WO2013007165A1 - Mimo antenna structure of multi-frequency band mobile phone - Google Patents

Abstract

Disclosed is a multiple input multiple output (MIMO) antenna structure of a multi-frequency band mobile phone applicable in the long term evolution (LTE) standard, including a medium substrate paved with a ground, a main antenna and a first secondary antenna, wherein the medium substrate includes a first side edge and a second side edge, the length of the first side edge being less than that of the second side edge, and the first side edge and second side edge being at a certain angle; the main antenna is arranged at the first side edge; the first secondary antenna is arranged at the second side edge and further includes: a coupling feeder line, a first feeding point and several bending branches; the coupling feeder line feeding energy to the several bending branches in a capacitive coupling manner; the first feeding point being connected to the coupling feeder line; the coupling feeder line not being in contact with the bending branches; each bending branch forms a gap with the ground and one end of each bending branch is connected to the ground; and the bending branch radiates energy in a capacitive coupling manner within a pre-determined working frequency band via the gap, and the total length of the bending branch is about one quarter of the wavelength corresponding to the central frequency of the working frequency band.

Description

 Multi-band mobile phone MIMO antenna structure

 The present invention relates to the field of mobile communications, and in particular to a multi-band mobile phone MIMO antenna structure suitable for the LTE standard. Background technique

 For the sake of understanding, we will give a definition of several common antennas:

 (1) Inductor-loaded capacitive coupling antenna: The antenna is grounded. The feeder is not directly connected to the antenna. Instead, it is fed by capacitive coupling. The length is generally less than 1/4 of the operating frequency.

 (2) Monopole antenna: The length is 1/4 wavelength of the working frequency, one end is connected to the output end of the signal, one end is open, and it needs to be suspended on the ground.

 (3) Loop antenna: The length is one wavelength of the working frequency, one end is connected to the output end of the signal, and one end is grounded.

 (4) Planar inverted F antenna (PIFA): The length is 1/4 wavelength of the working frequency, one end is connected to the signal output end and ground, and one end is open, PIFA can be placed on the ground, and the height is generally 5mm or more above the ground.

 (5) Inverted F antenna (IFA): The length is the 1/4 wavelength of the operating frequency. Similar to PIFA, one end is connected to the signal output and ground, and one end is open, but not placed on the ground, and clearance is required.

 (6) Slot antenna: It is obtained by cutting a groove on a piece of metal. The length of the groove can be 1/4 wavelength or 1/2 wavelength. The slot antenna is generally fed by a coupling feed.

 Long Term Evolution (LTE), also known as 3.9G, has a data download capability of 100 Mbps and is regarded as the mainstream technology for evolution from 3G to 4G.

As a next-generation wireless communication technology, LTE can provide faster data rates and better multimedia services. In LTE technology, Multiple-input Multiple Onput (MIMO) is the most critical technology. In order to achieve MIMO operation, two or more receiving and transmitting antennas operating at the same frequency are required. In order to achieve good performance, good isolation between these antennas is required, and there is also a low correlation coefficient between the antennas. Moreover, there are currently many standards in the world to meet different applications. These standards cover different frequency bands, and only the frequency bands covered by LTE are 700MHz up to 2690 MHz, so LTE antenna systems are required to achieve multi-band operation. In handheld devices such as cell phones, where the space is very small and the distance between the antennas is small, it is very difficult to design a MIMO antenna system that meets these requirements and has good performance.

 The invention patent of Chinese Patent Application No. 200980101818.X discloses a multi-band built-in antenna. The antenna includes: a substrate; an impedance matching/power supply unit formed on the substrate; a first radiating element combined with the impedance matching/power supply unit, and the impedance matching/power supply unit includes: having a predetermined length and grounded a first matching component connected and a second matching component having a predetermined length and disposed apart from the first matching component and electrically connected to the power supply point, and between the first matching component and the second matching component The interval changes locally. The antenna according to the present invention utilizes coupling matching in a multi-band design, thereby having the advantage of providing a multi-band internal antenna having wide-band characteristics. Although the antenna can work in multiple frequency bands, the structure is complicated and difficult to implement. Summary of the invention

 In order to overcome the deficiencies of the prior art, the present invention discloses a multi-band mobile MIMO antenna structure suitable for the LTE standard, which is designed to operate an LTE antenna system in multiple frequency bands in a narrow space such as a mobile phone. The designed antenna can operate in multiple frequency bands with good radiation performance, while achieving high isolation between antennas and low correlation coefficient.

 In accordance with one aspect of the invention, a multi-band handset MIMO antenna structure includes a ground substrate. The dielectric substrate includes a first side and a second side, wherein the length of the first side is less than the length of the second side, and the first side and the second side are at an angle. The antenna structure also includes a primary antenna and a first secondary antenna. The main antenna is placed on the first side. The first secondary antenna is disposed on the second side, and further includes a coupling feed line, a first feed point, and a plurality of bent branches. The coupled feeder feeds energy to a plurality of bent branches by capacitive coupling, and the first feed point is connected to the coupled feed line, and the coupled feed line is not in contact with the bent branch. A gap is formed between each of the bent branches and the ground, and is connected to the ground at one end. Each of the bent branches radiates energy in a coupled manner through the slit in a corresponding predetermined operating frequency band.

