A low-frequency tunable dual-band decoupling antenna structure

Abstract

The present invention discloses a low-frequency tunable dual-band decoupling antenna structure, comprising a dielectric substrate, a pair of F-type antennas, a first metal ground, a decoupling structure and a matching network. The matching network matches the output impedance of the pair of F-type antennas to 50 ohms in both the high and low frequency bands. The decoupling structure is implemented using a neutral line structure, a defective ground structure and a floor branch. The neutral line structure composed of a seventh rectangular metal block, an eighth rectangular metal block and a ninth rectangular metal block implements decoupling for the high frequency band. The defective ground structure and the floor branch composed of a tenth rectangular metal block, an eleventh rectangular metal block, a twelfth rectangular metal block and a thirteenth rectangular metal block implement low-frequency decoupling. By changing the capacitance value of the variable capacitor in the first rectangular slot, a tunable function is achieved in the low frequency band. The advantages are that dual-band decoupling can be achieved, the structure is relatively simple, and the tunable requirements of the low frequency band can be met, and the structure has high flexibility in practical applications.

Description

Technical Field

[0001] The present invention relates to a decoupling antenna structure, in particular to a low-frequency tunable dual-frequency decoupling antenna structure. Background Art

[0002] During the 1G and 2G development stages of mobile communications, the primary technology proposed was SISO (simple input, simple output). This typically involved a single antenna, and mobile communication devices typically operated within a single frequency band. With the advancement of mobile communication technology, and to meet the communication needs of modern society, the trend has been towards high integration, and the number of antennas in mobile communication devices has steadily increased. Antenna miniaturization is a sign of advanced integration, but it also leads to more compact antenna structures and reduced spacing between antennas. This reduced spacing significantly increases the correlation between antennas, leading to increased mutual coupling between antennas. With the widespread adoption of MIMO (Multiple-Input Multiple-Output) technology in the 5G era, mobile terminal devices and small base station equipment are subject to stricter size constraints. Consequently, the number of antennas used in both the transceiver and transmitter sides is increasing. This leads to significant coupling between antennas, which impacts transmission performance. For example, this significantly increases signal processing complexity, impacts channel capacity, and degrades antenna voltage standing wave ratio, gain, and efficiency. Therefore, antenna coupling performance is a critical technical issue that cannot be ignored.

