JPH11205032A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold low correlation between antenna elements without regardless of the receiving environment. SOLUTION: At least two, four antenna elements 1 to 4, e.g. are provided, and these elements 1 to 4 are arranged spatially away from each other (the intervals of the elements, for example, are set to be the degree of the about one wavelength of a signal to be used) on a ground plane 5. In addition, these elements 1 to 4 are constituted of elements with different radiation directivity like the antenna elements 1, 3 of a bottom loading monopole and the antenna elements 2, 4 of a top loading monopole. Then signals received by these elements 1 to 4 are selected or mixed to connect with a radio circuit of a poststage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device suitable for use, for example, in a home network system by wireless communication.

[0002]

2. Description of the Related Art For example, it has been studied to construct a network system for improving the convenience of an operator by interconnecting home appliances such as audio / video equipment provided in a home. In such a network system, the above-described mutual connection has conventionally been performed by extending a so-called transmission line using wired communication. However, such a method of extending transmission lines requires equipment for installing the transmission lines in advance, and it is not easy to construct such a network system.

[0003] On the other hand, means for using a so-called wireless communication to enable the construction of a network system without providing a facility or the like in advance have been studied.
However, when such wireless communication is performed, for example, indoors, a problem of so-called multipath fading due to reflection of a propagation path or the like occurs, and a situation occurs in which good communication cannot be performed in all places. Therefore, for the purpose of solving such a problem of multipath fading, it has been proposed to perform so-called diversity reception.

[0004] That is, the diversity reception includes, for example, at least two, for example, four antenna elements 41, 42, 43, and 44 as shown in FIG. The elements are spaced apart (the element spacing is set to, for example, about one wavelength of a signal to be used). Means (not shown) for selecting or synthesizing the signals received by these antenna elements 41 to 44 and connecting them to a radio circuit (not shown)
Is provided.

Thus, for example, by selecting the highest quality signal from the signals received by the above-described antenna elements 41 to 44 and connecting to the above-mentioned radio circuit, a stable high-quality reception signal is always obtained. Is to be obtained.

In the above device, the antenna element 4
Usually, for example, a monopole antenna is used for 1 to 44. In this case, the antenna elements 41 to 44 have a monopole length set to about 約 wavelength, for example, as shown in FIG. In this case, the antenna elements 41 to 44
In the current distribution, the in-phase portion occupies most as shown in B of the same figure, and the radiation directivity has a figure-eight characteristic as shown in the C of the same figure.

[0007]

However, in the above-described configuration, a desired received signal quality may not be obtained depending on the arrival state of the received wave. That is, in the above-described configuration, for example, in an environment where a large number of received beams having substantially the same strength arrive, the correlation between the antenna elements 41 to 44 is kept low, and desired reception signal quality can be obtained.

[0008] For example, in a situation where an object serving as a scattering source of radio waves (such as an electric appliance covered with metal) becomes hard in the vicinity,
Many received beams having substantially equal intensities will be generated. Therefore, at each of the spatially separated points, the received beams are superimposed with different phase differences, and are strengthened at a certain point and weakened at a certain point (Rayleigh fading).

[0009] Therefore, in such a situation, the strengths of the desired signal and the jamming interference received by the antennas located at the respective points are determined completely independently of the other antennas, and high quality ones are determined. There is plenty of room to choose. That is, in this case, the effect of diversity reception can be sufficiently expected.

However, for example, in an environment in which the intensity of a small number of received beams becomes prominently high, among these received beams, a low correlation between the antenna elements 41 to 44 cannot be maintained. The quality of the received signals of the antenna elements 41 to 44 becomes similar.

For example, in an environment such as a Japanese-style room where there are few radio wave scattering sources in the vicinity, the arriving radio waves are hardly reflected, but are absorbed or transmitted. Therefore, a situation occurs in which only one outstanding strong received wave exists (Nakagami-Rice fading). In such a case, even if the points are spatially separated, the strength due to the superimposition hardly occurs, so that the received signal strengths are almost equal.

That is, the intensity ratio between the desired signal and the interference does not change so much with any antenna, and if this ratio cannot be sufficiently obtained, the quality will surely deteriorate. For this reason, the probability that the quality of the received signals of all the antenna elements 41 to 44 is simultaneously reduced increases, and as a result, there is a possibility that a received signal of stable quality cannot be always obtained.

The present application has been made in view of the above points, and the problem to be solved is that a conventional apparatus cannot obtain a desired received signal quality depending on the arrival state of a received wave. That is the case.

[0014]

According to the present invention, at least one of at least two antenna elements for performing diversity reception has a radiation directivity different from the others. For example, a low correlation between antenna elements can be maintained even in an environment where the intensity of a small number of received element waves is prominently high, and the probability that the received signal quality of all the antenna elements is simultaneously reduced is reduced. By lowering it, a received signal of stable quality can always be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, the present invention provides at least two
An antenna device that includes two antenna elements and arranges the antenna elements spatially separated from each other, and provides means for selecting or combining signals received by the antenna elements and connecting to a radio circuit to perform diversity reception. , At least one of the antenna elements has a radiation directivity different from the others.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an example of an antenna device to which the present invention is applied.

