JPH104314A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the coupling attenuation between two linear antennas by synthesizing these antennas together in the same phase. SOLUTION: A 1st linear antenna 1 is placed separate from a 2nd linear antenna 2 with their planes of polarization arranged properly. Then a 3rd linear antenna 3 is placed on the straight line connecting the antennas 1 and 2 together with a space of about 1/2 wavelength secured to the antenna 2 with planes of polarization arranged properly between both antennas. Then both antennas 2 and 3 are synthesized together in the same phase. In such a constitution of this antenna device, the coupling attenuation is increased between two linear antennas despite increase of the antenna gains by using an array antenna of two elements for one of both antennas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna apparatus used in a fixed radio system or a mobile communication system that performs transmission and reception in substantially the same frequency band.

[0002]

2. Description of the Related Art In a mobile communication system or a fixed radio system, when transmission and reception are performed in the same frequency band, a transmitting antenna and a receiving antenna are often installed close to each other due to an installation location and other relations. In many cases, the amount of coupling attenuation cannot be sufficiently obtained. In such a case, interference due to coupling between antennas becomes a problem. Conventionally, in order to avoid such a problem, a filter is attached to the antenna to secure the coupling attenuation.

[0003]

However, if a filter is attached to the antenna, the required gain may not be obtained due to the passage loss. Further, there may be a situation where even if the gain of the antenna is improved, the effect is not so much obtained because the filter is connected.

[0004] It is an object of the present invention to solve such a problem and to provide an antenna device capable of securing the coupling attenuation between antennas even between antennas having insufficient spacing.

[0005]

SUMMARY OF THE INVENTION An antenna device according to the present invention is directed to an antenna device having first and second linear antennas whose polarization planes are aligned at positions separated for transmission and reception. A third linear antenna disposed substantially at a half wavelength from the second linear antenna with its polarization plane aligned substantially on a straight line connecting the first and second linear antennas; Wherein the third linear antenna is in-phase combined with the second linear antenna.

[0006] Further, the polarization plane is aligned substantially on a straight line connecting the first and second linear antennas, and the second linear antenna is disposed at a position approximately one-half wavelength from the first linear antenna. It is also possible to provide a configuration in which four linear antennas are provided, and the fourth linear antenna is in-phase combined with the first linear antenna.

[0007] By combining another linear antenna with at least one linear antenna in phase, the directivity in the direction between the antennas is reduced, and the amount of coupling attenuation between the antennas can be ensured.

[0008]

FIG. 1 is a diagram showing a first embodiment of the present invention. In this embodiment, a first linear antenna 1 is provided, and a second linear antenna 2 is disposed at a position distant from the first linear antenna with its polarization plane aligned. A third linear antenna having a polarization plane aligned on a straight line connecting the linear antenna 1 and the second linear antenna 2 and spaced from the second linear antenna 2 by an interval of about a half wavelength. The linear antenna 3 is provided, and the second linear antenna 2 and the third linear antenna 3 are combined in phase.

FIG. 2 is a diagram showing a second embodiment of the present invention. In this embodiment, in addition to the first embodiment, the polarization plane is located at a position about a half wavelength from the first linear antenna 1 on a straight line connecting the first to third linear antennas 1 to 3. And the fourth linear antenna 4 is arranged in-phase with the first linear antenna 1.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIG. 3 is a perspective view showing an antenna device according to a first embodiment of the present invention, in which a dipole antenna is used as a linear antenna. This embodiment includes three dipole antennas 11 to 13. The second dipole antenna 12 is the first dipole antenna 1
The center axis is made coincident with a straight line passing through the center axis of the first dipole antenna, and is disposed away from the first dipole antenna 11. The third dipole antenna 13 is formed on a straight line passing through the axes of the first and second dipole antennas 11 and 12,
The second dipole antenna 12 is disposed at a position approximately one half of the wavelength at the used frequency. The second dipole antenna 12 and the third dipole antenna 13 are combined in phase to form one array antenna.

FIG. 4 is a perspective view showing an antenna device of a comparative example, and FIG. 5 shows an example of measurement results of coupling attenuation between antennas according to the comparative example. In this measurement, two dipole antennas 11 and 12 are arranged with their central axes aligned on a straight line, and the first dipole antenna 11 is
The second dipole antenna 12 was used as a receiving antenna.
The distance between the two dipole antennas 11 and 12 was set to an interval of three wavelengths at the operating frequency.