[0003] In the document (Y.Wang and Z.Du, "AWideband Printed Dual-Antenna System With a Novel Neutralization Line for Mobile Terminals," in IEEE Antennas and Wireless Propagation Letters, vol. 12, pp. 1428-1431, 2013.), a decoupling solution using floor branches and neutralization lines is disclosed to achieve decoupling of a single frequency band. The decoupling solution in this document forms a decoupling antenna by adding a decoupling structure between a pair of antennas. However, the structure of the decoupling antenna is relatively complex and can only achieve decoupling of the pair of antennas in a single frequency band. Moreover, after the frequency band is fixed, the tunable function cannot be achieved. However, in order to improve the transmission rate, mobile terminal devices need to comply with multiple communication standards such as WLAN, 4G and 5G. Therefore, a single frequency band obviously cannot meet today's communication needs. Moreover, the decoupling is only satisfied within a fixed bandwidth within the decoupling frequency band, and it lacks flexibility in practical applications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a low-frequency tunable dual-frequency decoupling antenna structure, which can achieve decoupling of dual frequency bands, has a relatively simple structure, can meet the low-frequency band tunability requirements, and has high flexibility in practical applications.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a low-frequency tunable dual-band decoupling antenna structure, including a dielectric substrate, a pair of antennas, a first metal ground, a decoupling structure and a matching network, the dielectric substrate is in the shape of a rectangular parallelepiped, the material of the dielectric substrate is FR4, the relative dielectric constant is 4.4, and the loss tangent value is 0.02, the length of the dielectric substrate is 80mm, the width is 60mm, and the height is 1.6mm, the length of the dielectric substrate is along the front-to-back direction, and the width is along the left-to-right direction, the pair of antennas are a pair of F-type antennas, the decoupling structure is realized by using a neutral line structure, a defective ground structure and a floor branch, and can achieve high-frequency band decoupling, low-frequency dual-band decoupling and low-frequency band tunability, and the matching network is used for The output impedance of a pair of F-type antennas is matched to 50 ohms in both the high frequency band and the low frequency band; the first metal ground is attached to the upper surface of the dielectric substrate, the left end surface of the first metal ground is flush with the left end surface of the dielectric substrate, the right end surface of the first metal ground is flush with the right end surface of the dielectric substrate, the rear end surface of the first metal ground is flush with the rear end surface of the dielectric substrate, and the distance between the front end surface of the first metal ground and the rear end surface of the first metal ground is 36 mm; the pair of F-type antennas are called the first F-type antenna and the second F-type antenna, the first F-type antenna is located on the left side of the second F-type antenna, and the first F-type antenna and the second F-type antenna are respectively arranged on the dielectric substrate The upper surface of the plate is located in front of the first metal ground, and the two are symmetrical with respect to the symmetry line of the dielectric substrate along the front-to-back direction. The first F-shaped antenna includes a first rectangular metal block, a second rectangular metal block, a third rectangular metal block and a first port. The first rectangular metal block, the second rectangular metal block and the third rectangular metal block are all attached to the upper surface of the dielectric substrate. The front end face of the first rectangular metal block is parallel to the front end face of the dielectric substrate. There is a distance between the front end face of the first rectangular metal block and the front end face of the dielectric substrate. The second rectangular metal block is located on the rear side of the first rectangular metal block, and there is a distance between the two. The second rectangular metal block The block is parallel to the first rectangular metal block, the length of the second rectangular metal block in the left-right direction is less than the length of the first rectangular metal block in the left-right direction, the right end face of the second rectangular metal block is located in the same plane as the right end face of the first rectangular metal block, the third rectangular metal block is located to the right of the first rectangular metal block and the second rectangular metal block, the front end face of the third rectangular metal block is flush with the front end face of the first rectangular metal block, the left end face of the third rectangular metal block is bonded to the right end face of the first rectangular metal block and the right end face of the second rectangular metal block, and the rear end face of the third rectangular metal block is located on the rear side of the plane where the rear end face of the second rectangular metal block is located.There is a distance between the rear end face of the third rectangular metal block and the front end face of the first metal ground, and there is a distance between the right end face of the third rectangular metal block and the symmetry line of the dielectric substrate along the front-to-back direction. The first port is connected to the third rectangular metal block and the first metal ground respectively. The first port is implemented by a probe and is used to feed the first F-type antenna. The length of the first rectangular metal block in the left-right direction is 10 mm, and the width in the front-to-back direction is 1 mm. The length of the second rectangular metal block in the left-right direction is 5 mm, and the width in the front-to-back direction is 1 mm. The length of the third rectangular metal block in the front-to-back direction is 20 mm, and the width in the left-to-right direction is 1 mm, the distance between the front end face of the first rectangular metal block and the plane where the front end face of the dielectric substrate is located is 19 mm, the distance between the rear end face of the first rectangular metal block and the front end face of the second rectangular metal block is 7 mm, and the distance between the rear end face of the third rectangular metal block and the front end face of the first metal ground is 4 mm; the second F-type antenna includes a fourth rectangular metal block, a fifth rectangular metal block, a sixth rectangular metal block and a second port, the fourth rectangular metal block, the fifth rectangular metal block and the sixth rectangular metal block are all attached to the upper surface of the dielectric substrate, the front end face of the fourth rectangular metal block and the front end face of the first rectangular metal block are located in the same plane, The fourth rectangular metal block is symmetrical with the first rectangular metal block along the symmetry line of the dielectric substrate in the front-to-back direction. The fifth rectangular metal block is located on the rear side of the fourth rectangular metal block. The fifth rectangular metal block is symmetrical with the fourth rectangular metal block along the symmetry line of the dielectric substrate in the front-to-back direction. The sixth rectangular metal block is located on the left side of the fourth rectangular metal block and the fifth rectangular metal block. The front end face of the sixth rectangular metal block is flush with the front end face of the fourth rectangular metal block. The right end face of the sixth rectangular metal block is bonded to the left end face of the fourth rectangular metal block and the left end face of the fifth rectangular metal block. The sixth rectangular metal block The sixth rectangular metal block is bilaterally symmetrical with respect to the third rectangular metal block along a symmetry line relative to the dielectric substrate along the front-to-back direction. The left end face of the sixth rectangular metal block is 2 mm away from the right end face of the third rectangular metal block. The second port is connected to the sixth rectangular metal block and the first metal ground respectively. The second port is implemented via a probe and is used to feed the second F-type antenna. The decoupling structure includes a second metal ground, a variable capacitor, a seventh rectangular metal block, an eighth rectangular metal block, a ninth rectangular metal block, a tenth rectangular metal block, an eleventh rectangular metal block, a twelfth rectangular metal block, and a thirteenth rectangular metal block. The second metal ground is implemented by providing a first rectangular groove in the fourteenth rectangular metal block.The fourteenth rectangular metal block is attached to the lower surface of the dielectric substrate, the rear end face of the fourteenth rectangular metal block is flush with the rear end face of the dielectric substrate, the left end face of the fourteenth rectangular metal block is flush with the left end face of the dielectric substrate, the right end face of the fourteenth rectangular metal block is flush with the right end face of the dielectric substrate, the length of the fourteenth rectangular metal block in the front-to-back direction is 56 mm, the front end face of the first rectangular groove is flush with the front end face of the fourteenth rectangular metal block, the length of the first rectangular groove in the front-to-back direction is 12 mm, the width in the left-to-right direction is 1 mm, and the symmetry line of the first rectangular groove in the front-to-back direction is the symmetry line of the fourteenth rectangular metal block in the front-to-back direction. The lines coincide with each other, the dielectric substrate is exposed at the first rectangular groove, the variable capacitor is arranged at the first rectangular groove, the variable capacitor is respectively connected to the left and right parts of the fourteenth rectangular metal block located at the first rectangular groove, and the distance between its rear end and the rear end surface of the first rectangular groove is 10 mm, the second metal ground is connected to the first metal ground through a plurality of metallized through holes that pass through the dielectric substrate from top to bottom, and the plurality of metallized through holes are evenly spaced along a row from left to right, the seventh rectangular metal block, the eighth rectangular metal block and the ninth rectangular metal block are attached to the upper surface of the dielectric substrate, and the seventh rectangular metal block is located at On the right side of the third rectangular metal block, the left end face of the seventh rectangular metal block is parallel to the right end face of the third rectangular metal block, and the distance between the two is 0.2 mm. The rear end face of the seventh rectangular metal block is connected to the front end face of the first metal ground and the two are in a fitted state. The length of the seventh rectangular metal block along the front-to-back direction is 15 mm, and the width along the left-to-right direction is 0.2 mm. The eighth rectangular metal block is located on the left side of the sixth rectangular metal block. The right end face of the eighth rectangular metal block is parallel to the right end face of the sixth rectangular metal block, and the distance between the two is 0.2 mm. The rear end face of the eighth rectangular metal block is connected to the front end face of the first metal ground. The eight rectangular metal block is connected to each other in a fitted state, the length of the eighth rectangular metal block along the front-to-back direction is 15 mm, and the width along the left-to-right direction is 0.2 mm. The ninth rectangular metal block is located between the seventh rectangular metal block and the ninth rectangular metal block. The left end face of the ninth rectangular metal block is connected to the right end face of the seventh rectangular metal block and is in a fitted state. The right end face of the ninth rectangular metal block is connected to the left end face of the eighth rectangular metal block and is in a fitted state. The front end face of the ninth rectangular metal block is located in the same plane as the front end face of the seventh rectangular metal block. The length of the ninth rectangular metal block along the left-to-right direction is 1.2 mm, and the width along the front-to-back direction is 0.2 mm.The tenth rectangular metal block, the eleventh rectangular metal block, the twelfth rectangular metal block and the thirteenth rectangular metal block are respectively attached to the lower surface of the dielectric substrate, the rear end face of the tenth rectangular metal block is connected to the front end face of the fourteenth rectangular metal block and the two are in a fitted state, the right end face of the tenth rectangular metal block is flush with the left end face of the first rectangular groove, the eleventh rectangular metal block is located on the left side of the tenth rectangular metal block, the right end face of the eleventh rectangular metal block is connected to the left end face of the tenth rectangular metal block and the two are in a fitted state, the front end face of the eleventh rectangular metal block is flush with the front end face of the tenth rectangular metal block, the length of the tenth rectangular metal block in the front-to-back direction is 10 mm, and the width in the left-to-right direction is 1 mm, the width of the eleventh rectangular metal block in the front-to-back direction is 1 mm, and the length in the left-to-right direction is 2 mm, the rear end face of the twelfth rectangular metal block is connected to the front end face of the fourteenth rectangular metal block and the two are in a fitted state, the twelfth The left end face of the rectangular metal block is flush with the right end face of the first rectangular slot. The thirteenth rectangular metal block is located to the right of the twelfth rectangular metal block. The left end face of the thirteenth rectangular metal block is connected to the right end face of the twelfth rectangular metal block and the two are in a bonded state. The front face of the thirteenth rectangular metal block is flush with the front face of the twelfth rectangular metal block. The twelfth rectangular metal block has a length of 10 mm in the front-to-back direction and a width of 1 mm in the left-to-right direction. The thirteenth rectangular metal block has a width of 1 mm in the front-to-back direction and a length of 2 mm in the left-to-right direction. The matching network includes a first matching circuit disposed between the first F-type antenna and the first port, and a second matching circuit disposed between the second F-type antenna and the second port. The first matching circuit is used to match the output impedance of the first F-type antenna to 50 ohms in the high and low frequency bands, and the second matching circuit is used to match the output impedance of the second F-type antenna to 50 ohms in the high and low frequency bands.

