KR101392704B1 - Lte mimo lte mimo antenna with high isolation and brodband - Google Patents

Abstract

LTE frequency MIMO antenna with broadband characteristic resonating more than 100MHZ in 720-820MHZ band and isolation characteristic more than -10dB,
A MIMO antenna device is formed on a substrate
A ground (3) formed on one surface of the substrate,
A main antenna 1 and a sub antenna 2 which are formed on one surface of the substrate and are electrically connected to the ground and resonate at a bandwidth of 100 MHZ or more in 720 MHZ-820 MHZ and have an isolation characteristic of -10 dB or more,
And a T-shaped stub 4 electrically connected to the ground and formed at one end of the ground

Description

[0001] MIMO ANTENNA WITH HIGH SEISMICITY AND BROADBAND IN LTE BAND {

The present invention relates to a planar miniature MIMO antenna, and more particularly, to a miniaturized multiple input multiple output (MIMO) antenna for a mobile device having a wide bandwidth and a high isolation characteristic.

As the number of users receiving LTE service increases, MIMO technique and broadband are required for increasingly faster communication speed. As a result, there is an attempt to allocate a continuous idle frequency of about 100MHZ in the 700MHZ band (720-820MHZ), which is caused by the recent termination of analog TV broadcasting, to telecommunication service providers. However, in the 700MHZ band LTE system, , There is no research result for a resonant terminal having a wide band of 720-820 MHz (100 MHz), so that even if all of 100 MHz is allocated to an LTE frequency in a 700 MHz band, there is a problem that it can not be realized. If the frequency is not consecutive, it can be solved by CA (Carrier Aggregation) method. However, to be introduced into a specific 720-820 MHz band, the terminal itself must have a resonance characteristic at 720-820 MHZ. However, in order to resonate a low frequency (720-820 MHz) in a miniaturized terminal, a metal body such as a spiral or a meander must be used basically because an antenna having a long wavelength should be provided. When such a technique is applied to a microwave oven, (720-820MHZ). In case of MIMO of low frequency band (720-820MHZ), isolation and bandwidth are in trade off relationship. If one of them is satisfied, performance of the other side is degraded. Respectively. Therefore, a high isolation characteristic and a terminal having a wide bandwidth (100 MHz) in a low frequency band (720-820 MHz) are required.

Second, in order to improve isolation and bandwidth in 720-820 MHz band MIMO, techniques such as Split Ring Resonator (SRR), Artificial Magnetic Conductor (AMC), Electromagnetic Band Gab (EBG), Slot and Stub are added. Since the four elements of radiation pattern, isolation, bandwidth, and gain between the two antennas of the terminal are sensitively changed depending on the arrangement state and length of the sieve, there is no parameter that can satisfy the requirement, which makes it difficult to design.

8 and paragraph [0071] of Patent Document KR101217469B1 disclose a wide bandwidth having a gain of -10 dB or more at a low frequency of 700 MHz and a degree of isolation of -10 dB. However, the patent document shows that F1 and F2 are multiplexed Band MIMO antenna can not satisfy the gain and isolation in a single band. [0035] FIG. 5 shows a MIMO small terminal having a 15-18 dB isolation diagram. However, there is a problem that the bandwidth is as low as about 50 MHZ with a bandwidth of 746-794 MHz at a gain of -10 dB. 4 and 9 of Patent Document KR1020100122803A disclose a configuration in which a T-shaped stub is formed on the ground in order to improve the degree of isolation in MIMO. However, actually, when a T stub is arranged together with main and sub antennas, There is a problem that specific parameters for overcoming the gain and isolation degree and the radiation pattern which are sensitive due to the parasitic component can not be presented. [0043] Although FIG. 2 shows a -17 dB MIMO antenna as an isolation diagram, there is a problem in that it can not be satisfied at a low frequency of 700 MHZ by applying only to a high frequency (2GHZ 2). Since the monopole meander line is used to improve the degree of isolation, the patent document has a problem that the gain, isolation, and radiation pattern are sensitively changed when designing at a low frequency. In some MIMO antennas for improving the isolation of non-patent documents, isolation characteristics of -10 or more at a low frequency of 700 MHZ are presented. However, since the bandwidth is narrower than about 10 MHZ, there is a problem that it can not resonate in a wide band.