 Preferably, the total length of each of the bent branches is one quarter of the wavelength corresponding to the center frequency of the predetermined operating band.

Preferably, the plurality of bent branches comprise a first bent branch and a second bent branch. First bent branch A first gap is formed with the ground, and energy is radiated in the first low frequency band by the first slit, and the total length of the first bent branch is a quarter of a wavelength corresponding to a center frequency of the first low frequency band. a second gap is formed between the second bent branch and the ground, and the energy is radiated in the second low frequency band by the second slit, and the total length of the second bent branch is the center frequency of the second low frequency band corresponding to the wavelength of the quarter One.

 Preferably, the antenna structure further includes a second sub-antenna disposed on the second side of the dielectric substrate adjacent to the first sub-antenna. The second secondary antenna may be a folded metal sheet on which a corresponding second feed point is disposed.

 Preferably, the first secondary antenna further includes a lumped parameter component, and the coupled feeder is coupled to the first feed point via the lumped parameter component.

 Preferably, one end of the first bent branch is connected to the ground, and extends in the opposite direction of the end, extending to the second side of the dielectric substrate and then extending to the right for a distance. In addition, one end of the second bent branch is connected to the ground and extends in the opposite direction of the end, extends to the second side of the dielectric substrate, and then extends upward, extending upward by a distance and extending to the right for a distance. Wherein the first bent branch is disposed in the second slit of the second bent branch.

 Preferably, the first low frequency band is 791-821 MHz and the second low frequency band is 925-960 MHz.

 Preferably, the operating frequency of the second sub-antenna covers a high frequency band, and the coverage frequency band is

 1805-2170MHZ, and the total length of the second antenna is one quarter of the wavelength corresponding to the center frequency of the coverage band.

 Preferably, the plurality of bent branches comprise a first bent branch and a second bent branch. a first gap is formed between the first bent branch and the ground, and the first bent branch radiates energy in the first working frequency band through the first slit, and the first working frequency band is the first low frequency band or the first high frequency band; The total length of the folded branches is approximately one quarter of the wavelength corresponding to the center frequency of the first operating band. A second gap is formed between the second bent branch and the ground, and the second bent branch radiates energy in the second working frequency band through the second slit. The second working frequency band is the second low frequency band or the second high frequency band; the total length of the second bending branch is about one quarter of the wavelength corresponding to the center frequency of the second working frequency band.

Preferably, the first secondary antenna further includes a lumped capacitor, a first folded metal piece and a second folded metal piece. One end of the lumped capacitor is connected to the first feed point, and the other end is connected to the first end of the first folded metal piece. The second end of the first folded metal piece is opposite to one end of the second folded metal piece, and the other end of the second folded metal piece is connected to the ground. The first folded metal sheet radiates energy in a third high frequency band, and the second folded metal sheet radiates energy in a fourth high frequency band by coupling with the first folded metal sheet. Where the first fold The metal piece is about a quarter of the wavelength corresponding to the center frequency of the third high frequency band, and the second folded metal piece is about a quarter of the wavelength corresponding to the center frequency of the fourth high frequency band.

 Preferably, one end of the first bent branch is connected to the ground, and extends in the opposite direction of the end, extending to the second side of the dielectric substrate and then extending to the right for a distance. In addition, one end of the second bent branch is connected to the ground and extends in the opposite direction of the end, extends to the second side of the dielectric substrate, and then extends upward, extending upward by a distance and extending to the right for a distance. Wherein the first bent branch is disposed in the second slit of the second bent branch.

 Preferably, the first low frequency band is 734-749 MHz; the first high frequency band is 2000-2300 MHz; the second low frequency band is 869-894 MHz; and the second high frequency band is 2300-2600 MHz.

 Preferably, the third high frequency band is 1710-2000 MHz; the fourth high frequency band is 2600-2800 MHz. Preferably, the operating frequency band of the main antenna covers 698-960 MHz and 1710-2690 MHz.

 Preferably, the main antenna is one of the following: an inductively loaded capacitive coupled antenna, a monopole antenna, a loop antenna, an IFA antenna, a PIFA antenna, and a slot antenna.

 Compared with the prior art, the antenna structure proposed by the present invention has the following advantages:

 First: The prior art only involves how to achieve high isolation and low correlation coefficient between antennas in a narrow frequency band, and the antenna structure proposed by the present invention can achieve high isolation and low correlation in multiple frequency bands and wide frequency bands. Coefficient of coefficient.

 Second: Previous technologies tend to be more complex and require the introduction of multiple additional components, thus increasing the complexity of the design and reducing the performance of the antenna. However, the antenna structure proposed by the present invention does not require any additional components, has a simple structure, and does not introduce other additional losses.