[0006] The first matching circuit includes three elements and three rectangular metal patches, each element is either a capacitor or an inductor, the three elements are respectively referred to as the first element, the second element and the third element, the three rectangular patches are respectively referred to as the first rectangular metal patch, the second rectangular metal patch and the third rectangular metal patch, the first rectangular metal patch, the second rectangular metal patch and the third rectangular metal patch are attached to the upper surface of the dielectric substrate, the first rectangular metal patch and the second rectangular metal patch are located between the third rectangular metal block and the first metal ground, the first rectangular metal patch is located in front of the second rectangular metal patch, the third rectangular metal patch is located on the left side of the first rectangular metal patch, the first element is located between the third rectangular metal block and the first rectangular metal patch, and the One end of the first element is connected to the third rectangular metal block, and the other end of the first element is connected to the first rectangular metal patch. The second element is located between the first rectangular metal patch and the third rectangular metal patch. One end of the second element is connected to the first rectangular metal patch, and the other end of the second element is connected to the third rectangular metal patch. The third rectangular metal patch is connected to the fourteenth rectangular metal block via a metallized through-hole penetrating the dielectric substrate. The third element is located between the first rectangular metal patch and the second rectangular metal patch. One end of the third element is connected to the first rectangular metal patch, and the other end of the third element is connected to the second rectangular metal patch. The second rectangular metal patch is connected to the first port.The second matching circuit includes three elements and three rectangular metal patches, each element is either a capacitor or an inductor, the three elements are respectively referred to as the fourth element, the fifth element and the sixth element, and the three rectangular patches are respectively referred to as the fourth rectangular metal patch, the fifth rectangular metal patch and the sixth rectangular metal patch. The fourth rectangular metal patch, the fifth rectangular metal patch and the sixth rectangular metal patch are attached to the upper surface of the dielectric substrate, the fourth rectangular metal patch and the fifth rectangular metal patch are located between the sixth rectangular metal block and the first metal ground, the fourth rectangular metal patch is located in front of the fifth rectangular metal patch, the sixth rectangular metal patch is located on the right side of the fourth rectangular metal patch, and the fourth element is located between the sixth rectangular metal block and the fourth rectangular metal patch. One end of the fourth element is connected to the sixth rectangular metal block, and the other end of the fourth element is connected to the fourth rectangular metal patch. The fifth element is located between the fourth rectangular metal patch and the sixth rectangular metal patch. One end of the fifth element is connected to the fourth rectangular metal patch, and the other end of the fifth element is connected to the sixth rectangular metal patch. The sixth rectangular metal patch is connected to the fourteenth rectangular metal block via a metallized through-hole penetrating the dielectric substrate. The sixth element is located between the fourth rectangular metal patch and the fifth rectangular metal patch. One end of the sixth element is connected to the fourth rectangular metal patch, and the other end of the sixth element is connected to the fifth rectangular metal patch. The fifth rectangular metal patch is connected to the second port.

[0007] Compared with the prior art, the advantage of the present invention is that decoupling for the high frequency band is achieved by placing a neutral line structure composed of the seventh rectangular metal block, the eighth rectangular metal block and the ninth rectangular metal block on the upper surface of the dielectric substrate; and for the low frequency band, on the lower surface of the dielectric substrate, the second metal ground is a defective ground structure and two L-shaped floor branches are formed by the tenth rectangular metal block, the eleventh rectangular metal block and the twelfth rectangular metal block and the thirteenth rectangular metal block, so that the low frequency band has a better decoupling effect. At the same time, after adding a variable capacitor in the first rectangular slot, by changing the capacitance value of the variable capacitor, the low frequency band has a tunable function, which meets a wider range of practical engineering needs. Therefore, in the present invention, the decoupling structures on the upper and lower surfaces of the dielectric substrate influence and act on each other. On the basis of dual-frequency decoupling, frequency tunability of the low frequency band is also achieved. The overall decoupling structure is relatively simple, the specific implementation is relatively easy, and the production cost is reduced. At the same time, a matching network is added to make the final reflection coefficient S 11 Meet the target of less than -6dB within the decoupling band. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG1( a ) is a front view of a pair of antennas and a first metal ground of a low-frequency tunable dual-frequency decoupling antenna structure according to the present invention;

[0009] FIG1( b ) is a schematic structural diagram of the fourteenth rectangular metal block of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention;

[0010] FIG2( a ) is a schematic structural diagram of the lower surface portion of the dielectric substrate of the decoupling structure of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention;

[0011] FIG2( b ) is a schematic structural diagram of the decoupling structure of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention on the upper surface of the dielectric substrate;

[0012] FIG2( c ) is a front view of the low-frequency tunable dual-band decoupling antenna structure of the present invention without the matching network;

[0013] FIG2( d ) is a rear view of the low-frequency tunable dual-band decoupling antenna structure of the present invention excluding the matching network;

[0014] FIG2( e ) is a front view of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention;

[0015] Figure 3 This is a schematic diagram of S parameters of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention without using a decoupling structure and a matching network;

[0016] FIG4(a) shows a low-frequency tunable dual-frequency decoupling antenna structure of the present invention without using a matching network. 11 Schematic diagram;

[0017] FIG4( b ) is a low-frequency tunable dual-frequency decoupling antenna structure of the present invention without using a matching network S 12 Schematic diagram;

[0018] FIG5( a ) is a schematic diagram showing the connection between a pair of antennas and a matching network of a low-frequency tunable dual-frequency decoupling antenna structure according to the present invention;

[0019] FIG5( b ) is a structural schematic diagram of a first matching circuit of a low-frequency tunable dual-frequency decoupling antenna structure according to the present invention;

[0020] FIG5( c ) is a schematic structural diagram of a second matching circuit of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention;

[0021] FIG6(a) is a low-frequency tunable dual-frequency decoupling antenna structure of the present invention. 11 Schematic diagram;