FIG. 6 shows an example of measurement results of the coupling attenuation according to the first embodiment shown in FIG. In this measurement, the first dipole antenna 11 was used as a transmission antenna, and the array antenna composed of the second and third dipole antennas 12 and 13 was used as a reception antenna. The distance between the first and second dipole antennas 11 and 12 was set to an interval corresponding to three wavelengths at the operating frequency, and the third dipole antenna 13 was disposed outside the antenna. Examples of the measurement results include the loss of the distributor and the cable due to the arraying of the second and third dipole antennas 12 and 13.

FIG. 7 shows the passing loss of the distributor and the cable used for arraying the second and third dipole antennas 12 and 13. This passing loss was approximately 1 dB in the used frequency band. The coupling attenuation according to the first embodiment is obtained by subtracting the value of FIG. 7 from the value of FIG.

Therefore, from FIGS. 5 and 6, when one dipole antenna is used for each of transmission and reception, the coupling attenuation between the antennas is about 39 dB, while one of the antennas is arrayed. By doing so, the coupling attenuation is about 54 dB, and even if the loss of the distributor system is considered, about 5 dB
3 dB, indicating that an increase in the coupling attenuation of about 14 dB was obtained.

Second Embodiment FIG. 8 is a perspective view showing an antenna device according to a second embodiment of the present invention, and shows an example in which a dipole antenna is used as the linear antenna in the embodiment shown in FIG. That is, this embodiment includes four dipole antennas 11 to 14. The second dipole antenna 12 is disposed away from the first dipole antenna 11 with the center axis coincident with a straight line passing through the center axis of the first dipole antenna 11. The third dipole antenna 13 is disposed on a straight line passing through the axes of the first and second dipole antennas 11 and 12 at a position approximately one half of the wavelength at the working frequency from the second dipole antenna 12. . Fourth dipole antenna 1
4 denotes first and second dipole antennas 11 and 12
On the straight line passing through the axis of the first dipole antenna 11 at a position approximately one-half of the wavelength at the operating frequency. Second dipole antenna 12, third dipole antenna 13, and first dipole antenna 1
The first and fourth dipole antennas 14 are in-phase combined, respectively, to form one array antenna.

FIG. 9 shows an example of the measurement result of the coupling attenuation in this embodiment. In this measurement, the first and fourth dipole antennas 11 and 14 were used as transmitting antennas, and the second and third dipole antennas 12 and 13 were used as receiving antennas. First and second dipole antennas 11, 12
The distance between them was an interval of three wavelengths at the operating frequency, and the third and fourth dipole antennas 13 and 14 were disposed outside thereof. As shown in FIG. 9, the coupling attenuation between the transmitting and receiving antennas was about 57 dB in the used frequency band. Here, the measurement results include the transmission loss of the distributor and the cable of each antenna. To correct this, it is necessary to subtract twice the value of FIG. 7 from the value of FIG. Thus, the increase in coupling attenuation according to this embodiment is about 15 dB.

Third Embodiment FIG. 10 is a perspective view showing an antenna device according to a third embodiment of the present invention, in which dipole antennas are used as linear antennas and arranged in parallel to each other. In this embodiment, three dipole antennas 21 to 21 are used.
23. These three dipole antennas 21 and 2
3 are arranged parallel to each other and perpendicular to the straight line so that their centers are on the same straight line. The second dipole antenna 22 is disposed apart from the first dipole antenna 21, and the third dipole antenna 23 is disposed at a position approximately one half of the wavelength at the working frequency from the second dipole antenna 22. Second dipole antenna 22 and third dipole antenna 2
3 is combined in phase to form one array antenna.

FIG. 11 is a perspective view showing an antenna device of a comparative example, and FIG. 12 shows an example of measurement results of coupling attenuation between antennas according to the comparative example. In this measurement, two dipole antennas 21 and 22 are arranged parallel to each other and perpendicular to the straight line so that their centers are on the same straight line. The second dipole antenna 22 was used as a receiving antenna. The distance between the two dipole antennas 21 and 22 was set to an interval of three wavelengths at the used frequency.

FIG. 13 shows an example of measurement results of the coupling attenuation according to the third embodiment shown in FIG. In this measurement, the first dipole antenna 21 was a transmission antenna, and the array antenna including the second and third dipole antennas 22 and 23 was a reception antenna. The distance between the first and second dipole antennas 21 and 22 is 3 at the operating frequency.
The third dipole antenna 23 was disposed outside the space corresponding to the wavelength. An example of the measurement result includes the loss of the distributor and the cable for arraying the second and third dipole antennas 22 and 23.

