KR101166090B1 - Multi band mimo antenna - Google Patents

Abstract

A multi band MIMO antenna is disclosed. The multi-band MIMO antenna according to an embodiment of the present invention includes a first antenna and a second antenna which are connected to the ground formed on the substrate and are formed symmetrically at regular intervals and transmit and receive signals of the multi-frequency band. . In this case, the first antenna and the second antenna include a band reject filter for blocking a frequency component generated due to the coupling between the first antenna and the second antenna.

Description

MULTI BAND MIMO ANTENNA

Embodiments of the present invention relate to a multi-in multi-out (MIMO) antenna, and more particularly, to a multi-band MIMO antenna technology with improved isolation between antennas.

Recently, with the rapid development of wireless communication technology, research on the antenna of a mobile communication terminal suitable for it has been continuously conducted. In particular, MIMO (Multi Input Multi Output) antenna system is attracting attention to improve antenna performance of mobile communication terminals. In 4G mobile communication, MIMO antenna system technology is adopted to improve communication speed and increase data capacity. .

MIMO antenna system is provided with a plurality of antennas to enable high-speed data transmission by receiving different signals. That is, in the MIMO antenna system, a plurality of antennas may be arranged to increase the amount and reliability of data.

However, when the MIMO antenna system is used in the mobile communication terminal, due to the spatial constraints of the mobile communication terminal, mutual interference occurs between antennas, thereby reducing isolation, thereby degrading antenna performance. There is this.

In other words, in order to prevent performance degradation between antennas in a MIMO antenna system, spaces of 0.5λ or more are required. In a mobile communication terminal, interference is generated between antennas due to spatial constraints, and isolation is reduced, and capacity efficiency of the MIMO antenna system is reduced. This decreasing problem occurs.

In order to solve this problem, a method of minimizing mutual interference between antennas has been attempted by forming a partition of a three-dimensional structure between antennas arranged on a substrate or by using a modified ground structure.

However, such a scheme does not meet the trend of miniaturization of mobile communication terminals because it increases the volume of the MIMO antenna, and is particularly difficult to apply to low frequency bands (eg, LTE bands).

Embodiments of the present invention provide a multi-band MIMO antenna that can improve isolation by minimizing interference between antennas.

Embodiments of the present invention are to provide a multi-band MIMO antenna that can form the antennas in a narrow space while maintaining the normal performance as a MIMO antenna.

Multi-band MIMO antenna according to an embodiment of the present invention, the substrate; A ground formed on the substrate; A first antenna formed on the substrate and connected to the ground and transmitting and receiving a signal of a multi-frequency band; And a second antenna connected to the ground on the substrate and spaced apart from the first antenna at a predetermined interval, and transmitting and receiving a signal of a multi-frequency band, wherein the first antenna and the second antenna are the first antenna. And a band reject filter for rejecting frequency components generated due to coupling between the second antennas.

According to an embodiment of the present invention, the first antenna and the second antenna are implemented in each of the first antenna and the second antenna by implementing a band rejection filter for rejecting a frequency band generated due to coupling between the first antenna and the second antenna. Mutual interference between the antennas can be minimized, thereby improving the isolation between the antennas.

In addition, since the isolation between the antennas can be improved by forming the first antenna and the second antenna in a narrow space on the substrate without a separate structure, the overall antenna size can be reduced and the manufacturing process can be simplified.

1 illustrates a multi-band MIMO antenna in accordance with an embodiment of the present invention.
2 is a diagram illustrating a band-stop filter equivalent circuit of a multi-band MIMO antenna according to an embodiment of the present invention.
3 is a view showing the structure of a comparison antenna for comparing the characteristics of a multi-band MIMO antenna according to an embodiment of the present invention.
4 is a graph comparing return loss and isolation of a multi-band MIMO antenna and a comparison antenna according to an embodiment of the present invention.
5 is a graph showing the return loss characteristics according to the change of the inductor value according to an embodiment of the present invention.
6 is a graph showing correlation coefficients between antennas in a multi-band MIMO antenna according to an embodiment of the present invention.
7 illustrates a radiation beam pattern of a first antenna according to an embodiment of the present invention.
8 illustrates a radiation beam pattern of a second antenna according to an embodiment of the present invention.

Hereinafter, specific embodiments of the multi-band MIMO antenna of the present invention will be described with reference to FIGS. 1 to 8. However, this is only an exemplary embodiment and the present invention is not limited thereto.

In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

The technical spirit of the present invention is determined by the claims, and the following embodiments are merely means for effectively explaining the technical spirit of the present invention to those skilled in the art to which the present invention pertains.