[0022] FIG6( b ) is a low-frequency tunable dual-frequency decoupling antenna structure of the present invention. 12 Schematic diagram. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0024] Example: As shown in Figure 1(a), Figure 1(b), Figure 2(a) to Figure 2(e) 、 Figure 5(a) to Figure 5(c)As shown, a low-frequency tunable dual-band decoupling antenna structure includes a dielectric substrate 1, a pair of antennas, a first metal ground 2, a decoupling structure, and a matching network. The dielectric substrate 1 is in the shape of a rectangular parallelepiped. The material of the dielectric substrate 1 is FR4, the relative dielectric constant is 4.4, and the loss tangent value is 0.02. The dielectric substrate 1 is 80 mm long, 60 mm wide W0, and 1.6 mm high. The length of the dielectric substrate 1 is along the front-to-back direction, and the width is along the left-to-right direction. The pair of antennas are a pair of F-type antennas. The decoupling structure is implemented using a neutral line structure, a defective ground structure, and a floor branch. It can achieve high-frequency decoupling, low-frequency dual-band decoupling, and low-frequency tunability. The matching network is used to match the output impedance of the pair of F-type antennas to 50 ohms in both the high and low frequency bands. The first metal ground 2 is attached to the upper surface of the dielectric substrate 1, the left end surface of the first metal ground 2 is flush with the left end surface of the dielectric substrate 1, the right end surface of the first metal ground 2 is flush with the right end surface of the dielectric substrate 1, the rear end surface of the first metal ground 2 is flush with the rear end surface of the dielectric substrate 1, and the distance L0 between the front end surface of the first metal ground 2 and the rear end surface of the first metal ground 2 is 36mm; a pair of F-type antennas are referred to as the first F-type antenna 3 and the second F-type antenna 4, the first F-type antenna 3 is located on the left side of the second F-type antenna 4, the first F-type antenna 3 and the second F-type antenna 4 are respectively arranged on the upper surface of the dielectric substrate 1 and on the front side of the first metal ground 2, and the two are symmetrical with respect to the dielectric substrate 1 along the symmetry line in the front-to-back direction, and the first F-type antenna 3 includes a first rectangular metal Block 5, second rectangular metal block 6, third rectangular metal block 7 and first port 8, the first rectangular metal block 5, the second rectangular metal block 6 and the third rectangular metal block 7 are all attached to the upper surface of the dielectric substrate 1, the front end face of the first rectangular metal block 5 is parallel to the front end face of the dielectric substrate 1, and there is a distance between the front end face of the first rectangular metal block 5 and the front end face of the dielectric substrate 1, the second rectangular metal block 6 is located on the rear side of the first rectangular metal block 5, and there is a distance between the two, the second rectangular metal block 6 is parallel to the first rectangular metal block 5, the length of the second rectangular metal block 6 in the left-right direction is less than the length of the first rectangular metal block 5 in the left-right direction, the right end face of the second rectangular metal block 6 and the right end face of the first rectangular metal block 5 are located in the same plane, the third rectangular metal block 6 is located on the rear side of the first rectangular metal block 5, and the second rectangular metal block 6 is located on the rear side of the first rectangular metal block 5. Block 7 is located on the right side of the first rectangular metal block 5 and the second rectangular metal block 6. The front end face of the third rectangular metal block 7 is flush with the front end face of the first rectangular metal block 5. The left end face of the third rectangular metal block 7 is bonded to the right end face of the first rectangular metal block 5 and the right end face of the second rectangular metal block 6. The rear end face of the third rectangular metal block 7 is located on the rear side of the plane where the rear end face of the second rectangular metal block 6 is located. There is a distance between the rear end face of the third rectangular metal block 7 and the front end face of the first metal ground 2. There is a distance between the right end face of the third rectangular metal block 7 and the symmetry line of the dielectric substrate 1 along the front-to-back direction. The first port 8 is connected to the third rectangular metal block 7 and the first metal ground 2 respectively. The first port 8 is realized by a probe and is used to feed the first F-type antenna 3.The length W1 of the first rectangular metal block 5 along the left-right direction is 10 mm, and the width along the front-back direction is 1 mm. The length W2 of the second rectangular metal block 6 along the left-right direction is 5 mm, and the width along the front-back direction is 1 mm. The length L1 of the third rectangular metal block 7 along the front-back direction is 20 mm, and the width along the left-right direction is 1 mm. The distance between the front end face of the first rectangular metal block 5 and the plane where the front end face of the dielectric substrate 1 is located is 19 mm. The distance between the rear end face of the first rectangular metal block 5 and the front end face of the second rectangular metal block 6 is 7 mm. The distance between the rear end face of the third rectangular metal block 7 and the front end face of the first metal ground 2 is 4 mm. The second F-type antenna 4 includes a fourth rectangular metal block 9, a fifth rectangular metal block 10, and a sixth rectangular metal block. 11 and a second port 12, a fourth rectangular metal block 9, a fifth rectangular metal block 10, and a sixth rectangular metal block 11 are all attached to the upper surface of the dielectric substrate 1, a front end face of the fourth rectangular metal block 9 and a front end face of the first rectangular metal block 5 are located in the same plane, and the fourth rectangular metal block 9 and the first rectangular metal block 5 are symmetrical with respect to a line of symmetry along the front-to-back direction of the dielectric substrate 1, the fifth rectangular metal block 10 is located behind the fourth rectangular metal block 9, and the fifth rectangular metal block 10 and the fourth rectangular metal block 9 are symmetrical with respect to a line of symmetry along the front-to-back direction of the dielectric substrate 1, the sixth rectangular metal block 11 is located to the left of the fourth rectangular metal block 9 and the fifth rectangular metal block 10, and the front end face of the sixth rectangular metal block 11 is flush with the front end face of the fourth rectangular metal block 9, The right end face of the sixth rectangular metal block 11 is bonded to the left end face of the fourth rectangular metal block 9 and the left end face of the fifth rectangular metal block 10. The sixth rectangular metal block 11 and the third rectangular metal block 7 are symmetrical with respect to the symmetry line along the front-to-back direction of the dielectric substrate 1. The distance W3 between the left end face of the sixth rectangular metal block 11 and the right end face of the third rectangular metal block 7 is 2 mm. The second port 12 is connected to the sixth rectangular metal block 11 and the first metal ground 2 respectively. The second port 12 is implemented by a probe and is used to feed the second F-type antenna 4. The decoupling structure includes a second metal ground 13, a variable capacitor 14, a seventh rectangular metal block 15, an eighth rectangular metal block 16, a ninth rectangular metal block 17, a tenth rectangular metal block 18, an eleventh rectangular metal block 19, The twelfth rectangular metal block 20 and the thirteenth rectangular metal block 21, and the second metal ground 13 are realized by forming a first rectangular groove 23 in the fourteenth rectangular metal block 22. The fourteenth rectangular metal block 22 is attached to the lower surface of the dielectric substrate 1. The rear end surface of the fourteenth rectangular metal block 22 is flush with the rear end surface of the dielectric substrate 1, the left end surface of the fourteenth rectangular metal block 22 is flush with the left end surface of the dielectric substrate 1, and the right end surface of the fourteenth rectangular metal block 22 is flush with the right end surface of the dielectric substrate 1. The length of the fourteenth rectangular metal block 22 in the front-to-back direction is 56 mm. The front end surface of the first rectangular groove 23 is flush with the front end surface of the fourteenth rectangular metal block 22. The length L4 of the first rectangular groove 23 in the front-to-back direction is 12 mm, and the width W5 in the left-to-right direction is 1 mm.The symmetry line of the first rectangular groove 23 along the front-to-back direction coincides with the symmetry line of the fourteenth rectangular metal block 22 along the front-to-back direction. The dielectric substrate 1 is exposed at the first rectangular groove 23. The variable capacitor 14 is disposed at the first rectangular groove 23. The variable capacitor 14 is connected to the left and right portions of the fourteenth rectangular metal block 22 located at the first rectangular groove 23, respectively. The distance L5 between the rear end of the variable capacitor 14 and the rear end surface of the first rectangular groove 23 is 10 mm. The second metal ground 13 is connected to the first metal ground 2 via a plurality of metalized through-holes 24 that penetrate the dielectric substrate 1 vertically. The plurality of metalized through-holes 24 are evenly spaced along a row from left to right. The seventh rectangular metal block 15, the eighth rectangular metal block 16, and the ninth rectangular metal block 17 are attached to the upper surface of the dielectric substrate 1. The seventh rectangular metal block 15 is located on the right side of the third rectangular metal block 7, the left end face of the seventh rectangular metal block 15 is parallel to the right end face of the third rectangular metal block 7, and the distance between the two is 0.2mm. The rear end face of the seventh rectangular metal block 15 is connected to the front end face of the first metal ground 2, and the two are in a fitted state. The length of the seventh rectangular metal block 15 along the front-to-back direction is 15mm, and the width along the left-to-right direction is 0.2mm. The eighth rectangular metal block 16 is located on the left side of the sixth rectangular metal block 11, and the right end face of the eighth rectangular metal block 16 is parallel to the right end face of the sixth rectangular metal block 11, and the distance between the two is 0.2mm. The rear end face of the eighth rectangular metal block 16 is connected to the front end face of the first metal ground 2, and the two are in a fitted state. The length L6 of the rectangular metal block 16 along the front-to-back direction is 15 mm, and the width along the left-to-right direction is 0.2 mm. The ninth rectangular metal block 17 is located between the seventh rectangular metal block 15 and the ninth rectangular metal block 17. The left end face of the ninth rectangular metal block 17 is connected to the right end face of the seventh rectangular metal block 15 and is in a fitted state. The right end face of the ninth rectangular metal block 17 is connected to the left end face of the eighth rectangular metal block 16 and is in a fitted state. The front end face of the ninth rectangular metal block 17 is located in the same plane as the front end face of the seventh rectangular metal block 15. The length L6 of the ninth rectangular metal block 17 along the left-to-right direction is 1.2 mm, and the width along the front-to-back direction is 0.2 mm. The tenth rectangular metal block 18, the eleventh rectangular metal block 19, and the twelfth rectangular metal block 20 The first and thirteenth rectangular metal blocks 21 are respectively attached to the lower surface of the dielectric substrate 1. The rear end face of the tenth rectangular metal block 18 is connected to the front end face of the fourteenth rectangular metal block 22, and the two are in a bonded state. The right end face of the tenth rectangular metal block 18 is flush with the left end face of the first rectangular groove 23. The eleventh rectangular metal block 19 is located to the left of the tenth rectangular metal block 18. The right end face of the eleventh rectangular metal block 19 is connected to the left end face of the tenth rectangular metal block 18, and the two are in a bonded state. The front end face of the eleventh rectangular metal block 19 is flush with the front end face of the tenth rectangular metal block 18. The length of the tenth rectangular metal block 18 along the front-to-back direction is 10 mm, and the width along the left-to-right direction is 1 mm. The width of the eleventh rectangular metal block 19 along the front-to-back direction is 1 mm.The length W4 along the left-right direction is 2 mm. The rear end face of the twelfth rectangular metal block 20 is connected to the front end face of the fourteenth rectangular metal block 22 and the two are in a fitted state. The left end face of the twelfth rectangular metal block 20 is flush with the right end face of the first rectangular groove 23. The thirteenth rectangular metal block 21 is located on the right side of the twelfth rectangular metal block 20. The left end face of the thirteenth rectangular metal block 21 is connected to the right end face of the twelfth rectangular metal block 20 and the two are in a fitted state. The front end face of the thirteenth rectangular metal block 21 is flush with the front end face of the twelfth rectangular metal block 20. The length L of the twelfth rectangular metal block 20 along the front-back direction is 3 is 10 mm long and has a width of 1 mm in the left-right direction. The thirteenth rectangular metal block 21 has a width of 1 mm in the front-to-back direction and a length of 2 mm in the left-to-right direction. The matching network includes a first matching circuit MN1 disposed between the first F-type antenna 3 and the first port 8, and a second matching circuit MN2 disposed between the second F-type antenna 4 and the second port 12. The first matching circuit MN1 is used to match the output impedance of the first F-type antenna 3 to 50 ohms in the high and low frequency bands. The second matching circuit MN2 is used to match the output impedance of the second F-type antenna 4 to 50 ohms in the high and low frequency bands.

