[0037] The present invention will be further described in detail below in conjunction with the drawings. Since the present invention has two antenna units, namely the first antenna unit 15a and the second antenna unit 15b; two isolation slots, namely the first isolation slot 17a and the second isolation slot 17b; and the two C-like radiating units are the first type C The first type of C-shaped radiating element 18a and the second type of C-shaped radiating element 18b include a first branch 181a, a second branch 182a, a third branch 183a, and a fourth branch 184a. The C-like radiating element 18b further includes a first branch 181b, a second branch 182b, a third branch 183b and a fourth branch 184b; two inverted L-shaped radiating elements, namely the first inverted L-shaped radiating element 19a and the second inverted L-shaped radiating unit 19b, and the first inverted L-shaped radiating unit 19a includes horizontal stubs 191a and vertical stubs 192a, and the second inverted L-shaped radiating unit 19b includes horizontal stubs 191b and vertical stubs 192b; 2 microstrip feeders are The first microstrip feeder 20a and the second microstrip feeder 20b. In order to uniformly describe 2 antenna elements, 2 isolation slots, 2 C-like radiating elements and the first branch, second branch, third branch and fourth branch of the structure, 2 inverted L-shaped radiation In the case of the unit and the horizontal branches and vertical branches that make up its structure, as well as two microstrip feeders, in order to simplify the reference numbers of the above technical features, although the drawings do not clearly indicate 15, 17, 18, 181, 182, 183 , 184, 19, 191, 192 and 20 are the specific positions of the 11 reference signs, but they indicate that 15 is the unified representation of the antenna unit; 17 is the unified representation of the isolation slot; 18 is the unified representation of the C-like radiating unit Representation, of which 181, 182, 183 and 184 are the unified representations of the first, second, third and fourth branches respectively; 19 is the unified representation of the inverted L-shaped radiating element, of which 191 and 192 are respectively It is the unified representation of the horizontal and vertical branches; 20 is the unified representation of the microstrip feeder.
[0038] See figure 1 , A dual-unit MIMO array antenna with high isolation, including a dielectric substrate 11. In a preferred embodiment of the present invention, the dielectric substrate 11 is square or rectangular. The dielectric substrate 11 has two surfaces, namely a front surface 12 and a back surface 13, such as figure 2 Shown. among them:
[0039] The front side 12 of the dielectric substrate 11 is as image 3 As shown, a floor 14, an additional floor unit 16, two C-like radiating units 18, and two isolation grooves 17 opened on the floor 14 are printed.
[0040] The additional floor unit 16 is T-shaped as a whole, that is, the additional floor unit 16 is mainly composed of a left arm branch 161, a center branch 162 and a right arm branch 163. The left arm stub 161, the right arm stub 163 and the center stub 162 are arranged along the vertical direction of the dielectric substrate 11, wherein the ends of the left arm stub 161 and the right arm stub 163 are respectively bent downward by 90° and meet the upper end of the center stub 162. The left arm branch 161 and the right arm branch 163 are symmetrical with the central branch 162 as the symmetry line.
[0041] The isolation groove 17, that is, the first isolation groove 17a and the second isolation groove 17b are all in an inverted S shape or step shape as a whole, that is, the first end of the isolation groove 17 arranged along the horizontal direction of the dielectric substrate 11 is bent upward by 90°, and the end is bent downward Fold 90°.
[0042] The C-shaped radiating element 18, that is, the first C-shaped radiating element 18a and the second C-shaped radiating element 18b are all C-shaped as a whole, that is, the C-shaped radiating element 18 is mainly composed of the first branch 181 that is connected end to end in sequence. , The second branch 182, the third branch 183 and the fourth branch 184 constitute. That is, the end of the first branch 181 is connected to the head of the second branch 182, the end of the second branch 182 is connected to the head of the third branch 183, and the end of the third branch 183 is connected to the end of the fourth branch 184. The head end is connected. The first branch 181 and the third branch 183 are parallel to each other and are arranged along the horizontal direction of the dielectric substrate 11. The second branch 182 and the fourth branch 184 are parallel to each other and are arranged along the vertical direction of the dielectric substrate 11. The first branch 181 and the third branch 183 are perpendicular to the second branch 182 and the fourth branch 184, respectively.
[0043] The floor 14 is located below the front surface 12 of the dielectric substrate 11. The additional floor unit 16 and the two C-like radiation units 18 are both located on the upper part of the front surface 12 of the dielectric substrate 11. The additional floor unit 16 is located on the vertical axis of the dielectric substrate 11, and the center line of the central branch 162 of the additional floor unit 16 coincides with the vertical axis of the dielectric substrate 11. One end of each C-like radiating element 18 is the head end of the first branch 181 open, and the other end, the end of the fourth branch 184, is connected to the upper edge of the floor 14. The two C-like radiating units 18 are located on the left and right sides of the additional floor unit 16 and are mirror-symmetrical along the vertical axis of the dielectric substrate 11. In a preferred embodiment of the present invention, the upper edges of the first branches 181 of the two C-like radiation units 18 are flush with the upper edges of the dielectric substrate 11. The overall heights of the two C-like radiating elements 18 are the same. The overall height of the additional floor unit 16, that is, the height of the central branch 162 of the additional floor unit 16 is consistent with the overall height of the two C-like radiating units 18. The isolation groove 17 is embedded in the floor 14, and its head ends all extend upward to the upper edge of the floor 14. Each isolation groove 17 is located between the additional floor unit 16 and the C-like radiating unit 18 in the horizontal direction of the dielectric substrate 11. The two isolation grooves 17 are left and right mirror symmetry along the vertical axis of the dielectric substrate 11.