1 is a diagram illustrating a multi-band MIMO antenna according to an embodiment of the present invention.

Referring to FIG. 1, a multiband MIMO antenna includes a substrate 102, ground 104, a first antenna 106, and a second antenna 108. Here, the first antenna 106 and the second antenna 108 are formed symmetrically. Therefore, hereinafter, only the configuration of the first antenna 106 will be described, and a detailed description of the configuration of the second antenna 108 will be omitted.

The ground 104 has a predetermined area at the lower end of the substrate 102, and the first antenna 106 and the second antenna 108 have the ground 104 at the upper end of the substrate 102. And are connected to each other.

The first antenna 106 includes a first radiator pattern 110 for transmitting and receiving a signal of a first frequency band and a second radiator pattern 120 for transmitting and receiving a signal of a second frequency band. For example, the first radiator pattern 110 transmits and receives signals in a band 1.92 to 2.17 GHz, which is a wideband code division multiple access (WCDMA) band, and the second radiator pattern 120 transmits a long term evolution (LTE) band. Transmit and receive signals in the 698-800 MHz band. That is, the first antenna 106 and the second antenna 108 operates as a multi band antenna.

The first radiator pattern 110 includes a ground connection pattern 111, a loop forming pattern 113, and a patch 115. The ground connection pattern 111 is formed to be perpendicular to the ground 104 in the ground 104. Meanwhile, the ground connection pattern 161 of the second antenna 108 is formed to be spaced apart from the ground connection pattern 111 of the first antenna 106 by a predetermined interval. That is, the second antenna 108 is formed to be symmetrical with the first antenna 106 in a state spaced apart from the first antenna 106 at a predetermined interval.

The loop forming pattern 113 is connected at an end of the ground connection pattern 111 to be formed in parallel with the ground connection pattern 111 in a direction opposite to the ground connection pattern 111. In this case, the loop formation pattern 113 is formed to have a shorter length than the ground connection pattern 111.

The patch 115 is connected to the end of the loop forming pattern 113 and is formed to have a predetermined area. In this case, the patch 115 is formed to be spaced apart from the ground connection pattern 111. Although the shape of the patch 115 is shown as a rectangle here, the shape of the patch 115 is not limited thereto, and the patch 115 may be formed in various shapes other than that.

In addition, a feed point 130 is formed between the patch 115 and the ground connection pattern 111 by connecting the patch 115 and the ground connection pattern 111. The feed point 130 is electrically connected to, for example, a coaxial cable (not shown). In this case, a loop structure 150 is formed in the first antenna 106 due to the ground connection pattern 111, the loop formation pattern 113, and the feed point 130.

The second radiator pattern 120 is formed to surround the patch 115 at a predetermined interval from the patch 115. Here, the inductor 140 is formed by connecting the second radiator pattern 120 and the loop forming pattern 113 to one end of the second radiator pattern 120.

When the inductor 140 is formed by connecting the second radiator pattern 120 and the loop forming pattern 113, when the second radiator pattern 120 is directly connected to the loop forming pattern 113. In comparison, the resonance frequency of the second radiator pattern 120 may be lowered.

For example, when directly connecting the second radiator pattern 120 and the loop forming pattern 113, the resonance frequency of the second radiator pattern 120 is formed at 1.3 GHz, whereas the inductor 140 is formed. When the second radiator pattern 120 and the loop formation pattern 113 are connected to each other, a resonance frequency of the second radiator pattern 120 is formed at 0.77 GHz (ie, LTE band). In this case, the size of the first antenna 106 can be reduced by reducing the electrical length of the second radiator pattern 120 through the inductor 140.

In addition, when the resonance frequency of the second radiator pattern 120 is lowered through the inductor 140 to be formed at 0.77 GHz, the multiplication frequency is formed at 2.3 to 2.4 GHz, which is a WiBro band. In this case, the first antenna 106 may have a third frequency band (eg, WiBro band) in addition to the first frequency band (eg, WCDMA band) and the second frequency band (eg, LTE band). ) Can be transmitted and received.

According to the embodiment of the present invention, since the band reject filter can be configured for the coupling component due to the mutual interference between the first antenna 106 and the second antenna 108, the first antenna 106 can be configured. And it is possible to minimize the mutual interference between the second antenna 108, it is possible to improve the isolation between the first antenna 106 and the second antenna 108. This will be described with reference to FIG. 2. 2 is a diagram illustrating a band-stop filter equivalent circuit of a multi-band MIMO antenna according to an embodiment of the present invention.