In order to solve the above problem, first, an antenna that resonates at a bandwidth of 720 MHz - 820 MHz (100 MHz) in a single band MIMO and satisfies the isolation characteristic of -10 dB is designed, and secondly, , Thickness, and length

In a MIMO antenna device formed on a substrate,

A ground (3) formed on one surface of the substrate;

A main antenna 1 and a sub antenna 2 formed on one surface of the substrate and electrically connected to the ground to resonate at a bandwidth of 100 MHZ or more at 720 MHZ-820 MHZ and to satisfy an isolation characteristic of -10 dB or more;

A T-shaped stub 4 electrically connected to the ground and formed at one end of the ground;

The main antenna 1 has a first shape L2 having a linear shape along the spatial coordinate system X, Y, Z; A second shape portion (H1) having a right angle bent in the + Z axis along the first shape portion; A third feature L1 having a right angle bend in the + Y axis along the second feature; A fourth shape L3 having a right angle bend along the third shape along the + X axis; A fifth shape L6 having a right angle bend in the + Y axis along the fourth shape; A sixth feature L8 having a right angle bend in the + X axis along the fifth feature, a seventh feature L'1 having a right angle bend along the sixth feature in the -Y axis; An eighth feature (L'5) having a shape that is orthogonal to the + X axis along the sixth feature; A ninth feature (H'1) having a right angle bend along the -Z axis along the seventh feature; A tenth feature (L'2) having a right angle bend in the + X axis along the ninth feature; An eleventh feature (H'2) having a right angle bend in the + Z axis along the tenth feature; A twelfth feature (L'4) having a right angle bend in the + Y axis along the eleventh feature; A thirteenth feature (L'8) having a right angle bend in the + X axis along the twelfth feature; A fourteenth feature (L'9) having a right angle bend along the -X axis along the thirteenth feature; A fifteenth feature H'3 having a right angle bend along the -Z axis along the fourteenth feature; A sixteenth feature (L'10) having a right angle bend in the + Y axis along the fifteenth feature; A seventeenth feature (L'11) having a right angle bend with respect to the -Y axis along the eighth feature; An eighteenth feature H'3 having a right angle bend along the -Z axis along the seventeenth feature; And a nineteenth shape (L'12) having a right angle bent in the + Y axis along the eighteenth shape

The length of the first shape portion L2 is 13 mm and the length of the second shape portion is 2.8 mm. The length of the third shape portion L1 is 2.5 mm. The length of the fourth shape portion L3 The length of the fifth shape L6 is 5 mm. The length of the sixth shape L8 is 22 mm. The length of the seventh shape L 1 is 5.5 mm. The length of the fifth shape L 5 The length of the ninth feature H'1 is 2.8 mm, the length of the tenth feature L'2 is 3 mm, the length of the eleventh feature H'2 is 1.8 mm, The length of the twelfth shape portion L'4 is 3.5 mm, the length of the 13th shape portion L'8 is 9 mm, the length of the 14th shape portion L'9 is 2 mm, 3) is 5 mm, the length of the 16th configuration (L'10) is 4 mm, the length of the 17th configuration (L'11) is 5 mm, the length of the 18th configuration H'3 is 2 mm, 19 The length of the shaped portion (L'12) was 1.8 mm

The sub-antenna 2 is circularly symmetric with respect to the ground 3 in the same length and shape as the main antenna 1

The length of the T-shaped stub 4 is 118 mm on the Y axis and 2.2 mm on the X axis, and the Y axis length of the conductor connected to the ground is 1.4 mm;

Which resonates at a bandwidth of more than 100MHZ at 720MHZ-820MHZ and realizes an antenna that satisfies the isolation characteristic of -10dB or more

The MIMO antenna with a broadband characteristic resonating more than 100MHZ in the LTE frequency band of 720-820MHZ and an isolation characteristic of more than -10dB can be fabricated to greatly improve the transmission speed of the existing LTE system.

