half-value angle of the vertical plane and the horizontal plane of the vertical polarization can be considered.However, in this case, there is a problem that the characteristics of the horizontal polarization are deteriorated. Was.
In view of the above problems, an object of the present invention is to provide a microstrip antenna capable of making the transmission / reception area uniform by combining the half-value angle characteristics of the orthogonal directions of linearly polarized waves.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is configured such that a substantially square and planar ground conductor is erected so that four sides are arranged in a horizontal or vertical direction, and overlapped on one side of the ground conductor. the radiating element of the planar shape becomes disposed over the dielectric, the microstrip antenna and capable of emitting a respective linear polarization of the vertical polarization and horizontal polarization, the linear parasitic conductor, the ground conductor Two adjacent to the left and right sides are arranged in parallel in the vertical direction outside the left and right sides of the ground conductor, and parallel to the horizontal direction adjacent to the upper and lower sides outside the upper and lower sides of the ground conductor. 2 adjacent to each other, the length of each parasitic conductor is 0.5 times the radiation wavelength, and the width of each parasitic conductor and the gap between each parasitic conductor is 0.1 times the radiation wavelength . It is characterized by that.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory front view showing an example of a microstrip antenna according to the present invention. A square plate-like ground conductor 1 and a square ground conductor in a similar manner so as to overlap the center of one side surface (the front face in the drawing) of the ground conductor 1. A radiating element 2 formed smaller than 1 is arranged with a dielectric interposed therebetween.
Incidentally, 3a is a horizontal polarization feed point, 3b is a vertical polarization feed point, and the four sides around the antenna are arranged in the horizontal direction and the vertical direction, respectively. Further, if the dielectric is a resin plate, the installation conductor and the radiating element can be easily formed by using both surfaces thereof, but it may be simply air.
[0010]
Two parasitic conductors 4 are provided in parallel in the vertical direction adjacent to the left and right sides of the ground conductor 1. The length L1 of the parasitic conductor 4 is 0.5λ, where λ is the radiation wavelength of the antenna, and the width W1 and the conductor interval P1 are 0.1λ.
The half-value angle of the vertical plane and horizontal plane of this antenna is the value shown in FIG. 2, and the horizontal plane half-value angle of the vertical polarization is the same value as the vertical plane half-value angle.
[0011]
In this way, for antennas that radiate vertically polarized waves, the horizontal half-value angle and the vertical half-value angle can be adjusted in both directions with a simple configuration in which parasitic conductors are provided adjacent to the left and right sides of the ground conductor. The service area can be made uniform.
Since the parasitic conductor is arranged in the same direction as the electric field of the vertically polarized wave, the electric field direction of the horizontally polarized wave is orthogonal to the horizontal polarized wave and does not affect the characteristics of the horizontally polarized wave.
The length L1 of the parasitic conductor is preferably 0.4λ to 1.1λ, the width W1 is 0.25λ or less, and the gap P1 between adjacent parasitic conductors is 0.5λ or less.
[0012]
3, in addition to the configuration of FIG. 1, two parasitic conductors 5 are provided in the left-right direction adjacent to the upper and lower sides of the ground conductor. A length L2 of the parasitic conductor 5 in the left-right direction is formed with a length of 0.5λ, and a width W2 and a conductor interval P2 are formed with a length of 0.1λ.
The vertical plane half-value angle and horizontal plane half-value angle of this antenna are the values shown in Fig. 4, and the horizontal plane half-value angle and vertical plane half-value angle of both vertical and horizontal polarization are the same. It is a value.
[0013]
Thus, by providing a parasitic conductor adjacent to the upper and lower sides of the ground conductor, the horizontal half-value angle and the vertical half-value angle of horizontal polarization can be matched. In addition, since the parasitic conductors placed above and below are in the same direction as the electric field of horizontal polarization, they are perpendicular to the electric field direction of vertical polarization and do not affect the characteristics of vertical polarization. The horizontal half-value angle and the vertical half-value angle of both horizontal polarization and vertical polarization can be matched with the parasitic conductor provided, and both service areas can be made uniform even when both polarizations are emitted.
The length L2 of the parasitic conductor provided above and below the ground conductor is preferably 0.5λ or less, the width W2 is 0.25λ or less, and the gap P2 is 0.5λ or less. In addition, although the two parasitic conductors are formed two by two, one may be provided, or a plurality of parasitic conductors may be arranged adjacent to each other.
[0014]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to match the half-value angle in the horizontal plane and the vertical plane direction with a simple configuration with respect to vertical or horizontal radiation linearly polarized waves. In particular, according to the first aspect of the invention, the half-value angle between the horizontal plane of the vertical polarization and the vertical plane can be matched, and according to the first aspect of the invention, the half-value angle between the horizontal plane of the horizontal polarization and the vertical plane is matched. It is possible to make the service area of both vertical polarization and horizontal polarization uniform.
[Brief description of the drawings]
FIG. 1 is a front view of a microstrip antenna showing an example of an embodiment of the present invention.
FIG. 2 is a table showing the half-value angle characteristics of the antenna of FIG.
FIG. 3 is a front view of a microstrip antenna showing another embodiment of the present invention.
4 is a table showing half-value angle characteristics of the antenna of FIG. 3;
FIG. 5 is a front view of a conventional microstrip antenna.
6 is a table showing the half-value angle characteristics of the antenna of FIG.
[Explanation of symbols]
1 .... ground conductor, 2 .... radiation element, 3a ... horizontal polarization feed point, 3b ... vertical polarization feed point, 4,5 ... parasitic conductor.

Claims (1)

A substantially square and planar ground conductor is erected so that the four sides are horizontally or vertically arranged, and the planar radiating element is disposed via a dielectric so as to overlap one side of the ground conductor. In the microstrip antenna that can radiate each linearly polarized wave of vertical polarization and horizontal polarization,
Two linear parasitic conductors are arranged adjacent to the left and right sides on the outside of the left and right sides of the ground conductor in parallel in the vertical direction, respectively, and on the outside of the top and bottom sides of the ground conductor. Adjacent to the top and bottom sides, two adjacent to each other in parallel in the left-right direction,
The length of each parasitic conductor is 0.5 times the radiation wavelength,
A microstrip antenna characterized in that the width of each parasitic conductor and the gap between each parasitic conductor are 0.1 times the radiation wavelength .

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