In FIG. 1, at least two, for example, 4
Antenna elements 1, 2, 3, and 4, and these antenna elements 1 to 4 are spatially separated from each other on the ground plane 5 (element spacing is set to, for example, about one wavelength of a signal to be used). The antenna elements 1 to 4 are configured by elements having different radiation directivities, for example, antenna elements 1 and 3 of a bottom loading monopole and antenna elements 2 and 4 of a top loading monopole. . And these antenna elements 1 to
Means (not shown) for selecting or synthesizing the signal received by 4 and connecting it to a radio circuit (not shown).

In this device, the antenna elements 1 and 3 of the bottom loading monopole have a top monopole length of about 波長 wavelength and a loading length of about ４ wavelength as shown in FIG. Is set. In this case,
The in-phase portion occupies most of the current distribution of this antenna element as shown in B of the same figure, and the radiation directivity is an eight-shaped characteristic that is slightly sharper than the conventional monopole antenna as shown in C of the same figure. Present.

On the other hand, the antenna elements 2 and 4 of the top loading monopole have a bottom monopole length of about 1/2 wavelength and a loading length of about 1/4 wavelength as shown in FIG. 3A, for example. You. In this case, most of the current distribution of the antenna element is in the opposite phase as shown in B of the figure, and the radiation directivity exhibits a four-leaf type characteristic as shown in C of the figure.

Therefore, by using the antenna elements 1 to 4 having different radiation directivities, for example, even in an environment where the intensity of the above-mentioned small number of received light waves becomes prominently high,
Low correlation between antenna elements 1 to 4 can be maintained,
It is possible to reduce the probability that the quality of the received signals of all the antenna elements 1 to 4 is reduced at the same time, and to always obtain a stable received signal.

For example, even in an environment such as a Japanese-style room where there are almost no radio wave scattering sources in the vicinity described above, between antennas having different directivities, the intensity ratio of a desired signal arriving from different directions and the interference interference intensity is different. Has definitely changed, leaving room for choosing the better quality. That is, the effect of diversity reception can be expected.

According to the present invention, although the conventional apparatus has a problem that a desired received signal quality may not be obtained depending on the arrival state of a received wave, the present invention solves these problems. It can be easily eliminated.

Therefore, by using this device as an antenna device in a home network system using wireless communication, for example, a received signal of stable quality can always be obtained without being affected by the arrival state of the received wave.

Thus, according to the above-described antenna device, at least two antenna elements are provided, and the antenna elements are arranged spatially separated from each other, and a signal received by the antenna element is selected or combined to form a radio circuit. In an antenna apparatus in which diversity reception is performed by providing a connecting means, at least one of the antenna elements has a radiation directivity different from the other, so that, for example, the intensity of the aforementioned small number of received element waves is prominently increased. It is possible to maintain a low correlation between antenna elements even in an unfavorable environment, reduce the probability that the received signal quality of all the antenna elements is reduced at the same time, and always obtain a stable received signal. You can do it.

[0025]

Therefore, according to the first aspect of the present invention, by using antenna elements having different radiation directivities, for example, even in an environment in which the intensity of the above-mentioned small number of received light waves becomes remarkably high, It is possible to maintain a low correlation between the signals, reduce the probability that the received signal quality of all the antenna elements is simultaneously reduced, and always obtain a stable received signal.

According to the present invention, there have been problems that the conventional apparatus may not be able to obtain a desired received signal quality depending on the arrival state of a received wave. According to the present invention, these problems are solved. It can be easily eliminated.

Therefore, by using this device as an antenna device in a home network system by wireless communication, for example, it is possible to always obtain a received signal of stable quality without being influenced by the arrival state of a received wave. It is.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of an antenna device to which the present invention is applied.

FIG. 2 is a diagram for explaining this.

FIG. 3 is a diagram for explaining this.

FIG. 4 is a configuration diagram of a conventional antenna device.

FIG. 5 is a diagram for explaining this.

[Explanation of symbols]

1,3 ... antenna element of bottom loading monopole, 2,4 ... antenna element of top loading monopole, 5 ... ground plane

Claims (2)

[Claims] 1. At least two antenna elements are provided, and said antenna elements are arranged spatially separated from each other, and means for selecting or combining signals received by said antenna elements and connecting to a radio circuit is provided. An antenna device for performing diversity reception, wherein at least one of the antenna elements has a radiation directivity different from the others. 2. The antenna device according to claim 1, wherein the antenna element includes a bottom loading monopole antenna and a top loading monopole antenna.