1 is a view illustrating a structure of a MIMO antenna according to an embodiment of the present invention;
Fig. 2 is a graph showing a specific reflection loss value and an isolation diagram
FIG. 3 is a graph illustrating the HFSS simulation of the main and sub antenna gain and resonance bandwidth variations and isolation characteristics in the 700-800 MHz band.
4 is a view showing a state of binding between a terminal case and a ground panel
Fig. 5 is a schematic view showing a configuration in which an antenna for resonating 700 MHZ and a stub are combined together
6 is a view showing an example of a T-shaped stub electrically connected to the ground plate
7 is a view showing a specific shape of a MIAN antenna resonating at 700 MHZ
8 is a view showing a specific shape of a SUB antenna resonating at 700 MHZ
FIG. 9 is a graph showing a gain change of a sub antenna according to a change in L5 length of a main antenna and a parameter measurement value
FIG. 10 is a graph showing a gain change of the sub antenna according to the length change of L6,7 of the main antenna and a parameter measurement value
FIG. 11 is a graph showing a change in gain of a sub antenna according to a change in length H1 of a main antenna and a parameter measurement value
12 is a measurement chart simulating a radiation pattern at 750 MHZ

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

The present invention is an ultra-small wide-band MIMO antenna resonating at a bandwidth of 100 MHZ or more in LTE 720-820 MHZ and having an isolation characteristic of -10 dB or more

First, the antenna was designed to fit 69x140x7.8mm, which is a size that can be mounted on a portable terminal that is commercially available. The FR4 epoxy with a relative dielectric constant of 4.4 was used as the dielectric. Then, the main antenna 1, the sub-antenna 2, the ground 3, and the T-shaped stub 4 are used to configure the antenna.

The design process first adjusts the length of the main antenna and the sub-antenna so that the two antennas can resonate at a wide band of 720-820 MHZ by V = F * (V = propagation speed, F = frequency, A slot or a stub may be used to improve the isolation characteristic. In the present invention, a T-shaped stub is used according to the following principle.

 The T-type stub is used to solve the interference between the SUB antenna and the main antenna, and it is a method to improve the isolation level that the signals of the main antenna and the sub antenna meet each other due to the structure using the same ground . In a typical communication, a signal is received by an antenna in the air, and its properties are changed electrically. At this time, the problem is solved by using the characteristic of the current flowing in the conductor,

For example, a lightning rod installed in an apartment is made to guide the direction of electricity to the ground. In this way, a stub is placed on the side of the ground to change the current flow. The shape of the stub is similar to that of the dipole antenna. Due to the characteristics of the current collected at the edge of the conductor, interference is reduced as the signal current of the main antenna and the sub antenna are induced to the stub. In the absence of an antenna, the electric field radiation pattern, which is an eight-figured feature of omni-directional, is a principle that can change the radiation pattern by the energy radiated from the stub.

In order to design an antenna with a long wavelength of 700 [Mhz] in a narrow space, the electric length of the inverted F antenna was made three-dimensionally to maximize it.

Therefore, the antenna is constituted by using the main antenna 1, the sub antenna 2, the ground 3, and the T-shaped stub 4. However, since the T-shaped stub 4 is added to improve the isolation degree, the bandwidth characteristic is deteriorated due to the resonance bandwidth of the antenna and the TRADE OFF relationship. Therefore, the arrangement and length parameters of the main antenna and the sub- It becomes.

A method of improving the bandwidth using a T-shaped stub that improves the isolation is that the length of the stub should be long enough not to affect the resonance frequency of the main antenna and the sub antenna, so that the length of the stub becomes excessively long, It is necessary to design the antenna so that a capacitance component is generated between the stub and the antenna and does not affect the characteristics of the antenna. A capacitive component is generated between the current carrying conductor and the conductor, which in turn affects the gain of the signal in the required frequency band. Also note that the width of the stub is less important than its length, but if it is too thick, there will be design limitations.

That is, if the signal current between the main antenna and the sub antenna is reduced by using a stub on the ground, the antenna performance of the low frequency band is increased.

Accordingly, when the parameters of the main antenna, the sub-antenna, and the T-shaped stub are adjusted according to the above-mentioned principle, the results shown in FIGS. 9 to 12 are obtained.