[0025] In this embodiment, the first matching circuit MN1 includes three elements and three rectangular metal patches. Each element is either a capacitor or an inductor. The three elements are respectively referred to as a first element 25, a second element 26, and a third element 27. The three rectangular patches are respectively referred to as a first rectangular metal patch 28, a second rectangular metal patch 29, and a third rectangular metal patch 30. The first rectangular metal patch 28, the second rectangular metal patch 29, and the third rectangular metal patch 30 are attached to the upper surface of the dielectric substrate 1. The first rectangular metal patch 28 and the second rectangular metal patch 29 are located between the third rectangular metal block 7 and the first metal ground 2. The first rectangular metal patch 28 is located in front of the second rectangular metal patch 29. The third rectangular metal patch 30 is located on the left side of the first rectangular metal patch 28. The first element 25 is located between the third rectangular metal block 7 and the first Between the rectangular metal patches 28, one end of the first element 25 is connected to the third rectangular metal block 7, and the other end of the first element 25 is connected to the first rectangular metal patch 28. The second element 26 is located between the first rectangular metal patch 28 and the third rectangular metal patch 30. One end of the second element 26 is connected to the first rectangular metal patch 28, and the other end of the second element 26 is connected to the third rectangular metal patch 30. The third rectangular metal patch 30 is connected to the fourteenth rectangular metal block 22 via a metallized through-hole 31 that penetrates the dielectric substrate 1. The third element 27 is located between the first rectangular metal patch 28 and the second rectangular metal patch 29. One end of the third element 27 is connected to the first rectangular metal patch 28, and the other end of the third element 27 is connected to the second rectangular metal patch 29. The second rectangular metal patch 29 is connected to the first port 8;The second matching circuit MN2 includes three elements and three rectangular metal patches, each element is either a capacitor or an inductor, the three elements are respectively referred to as the fourth element 32, the fifth element 33 and the sixth element 34, and the three rectangular patches are respectively referred to as the fourth rectangular metal patch 35, the fifth rectangular metal patch 36 and the sixth rectangular metal patch 37. The fourth rectangular metal patch 35, the fifth rectangular metal patch 36 and the sixth rectangular metal patch 37 are attached to the upper surface of the dielectric substrate 1, the fourth rectangular metal patch 35 and the fifth rectangular metal patch 36 are located between the sixth rectangular metal block 11 and the first metal ground 2, the fourth rectangular metal patch 35 is located in front of the fifth rectangular metal patch 36, the sixth rectangular metal patch 37 is located on the right side of the fourth rectangular metal patch 35, and the fourth element 32 is located between the sixth rectangular metal block 11 and the fourth rectangular metal The fourth element 32 is located between the fourth and sixth rectangular metal patches 35. One end of the fourth element 32 is connected to the sixth rectangular metal block 11, and the other end of the fourth element 32 is connected to the fourth rectangular metal patch 35. The fifth element 33 is located between the fourth and sixth rectangular metal patches 35. One end of the fifth element 33 is connected to the fourth rectangular metal patch 35, and the other end of the fifth element 33 is connected to the sixth rectangular metal patch 37. The sixth rectangular metal patch 37 is connected to the fourteenth rectangular metal block 22 via a metallized through-hole 38 that penetrates the dielectric substrate 1. The sixth element 34 is located between the fourth and fifth rectangular metal patches 35. One end of the sixth element 34 is connected to the fourth rectangular metal patch 35, and the other end of the sixth element 34 is connected to the fifth rectangular metal patch 36. The fifth rectangular metal patch 36 is connected to the second port 12.