Here, L1 represents the inductor 140, C1 represents the coupling through the spaced gap between the second radiator pattern 120 and the patch 115, L2 represents the loop structure 150, C2 represents a coupling through a gap between the ground connection pattern 111 of the first antenna 106 and the ground connection pattern 161 of the second antenna 108.

As shown in FIG. 2, each of the first antenna 106 and the second antenna 108 acts as a band suppression filter, thereby the first antenna 106 and the second antenna 108. It is possible to effectively eliminate the coupling component due to mutual interference between them.

In this case, the frequency band to be blocked may be different according to the values of L1, C1, L2, and C2. For example, by adjusting the values of L1, C1, L2, and C2, the band reject filter may be used to resonate the frequency bands of the first antenna 106 and the second antenna 108 (eg, LTE band and When configured to block the WCDMA band, the frequency components (ie, components due to coupling) of the LTE band and the WCDMA band that appear due to mutual interference between the first antenna 106 and the second antenna 108 The interference between the first antenna 106 and the second antenna 108 can be minimized, and the isolation can be improved.

On the other hand, since the multi-band MIMO antenna according to an embodiment of the present invention is formed on the substrate 102 and does not require a separate structure for improving the isolation, the antenna can be reduced in size, thereby miniaturizing the antenna. It is possible to reduce the cost according to the manufacture of the antenna.

3 is a diagram illustrating a structure of a comparison antenna for comparing characteristics of a multi-band MIMO antenna according to an embodiment of the present invention. Referring to FIG. 3, the comparison antenna is formed by directly connecting the second radiator pattern 120 to the loop forming pattern 113 of the first radiator pattern 110 without the inductor 140.

4 is a graph comparing return loss and isolation of a multi-band MIMO antenna and a comparison antenna according to an embodiment of the present invention. Referring to Figure 4 (a), it can be seen that the resonance frequency is formed at about 1.3 GHz for the comparison antenna. That is, the comparison antenna can transmit and receive only signals of a single frequency band.

On the other hand, the multi-band MIMO antenna can be seen that the resonant frequency is formed in the LTE band 0.746 ~ 0.787 GHz, the WCDMA band 1.92 ~ 2.17 GHz, and the WiBro band 2.3 ~ 2.4 GHz. That is, the multi-band MIMO antenna can transmit and receive signals of three frequency bands.

The multi-band MIMO antenna may connect the second radiator pattern 120 and the loop forming pattern 113 through the inductor 140 to reduce the resonance frequency formed at 1.3 GHz to 0.746 to 0.787 GHz, which is an LTE band. Will be. In this case, the multiplication frequency of the LTE band is formed in the 2.3 ~ 2.4 GHz it is possible to form a resonance frequency in the WiBro band.

Referring to FIG. 4B, it can be seen that, in the case of the comparison antenna, the isolation between the first antenna 106 and the second antenna 108 is greater than or equal to -15 dB as a reference value. In this case, antenna performance is degraded due to interference between the first antenna 106 and the second antenna 108.

Multiband MIMO antennas, on the other hand, have -18 dB isolation in the LTE band (0.746-0.787 GHz) and -17--18 dB isolation in the WCDMA band (1.92-2.17 GHz) and the WiBro band (2.3-2.4 GHz). It can be seen that the isolation is improved.

The isolation is improved because the band rejection filter is configured for the coupling component due to mutual interference between the first antenna 106 and the second antenna 108 through the configuration shown in FIG. 1.

Meanwhile, the multi-band MIMO antenna according to an embodiment of the present invention exhibits excellent isolation characteristics even though the distance between the first antenna 106 and the second antenna 108 is a very short distance (for example, 1 mm). do. In this case, the MIMO antenna system can be implemented while minimizing interference between antennas even in a narrow space.

5 is a graph illustrating return loss characteristics according to a change of an inductor value according to an exemplary embodiment of the present invention.

Referring to FIG. 5, it can be seen that as the inductor value of the inductor 140 decreases, the resonance frequencies of the first radiator pattern 110 and the second radiator pattern 120 are increased. In this case, it can be seen that the change in the resonance frequency of the second radiator pattern 120 is larger than the change in the resonance frequency of the first radiator pattern 110.

6 is a graph illustrating correlation coefficients between antennas in a multi-band MIMO antenna according to an embodiment of the present invention.

Referring to FIG. 6, it can be seen that the correlation coefficient is 0.3 to 0.4 in the LTE band (0.746 to 0.787 GHz), and the correlation coefficient is less than 0.1 in the WCDMA band (1.92 to 2.17 GHz) and the WiBro band (2.3 to 2.4 GHz). It can be seen that.