9, as the length of the main antenna 1 is increased, the gain and isolation of the main antenna and the sub antenna are improved, and the optimum value is obtained at 29 mm

In FIG. 10, the gain and isolation of the main antenna and the sub antenna are improved as the length of the main antenna 1 L 6 is shortened, and the optimum value is shown at 0.5 mm.

In FIG. 11, the gain and bandwidth of the main antenna and the sub antenna increase as the length of the main antenna H1 becomes longer, and the optimum value is obtained at 2 mm.

If the gain and the degree of isolation that change sensitively according to the arrangement state and the length of each shape are configured to have optimum values with the above parameters,

The main antenna 1 has a first shape L2 having a linear shape along the spatial coordinate system (X, Y, Z); A second shape portion (H1) having a right angle bent in the + Z axis along the first shape portion; A third feature L1 having a right angle bend in the + Y axis along the second feature; A fourth shape L3 having a right angle bend along the third shape along the + X axis; A fifth shape L6 having a right angle bend in the + Y axis along the fourth shape; A sixth feature L8 having a right angle bend in the + X axis along the fifth feature, a seventh feature L'1 having a right angle bend along the sixth feature in the -Y axis; An eighth feature (L'5) having a shape that is orthogonal to the + X axis along the sixth feature; A ninth feature (H'1) having a right angle bend along the -Z axis along the seventh feature; A tenth feature (L'2) having a right angle bend in the + X axis along the ninth feature; An eleventh feature (H'2) having a right angle bend in the + Z axis along the tenth feature; A twelfth feature (L'4) having a right angle bend in the + Y axis along the eleventh feature; A thirteenth feature (L'8) having a right angle bend in the + X axis along the twelfth feature; A fourteenth feature (L'9) having a right angle bend along the -X axis along the thirteenth feature; A fifteenth feature H'3 having a right angle bend along the -Z axis along the fourteenth feature; A sixteenth feature (L'10) having a right angle bend in the + Y axis along the fifteenth feature; A seventeenth feature (L'11) having a right angle bend with respect to the -Y axis along the eighth feature; An eighteenth feature H'3 having a right angle bend along the -Z axis along the seventeenth feature; And a nineteenth shape (L'12) having a right angle bent in the + Y axis along the eighteenth shape

The length of the first shape portion L2 is 13 mm and the length of the second shape portion is 2.8 mm. The length of the third shape portion L1 is 2.5 mm. The length of the fourth shape portion L3 The length of the fifth shape L6 is 5 mm. The length of the sixth shape L8 is 22 mm. The length of the seventh shape L 1 is 5.5 mm. The length of the fifth shape L 5 The length of the ninth feature H'1 is 2.8 mm, the length of the tenth feature L'2 is 3 mm, the length of the eleventh feature H'2 is 1.8 mm, The length of the twelfth shape portion L'4 is 3.5 mm, the length of the 13th shape portion L'8 is 9 mm, the length of the 14th shape portion L'9 is 2 mm, 3) is 5 mm, the length of the 16th configuration (L'10) is 4 mm, the length of the 17th configuration (L'11) is 5 mm, the length of the 18th configuration H'3 is 2 mm, 19 The length of the shaped portion (L'12) was 1.8 mm

The sub-antenna 2 is circularly symmetric with respect to the ground 3 in the same length and shape as the main antenna 1

The length of the T-shaped stub 4 is 118 mm on the Y axis and 2.2 mm on the X axis, and the Y axis length of the conductor connected to the ground is 1.4 mm.

The following describes the drawings.

Representative views are formed on a substrate having a predetermined width W and length L as a MIMO antenna apparatus according to the present invention, and the substrate may be a substrate of a mobile communication terminal, but it is obvious to a person skilled in the art .

The lengths and specific shapes of the main antenna 1, the sub-antenna 2, the ground 3, and the T-shaped stub 4 are shown.

FIG. 2 shows the 100MHZ bandwidth and the -10 dB isolation characteristic of the antenna of the present invention.

In FIG. 3, the isolation characteristics of the main and sub antennas vary according to the length adjustment of the T-stub, and the parameters of the gain value are shown, and the T-stub has an optimum value at a width of 102 mm

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. Accordingly, all such appropriate modifications and changes, and equivalents thereof, should be regarded as within the scope of the present invention.