[0026] The schematic diagram of the S parameters of a pair of antennas in the low-frequency tunable dual-frequency decoupling antenna structure of the present invention when the decoupling structure is not used for decoupling is as shown in FIG. Figure 3 As shown, Figure 3 In, S 11 Represents the reflection coefficient, S 12 The design purpose of the present invention requires the reflection coefficient S 11 Less than -6dB, transmission coefficient S 12 Less than -10dB, so the low frequency band of this pair of antennas is around 4GHz. 12 The target of less than -10dB is not achieved in this frequency band; the high frequency band uses the frequency band around 6GHz, and the S 11 The target requirement of less than -6dB was not met.

[0027] The pair of antennas of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention are decoupled by the decoupling structure. 11 As shown in FIG4(a), a pair of antennas of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention are decoupled by the decoupling structure. 12The schematic diagram is shown in Figure 4(b). The capacitance value of the variable capacitor varies from 0.1pF to 0.7pF, and the decoupling frequency point in the low frequency band can be changed. The capacitance value of the variable capacitor corresponding to the tunable range is 0.1pF-0.7pF. In Figure 4(a) and Figure 4(b), three representative capacitance values ​​of 0.1pF, 0.4pF, and 0.7pF are selected to draw the schematic diagram of the S parameter. Analysis of Figure 4(b) shows that the low frequency band decoupling frequency corresponding to 0.1pF is 4.63GHz, and the transmission coefficient S corresponding to this point is 0. 12 =-21.23dB; the low-frequency decoupling frequency corresponding to 0.4pF is 4.24GHz, and the transmission coefficient S corresponding to this point 12 =-22.11dB; the low-frequency decoupling frequency corresponding to 0.7pF is 3.85GHz, and the transmission coefficient S corresponding to this point 12 =-27.02dB; From this we can see that the tunable range is 3.85GHz-4.63GHz, and the larger the capacitance of the adjustable capacitor, the smaller the corresponding low-frequency decoupling frequency. For the high-frequency band, as the capacitance of the adjustable capacitor changes, the high-frequency decoupling frequency is 6.3GHz. The transmission coefficient S of 0.1pF at 6.3GHz is 12 =-28.60dB; 0.4pF transmission coefficient S at 6.3GHz 12 =-24.53dB; 0.7pF transmission coefficient S at 6.3GHz 12 =-23.71dB. As the capacitance value increases, the S 12 The parameter has increased, but the worst case can still be kept below -23dB, which meets the design purpose. As can be seen from Figure 4(a), the S 11 The parameter is to be able to satisfy the reflection coefficient S 11 Less than -6dB requirement, and for the S in the tunable range of 4.15GHz-4.63GHz 11 The parameters cannot meet the requirements. Similarly, the reflection coefficient in the high frequency band cannot meet the conditions, so a matching network needs to be added on the basis of the decoupling structure to make S 11 The parameters meet the requirement of less than -6dB in the entire tunable range of the low frequency band and the high frequency band of 6.3GHz.

[0028] In the present invention, each component in the matching network adopts a capacitor or an inductor. The following table shows the capacitance value or inductance value of each component in the matching circuit network after decoupling is completed when the variable capacitance in the decoupling structure is 0.1pF, 0.4pF, and 0.7pF.

[0029]

[0030] The low-frequency tunable dual-frequency decoupling antenna structure of the present invention is S 11 As shown in FIG6(a), the low-frequency tunable dual-frequency decoupling antenna structure of the present invention is S 12 The schematic diagram is shown in FIG6(b). According to FIG6(a), it can be found that the S of the low-frequency tunable dual-frequency decoupling antenna structure of the present invention is 11 The resonance point of the parameters in the low frequency band is controlled between 3.85-4.63GHz, and the high frequency resonance point is 6.3GHz. The corresponding S 11 The parameter is always lower than -8dB. As shown in Figure 6(b), due to the matching network, S 12 The coupling degree of the parameters is slightly worse than that after decoupling, but it can meet the target of less than -10dB in the entire low frequency range of 3.85-4.63GHz, and compared with the S of the original pair of antennas 12 The parameters are optimized by 5dB-15dB; the S 12 The parameters fluctuate slightly with the change of capacitance value, and are all less than -20dB at this frequency point, meeting the design purpose.

Claims

1. A low-frequency tunable dual-band decoupling antenna structure, comprising a dielectric substrate, a pair of antennas, a first metal ground, a decoupling structure, and a matching network. The dielectric substrate is rectangular, made of FR4, has a relative dielectric constant of 4.4, and a loss tangent of 0.