[0044] The backside 13 of the dielectric substrate 11 is as Figure 4 As shown, two inverted L-shaped radiating elements 19 and two microstrip feeders 20 are printed.
[0045] The inverted L-shaped radiating unit 19 is in an inverted L shape as a whole, that is, the inverted L-shaped radiating unit 19 is mainly composed of horizontal branches 191 and vertical branches 192. The horizontal branches 191 are arranged along the horizontal direction of the dielectric substrate 11. The vertical branches 192 are arranged along the vertical direction of the dielectric substrate 11. The end of the horizontal branch 191 and the head end of the vertical branch 192 are connected. The microstrip feeder 20 has a long straight strip shape and is arranged along the vertical direction of the dielectric substrate 11. The inverted L-shaped radiation unit 19 is located on the upper part of the back 13 of the dielectric substrate 11.
[0046] The microstrip feeder 20 is located at the lower part of the back 13 of the dielectric substrate 11. The end of the vertical branch 192 of the inverted L-shaped radiating unit 19 is connected to the head of the microstrip feeder 20.
[0047] When the inverted L-shaped radiating unit 19 is projected onto the front surface 12 of the dielectric substrate 11, its horizontal branch 191 is between the first branch 181 and the third branch 183, and the end of the vertical branch 192 is just on the upper edge of the floor 14. When the microstrip feeder 20 is projected onto the front surface 12 of the dielectric substrate 11, the head end of the microstrip feeder 20 is at the upper edge of the floor 14, and the end is at the lower edge of the floor 14. See figure 1.
[0048] The two antenna units 15 namely the first antenna unit 15a and the second antenna unit 15b form the main radiation structure of the present invention. The first antenna unit 15 a and the second antenna unit 15 b are installed symmetrically on the upper part of the dielectric substrate 11 along the vertical axis of the dielectric substrate 11. The first antenna unit 15a includes a first type C-shaped radiating element 18a and a first inverted L-shaped radiating element 19a. The first type of C-shaped radiating element 18a is printed on the front surface 12 of the dielectric substrate, and the first inverted L-shaped radiating element 19a is printed on Made on the backside of the dielectric substrate 13. The second antenna unit 15b includes a second type C-shaped radiating unit 18b and a second inverted L-shaped radiating unit 19b. The second type C-shaped radiating unit 18b is printed on the front surface 12 of the dielectric substrate 11, and the second inverted L-shaped radiating unit 19b Printed on the back side 13 of the dielectric substrate 11. The radiation units printed on the front and back sides of the dielectric substrate 11 use meandering technology. While ensuring the resonant path for the antenna unit to generate radiation, it reduces the space occupied by the two antenna units 15 on the dielectric substrate 11 and connects the first antenna unit 15a with The second antenna units 15b are installed side by side on the upper part of the dielectric substrate 11, and are symmetrically distributed along the vertical axis of the dielectric substrate 11. The use of angle diversity enables the antenna to obtain additional diversity gain. The blank area between the two antenna units 15 facilitates the design and installation of the decoupling structure, thereby making the overall layout of the antenna more compact. The first type C-shaped radiating element 18a, the second type C-shaped radiating element 18b, the first inverted L-shaped radiating element 19a, and the second inverted L-shaped radiating element 19b share the floor 14. The antenna adopts a microstrip line feeding method. The end of the vertical branch 192a of the first inverted L-shaped radiating element 19a is connected to one end of the first microstrip feeder 20a; the end of the vertical branch 192b of the second inverted L-shaped radiating element 19b is connected to one end of the second microstrip feeder 20b. The first inverted L-shaped radiating unit 19a and the second inverted L-shaped radiating unit 19b respectively couple a part of the energy to the first-type C-shaped radiating element 18a and the second-type C-shaped radiating element 18b to form an effective power supply, and at the same time The coupling structure of the first type C-shaped radiating element 18a and the first inverted L-shaped radiating element 19a and the coupling structure of the second type C-shaped radiating element 18b and the second inverted L-shaped radiating element 19b introduce additional capacitance, which is beneficial to improve the impedance characteristics. The frequency bandwidth is expanded, and the impedance characteristic and radiation characteristic of the antenna are finally formed, so as to achieve the purpose of dual-frequency and wide-band antenna.
[0049] The additional floor unit 16 and the two isolation grooves 17 form the decoupling structure of the present invention. The additional floor unit 16 is installed in a blank area between the first antenna unit 15a and the second antenna unit 15b. The ends of the left arm stub 161 and the right arm stub 163 of the additional floor unit 16 are respectively bent downward by 90 degrees, which can reduce the lateral space occupied by the introduction of the additional floor unit 16. At the same time, the height of the central branch 162 of the additional floor unit 16 is the same as that of the two antenna units 15 and does not extend outward, which further facilitates the layout of the additional floor unit structure and makes the two antenna units 15 more compact. Two isolation slots 17 are embedded in the floor 14 between the two antenna units 15. With dual slots, for the two-unit MIMO array, it can block most of the currents excited by the floor 14, and the decoupling is more effective. That is, when the first antenna unit 15a is excited, the first isolation slot 17a blocks most of the current flow to the second antenna unit 15b excited by the floor 14; and when the second antenna unit 15b is excited, the second isolation slot 17b blocks Most of the current flowing to the first antenna unit 15a caused by the floor 14 is eliminated. Since the number of antenna units 15 is two, the double-slot structure is adopted, which is more conducive to blocking the surface current caused by the floor 14 between the two antenna units 15. At the same time, the isolation groove 17 has an inverted S shape, that is, a stepped shape. Compared with the common U-shaped single groove, it has more adjustable parameters, which makes it easy to tune the relationship between the impedance bandwidth and the isolation performance, which can be reduced While the antenna units are mutually coupled, they also take into account bandwidth performance.
[0050] The core point of the present invention lies in the proposed decoupling structure, that is, an additional floor unit 16 and two isolation grooves 17. The decoupling structure can effectively improve the isolation between the antenna units in the two frequency bands. To further explain, when the antenna unit is excited in one of the frequency bands, the additional floor unit 16 weakens part of the mutual coupling influence from the space wave, and at the same time can concentrate most of the current excited on the surface of the floor 14 in the structure to reduce the impact on the other Coupling of antenna elements. When the antenna unit is excited in another frequency band, the isolation slot 17 opened in the floor 14 between the two antenna units 15 "clamps" most of the coupling current flowing from the surface of the floor 14 to the other antenna unit in the groove. In this way, the resonance of a certain frequency is generated, and the coupling energy is radiated into the air in the form of electromagnetic waves. Therefore, the mutual coupling between the antenna units when the antenna works in this frequency band can be reduced, and the isolation is further increased. Since the two decoupling structures of the additional floor unit 16 and the isolation slot 17 are introduced at the same time, the isolation of the antenna is improved when the antenna is working in dual bands, and the parameters of the respective decoupling structures can be relatively independently adjusted to weaken the antenna corresponding to different working frequency bands. The correlation between the units can also take into account the isolation and bandwidth performance between the antenna units in the dual-frequency mode.
[0051] Now take the relatively common 2.4G and 3.5G dual frequency bands as an example. In order to simplify the description of the data chart, Figure 5 to Figure 12 S11 represents the return loss value, and S21 represents the isolation value. Since the two antenna elements have network reciprocity symmetry, only the value of the scattering matrix of the 15 port of one antenna element is given. Among them, by loading different graphics and English words measured (measured) and simulated (simulation), the measured value and the simulated value curve have been clearly distinguished. Figure 5 , Image 6 The S11 and S21 diagrams of the MIMO dual-element antenna without any decoupling measures are given. It can be observed that the antenna can work in two frequency bands, 2.4G and 3.5G, with wide impedance characteristics, and the isolation in the working frequency band is lower than -10db. It can be seen that the structure and layout of the antenna unit given by this scheme have a certain inhibitory effect on decoupling. In order to further reduce the correlation between the two MIMO antennas and improve the isolation, a decoupling structure is introduced to make the isolation reach -15db, while ensuring the dual-frequency antenna bandwidth performance.
[0052] In order to compare the decoupling structure proposed by the present invention, the isolation is improved when the antenna is working in dual frequency. First, the S11 diagram and S21 diagram after adding only the additional floor unit 16 structure are given. Respectively as Figure 7 , Figure 8 Shown. Next, the S11 diagram and S21 diagram under the structure of opening the isolation groove 17 are given. Respectively as Picture 9 , Picture 10 Shown. Through the above data, we can observe that with only the additional floor unit 16 added, the isolation of the high frequency band has been greatly improved, but the isolation of the low frequency band has not changed much, and the operating frequency has a certain drift. However, only in the case that the structure of the isolation groove 17 is given, the isolation degree is significantly improved within the working bandwidth, but the matching performance of the high frequency band is reduced. When any one of the decoupling structures is given, the bandwidth of the working frequency band and the performance of isolation cannot be better considered. Under the decoupling structure adopted in the present invention, such as Picture 11 , Picture 12 , Not only improves the isolation between antenna units when the antenna is working in dual frequency, but also takes into account the bandwidth performance of the working frequency band.
