JP3185442B2 - Mobile radio antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna mainly used for mobile radio.

[0002]

2. Description of the Related Art Mobile radio antennas are required to have a small and low-profile structure. Hereinafter, an example of the above-mentioned conventional mobile radio antenna will be described with reference to the drawings.

FIGS. 6 (a) and 6 (b) show a configuration of a conventional mobile radio antenna, where (a) is a view of the antenna from the side and (b) is a view of the antenna from the axial direction. It is. In FIG. 6, reference numeral 601 denotes a wire-wound antenna, 602 denotes a feeding point, 403 denotes a ground plane, and the antenna of the wire-wound antenna is installed in parallel with the ground plane so as not to contact the ground plane. The diameter and length of the wire-wound antenna 601 are sufficiently smaller than the wavelength used. At this time, the wire-wound antenna can be considered as a serially connected antenna of a loop antenna and a dipole antenna through which a uniform current flows. Since the loop antenna is equivalent to a magnetic current element placed at the center of the loop perpendicular to the loop surface, the wire-wound antenna 601 eventually combines the magnetic current 604 and the current 605 as shown in FIGS. It is equivalent to the antenna. The image 606 of the magnetic current with respect to the ground plane is in phase with the magnetic current 604, while the image 607 of the current is
05 is the opposite phase. Therefore, the radiated electromagnetic fields from the current cancel each other out, and the wire-wound antenna 601 forms a magnetic current with the image and radiates in the front direction perpendicular to the ground plane.

[0004]

However, in the above antenna configuration, the height of the antenna is greater than the diameter of the antenna, and is not suitable for applications requiring an extremely low-profile antenna such as a portable telephone. Further, the resonance frequency of the above-mentioned antenna changes relatively greatly depending on the positional relationship between the antenna and the ground plane. However, in the configuration of FIG. Fluctuations were a major problem. Further, the antenna has a problem that the input impedance of the antenna is low and the matching state is poor.

The present invention has been made in view of the above problems, and has as its object to provide a small antenna suitable for mobile radio, which has an extremely low profile shape, has little variation in resonance frequency, and can improve input impedance. Aim.

[0006]

In order to solve the above-mentioned problems, a mobile radio antenna according to the present invention has a groove formed in a ground plane, and a wire wound antenna is inserted in the groove so that the antenna axis is parallel to the ground plane. So that a feed point is provided between one end of the wire-wound antenna and a ground plane.

[0007]

According to the present invention, the height of the antenna can be made equal to or less than the diameter of the antenna by the above configuration.
The structure in which the antenna is supported by the groove and does not easily move can be employed, so that the variation in resonance frequency is small and the input impedance can be increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an antenna device according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A, 1B and 1C show the structure of a mobile radio antenna according to a first embodiment of the present invention. FIG. 1A shows only the wire-wound antenna 101, and 102 is a feeding point. FIG. 1B is a side view showing a state where the wire-wound antenna is mounted on a ground plane, and FIG. 1C is a view seen from an axial direction of the antenna. As shown in the figure, a rectangular groove 104 is formed in the ground plane, and the wire-wound antenna is placed in the groove. With this configuration, the height of the antenna can be made extremely low profile lower than the diameter of the winding of the antenna. In addition, since the antenna is supported by the groove by interposing an insulator between the wound antenna and the bottom and side walls of the groove, the relative positional relationship between the antenna and the ground plane is not easily changed, and the fluctuation of the resonance frequency is reduced. Can be reduced.

FIGS. 1D and 1E show an image 10 of a magnetic current 105 of a wire-wound antenna and a magnetic current formed on a ground plane.
6, 107 are shown. Unlike the conventional example of FIG. 6, a plurality of images are generated due to the magnetic current. However, since the phases thereof are the same as the magnetic current 105, the antenna radiates in the front direction perpendicular to the ground plane.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. 2A, 2B, and 2C are configuration diagrams of a mobile radio antenna according to a second embodiment of the present invention. In FIG. 2A, windings 201 and 202 are windings having a half-wave length, and have a structure in which a plurality of windings are arranged in a line in series with the winding direction being opposite to that of an adjacent winding. And form a wire-wound antenna 203 as a whole. 10
2 is a feeding point. FIG. 2B is a side view showing a state where the wire-wound antenna is mounted on the ground plane.
(C) is the figure seen from the axial direction of the antenna. As shown in the figure, a rectangular groove 104 is formed in the ground plane, and the wire-wound antenna is placed in the groove. With this configuration, the height of the antenna can be made extremely low profile lower than the diameter of the winding of the antenna. In addition, since the antenna is supported by the groove by interposing an insulator between the wound antenna and the bottom and side walls of the groove, the relative positional relationship between the antenna and the ground plane is not easily changed, and the fluctuation of the resonance frequency is reduced. Can be reduced.

FIGS. 2D and 2E show windings 201 and 202, respectively.
Currents 204 and 205 formed in the image and image 20 of the magnetic current
6 to 209. The windings 201 and 202 have a winding length of half a wavelength, and are connected in the vertical direction with the winding direction being opposite to the adjacent direction, so that the magnetic currents 204 and 202 are
The directions of 205 are all the same as shown in FIG. 4D, and the radiation electromagnetic fields are combined. Therefore, FIG.
1 operates as a magnetic current array antenna as a whole, and can realize an antenna having a sharper directivity than the mobile wireless antenna of FIG. 1 shown in the first embodiment. In the description of FIG. 2, two wire-wound antennas are connected, but the number of connected antennas can be arbitrarily selected.