 Third: Previous technologies tend to occupy a large area and are not suitable for small handheld mobile terminal devices such as low frequency bands and mobile phones. However, the antenna structure proposed by the present invention has a small footprint and can be integrated into a small handheld terminal device such as a mobile phone, and the working frequency band can include a low frequency band such as LTE700. BRIEF abstract

 Features and capabilities of the present invention are further described by the following examples and the accompanying drawings.

 1 is a schematic diagram of a multi-band mobile phone MIMO antenna structure suitable for the LTE standard according to Embodiment 1 of the present invention;

2 is an enlarged view of a main antenna according to Embodiment 1 of the present invention; 3 is an enlarged view of a first sub-antenna according to Embodiment 1 of the present invention;

 4 is an enlarged view of a second sub-antenna of Embodiment 1 of the present invention;

 5 is a measurement diagram of reflection coefficient and isolation of a main antenna and a first sub-antenna according to Embodiment 1 of the present invention; FIG. 6 is a measurement diagram of reflection coefficient and isolation of a main antenna and a second sub-antenna according to Embodiment 1 of the present invention; FIG. 8 is a measurement diagram of a reflection coefficient and an isolation degree of a first sub-antenna and a second sub-antenna according to Embodiment 1 of the present invention; FIG.

 9 is a measurement diagram of total radiation efficiency of a main antenna and a second sub-antenna according to Embodiment 1 of the present invention; FIG. 10 is an analysis diagram of an envelope correlation coefficient of a main antenna and a first sub-antenna in a low frequency band according to Embodiment 1 of the present invention;

 11 is an analysis diagram of an envelope correlation coefficient of a main antenna and a second sub-antenna in a high frequency band according to Embodiment 1 of the present invention;

 12 is a schematic diagram of a multi-band mobile phone MIMO antenna structure suitable for the LTE standard according to Embodiment 2 of the present invention;

 Figure 13 is an enlarged view of a first sub-antenna according to Embodiment 2 of the present invention;

 14 is a measurement diagram of reflection coefficient and isolation of a main antenna and a first sub-antenna according to Embodiment 2 of the present invention; FIG. 15 is a measurement diagram of total radiation efficiency of a main antenna and a first sub-antenna in a low frequency band according to Embodiment 2 of the present invention;

 16 is a measurement diagram of total radiation efficiency of a main antenna and a first sub-antenna in a high frequency band according to Embodiment 2 of the present invention;

 17 is an analysis diagram of an envelope correlation coefficient of a main antenna and a first sub-antenna in a low frequency band according to Embodiment 2 of the present invention;

 18 is an analysis diagram of an envelope correlation coefficient of a main antenna and a first sub-antenna in a high frequency band according to Embodiment 2 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

In summary, embodiments of the present invention provide a multi-band mobile phone MIMO antenna structure suitable for the LTE standard, including a ground substrate. The dielectric substrate includes a first side and a second side, and the length of the first side is smaller than the length of the second side, and the first side and the second side are at an angle Degree. The antenna structure further includes a primary antenna and a first secondary antenna. The main antenna is placed on the first side. The first secondary antenna is disposed on the second side, and further includes a coupling feed line, a first feed point, and a plurality of bent branches. The coupled feed line feeds energy to a plurality of bent branches by capacitive coupling, the first feed point is connected to the coupled feed line, and the coupled feed line is not in contact with the bent branch. A gap is formed between each of the bent branches and the ground, and is connected to the ground at one end thereof. Each of the bent branches radiates energy in a capacitive coupling manner in the corresponding predetermined operating frequency band through the aforementioned slit.

 The present invention is further described below in conjunction with the drawings and specific embodiments:

 Example 1

 As shown in FIG. 1 to FIG. 4, a multi-band mobile phone MIMO antenna structure 100 suitable for the LTE standard includes a dielectric substrate 1 1 on which a ground 12 is laid, a main antenna 13, a first sub-antenna 14 and a second sub-antenna 15. The first secondary antenna 14 is a low frequency diversity antenna that covers two low frequency operating bands. The second sub antenna 15 is a high frequency diversity antenna.

 The dielectric substrate 1 1 includes a first side 11 1 and a second side 112, and the length of the first side 11 1 is smaller than the length of the second side 112, between the first side 11 1 and the second side 112 At a certain angle. For example, in the present embodiment, the first side edge 11 1 and the second side edge 112 are at an angle of 90 degrees.

 The main antenna 13 is disposed on the first side 11 1 . The main antenna's operating frequency band can cover 698-960MHZ and 1710-2690MHz. In this embodiment, the main antenna 13 is an inductively loaded capacitive coupled antenna. Here, for example only, the main antenna 13 may also be a monopole antenna, a loop antenna, an IFA antenna, a PIFA antenna, a slot antenna, or the like.

 Referring to Fig. 2, the main antenna 13 includes a radiating sheet 13 1 , a ground line 132 , a capacitive coupling feed line 133 , and a main antenna feed point 134 . The radiation piece 13 1 is connected to one end of the ground line 132, and the other end of the ground line 132 is connected to the ground 12; the capacitive coupling feed line 133 is not in contact with the radiation piece 13 1 and the ground line 132, and is connected to the main antenna feeding point 134. . Energy is input from the main antenna feed point 134 to the main antenna 13, i.e., the main antenna feed point 134 is the energy input point of the main antenna 13.

