JP4008701B2 - Dual-wave antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a suitable dual-wave antenna apparatus for selectively receiving, for example, either satellite broadcasting or terrestrial broadcasting provided at the same frequency.
[0002]
[Prior art]
Recently, a digital broadcasting communication broadcasting service using satellite waves with circularly polarized waves of the same frequency and terrestrial waves with linearly polarized waves has been planned. In order to receive this, it is mounted on mobile bodies such as automobiles and diversity. There is an urgent need to develop an omnidirectional dual-wave antenna device that can receive signals.
[0003]
FIG. 5 shows a case where a four-wire helical antenna 13 is erected on a ground 11 via a spacer 12 and a monopole antenna 14 is erected in parallel at an appropriate interval from the four-wire helical antenna 13. The external configuration is exemplified.
[0004]
The 4-wire helical antenna 13 is installed to receive left-handed circularly polarized waves, has a feeding point 15 at the center of the top of the head, and has two sets of antennas at the lower end surface (not shown) in contact with the spacer 12. The elements are short-circuited and the effective antenna length of each set is 1λ. On the other hand, the monopole antenna 14 is erected to receive vertically polarized waves, and has an antenna length of λ / 4.
[0005]
FIG. 6 shows directivity patterns of the antennas 13 and 14 when the direction of the monopole antenna 14 with respect to the 4-wire helical antenna 13 is set to 0 °. 6A shows the H-plane directivity pattern of the 4-wire helical antenna 13, and FIG. 6B shows the H-plane directivity pattern of the monopole antenna 14.
[0006]
[Problems to be solved by the invention]
As shown in FIGS. 6 (1) and (2), omnidirectionality cannot be obtained due to mutual interference between the 4-wire helical antenna 13 and the monopole antenna. In addition, if the distance between the antennas 13 and 14 is not large, isolation characteristics cannot be obtained, and as a result, a structure with a very large installation area is required to achieve sufficient characteristics. It is not practical as this type of antenna device that requires miniaturization.
[0007]
In addition, there are techniques described in Japanese Patent No. 3169378, Japanese Patent Application Laid-Open No. 2001-144431, and Japanese Patent Application Laid-Open No. 2001-196823 as an integrated structure of these two types of antennas. Although the structure on the mounting, such as those with multiple dipole antennas on the middle shaft part and those with loops and feed points formed in the middle of the pole-shaped antenna, are both effective as an idea, From the viewpoint of manufacturing cost, it is not practical.
[0008]
The present invention has been made in view of the above circumstances, and the object of the present invention is to eliminate omnidirectionality by eliminating interference between antennas while having a simple integrated structure that is easy to manufacture. An object of the present invention is to provide a dual-wave antenna device that can be realized.
[0009]
[Means for Solving the Problems]
First aspect of the present invention, are erected on the ground, and the monopole antenna which arranged the feeding point on the outer peripheral surface lower end is coaxially disposed via an insulating spacer on the monopole antenna, parietal center And a two-wire or four-wire helical antenna provided with a feeding point.
[0010]
With such a configuration, it is possible to realize omnidirectionality by eliminating interference between the antennas while having a simple integrated structure that is easy to manufacture.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the monopole antenna has a hollow cylindrical shape .
[0012]
With such a configuration, in addition to the operation of the invention described in claim 1 , it is suitable for mass production, and the manufacturing cost and the like can be kept extremely low.
[0013]
The invention described in claim 3 is the invention described in claim 1, characterized in that the monopole antenna, the insulating spacer, and the helical antenna have a cylindrical shape with the same diameter.
[0014]
According to such a configuration, in addition to the operation of the invention described in claim 1 , the installation area can be made very small by adopting a single pole configuration, and the antenna device for vehicle installation It can greatly contribute to the required miniaturization.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0016]
FIG. 1 shows an external configuration of the dual-polarization antenna device according to the embodiment, FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a side view showing a structure of a feed output system. . As shown in the figure, a cylindrical monopole antenna 23 is erected on a ground 21 via a spacer 22. The monopole antenna 23 has a feeding point 25 at a connection point with the feeding member 24 protruding from the ground 21 at the lower end portion of the outer peripheral surface.