02. The dielectric substrate is 80 mm long, 60 mm wide, and 1.6 mm high. The length of the dielectric substrate is along the front-to-back direction, and the width is along the left-to-right direction. The pair of antennas are a pair of F-shaped antennas. The decoupling structure is implemented using a neutral line structure, a defective ground structure, and a floor branch, capable of achieving high-frequency decoupling, low-frequency dual-band decoupling, and low-frequency tunability. The matching network is used to match the output impedance of the pair of F-shaped antennas to 50 ohms in both the high and low frequency bands. The first metal ground is attached to the upper surface of the dielectric substrate. The left end surface of the first metal ground is flush with the left end surface of the dielectric substrate, the right end surface of the first metal ground is flush with the right end surface of the dielectric substrate, and the rear end surface of the first metal ground is flush with the rear end surface of the dielectric substrate. The distance between the front end surface of the first metal ground and the rear end surface of the first metal ground is 36 mm. A pair of F-type antennas are referred to as a first F-type antenna and a second F-type antenna. The first F-type antenna is located on the left side of the second F-type antenna. The first F-type antenna and the second F-type antenna are respectively arranged on the upper surface of the dielectric substrate and are located in front of the first metal ground. The two are symmetrical with respect to the dielectric substrate along the symmetry line in the front-to-back direction. The first F-type antenna includes a first rectangular metal block, a second rectangular metal block, a third rectangular metal block and a first port. The first rectangular metal block, the second rectangular metal block and the third rectangular metal block are all attached to the upper surface of the dielectric substrate. The front end surface of the first rectangular metal block is adjacent to the dielectric substrate. The front end surface of the substrate is parallel, there is a distance between the front end surface of the first rectangular metal block and the front end surface of the dielectric substrate, the second rectangular metal block is located on the rear side of the first rectangular metal block, and there is a distance between the two, the second rectangular metal block is parallel to the first rectangular metal block, the length of the second rectangular metal block in the left-right direction is less than the length of the first rectangular metal block in the left-right direction, the right end surface of the second rectangular metal block and the right end surface of the first rectangular metal block are located in the same plane, the third rectangular metal block is located on the right side of the first rectangular metal block and the second rectangular metal block, and the front end surface of the third rectangular metal block is parallel to the first rectangular metal block. The front end face of the first rectangular metal block is flush, the left end face of the third rectangular metal block is fitted and connected with the right end face of the first rectangular metal block and the right end face of the second rectangular metal block, the rear end face of the third rectangular metal block is located on the rear side of the plane where the rear end face of the second rectangular metal block is located, there is a distance between the rear end face of the third rectangular metal block and the front end face of the first metal ground, and there is a distance between the right end face of the third rectangular metal block and the symmetry line of the dielectric substrate along the front-to-back direction. The first port is respectively connected to the third rectangular metal block and the first metal ground, and the first port is realized by a probe for calibrating the first F-type antenna feed, the first rectangular metal block has a length of 10 mm in the left-right direction and a width of 1 mm in the front-to-back direction, the second rectangular metal block has a length of 5 mm in the left-to-right direction and a width of 1 mm in the front-to-back direction, the third rectangular metal block has a length of 20 mm in the front-to-back direction and a width of 1 mm in the left-to-right direction, the distance between the front end surface of the first rectangular metal block and the plane where the front end surface of the dielectric substrate is located is 19 mm, the distance between the rear end surface of the first rectangular metal block and the front end surface of the second rectangular metal block is 7 mm, and the distance between the rear end surface of the third rectangular metal block and the front end surface of the first metal ground is 4 mm;The second F-shaped antenna includes a fourth rectangular metal block, a fifth rectangular metal block, a sixth rectangular metal block and a second port. The fourth rectangular metal block, the fifth rectangular metal block and the sixth rectangular metal block are all attached to the upper surface of the dielectric substrate. The front end face of the fourth rectangular metal block and the front end face of the first rectangular metal block are located in the same plane. The fourth rectangular metal block and the first rectangular metal block are symmetrical with respect to the dielectric substrate along the front-to-back direction. The fifth rectangular metal block is located on the rear side of the fourth rectangular metal block. The fifth rectangular metal block and the fourth rectangular metal block are symmetrical with respect to the dielectric substrate along the front-to-back direction. The sixth rectangular metal block is located On the left side of the fourth rectangular metal block and the fifth rectangular metal block, the front end face of the sixth rectangular metal block is flush with the front end face of the fourth rectangular metal block, the right end face of the sixth rectangular metal block is bonded to the left end face of the fourth rectangular metal block and the left end face of the fifth rectangular metal block, the sixth rectangular metal block is symmetrical with the third rectangular metal block along a symmetry line in the front-to-back direction relative to the dielectric substrate, the distance between the left end face of the sixth rectangular metal block and the right end face of the third rectangular metal block is 2 mm, the second port is respectively connected to the sixth rectangular metal block and the first metal ground, the second port is implemented via a probe and is used to feed the second F-shaped antenna; The decoupling structure includes a second metal ground, a variable capacitor, a seventh rectangular metal block, an eighth rectangular metal block, a ninth rectangular metal block, a tenth rectangular metal block, an eleventh rectangular metal block, a twelfth rectangular metal block, and a thirteenth rectangular metal block. The second metal ground is realized by providing a first rectangular groove on the fourteenth rectangular metal block. The fourteenth rectangular metal block is attached to the lower surface of the dielectric substrate. The rear end surface of the fourteenth rectangular metal block is flush with the rear end surface of the dielectric substrate. The left end surface of the fourteenth rectangular metal block is flush with the left end surface of the dielectric substrate. The right end surface of the fourteenth rectangular metal block is flush with the dielectric substrate. The right end surface of the substrate is flush, the length of the fourteenth rectangular metal block in the front-to-back direction is 56 mm, the front end surface of the first rectangular groove is flush with the front end surface of the fourteenth rectangular metal block, the length of the first rectangular groove in the front-to-back direction is 12 mm, and the width in the left-to-right direction is 1 mm. The symmetry line of the first rectangular groove in the front-to-back direction coincides with the symmetry line of the fourteenth rectangular metal block in the front-to-back direction. The dielectric substrate is exposed at the first rectangular groove, and the variable capacitor is arranged at the first rectangular groove. The variable capacitor is respectively aligned with the left and right portions of the fourteenth rectangular metal block located at the first rectangular groove. The seventh rectangular metal block is connected to the dielectric substrate, and the distance between its rear end and the rear end surface of the first rectangular groove is 10 mm. The second metal ground is connected to the first metal ground through a plurality of metallized through holes that pass through the dielectric substrate from top to bottom. The plurality of metallized through holes are evenly spaced along a row from left to right. The seventh rectangular metal block, the eighth rectangular metal block and the ninth rectangular metal block are attached to the upper surface of the dielectric substrate. The seventh rectangular metal block is located to the right of the third rectangular metal block. The left end surface of the seventh rectangular metal block is parallel to the right end surface of the third rectangular metal block, and the distance between the two is 0.2 mm. The seventh The rear end face of the rectangular metal block is connected to the front end face of the first metal ground, and the two are in a bonded state. The length of the seventh rectangular metal block in the front-to-back direction is 15 mm, and the width in the left-to-right direction is 0.2 mm. The eighth rectangular metal block is located to the left of the sixth rectangular metal block. The right end face of the eighth rectangular metal block is parallel to the right end face of the sixth rectangular metal block, and the distance between the two is 0.2 mm. The rear end face of the eighth rectangular metal block is connected to the front end face of the first metal ground, and the two are in a bonded state. The length of the eighth rectangular metal block in the front-to-back direction is 15 mm, and the width in the left-to-right direction is 0.2mm, the ninth rectangular metal block is located between the seventh rectangular metal block and the ninth rectangular metal block, the left end face of the ninth rectangular metal block is connected to the right end face of the seventh rectangular metal block and is in a bonded state, the right end face of the ninth rectangular metal block is connected to the left end face of the eighth rectangular metal block and is in a bonded state, the front end face of the ninth rectangular metal block and the front end face of the seventh rectangular metal block are located in the same plane, the length of the ninth rectangular metal block in the left-right direction is 1.2mm, and the width in the front-back direction is 0.2mm, the tenth rectangular metal block, the eleventh rectangular metal block, the twelfth rectangular metal block and the thirteenth rectangular metal block are respectively attached to the lower surface of the dielectric substrate, the rear end face of the tenth rectangular metal block is connected to the front end face of the fourteenth rectangular metal block and the two are in a bonded state, the right end face of the tenth rectangular metal block is flush with the left end face of the first rectangular groove, the eleventh rectangular metal block is located on the left side of the tenth rectangular metal block, and the right end face of the eleventh rectangular metal block is aligned with the left end face of the tenth rectangular metal block. The left end faces of the metal blocks are connected and the two are in a fitted state, the front end face of the eleventh rectangular metal block is flush with the front end face of the tenth rectangular metal block, the length of the tenth rectangular metal block along the front-to-back direction is 10mm, and the width along the left-to-right direction is 1mm, the width of the eleventh rectangular metal block along the front-to-back direction is 1mm, and the length along the left-to-right direction is 2mm, the rear end face of the twelfth rectangular metal block is connected to the front end face of the fourteenth rectangular metal block and the two are in a fitted state, the left end face of the twelfth rectangular metal block is flush with the first rectangular metal block The right end surface of the 13th rectangular metal block is flush with the right end surface of the 12th rectangular metal block. The 13th rectangular metal block is located to the right of the 12th rectangular metal block. The left end surface of the 13th rectangular metal block is connected to the right end surface of the 12th rectangular metal block and the two are in a bonded state. The front end surface of the 13th rectangular metal block is flush with the front end surface of the 12th rectangular metal block. The 12th rectangular metal block has a length of 10 mm in the front-to-back direction and a width of 1 mm in the left-to-right direction. The 13th rectangular metal block has a width of 1 mm in the front-to-back direction and a length of 2 mm in the left-to-right direction. The matching network includes a first matching circuit arranged between the first F-type antenna and the first port and a second matching circuit arranged between the second F-type antenna and the second port. The first matching circuit is used to match the output impedance of the first F-type antenna in the high frequency band and the low frequency band to 50 ohms, and the second matching circuit is used to match the output impedance of the second F-type antenna in the high frequency band and the low frequency band to 50 ohms.