Referring to FIG. 3, the first secondary antenna 14 is disposed on the second side 112, which further includes: a coupling feed line 143, a first feed point 145, and a plurality of bent branches. The coupled feed line 143 feeds energy to the bent branch by capacitive coupling; the first feed point 145 is coupled to the coupled feed line 143. A gap is formed between each of the bent branches and the ground 12, and one end thereof is connected to the ground 12. The bent branch radiates energy by capacitive coupling in a certain working frequency band through the slit, and the total length of the bent branch The degree is approximately one quarter of the wavelength corresponding to the center frequency of the operating band. The center frequency of the operating band is obtained by summing the two endpoints of the operating band and dividing by two.

 The coupled feed line 143 is non-contact with the bent branch, and energy is input from the first feed point 145 to the first secondary antenna 14, i.e., the first feed point 145 is the energy input point of the first secondary antenna 14.

 The first secondary antenna 14 also includes a lumped parameter component through which the coupled feed 13 is coupled to the first feed point 145. In this embodiment, the lumped parameter component is a lumped inductor 144, which is merely an example. In the specific implementation, the lumped inductance here may be eliminated or other lumped parameter components may be added to improve the antenna characteristics.

 In the present embodiment, the plurality of bent branches include a first bent branch 141 and a second bent branch 142. For example only, the number of bent branches is not limited in specific implementation. The operator can change the number of operating bands of the antenna structure of the present invention by varying the number of bent branches that can form a gap with the ground. Therefore, the embodiment is merely an example and is not limited thereto.

 A first slit 101 is formed between the first bent branch 141 and the ground, and the first bent branch 141 radiates energy in the first low frequency band through the first slit 101; the total length of the first bent branch 141 is about the first low The center frequency of the band corresponds to a quarter of the wavelength.

 A second slit 102 is formed between the second bent branch 142 and the ground, and the second bent branch 142 radiates energy in the second low frequency band through the second slit 102; the total length of the second bent branch 142 is about the second lowest The center frequency of the band corresponds to a quarter of the wavelength.

 The first bent branch 141 has an inverted L shape, one end of which is connected to the ground 12, and extends in the opposite direction along the end, extending all the way to the second side 112 and then extending a distance to the right.

 One end of the second bent branch 142 is connected to the ground 12 and extends in the opposite direction of the end, extending to the second side 112 and then extending upward, extending a certain distance upward and extending to the right for a distance.

 The first bent branch 141 is disposed in the second slit 102 of the second bent branch 142.

In this embodiment, the first low frequency band is 791-821 MHz, and the second low frequency band is 925-960 MHz. Referring to FIG. 4, the second sub-antenna 15 is disposed on the second side 1 12 of the dielectric substrate 11 adjacent to the first sub-antenna 14. The second sub-antenna 15 is a folded metal piece having a three-dimensional zigzag structure on which a corresponding second feed point 151 is disposed. The operating frequency of the second sub-antenna 15 covers the high frequency band, and the coverage frequency band is 1805-2170 MHz, and the total length of the second sub-antenna 15 is one quarter of the wavelength corresponding to the center frequency of the coverage band. FIG. 5 is a measurement diagram of reflection coefficient and isolation of a main antenna and a first sub-antenna according to Embodiment 1 of the present invention. In this measurement, the primary antenna 13 and the first secondary antenna 14 are connected to the instrument output and the second secondary antenna 15 is connected to a 50 ohm load. Wherein the curve FS 11 represents the return loss of the main antenna 13 over the entire frequency band, the curve FS22 represents the return loss of the first sub-antenna 14 over the entire frequency band, and the curve FS21 represents the coupling between the main antenna 13 and the first sub-antenna 14 Happening. The curve FS21 is less than -15 dB in the low frequency band, indicating that there is a fairly good isolation between the main antenna 13 and the first sub-antenna 14.

 Fig. 6 is a graph showing measurement results of reflection coefficient and isolation of a main antenna and a second sub-antenna according to Embodiment 1 of the present invention. In this measurement, the primary antenna 13 and the second secondary antenna 15 are connected to the instrument output and the first secondary antenna 14 is connected to a 50 ohm load. Wherein the curve FS 11 represents the return loss of the main antenna 13 over the entire frequency band, the curve FS33 represents the return loss of the second sub-antenna 15 over the entire frequency band, and the curve FS31 represents the coupling between the main antenna 13 and the second sub-antenna 15 Happening. The curve FS31 is less than -12dB in the low frequency band, indicating that there is sufficient isolation between the main antenna 13 and the second sub-antenna 15.