[0017]
The monopole antenna 23 has an antenna length of λ / 4 and is configured to receive vertically polarized waves. The monopole antenna 23 has the same diameter on the upper end surface of the monopole antenna 23 via an insulating spacer 26 having the same diameter. A cylindrical four-wire helical antenna 27 is coaxially disposed.
[0018]
The helical antenna 27 is mounted to receive left-handed circularly polarized waves, and has a feeding point 28 at the center of the top, which is a cylindrical upper end surface, and is in contact with the insulating spacer 26 (not shown). Two sets of antenna elements are short-circuited at the lower end surface.
[0019]
In addition, in this helical antenna 27, for example, a rectangular phase adjustment load 29 is mounted in the middle of the element line at a ratio of one line to two lines for each pair of antenna elements. The effective antenna length is 1λ.
[0020]
With this phase adjustment load 29, the lengths of the respective element lines of the two sets of antenna elements can be shortened, and only one element line of each group protrudes further downward from the lower end surface of the helical antenna 27. , Etc. can be avoided.
[0021]
As shown in FIG. 1B, the helical antenna 27 includes a semi-rigid cable 30 disposed in the central axis portion up to the feeding point 28 so as to penetrate the insulating spacer 26, the insulating spacer 26, and the monopole antenna 23 together. The semi-rigid cable 30 passes through the ground 21 and is led out to the back side thereof.
[0022]
Similarly, the feeding member 24 of the monopole antenna 23 is also connected to a semi-rigid cable 31 penetrating the ground 21 and led to the back side of the ground 21 so as to feed and receive the monopole antenna 23. Become.
[0023]
The ground 21 includes a ground wave and a satellite wave LNA (Low Noise Amp.) In the plate, and the semi-rigid cables 30 and 31 are directly soldered to the LNA substrate.
[0024]
FIG. 2 shows the directivity patterns of the antennas 27 and 23 when the direction in which the power supply member 24 is provided with respect to the monopole antenna 23 is the 0 ° direction in the configuration as described above.
[0025]
The data used here is a measurement example in the case where the ground 21 has a size of 1 [m] × 1 [m], and the above-described antenna length is realized in the center with 2.332 [GHz] as a target frequency.
[0026]
This assumes that the mobile antenna performs diversity reception, assuming that the helical antenna 27 receives satellite waves with left-handed circular polarization and the monopole antenna 23 receives ground waves from a base station with vertical polarization. This is an example of measurement.
[0027]
2 (1) shows the H-plane directivity pattern of the helical antenna 27, and FIG. 2 (2) shows the H-plane directivity pattern of the monopole antenna 23. FIG. As shown in FIGS. 2 (1) and 2 (2), the helical antenna 27 and the monopole antenna 23 can obtain satisfactory omnidirectionality.
[0028]
This is because the helical antenna 27 and the monopole antenna 23 are integrated so that the positions farthest from the feed points 28 and 25, that is, the positions where the impedance is high and the characteristics of the antenna are worried are changed. Although it is configured, it is shown that mutual interference can be avoided by interposing an insulating spacer 26 having a sufficient height (thickness) so as to be appropriately separated.
[0029]
In addition, FIG. 3A shows the E plane directivity pattern of the helical antenna 27 and FIG. 3B shows the E plane directivity pattern of the monopole antenna 23 under the same conditions as FIG.
[0030]
As shown in FIGS. 3 (1) and 3 (2), the upward direction is 0 ° vertically along the antenna axis, while the helical antenna 27 has a certain degree of elevation and has an upward directivity. The monopole antenna 23 has directivity toward a low elevation angle slightly above the horizontal plane.
[0031]
As a result, the helical antenna 27 and the monopole antenna 23 have a satellite wave helical antenna 27 having directivity in the zenith direction at the top, even in a directivity pattern in the vertical plane, and a ground wave having directivity in the lateral direction. With the configuration in which the monopole antenna 23 for use is arranged at the lower part, it can be determined that there is little mutual interference and sufficient isolation characteristics are provided.