In general, it is determined that the correlation coefficient between the two antennas has excellent diversity performance when it is 0.5 or less, and the multi-band MIMO antenna has a correlation coefficient of less than 0.5 in both the LTE band, the WCDMA band, and the WiBro band. Therefore, according to the embodiment of the present invention, it is possible to perform an excellent diver seat function while minimizing mutual interference between two antennas.

7 is a view showing a radiation beam pattern of the first antenna according to an embodiment of the present invention, Figure 8 is a view showing a radiation beam pattern of the second antenna according to an embodiment of the present invention. Here, FIG. 7 measures the radiation beam pattern of the first antenna in a state where the second antenna is terminated by 50 Ω, and FIG. 8 measures the radiation beam pattern of the second antenna in the state where the first antenna is terminated by 50 Ω. will be. The first antenna and the second antenna each have a resonance frequency of 0.77 GHz, 2.05 GHz, and 2.35 GHz.

7 and 8, the first antenna and the second antenna can be seen that the radiation beam pattern appears evenly in all directions. That is, it can be seen that the radiation beam patterns of the first antenna and the second antenna are omni-directional.

In this case, the antenna gain and antenna efficiency of the first antenna and the second antenna are shown in Table 1.

  Antenna gain (dBi)    f = 0.77 GHz    f = 2.05 GHz    f = 2.35 GHz     First antenna       -0.52        3.8       3.4     Second antenna       -0.64        3.5       3.2   Antenna efficiency (%)    f = 0.77 GHz    f = 2.05 GHz    f = 2.35 GHz     First antenna        28        56.8       53     Second antenna        29        56.2       53.6

Referring to Table 1, it can be seen that the antenna gains of the first antenna and the second antenna are -0.52 and -0.64 dBi, respectively, at 0.77 GHz. Since the reference antenna gain of the corresponding frequency band is -3 dBi, the first antenna And it can be seen that the second antenna shows a good antenna gain at 0.77 GHz.

The antenna gains of the first antenna and the second antenna are 3.8 and 3.5 dBi at 2.05 GHz, and 3.4 and 3.2 dBi at 2.35 GHz, respectively. The reference antenna gain of the corresponding frequency band is 0 dBi. It can be seen that the first antenna and the second antenna show good antenna gains at 2.05 GHz and 2.35 GHz.

In addition, the efficiency of the first antenna and the second antenna can be seen to maintain a normal level in the frequency band.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. I will understand.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

102: substrate 104: ground
106: first antenna 108: second antenna
110: first radiator pattern 111: ground connection pattern
113: loop formation pattern 115: patch
120: second radiator pattern 130: feeding point
140: inductor 150: loop structure

Claims (8)

Board;
A ground formed on the substrate;
A first antenna formed on the substrate and connected to the ground and transmitting and receiving a signal of a multi-frequency band; And
A second antenna connected to the ground on the substrate and spaced apart from each other by a symmetrical relationship with the first antenna, and transmitting and receiving a signal of a multi-frequency band;
Each of the first antenna and the second antenna includes a band reject filter for rejecting frequency components generated due to coupling between the first antenna and the second antenna.
The first antenna,
A first radiator pattern connected to the ground and transmitting and receiving a signal of a first frequency band;
A second radiator pattern formed to be spaced apart from the first radiator pattern by a predetermined interval and transmitting and receiving a signal of a second frequency band; And
And an inductor formed by connecting the first radiator pattern and the second radiator pattern.
delete delete The method of claim 1,
The first radiator pattern is,
A ground connection pattern formed in the ground to be perpendicular to the ground;
A loop forming pattern connected to an end of the ground connection pattern, the loop forming pattern being spaced apart from the ground connection pattern in a direction opposite to the ground connection pattern in parallel; And
And a patch connected to an end of the loop formation pattern, the patch being spaced apart from the ground connection pattern at a predetermined interval.
The method of claim 4, wherein
The first antenna,
And a feed point formed by connecting the patch and the ground connection pattern between the patch and the ground connection pattern.
The method of claim 5,
The first antenna,
And a loop structure consisting of the ground connection pattern, the loop formation pattern, and the feed point.
The method of claim 4, wherein
The second radiator pattern is,
A multi-band MIMO antenna formed to surround the patch spaced apart from the patch.
The method of claim 7, wherein
The inductor is,
And connecting the second radiator pattern and the loop forming pattern between one end of the second radiator pattern and the loop forming pattern.

Images