 Figure 7 is a graph showing reflection coefficient and isolation of a first sub-antenna and a second sub-antenna according to Embodiment 1 of the present invention. In this measurement, the first sub-antenna 14 and the second sub-antenna 15 are connected to the instrument output and the main antenna 13 is connected to a 50 ohm load. The curve FS22 represents the return loss of the first sub-antenna 14 over the entire frequency band, the curve FS33 represents the return loss of the second sub-antenna 15 over the entire frequency band, and the curve FS32 represents the first sub-antenna 14 and the second sub-antenna 15 The coupling between the two. The curve FS32 is less than -20 dB in the low frequency band, indicating that there is considerable isolation between the first secondary antenna 14 and the second secondary antenna 15.

 Figure 8 is a graph showing the measurement of the total radiation efficiency of the main antenna and the first sub-antenna according to Embodiment 1 of the present invention. FRL1 represents the total radiation efficiency of the main antenna 13 at the low frequency band. FRL2 represents the total radiation efficiency of the first secondary antenna 14 at the low frequency band. As can be seen from Fig. 8, the main antenna 13 and the first sub-antenna 14 have good radiation performance in the designed frequency band.

 Figure 9 is a graph showing the measurement of the total radiation efficiency of the main antenna and the second sub-antenna according to Embodiment 1 of the present invention. FRH1 represents the total radiation efficiency of the main antenna 13 at the high frequency band. FRH2 represents the total radiation efficiency of the second secondary antenna 15 at the high frequency band. As can be seen from Figure 9, the main antenna 13 and the second sub-antenna 15 have good radiation performance in the designed frequency band.

10 is an analysis diagram of an envelope correlation coefficient of a main antenna and a first sub-antenna in a low frequency band according to Embodiment 1 of the present invention, which represents independence between a low-frequency main antenna 13 and a first sub-antenna 14. FCL1 is set to 0.5 in XPR (cross-polarization discrimination) and uni (azimuth) distribution file is selected as uniform Distribution, theta (pitch angle) distribution file is selected for normal distribution calculation. FCL2 is calculated when the XPR value is set to 0.5, the phi distribution file is selected as the uniform distribution, and the theta distribution file is selected as the uniform distribution. FCL3 is calculated when the XPR value is set to 1, the phi distribution file is selected as the uniform distribution, and the theta distribution file is selected as the normal distribution. FCL4 is calculated when the XPR value is set to 1, the phi distribution file is selected as the uniform distribution, and the theta distribution file is selected as the uniform distribution. It can be seen from the figure that the calculated envelope correlation coefficient is less than 0.3 in the frequency band where the two antennas overlap, indicating that the main antenna 13 and the first sub-antenna 14 have good independence in the low frequency band.

 11 is an analysis diagram of an envelope correlation coefficient of a main antenna and a second sub-antenna in a high frequency band according to Embodiment 1 of the present invention, which is an envelope correlation coefficient analysis diagram of the first structure proposed by the present invention, which is represented by The independence between the high-band main antenna 13 and the second sub-antenna 15. FCH1 is calculated by setting the XPR value to 0.5, selecting the phi distribution file as the uniform distribution, and selecting the theta distribution file as the normal distribution. FCH2 is calculated with the XPR value set to 0.5, the phi distribution file selected as the uniform distribution, and the theta distribution file selected as the uniform distribution. FCH3 is calculated by setting the XPR value to l, the phi distribution file to be uniform, and the theta distribution file to normal distribution. FCH4 is calculated by setting the XPR value to l, selecting the phi distribution file as the uniform distribution, and the theta distribution file as the uniform distribution. It can be seen from the figure that the calculated envelope correlation coefficient is less than 0.3 in the frequency band where the two antennas coincide, indicating that the primary antenna 13 and the second secondary antenna 15 have good independence in the high frequency band. Example 2

 As shown in FIG. 12, a multi-band mobile phone MIMO antenna structure 100 suitable for the LTE standard includes a dielectric substrate 11 on which a ground 12 is laid, a main antenna 13, and a first sub-antenna 24.

 The dielectric substrate 1 1 includes a first side 11 1 and a second side 112, and the length of the first side 11 1 is smaller than the length of the second side 112, between the first side 11 1 and the second side 112 At a certain angle. In the present embodiment, the first side 1 11 and the second side 112 are at an angle of 90 degrees.

The main antenna 13 is disposed on the first side 11 1 . The main antenna's operating frequency band can cover 698-960MHZ and 1710-2690MHz. In this embodiment, the main antenna 13 is an inductively loaded capacitive coupled antenna. Here, for example only, the main antenna 13 may also be a monopole antenna, a loop antenna, an IFA antenna, a PIFA antenna, a slot antenna, or the like. The main antenna 13 includes a radiating sheet 131, a ground line 132, a capacitive coupling feed line 133, and a main antenna feed point 134. The radiation piece 131 is connected to the grounding wire 132 end, and the other end of the grounding wire 132 is connected to the ground 12; the capacitive coupling feeding wire 133 is not in contact with the radiation piece 13 1 and the grounding wire 132, and is connected to the main antenna feeding point 134. Energy is input from the primary antenna feed point 134 to the primary antenna 13, i.e., the primary antenna feed point 134 is the energy input point of the primary antenna 13.