FIG. 3 shows a measured value 301 of the impedance characteristic of the mobile radio antenna shown in FIG. The diameter of the winding is 9.3 mm, and the interval (pitch) between the windings is 10 mm. A groove having a cross section of 10 mm × 10 mm and a length of 60 cm was provided at the center of a ground plane of a brass plate having a length of 100 cm and a width of 100 cm. 30
Reference numeral 2 denotes a measurement obtained by placing a wire-wound antenna on a flat conductor plate without providing a groove on the ground surface. The measurement frequency range is from 950 MHz to 1050 MHz. The return loss at a frequency of 1000 MHz was 0.46 dB when inserted into the groove, and 0.26 dB on the conductor plate, which was twice as large when inserted into the groove, and the input impedance of the antenna could be increased. .

FIG. 4 shows a measurement result of directivity. The shape of the antenna is the same as the antenna whose impedance was measured in FIG. In FIG. 4, reference numeral 401 denotes a main polarization component (Eφ),
Reference numeral 402 denotes a cross polarization component (Eθ). The radiation pattern is rotated around the X axis as measured in the coordinate shown in FIG. Electromagnetic waves are radiated in the front direction (Y direction), indicating that the antenna operates normally as a magnetic current antenna.

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram of a mobile radio antenna according to a third embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 or FIG. In FIG. 5, the wire-wound antenna 101 is placed in a circular groove 501 formed on the ground plane 103.

FIGS. 5D and 5E show an image 50 of the magnetic current 105 of the wire-wound antenna and the magnetic current formed on the ground plane.
2 is shown. In this case, although 502 is drawn as a finite number (seven) of magnetic currents in the drawing, it is actually 105 magnetic currents.
Is a magnetic current distributed on a circle centered at. Since the phases are the same as the magnetic current 105, the antenna radiates in the front direction perpendicular to the ground plane.

In FIG. 5, it is possible to use a wire-wound antenna in which a plurality of half-wavelength windings as described in FIG. 2 are arranged in series in a line.

[0018]

As described above, according to the present invention, a groove is formed in the ground plane, and a wire-wound antenna is inserted into the groove so that the antenna axis is parallel to the ground plane. It is configured so that the feeding point is between the end and the ground plane. The height of the antenna can be less than the diameter of the antenna, and the antenna is supported by the groove and does not move easily. Therefore, the fluctuation of the resonance frequency is small, and the input impedance can be increased.

[Brief description of the drawings]

FIG. 1A is a side view showing a configuration of a wire wound antenna of a mobile radio antenna according to a first embodiment of the present invention. FIG. 1B is a configuration of a mobile radio antenna according to the first embodiment of the present invention. (C) is a view from the axial direction of the antenna for illustrating the configuration of the mobile radio antenna according to the first embodiment of the present invention. (D) is a view illustrating the mobile radio antenna according to the first embodiment of the present invention. FIG. 7E is a side view showing the operation of the antenna. FIG. 7E is a diagram viewed from the axial direction of the antenna to show the operation of the mobile radio antenna according to the first embodiment of the present invention.

FIG. 2A is a side view showing a configuration of a wire wound antenna of a mobile radio antenna according to a second embodiment of the present invention; FIG. 2B is a configuration of a mobile radio antenna according to a second embodiment of the present invention; (C) is a view from the axial direction of the antenna for illustrating the configuration of the mobile radio antenna according to the second embodiment of the present invention, and (d) is a diagram illustrating the mobile radio antenna according to the second embodiment of the present invention. FIG. 5E is a side view showing the operation of the antenna. FIG. 7E is a diagram viewed from the axial direction of the antenna to show the operation of the mobile radio antenna according to the second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing measured values of impedance of a mobile radio antenna according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing measured values of directivity of a mobile radio antenna according to a second embodiment of the present invention.

FIG. 5A is a side view showing a configuration of a wire wound antenna of a mobile radio antenna according to a third embodiment of the present invention; FIG. 5B is a configuration of a mobile radio antenna according to a third embodiment of the present invention; (C) is a view seen from the axial direction of the antenna for illustrating the configuration of the mobile radio antenna according to the third embodiment of the present invention. (D) is the mobile radio antenna according to the third embodiment of the present invention. FIG. 9E is a side view showing the operation of the antenna. FIG. 10E is a diagram viewed from the axial direction of the antenna to show the operation of the mobile radio antenna according to the third embodiment of the present invention.

FIG. 6A is a side view showing the configuration of a conventional mobile radio antenna. FIG. 6B is a diagram showing the configuration of the conventional mobile radio antenna viewed from the axial direction of the antenna. (D) is a view from the axial direction of the antenna to show the operation of the conventional mobile radio antenna.

[Explanation of symbols]

101, 203 Wound antenna 102 Feed point 103 Ground plane 104 Rectangular groove 105, 204, 205 Magnetic current 106, 107, 206-209, 502 Image of magnetic current 201, 202 Winding 501 Circular groove

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-262629 (JP, A) JP-A-63-92103 (JP, A) JP-A-1-146613 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H01Q 11/08 H04B 7/10 H04B 7/26 H01Q 1/18-1/24

Claims (2)

(57) [Claims] 1. A groove is formed in a ground surface, and a wire-wound antenna is inserted into the groove so that the antenna axis is parallel to the ground surface, and a gap between one end of the wire-wound antenna and the ground surface is provided. An antenna for mobile radio, wherein the antenna is a feeding point. 2. A winding type antenna in which a half-wavelength winding is used as a basic unit, and one or a plurality of windings whose winding directions are opposite to those of the adjacent windings are arranged in series in a line. The mobile radio antenna according to claim 1, wherein: