A broadband filtering unit and an antenna array

Abstract

The present invention provides a broadband filtering unit, which includes a grounding support base, a feeding balun, and a square radiation surface. Both the front and back surfaces of the square radiation surface are copper-clad. Among them, the shape of the copper cladding on the front is similar to four combined square structures. Two square structures located on the diagonal form two oscillator arms in one polarization direction. The middle positions of each oscillator arm are all hollowed out. The oscillator arm is composed of multiple cascaded LC circuits. Multiple open-circuit filtering stub segments are also arranged on the oscillator arm. The present invention is used in a multi-frequency and multi-array combined antenna, which can well avoid interference with adjacent arrays. Its special multiple filtering structure can adapt to various irregular arrays, effectively reduce the size of the antenna, improve the performance of the antenna interleaved array, and has a simple structure, convenient installation, and low cost. At the same time, by adjusting the positions of the LC circuits and the lengths of the filtering stub segments on the unit radiation surface, the expansion of different frequency bands and the filtering of different frequency bands can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-frequency and multi-array combined antennas, and particularly relates to a broadband filtering unit and an antenna array. Background Art

[0002] In order to ensure the performance indicators of each frequency band, conventional multi-frequency and multi-array combined antennas separately divide regions for each array inside the antenna, resulting in problems such as large antenna size and high antenna operation costs. When the size is controlled, the array layout is very compact, and the mutual coupling effect is very large, thus causing a serious decline in indicators. Therefore, when antenna manufacturers control the size, they also need to solve the problem of array mutual coupling, and the key to solving the problem lies in the decoupling technology of antenna oscillator units.

[0003] The problem of broadband antenna decoupling for multi-frequency and multi-array has always been an important research field in the industry and has also always been a technical problem that is difficult to solve. Summary of the Invention

[0004] The purpose of the present invention is to provide a broadband filtering unit and an antenna array. While solving the antenna size problem, the present invention can also provide good radiation performance. Especially in the case of combined network deployment of 4G and 5G, when the broadband filtering unit is used in the antenna of a dual system, it can greatly reduce the antenna application cost, improve the base station capacity and user experience.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a broadband filtering unit, including a grounding support base, a feeding balun, and a square radiation surface with ±45° dual polarization directions. Both the front and back sides of the square radiation surface are copper-clad. Among them, the copper-clad shape on the front side is similar to four square structures combined together. Two square structures located on the diagonal form two oscillator arms of one polarization direction. The middle position of each oscillator arm is completely hollowed out. The oscillator arm is composed of multiple LC circuits connected in series. Multiple open-circuit filtering branches are also arranged on the oscillator arm. The bottom middle position of the square radiation surface is connected with a feeding balun for feeding and supporting the square radiation surface. The free end of the feeding balun is connected to the grounding support base. By adjusting the positions of multiple LC circuits on the square radiation surface and the lengths of the open-circuit filtering branches, the expansion and filtering of different frequency bands can be achieved.

[0006] Further, the copper-clad shape on the back side of the square radiation surface is a square ring structure, and the inside of the square ring structure is hollowed out for coupling the energy of the four oscillator arms, thereby forming a current loop to extend the electrical length of the oscillator.

[0007] Further, the part of the oscillator arm at the middle position of the square radiation surface is connected to the feeding balun, and this part is an angular structure formed by sequentially connecting and integrally arranging three quasi-triangular structures. Among them, the quasi-triangular structure in the middle is used to enlarge the feeding pad and connect to the feeding balun, and the two quasi-triangular structures at both ends are used to form resonant cavities to reduce the return loss of the oscillator.

[0008] Further, the feeding balun is made of PCB double-sided copper-clad material, with microstrip lines for impedance matching arranged on one side and a grounding sheet arranged on the other side.

[0009] Further, the number of the LC circuits is three, namely the first LC circuit, the third LC circuit and the second LC circuit connected in sequence. The first LC circuit and the second LC circuit have the same structure and are both semi-closed rectangular structures. The third LC circuit is coupled by the corner for connecting the first LC circuit and the second LC circuit and the L-shaped copper-clad strip arranged on the back surface of the square radiation surface. Capacitance-inductance connections are formed between the third LC circuit and the first LC circuit and the second LC circuit respectively, so as to achieve the filtering effect.

[0010] Further, the length of the open-circuit filtering stub is close to a quarter wavelength of the filtered frequency band.