Main antenna (1) Sub-antenna (2)
Ground (3) T-shaped stubs (4)
The first shape L2, the second shape L2,
The second shape portion H1, the third shape portion L1,
The fourth shape L3, the fifth shape L6,
Sixth feature L8, seventh feature L'1,
Eighth Configuration (L'5) The ninth configuration (H'1)
Tenth feature (L'2) The eleventh feature (H'2)
12th Configuration (L'4) 13th Configuration (L'8)
Fourteenth Shape (L'9) The fifteenth Shape (H'3)
16th feature (L'10) 17th feature (L'11)
18th Shape (H'3) 19th Shape (L'12)

Claims (1)

In a MIMO antenna device formed on a substrate,
A ground (3) formed on one surface of the substrate;
A main antenna 1 and a sub antenna 2 formed on one surface of the substrate and electrically connected to the ground to resonate at a bandwidth of 100 MHz in a gain of -10 dB or more at 720 MHZ-820 MHz, ;
A T-shaped stub 4 electrically connected to the ground and formed at one end of the ground;
The main antenna 1 has a first shape L2 having a linear shape along the spatial coordinate system X, Y, Z; A second shape portion (H1) having a right angle bent in the + Z axis along the first shape portion; A third feature L1 having a right angle bend in the + Y axis along the second feature; A fourth shape L3 having a right angle bend along the third shape along the + X axis; A fifth shape L6 having a right angle bend in the + Y axis along the fourth shape; A sixth feature L8 having a right angle bend in the + X axis along the fifth feature, a seventh feature L'1 having a right angle bend along the sixth feature in the -Y axis; An eighth feature (L'5) having a shape that is orthogonal to the + X axis along the sixth feature; A ninth feature (H'1) having a right angle bend along the -Z axis along the seventh feature; A tenth feature (L'2) having a right angle bend in the + X axis along the ninth feature; An eleventh feature (H'2) having a right angle bend in the + Z axis along the tenth feature; A twelfth feature (L'4) having a right angle bend in the + Y axis along the eleventh feature; A thirteenth feature (L'8) having a right angle bend in the + X axis along the twelfth feature; A fourteenth feature (L'9) having a right angle bend along the -X axis along the thirteenth feature; A fifteenth feature H'3 having a right angle bend along the -Z axis along the fourteenth feature; A sixteenth feature (L'10) having a right angle bend in the + Y axis along the fifteenth feature; A seventeenth feature (L'11) having a right angle bend with respect to the -Y axis along the eighth feature; An eighteenth feature H'3 having a right angle bend along the -Z axis along the seventeenth feature; And a nineteenth shape (L'12) having a right angle bent in the + Y axis along the eighteenth shape
The length of the first shape portion L2 is 13 mm and the length of the second shape portion is 2.8 mm. The length of the third shape portion L1 is 2.5 mm. The length of the fourth shape portion L3 The length of the fifth shape L6 is 5 mm. The length of the sixth shape L8 is 22 mm. The length of the seventh shape L 1 is 5.5 mm. The length of the fifth shape L 5 The length of the ninth feature H'1 is 2.8 mm, the length of the tenth feature L'2 is 3 mm, the length of the eleventh feature H'2 is 1.8 mm, The length of the twelfth shape portion L'4 is 3.5 mm, the length of the 13th shape portion L'8 is 9 mm, the length of the 14th shape portion L'9 is 2 mm, 3) is 5 mm, the length of the 16th configuration (L'10) is 4 mm, the length of the 17th configuration (L'11) is 5 mm, the length of the 18th configuration H'3 is 2 mm, 19 The length of the shaped portion (L'12) was 1.8 mm
The sub-antenna 2 is circularly symmetric with respect to the ground 3 in the same length and shape as the main antenna 1
The length of the T-shaped stub 4 is 118 mm on the Y axis and 2.2 mm on the X axis, and the Y axis length of the conductor connected to the ground is 1.4 mm;
Antenna that resonates at a bandwidth of more than 100MHZ in 720MHZ-820MHZ and satisfies the isolation characteristic of more than -10dB

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