Structure and method for improving cross polarization discrimination rate of dual-linear polarization base station antenna

Abstract

The invention relates to a structure and method for improving the cross polarization discrimination rate of a dual-linear polarization base station antenna. The structure comprises a radiation unit, a folding arm, a parasitic patch unit, a feed balun structure, an SMA connector, a parasitic radiation unit and a supporting structure. The radiation unit comprises two pairs of rhombic half-wavelength metal radiators which are orthogonally arranged, are supported by a dielectric plate and are fed through a quarter-wavelength balun; the folding arms are formed by vertically folding the two ends of the two pairs of rhombic radiators; the parasitic patch unit is a metal plane on the dielectric plate and is fixed at a proper position through the dielectric plate; the feed balun structure is manufactured on the dielectric plate as a feeder and is connected with the SMA connector; the parasitic radiation unit is a metal plane, is supported by a dielectric plate, and is fixed at a specific position through a dielectric bracket. The parasitic radiation element is loaded around the original antenna, so that the phenomenon that the cross polarization discrimination of the original antenna becomes poor along with the increase of the frequency is improved on the premise that other performances of the original antenna are not influenced.

Description

Technical Field

[0001] The present application relates to the technical field of antennas, and in particular to a structure and method for improving the cross-polarization discrimination rate of a dual-polarization base station antenna. Background Art

[0002] The history of base station antennas can be traced back to the early 20th century. The earliest base station antenna was proposed by John Robert Ruess, an American radio engineer in the 1920s. During this period, he developed the first generation of wireless communication systems that used base station antennas to transmit signals.

[0003] Base station antenna technology has continued to develop over time. In the 1950s, with the development of microwave communications, the use of base station antennas gradually became popular. In the 1960s, with the emergence of mobile communication technology, the design and manufacture of base station antennas were further improved.

[0004] In the 1980s, the emergence of the second generation mobile communication system (2G) led to a significant increase in the demand for base station antennas. During this period, the design of base station antennas began to focus on coverage and signal quality. In the 1990s, the emergence of the third generation mobile communication system (3G) further promoted the development of base station antenna technology. The design of base station antennas began to use more efficient materials and more advanced technologies to improve the quality and efficiency of signal transmission.

[0005] Entering the 21st century, the emergence of the fourth generation mobile communication system (4G) and the fifth generation mobile communication system (5G) has brought base station antenna technology into a new stage of development. Modern base station antennas are not only required to have a wider coverage range and higher signal quality, but also to be able to support higher data transmission rates. In order to meet these requirements, the design and manufacturing technology of base station antennas are constantly innovating, using more advanced materials and technologies.

[0006] In modern communication systems, especially MIMO (Multiple Input Multiple Output) technology and 5G networks, the polarization diversity and high XPD of antennas are becoming increasingly important. Dual-polarized antennas can receive horizontal and vertical polarization signals at the same time, increasing channel capacity and data transmission rate. In mobile communication base stations, high XPD antennas can improve network coverage and user experience.

[0007] The cross-polarization discrimination rate XPD refers to the ratio of the main polarization component of the channel to the cross-polarization component generated by another channel in the channel. It is used to measure the size of the cross-polarization component. Simply put, it is the extent to which the antenna can distinguish and eliminate the interference of different polarization signals. A high XPD value means that the antenna can better filter out non-target polarization signals, thereby improving the clarity and quality of the signal.

[0008] Cross-polarization discrimination (XPD) is particularly critical in antenna systems. Studies have pointed out that there is a great relationship between XPD and channel performance. Studies have shown that the higher the XPD level of the ±45° dual-polarized antenna pair, the higher the channel throughput. In large-scale cellular networks, high XPD can optimize the capacity of the antenna system, support more user devices to connect simultaneously, and improve the efficiency of the overall network.

[0009] Therefore, many methods have been proposed in previous studies to improve the cross-polarization of base station antennas, such as improving cross-polarization by folding the current on the arm or by loading some parasitic elements. However, these studies mainly involve general base station antennas, and rarely mention the change of cross-polarization with frequency. Summary of the invention

[0010] The technical problem to be solved by the present invention is to propose a structure and method for improving the cross-polarization discrimination rate of a dual-polarization base station antenna. The antenna achieves improvement of cross-polarization at different frequencies through parasitic radiation units loaded around it.

[0011] In order to solve the above technical problems, the present invention provides a structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna, comprising a radiating unit, a folding arm, a parasitic patch unit, a feeding balun structure, an SMA connector, a parasitic radiating unit and a supporting structure;

[0012] The radiation unit includes two pairs of orthogonally placed rhombus half-wavelength radiators, the radiation unit is supported by a dielectric plate and fed by a quarter-wavelength balun structure;

[0013] The folded arm is produced by folding the two ends of the rhombus half-wavelength radiator; the parasitic patch unit is a metal plane fixed by the dielectric plate, and is placed above the radiating unit through the dielectric plate;

[0014] The balun structure couples and feeds the radiation unit through the dielectric plate support, and the bottom end thereof passes through the metal floor and is connected to the inner conductor of the connector; the inner conductor of the SMA connector passes through the central circular hole of the metal bottom plate and is connected to the balun structure, and the outer conductor of the SMA connector is connected to the metal floor;

[0015] The parasitic radiation unit is attached to the supporting structure and fixed around the antenna through the supporting structure.