 Referring to Figure 13, a first secondary antenna 24 is disposed on the second side 112, which further includes: a coupling feed 243, a first feed point 245, and a plurality of bent branches. The coupled feed line 243 feeds energy to the bent branch by capacitive coupling; the first feed point 245 is coupled to the coupled feed line 243. A slit is formed between each of the bent branches and the ground 12, and one end thereof is connected to the ground 12; the bent branch radiates energy by coupling in a certain working frequency band, and the total length of the bent branch is about The center frequency of the operating band corresponds to a quarter of the wavelength. The center frequency of the operating band is obtained by summing the two endpoints of the working band and dividing by two.

 The coupled feed line 243 is not in contact with the bent branch, and energy is input from the first feed point 245 to the first secondary antenna 24, i.e., the first feed point 245 is the energy input point of the first secondary antenna 24.

 In Fig. 13, the coupled feed line 13 is directly connected to the first feed point 245. In a specific implementation, the coupling feeder 13 can also be connected to the first feeding point 245 through a lumped parameter element, which can change the antenna performance of the antenna structure of the embodiment.

 In this embodiment, the plurality of bent branches include the first bent branch 241 and the second bent branch.

242.

The first bending branch 241 forms a first gap 201 with the ground 12, and the first bending branch 241 radiates energy in the first working frequency band through the first slot 201; the first working frequency band is the first low frequency band or the first High frequency band; the total length of the first bending branch is about one quarter of the wavelength corresponding to the center frequency of the first working frequency band. In this embodiment, the first low frequency band is 734-749 MHz; the first high frequency band is

第一弯折分支 241呈倒 L型， 其一端与地面 12连接， 且其沿着该端反方 向延伸， 一直延伸到第二侧边 112后再向右延伸一段距离。 A second slit 202 is formed between the second bent branch 242 and the ground 12, and the second bent branch 242 radiates energy in the second working frequency band through the second slit 202; the second working frequency band is the second low frequency band or the second High frequency band; the total length of the second bending branch is about one quarter of the wavelength corresponding to the center frequency of the second working frequency band. In this embodiment, the second low frequency band is 869-894 MHz; the second high frequency band is

The first bent branch 241 has an inverted L shape, one end of which is connected to the ground 12, and extends in the opposite direction of the end, extending to the second side 112 and then extending to the right for a distance.

 One end of the second bent branch 242 is connected to the ground 12 and extends in the opposite direction of the end, extending to the second side 112 and then extending upward, extending a certain distance upward and extending to the right for a distance.

 The first bent branch 241 is disposed in the second slit 202 of the second bent branch 242.

 The first sub-antenna 24 further includes a lumped capacitor 246 and a first folded metal piece 247 and a second folded metal piece 248; the lumped capacitor 246-end is connected to the first feed point 245, and the other end is connected to the first folded metal The first end of the sheet 247 is joined; the second end of the first folded metal piece 247 is opposite the one end of the second folded metal piece 248, and the other end of the second folded metal piece 248 is connected to the ground 12.

 The first folded metal piece 247 radiates energy in a third high frequency band; the second folded metal piece 248 radiates energy in a fourth high frequency band by coupling with the first folded metal piece 247; wherein, the first folded metal piece 247 The length of the second high frequency band is about one quarter of the wavelength corresponding to the center frequency of the third high frequency band, and the length of the second folded metal piece 248 is about one quarter of the wavelength corresponding to the center frequency of the fourth high frequency band. In this embodiment, the third high frequency band is 1710-2000 MHz; the fourth high frequency band is 2600-2800 MHz.

 Compared with the first embodiment, the second sub-antenna of the embodiment 2 only needs one input port to cover the low frequency and the high frequency band, which greatly simplifies the design of the subsequent circuit.

 Figure 14 is a graph showing measurement of reflection coefficient and isolation of a main antenna and a first sub-antenna according to Embodiment 2 of the present invention. In this measurement, the main antenna 13 and the first sub-antenna 24 are connected to the instrument output. Wherein the curve SS 1 1 represents the return loss of the main antenna 13 over the entire frequency band, the curve SS22 represents the return loss of the first sub-antenna 24 over the entire frequency band, and the curve SS21 represents the relationship between the main antenna 13 and the first sub-antenna 24 Coupling situation. The curve SS21 is less than -15dB in the low frequency band and less than -10dB in the high frequency band, indicating that the main antenna 13 and the first secondary antenna 24 have a fairly good isolation.

 Figure 15 is a graph showing the measurement of the total radiation efficiency of the main antenna and the first sub-antenna in the low frequency band according to the second embodiment of the present invention. SRL1 represents the total radiation efficiency of the main antenna 13 at the low frequency band. SRL2 represents the total radiation efficiency of the first secondary antenna 24 at the low frequency band. As can be seen from Fig. 15, the main antenna 13 and the first sub-antenna 24 have good radiation performance in the designed frequency band.