Second and third dipole antennas 2
The distributors and cables used to form the arrays 2 and 23 are the same as those in the first embodiment, and the passing loss is as shown in FIG. Therefore, the coupling attenuation according to the third embodiment is obtained by subtracting the value of FIG. 7 from the value of FIG.

Therefore, from FIGS. 12 and 13, the coupling attenuation between the antennas when one dipole antenna is used for transmission and for reception is approximately 29 dB, whereas one of the antennas is arrayed. by doing,
The coupling attenuation is about 49 dB, which is about 48 dB even when the loss of the distributor system is taken into consideration. It can be seen that the coupling attenuation is increased by about 14 dB.

Fourth Embodiment FIG. 14 is a perspective view showing an antenna device according to a fourth embodiment of the present invention. In the embodiment shown in FIG. 2, dipole antennas arranged in parallel are used as linear antennas. Here is an example. That is, this embodiment includes four dipole antennas 21 to 24. The four dipole antennas 21 to 24 are arranged parallel to each other and perpendicular to the straight line so that their centers are on the same straight line. The second dipole antenna 22 is arranged at a distance from the first dipole antenna 21, the third dipole antenna 23 is arranged at a position approximately half the wavelength at the operating frequency from the second dipole antenna 22, The fourth dipole antenna 24 is arranged at a position approximately one half of the wavelength at the used frequency from the first dipole antenna 21. Second dipole antenna 22 and third dipole antenna 2
3, and the first dipole antenna 21 and the fourth dipole antenna 24 are in-phase combined, respectively, to form one array antenna.

FIG. 15 shows an example of the measurement result of the coupling attenuation according to this embodiment. In this measurement, the first and fourth dipole antennas 21 and 24 were used as transmitting antennas, and the second and third dipole antennas 22 and 23 were used as receiving antennas. First and second dipole antennas 21, 22
The distance between them was an interval of three wavelengths at the operating frequency, and the third and fourth dipole antennas 23 and 24 were arranged outside thereof. As shown in FIG. 15, the coupling attenuation between the transmitting and receiving antennas is about 70 dB in the operating frequency band.
It became. Here, this measurement result includes the passage loss of the distributor and cable of each antenna,
To correct this, it is necessary to subtract twice the value in FIG. 7 from the value in FIG. Thus, the increase in coupling attenuation according to this embodiment is about 38 dB.

[0025]

As described above, the antenna device of the present invention can increase the coupling attenuation between two antennas. Also, conventionally, when the gain of the antenna increased, the coupling attenuation decreased by the increase,
By using at least one element as a two-element array antenna, there is an effect that the amount of coupling attenuation can be increased despite an increase in antenna gain.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a perspective view showing the antenna device according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing an antenna device of a comparative example.

FIG. 5 is a diagram showing an example of measurement results of coupling attenuation between antennas according to a comparative example.

FIG. 6 is a diagram illustrating an example of a measurement result of a coupling attenuation amount according to the first embodiment.

FIG. 7 is a diagram illustrating a passage loss of a distributor and a cable.

FIG. 8 is a perspective view showing an antenna device according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a measurement result example of a coupling attenuation amount according to the second embodiment.

FIG. 10 is a perspective view showing an antenna device according to a third embodiment of the present invention.

FIG. 11 is a perspective view showing an antenna device of a comparative example.

FIG. 12 is a diagram showing a measurement result example of a coupling attenuation amount between antennas according to a comparative example.

FIG. 13 is a diagram illustrating an example of a measurement result of a coupling attenuation amount according to the third embodiment.

FIG. 14 is a perspective view showing an antenna device according to a fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating an example of a measurement result of a coupling attenuation amount according to a fourth embodiment.

[Explanation of symbols]

 1-4 linear antenna 11-14, 21-24 dipole antenna

Claims (2)

[Claims] An antenna device comprising first and second linear antennas arranged with their polarization planes aligned at separate positions for transmission and reception, wherein the first and second linear antennas are substantially arranged. A third linear antenna having a plane of polarization aligned on a straight line connecting the linear antennas and arranged at a position approximately one-half wavelength from the second linear antenna; An antenna device, wherein an antenna is in-phase combined with the second linear antenna. 2. The antenna according to claim 1, wherein said first linear antenna and said first linear antenna are disposed substantially at a half wavelength from said first linear antenna with their polarization planes substantially aligned on a straight line connecting said first and second linear antennas. The antenna device according to claim 1, further comprising a fourth linear antenna, wherein the fourth linear antenna is in-phase combined with the first linear antenna.