[0032]
FIG. 4 shows the isolation level characteristics of the satellite wave helical antenna 27 and the terrestrial monopole antenna 23, and is required in the vicinity of 2.3 [GHz], which is the target frequency band. A value that is significantly lower than [dB] or less and −35 [dB] or less is obtained, and it can be seen that the two antennas 27 and 23 are sufficiently isolated.
[0033]
Therefore, by mounting this antenna device having the structure shown in FIG. 1 on a mobile body, diversity reception can be realized in which a satellite wave or a terrestrial wave having a good reception state is appropriately selected and received. .
[0034]
In this way, the antennas 27 and 23 have sufficient characteristics, but by combining them vertically to form a single pole-like structure, the installation area can be greatly reduced. This can greatly contribute to the downsizing required for an in-vehicle antenna device.
[0035]
In addition, in the 4-wire helical antenna 27, the phase adjustment load 29 is mounted at a ratio of one line to each pair of the element lines, and the lengths of the paired antenna element lines can be shortened. The manufacturing process at the lower end side of the 4-wire helical antenna 27 is also facilitated, and the length of the entire antenna can be suppressed to be short, thereby contributing to further miniaturization.
[0036]
Further, each of the monopole antenna 23 and the helical antenna 27 can be realized as a mounting structure in which a conductor is formed by plating on a dielectric surface such as FRP, and can be easily formed as an integral structure. It is suitable for production, and it is possible to keep manufacturing costs and the like extremely low.
[0037]
In addition, as described above, the ground 21 has a structure in which the terrestrial and satellite wave LNAs are built in the plate, and the semi-rigid cables 30 and 31 are directly soldered to the LNA substrate. The overall configuration of the antenna can be further reduced.
[0038]
Although the 4-wire helical antenna 27 has been described as having 4 wires, the present invention is not limited to this, and it is of course possible to have 2 wires, as well as the case of 4 wires. It has been proved by measurement that a good effect is obtained.
[0039]
In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
[0040]
Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, at least one of the problems described in the column of the problem to be solved by the invention can be solved, and described in the column of the effect of the invention. In a case where at least one of the obtained effects can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0041]
【The invention's effect】
According to the first aspect of the present invention, it is possible to realize omnidirectionality by eliminating interference between antennas, while having a simple integrated structure that is easy to manufacture.
[0042]
According to the invention described in claim 2, in addition to the effect of the invention described in claim 1 , it is suitable for mass production, and the manufacturing cost can be kept extremely low.
[0043]
According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 , the installation area can be made very small by adopting a single pole-like configuration, and the vehicle-mounted antenna It can greatly contribute to the downsizing required for the device.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a two-wave shared antenna device according to an embodiment of the present invention.
FIG. 2 is a view illustrating an H-plane directivity pattern of each antenna element according to the embodiment;
FIG. 3 is a diagram illustrating an E plane directivity pattern of each antenna element according to the embodiment;
FIG. 4 is a view showing isolation characteristics between antenna elements according to the embodiment;
FIG. 5 is a perspective view showing a configuration example of a conventional dual-wave antenna apparatus.
6 is a diagram illustrating an H-plane directivity pattern of each antenna element in FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Ground 12 ... Spacer 13 ... 4-wire helical antenna 14 ... Monopole antenna 15 ... Feeding point 21 ... Ground 22 ... Spacer 23 ... Monopole antenna 24 ... Feeding member 25 ... Feeding point 26 ... Insulating spacer 27 ... Helical antenna 28 ... Feed point 29 ... Load for phase adjustment 30, 31 ... Semi-rigid cable

Claims (3)

A monopole antenna that is erected on the ground and has a feeding point at the lower end of its outer peripheral surface;
A two-wave shared antenna device comprising a two-wire or four-wire helical antenna disposed coaxially on an insulating spacer on the monopole antenna and having a feeding point disposed at the center of the top of the head . 2. The dual-wave antenna device according to claim 1, wherein the monopole antenna has a hollow cylindrical shape . The dual-wave antenna apparatus according to claim 1 , wherein the monopole antenna, the insulating spacer, and the helical antenna have a cylindrical shape with the same diameter .

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