16 is a graph showing total radiation efficiency measurement of a main antenna and a first sub-antenna in a high frequency band according to Embodiment 2 of the present invention. SRH1 represents the total radiation efficiency of the main antenna 13 at a high frequency band. SRH2 represents the total radiation efficiency of the secondary antenna 24 at the high frequency band. As can be seen from Fig. 16, the main antenna 13 and the first sub-antenna 24 are in a very Good radiation performance in a wide frequency band.

 Figure 17 is a diagram showing an envelope correlation coefficient analysis of a main antenna and a first sub-antenna at a low frequency band according to Embodiment 2 of the present invention, which represents independence between the low-frequency main antenna 13 and the first sub-antenna 24. SCL1 is calculated by setting the XPR value to 0.5, the phi distribution file to be uniform, and the theta distribution file to normal distribution. SCL2 is calculated with the XPR value set to 0.5, the phi distribution file selected as the uniform distribution, and the theta distribution file selected as the uniform distribution. SCL3 is calculated by setting the XPR value to l, the phi distribution file to be uniform, and the theta distribution file to normal distribution. SCL4 is calculated by setting the XPR value to l, the phi distribution file to be uniform, and the theta distribution file to be uniform distribution. It can be seen from the figure that the calculated envelope correlation coefficient is less than 0.3 in the frequency band where the two antennas coincide, indicating that the main antenna 23 and the first sub-antenna 24 have good independence in the low frequency band.

 Figure 18 is a diagram showing an envelope correlation coefficient analysis of a main antenna and a first sub-antenna at a high frequency band according to Embodiment 2 of the present invention, which represents independence between a high-frequency main antenna 13 and a first sub-antenna 24. SCH1 is calculated by setting the XPR value to 0.5, the phi distribution file to be uniform, and the theta distribution file to be normal distribution. SCH2 is calculated with the XPR value set to 0.5, the phi distribution file selected as the uniform distribution, and the theta distribution file selected as the uniform distribution. SCH3 is calculated by setting the XPR value to l, the phi distribution file to be uniform, and the theta distribution file to normal distribution. SCH4 is calculated by setting the XPR value to l, the phi distribution file to be uniform, and the theta distribution file to be uniform distribution. It can be seen from the figure that the calculated envelope correlation coefficient is less than 0.3 in the frequency band where the two antennas overlap, indicating that the main antenna 13 and the first sub-antenna 24 have good independence in the high frequency band.

 Compared with the prior art, the antenna structure proposed by the embodiment of the present invention has the following advantages: First: The prior art only relates to how to achieve high isolation between antennas and low correlation coefficient in a narrow frequency band, and the present invention The proposed antenna structure can achieve high isolation and low correlation coefficients in multiple frequency bands and wide frequency bands.

 Second: Previous technologies tend to be more complex and require the introduction of multiple additional components, thus increasing the complexity of the design and reducing the performance of the antenna. However, the antenna structure proposed by the present invention does not require any additional components, has a simple structure, and does not introduce other additional losses.

Third: The previous technology often occupies a large area and is not suitable for small cells such as low frequency bands and mobile phones. Handheld on a mobile terminal device. However, the antenna structure proposed by the present invention has a small footprint and can be integrated into a small handheld terminal device such as a mobile phone, and the working frequency band can include a low frequency band such as LTE700.

 Fourth: The low correlation coefficient is obtained due to the significant difference (close to orthogonal) of the radiation pattern between the inventive diversity antenna and the conventional main antenna. This is very difficult to implement for other known diversity antenna solutions, especially at low frequencies below 1 GHz.

 Fifth: The diversity antenna scheme of the embodiment of the present invention can also be implemented without any headroom, and the diversity antenna can also be placed on the upper portion of the PCB.

 Sixth: The diversity antenna of the embodiment of the present invention can be manufactured by various manufacturing methods such as LDS, flexible board, metal sheet, MID technology.

 The preferred embodiments of the invention are only intended to aid in the description of the invention. The preferred embodiments are not intended to be exhaustive or to limit the details. Obviously, many modifications and variations are possible in light of the teachings herein. The present invention has been chosen and described in detail to explain the principles and embodiments of the present invention, so that those skilled in the art can. The invention is to be limited only by the scope of the appended claims and the appended claims.