2. A low-frequency tunable dual-band decoupling antenna structure according to claim 1, characterized in that The first matching circuit includes three elements and three rectangular metal patches, each element is either a capacitor or an inductor, the three elements are respectively referred to as the first element, the second element and the third element, the three rectangular patches are respectively referred to as the first rectangular metal patch, the second rectangular metal patch and the third rectangular metal patch, the first rectangular metal patch, the second rectangular metal patch and the third rectangular metal patch are attached to the upper surface of the dielectric substrate, the first rectangular metal patch and the second rectangular metal patch are located between the third rectangular metal block and the first metal ground, the first rectangular metal patch is located in front of the second rectangular metal patch, the third rectangular metal patch is located on the left side of the first rectangular metal patch, the first element is located between the third rectangular metal block and the first rectangular metal patch, and the One end of the first element is connected to the third rectangular metal block, and the other end of the first element is connected to the first rectangular metal patch. The second element is located between the first rectangular metal patch and the third rectangular metal patch. One end of the second element is connected to the first rectangular metal patch, and the other end of the second element is connected to the third rectangular metal patch. The third rectangular metal patch is connected to the fourteenth rectangular metal block via a metallized through-hole penetrating the dielectric substrate. The third element is located between the first rectangular metal patch and the second rectangular metal patch. One end of the third element is connected to the first rectangular metal patch, and the other end of the third element is connected to the second rectangular metal patch. The second rectangular metal patch is connected to the first port.The second matching circuit includes three elements and three rectangular metal patches, each element is either a capacitor or an inductor, the three elements are respectively referred to as the fourth element, the fifth element and the sixth element, and the three rectangular patches are respectively referred to as the fourth rectangular metal patch, the fifth rectangular metal patch and the sixth rectangular metal patch. The fourth rectangular metal patch, the fifth rectangular metal patch and the sixth rectangular metal patch are attached to the upper surface of the dielectric substrate, the fourth rectangular metal patch and the fifth rectangular metal patch are located between the sixth rectangular metal block and the first metal ground, the fourth rectangular metal patch is located in front of the fifth rectangular metal patch, the sixth rectangular metal patch is located on the right side of the fourth rectangular metal patch, and the fourth element is located between the sixth rectangular metal block and the fourth rectangular metal patch. One end of the fourth element is connected to the sixth rectangular metal block, and the other end of the fourth element is connected to the fourth rectangular metal patch. The fifth element is located between the fourth rectangular metal patch and the sixth rectangular metal patch. One end of the fifth element is connected to the fourth rectangular metal patch, and the other end of the fifth element is connected to the sixth rectangular metal patch. The sixth rectangular metal patch is connected to the fourteenth rectangular metal block via a metallized through-hole penetrating the dielectric substrate. The sixth element is located between the fourth rectangular metal patch and the fifth rectangular metal patch. One end of the sixth element is connected to the fourth rectangular metal patch, and the other end of the sixth element is connected to the fifth rectangular metal patch. The fifth rectangular metal patch is connected to the second port.

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