[0011] An antenna array includes an antenna array and the broadband filtering unit as described in claim 1. The grounding support base arranged on the broadband filtering unit is placed on the reflector of the antenna array and forms a coupled grounding with the reflector.

[0012] Further, the antenna array includes but is not limited to FDD antennas, FDD+TDD antennas and FDD+MIMO antennas.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention is used in multi-frequency and multi-array combined antennas, can well avoid interference with adjacent arrays, its special multiple filtering structure can adapt to various special-shaped arrays, effectively reduce the antenna size, improve the performance of the antenna interleaved array, and has a simple structure, convenient installation and low cost; at the same time, by adjusting the positions of the LC circuits on the unit radiation surface and the lengths of the filtering stubs, different frequency band expansions and filtering of different frequency bands can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic front view structure of a broadband filtering unit of the present invention;

[0015] Figure 2 is a schematic back view structure of a broadband filtering unit of the present invention;

[0016] Figure 3It is a schematic diagram of the connection relationship among the square reflector, the feeding balun, and the grounding support base;

[0017] Figure 4 It is a coupling schematic diagram of the third LC circuit;

[0018] Figure 5 It is a schematic diagram of the broadband filtering unit of the present invention used in the FDD array;

[0019] Figure 6 It is a schematic diagram of the broadband filtering unit of the present invention used in the FDD+TDD array;

[0020] Figure 7 It is a schematic diagram of the broadband filtering unit of the present invention nested in the MIMO array;

[0021] Figure 8 It is a high-frequency simulation result diagram of the broadband filtering unit of the present invention used in the FDD array;

[0022] Figure 9 It is a high-frequency simulation result diagram of the conventional non-filtering unit used in the FDD array. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative efforts belong to the scope of protection of the present invention.

[0024] A broadband filtering unit, as Figure 1 and Figure 2 shown, the broadband filtering unit consists of three parts, namely a square radiation surface 1 with ±45° dual polarization directions, a feeding balun 2 for PCB coupling feeding, and a grounding support base 3.

[0025] Both the front and back sides of the square radiation surface 1 are copper - clad. The copper - clad shape on the front is similar to four square structures 1A, 1B, 1C, and 1D combined together. Two square structures located on one diagonal form two oscillator arms in one polarization direction, and two square structures located on the other diagonal form two oscillator arms in the other polarization direction. The middle part of each oscillator arm is completely hollowed out, and the actual width of most of the copper - clad area is only 0.8 mm. There are 3 LC circuits on the oscillator arms. Among them, the first LC circuit 1a and the second LC circuit 1b are placed directly above the square radiation surface 1, and their shape is similar to a semi - closed rectangle. A completely closed rectangle can produce a capacitance effect, while a semi - closed rectangle can produce a capacitance effect on the one hand and provide an inductance effect for the third LC circuit 6a on the other hand. The capacitance of the third LC circuit 6a is formed by the coupling of the corner 1c set on the front of the square radiation surface 1 and the corresponding L - shaped copper - clad strips 5a, 5b, 5c, 5d set on the back. At the same time, the third LC circuit 6a forms a capacitance - inductance connection with the other two LC circuits, so as to achieve a filtering effect. The schematic diagram of the third LC circuit 6a is as Figure 4 shown.

[0026] There are also 2 open - circuit filter stubbs 2a, 2b on the oscillator arms of the square radiation surface 1. Their lengths are close to one - quarter wavelength of the filtered frequency band, which can further enhance the filtering performance of the oscillator, so as to meet the filtering performance in a wider frequency band.

[0027] On the back of the square radiation surface 1, there is a copper - clad area 4a in the shape of a square ring structure. The inside of the square ring structure is completely hollowed out, and the actual line width is only 0.8 mm. The square ring structure can couple the energy of 4 square oscillator arms, so as to form a current loop to extend the electrical length of the oscillator. The longer the electrical length of the oscillator, the wider the bandwidth it satisfies. Therefore, under the action of the square ring structure, the filtering unit described in the present invention can increase the relative bandwidth by 40%.