Claims

Rights request A multi-band mobile phone multi-input multi-output antenna structure, comprising a dielectric substrate on which a ground is disposed, the dielectric substrate comprising a first side and a second side, and the length of the first side is smaller than that of the second side The length, the first side and the second side are at an angle; wherein the antenna structure further includes: a main antenna, the main antenna is disposed on the first side;  a first secondary antenna, the first secondary antenna being disposed on the second side, further comprising a coupling feed line, a first feed point, and a plurality of bent branches, the coupled feed line coupling energy by capacitive coupling Feeding the plurality of bending branches; the first feeding point is connected to the coupling feed line, and the coupling feed line is non-contact with the plurality of bending branches;  Forming a gap between each of the bent branches and the ground and connecting to the ground at one end, each of the bent branches radiating energy through the gap in a corresponding predetermined operating frequency band by capacitive coupling .  2. The multi-band mobile phone multiple input multiple output antenna structure according to claim 1, wherein a total length of each of the bent branches is one quarter of a wavelength corresponding to a center frequency of the predetermined operating frequency band.  3. The multi-band mobile phone multiple input multiple output antenna structure according to claim 1, wherein the plurality of bending branches comprise a first bending branch and a second bending branch;  Forming a first gap between the first bending branch and the ground, and radiating energy in the first low frequency band by the first slot, the total length of the first bending branch is the first low The center frequency of the frequency band corresponds to one quarter of the wavelength;  Forming a second gap between the second bent branch and the ground, and radiating energy in the second low frequency band by the second slit, the total length of the second bent branch being the second low The center frequency of the band corresponds to a quarter of the wavelength.  The multi-band mobile phone multiple-input multiple-output antenna structure according to claim 3, wherein the antenna structure further includes a second sub-antenna, and the second sub-antenna is disposed on a second side of the dielectric substrate And adjacent to the first sub-antenna, the second sub-antenna is a folded metal piece, and a corresponding second feeding point is disposed thereon. 5. The multi-band mobile phone multiple input multiple output antenna structure according to claim 1, characterized in that The first secondary antenna further includes a lumped parameter component, and the coupled feeder is connected to the first feed point by the lumped parameter component.  6. The multi-band mobile phone multiple input multiple output antenna structure according to claim 3, wherein:  One end of the first bending branch is connected to the ground and extends in the opposite direction of the end, extending to the second side of the dielectric substrate and then extending to the right for a distance;  One end of the second bent branch is connected to the ground and extends in the opposite direction of the end, extends to the second side of the dielectric substrate, and then extends upward, extending upward by a distance and extending to the right by a distance ;  The first bent branch is disposed in the second slit.  7. The multi-band mobile phone multiple input multiple output antenna structure according to claim 3, wherein the first low frequency band is 791-821 MHz, and the second low frequency band is 925-960 MHz.  The multi-band mobile phone multiple-input multiple-output antenna structure according to claim 4, wherein the operating frequency of the second sub-antenna covers a frequency band of 1805-2170 MHz, and the total length of the second sub-antenna is The center frequency of the coverage band corresponds to one quarter of the wavelength.  9. The multi-band mobile phone multiple input multiple output antenna structure according to claim 1, wherein the plurality of bent branches comprise a first bent branch and a second bent branch;  Forming a first gap between the first bending branch and the ground, and radiating energy in the first working frequency band by using the first slot; the first working frequency band is a first low frequency band or a first high frequency band; The total length of the first bending branch is about a quarter of the wavelength corresponding to the center frequency of the first working frequency band, and the second bending branch forms a second gap between the second bending branch and the ground, and The second slot transmits energy in the second working frequency band; the second working frequency band is the second low frequency band or the second high frequency band; the total length of the second bending branch is about the wavelength corresponding to the center frequency of the second working frequency band One quarter of the. The multi-band mobile phone multiple input multiple output antenna structure according to claim 9, wherein the first secondary antenna further comprises a lumped capacitor, a first folded metal piece and a second folded metal piece; One end of the total capacitor is connected to the first feed point, and the other end is connected to the first end of the first folded metal piece; the second end of the first folded metal piece and one end of the second folded metal piece Relatively, and The other end of the second folded metal piece is connected to the ground;  The first folded metal sheet radiates energy in a third high frequency band, and the second folded metal sheet radiates energy in a fourth high frequency band by coupling with the first folded metal sheet; wherein The length of the folded metal piece is about one quarter of the wavelength corresponding to the center frequency of the third high frequency band, and the length of the second folded metal piece is about one quarter of the wavelength corresponding to the center frequency of the fourth high frequency band.  11. The multi-band mobile phone multiple input multiple output antenna structure according to claim 9, wherein:  One end of the first bending branch is connected to the ground and extends in the opposite direction of the end, extending to the second side of the dielectric substrate and then extending to the right for a distance;  One end of the second bent branch is connected to the ground and extends in the opposite direction of the end, extends to the second side of the dielectric substrate, and then extends upward, extending upward by a distance and extending to the right by a distance ;  The first bent branch is disposed in the second slit.  12. The multi-band mobile phone multiple input multiple output antenna structure according to claim 9, wherein:  The first low frequency band is 734-749 MHz; the first high frequency band is 2000-2300 MHz; the second low frequency band is 869-894 MHz; and the second high frequency band is 2300-2600 MHz.  13. The multi-band mobile phone multiple input multiple output antenna structure according to claim 10, wherein: the third high frequency band is 1710-2000 MHz; and the fourth high frequency band is 2600-2800 MHz.  14. The multi-band mobile phone multiple input multiple output antenna structure according to claim 1, wherein the working frequency band of the main antenna covers 698-960 MHz and 1710-2690 MHz.  The multi-band mobile phone multiple-input multiple-output antenna structure according to claim 2, wherein the main antenna is one of the following: an inductor-loaded capacitive coupling antenna, a monopole antenna, a loop antenna, and an inverted-F antenna , planar inverted F antenna, and slot antenna.