[0028] As Figure 3 shown, the middle position at the bottom of the square radiation surface 1 is connected to the feeding balun 2. The feeding balun 2 feeds the square radiation surface 1 and plays a supporting role. In this embodiment, the part of the oscillator arm at the middle position of the square radiation surface 1 is connected to the feeding balun 2, and this part is a corner structure formed by the sequential connection and integral setting of three triangular - like structures. Among them, the middle triangular structure 3a aims to increase the feeding pad to ensure the integrity of the structural process. The two connected triangular structures 3b, 3c aim to form a resonant cavity to reduce the return loss of the oscillator. The feeding balun 2 is made of a PCB double - sided copper - clad material. One side is a microstrip line for impedance matching, and the other side is a grounding sheet. Below the feeding balun 2 is a grounding support 3. The grounding support 3 is placed on the reflector of the antenna and forms a coupled grounding method with the reflector.

[0029] Figure 5 This is a schematic diagram of the broadband filtering unit in the present invention used in an FDD antenna. Due to the effect of the multiple filtering structures on the oscillator arms, when combined with other arrays, a special-shaped arrangement can be adopted, and the relative position with other arrays can also be appropriately adjusted by dimensions.

[0030] Figure 6 、 Figure 7 These are respectively schematic diagrams of the broadband filtering unit in the present invention used in FDD+TDD and FDD+MIMO to form a 4G+5G dual-system integrated antenna. After the integration of the 4G+5G dual systems, the quality and capacity of 5G coverage can be further improved, as well as the user experience.

[0031] Figure 8 and Figure 9 These are array simulation diagrams of using the broadband filtering unit and the conventional non-filtering unit of the present invention. The simulation results show that under the effect of the filtering unit in the present invention, the average gain of the high-frequency array is higher than the conventional gain, and the beam convergence is better.

[0032] In summary, the present invention is used in a multi-frequency multi-array combined antenna, which can well avoid interference with adjacent arrays. Its special multiple filtering structure can adapt to various special-shaped arrays, effectively reduce the antenna size, improve the performance of the antenna interleaved array, and has a simple structure, convenient installation and low cost.

[0033] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broadband filter unit comprising a ground support, a feed balun, and a square radiating surface with ±45° dual polarization directions, characterized in that: The front and back surfaces of the square radiating surface are both copper-clad, wherein the copper-clad front surface is shaped like four square structures combined together, and the two square structures located on the diagonal constitute two dipole arms in one polarization direction, and the middle position of each dipole arm is completely hollowed out. The dipole arm is composed of multiple LC circuits connected in series, and multiple open-circuit filter branches are also provided on the dipole arm. A feed balun for feeding and supporting the square radiating surface is connected to the middle position of the bottom of the square radiating surface, and the free end of the feed balun is connected to the ground support base. By adjusting the position of the multiple LC circuits on the square radiating surface and the length of the open-circuit filter branches, expansion and filtering of different frequency bands can be achieved; The copper clad shape on the back of the square radiating surface is a square ring structure, the interior of the square ring structure is hollowed out, and is used to couple the energy of the four vibrator arms, thereby forming a current loop to extend the electrical length of the vibrator; the number of LC circuits is three, namely the first LC circuit, the third LC circuit, and the second LC circuit connected in sequence. The first LC circuit and the second LC circuit have the same structure and are both semi-closed rectangular structures. The third LC circuit is formed by coupling the corners used to connect the first LC circuit and the second LC circuit and the L-shaped copper clad strip arranged on the back of the square radiating surface. The third LC circuit forms a capacitor-inductor connection with the first LC circuit and the second LC circuit, thereby achieving a filtering effect.

2. The broadband filter unit according to claim 1, characterized in that: The part of the dipole arm located in the middle of the square radiation surface is connected to the feeding balun, and this part is an angular structure formed by three triangular-like structures connected in sequence and arranged as an integral whole. Among them, the triangular-like structure located in the middle is used to enlarge the feeding pad and connect to the feeding balun, and the two triangular-like structures located at both ends are used to form a resonant cavity to reduce the return loss of the dipole.

3. The broadband filter unit according to claim 2, characterized in that: The feed balun is made of double-sided copper-clad PCB material, one side of which is provided with an impedance-matching microstrip line, and the other side is provided with a grounding plate.

4. The broadband filter unit according to claim 1, wherein: The length of the open-circuit filter branch is close to a quarter of the wavelength of the filtered frequency band.

5. An antenna array, characterized in that: The invention comprises an antenna array and the broadband filter unit as claimed in claim 1, wherein the ground support base provided on the broadband filter unit is placed on the reflector of the antenna array and forms a coupling ground with the reflector.

6. The antenna array according to claim 5, wherein: The antenna array includes but is not limited to FDD antennas, FDD+TDD antennas and FDD+MIMO antennas.

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