[0016] In a preferred embodiment: the base station antenna has two ports, each port excites a pair of rhombus half-wavelength radiators;

[0017] The two pairs of rhombus-shaped half-wavelength radiators radiate ±45° dual-linear polarized waves.

[0018] In a preferred embodiment, the input impedance of the feeding port can be changed by adjusting the balun structure.

[0019] In a preferred embodiment: the parasitic radiation unit acts as a parasitic element to generate a parasitic current;

[0020] By controlling the amplitude and phase of the parasitic current generated by the parasitic element, the cross-polarization discrimination rate is improved.

[0021] In a preferred embodiment: the parasitic radiation unit is wound with equivalent inductance and introduces distributed capacitance at both ends, so that the amplitude of the parasitic current generated by the parasitic element can achieve the required size at different frequencies.

[0022] In a preferred embodiment: the parasitic radiation unit is placed at a position that controls the phase of the parasitic current generated by the parasitic element.

[0023] The present invention also provides a method for improving the cross-polarization discrimination rate of a dual-line polarization base station antenna, comprising the following steps:

[0024] Step 1, using two pairs of orthogonally placed rhombus half-wavelength radiators, and feeding them respectively with two feeding baluns, the two pairs of radiators constitute a radiating unit; and forming a ±45° dual-linear polarized wave by virtue of their placement positions;

[0025] Step 2: introducing a folded arm and a parasitic patch unit into the designed radiation unit. The introduction of the folded arm and the parasitic patch unit requires adjusting the size of the antenna again.

[0026] Step 3, introducing a parasitic radiating unit around the antenna, adjusting the amplitude and phase of the generated parasitic current by changing the structure and position of the parasitic radiating unit; and improving the cross-polarization discrimination rate by using the generated parasitic current;

[0027] Step 4: According to the cross-polarization conditions at different frequencies, the winding wire is adjusted to be equivalent to inductances of different sizes, so that the parasitic elements show different trends with frequency changes;

[0028] Step 5: Test the above antenna using a vector network and a microwave darkroom

[0029] Compared with the prior art, the technical solution of the present invention includes the following beneficial effects:

[0030] 1. In terms of antenna structure, the base station antenna in the present invention is the first to find that when a dual-polarized dipole antenna has both folded arms and parasitic patch units, the cross-polarization discrimination rate will deteriorate with frequency. Folded arms and parasitic patches are commonly used structures for base station antennas and are often used to achieve miniaturization and broadband of base station antennas. The present invention can effectively improve the cross-polarization discrimination rate of the base station antenna with this structure.

[0031] 2. The present invention improves cross-polarization by introducing a parasitic radiation unit. This method can improve the cross-polarization discrimination rate without affecting the remaining radiation performance of the original antenna as much as possible.

[0032] 3. The special design of the parasitic radiation unit in the present invention makes the winding wire in the parasitic element equivalent to an inductor. According to the size of the equivalent inductance, different sizes of induced current are generated at different frequencies, thereby achieving wide-band cross-polarization improvement; the control of the parasitic current phase is achieved by selecting the position of the parasitic element.

[0033] 4. It has certain application value in base stations. The method and ideas for improving cross-polarization in this design are generally applicable to improving cross-polarization of base station antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a three-dimensional splitting schematic diagram of the original dual-linear polarization base station;

[0035] Figure 2 It is a three-dimensional assembly diagram of the original dual-linear polarization base station;

[0036] Figure 3-Figure 4 It is a side schematic diagram of the original dual-linear polarization base station;

[0037] Figure 5 It is a schematic diagram of loading a parasitic radiation element around an original dual-linear polarization base station proposed by the present invention;

[0038] Figure 6 is a structural diagram of a parasitic radiation element proposed by the present invention;

[0039] Figure 7 - Figure 9 is a performance diagram of the antenna in the present invention;

[0040] Fig.10 It is a schematic diagram of loading parasitic radiation elements around the original dual-polarization base station for array proposed by the present invention. DETAILED DESCRIPTION

[0041] In order to make the technical solutions and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0042] The purpose of the present invention is to improve the cross-polarization discrimination rate of a dual-polarization base station antenna, and proposes a method of loading a parasitic radiating element around the original dual-polarization base station antenna, and improving the cross-polarization discrimination rate at different frequencies based on the parasitic current generated by the parasitic radiating element; the original dual-polarization base station antenna uses two ports to respectively excite a pair of half-wavelength rhombus radiators, thereby realizing dual polarization; in addition to the basic radiating unit, a folding arm and a parasitic patch unit are also loaded, thereby realizing the miniaturization and wide bandwidth of the antenna, but loading these two structures at the same time makes the original antenna appear with the increase of frequency, the cross-polarization discrimination rate of the phenomenon of obvious deterioration; for this reason, we load the parasitic radiating element around the original antenna, adjust the position and structure of the parasitic element, obtain the desired parasitic current amplitude at different frequencies, and finally improve the cross-polarization discrimination rate of the original antenna through the generated parasitic current.

[0043] To achieve the above object, the present invention adopts the following technical solution.

[0044] 1) Preparation: The main part of the base station antenna is formed by the metal surface fixed on the dielectric plate, and the structure of the entire base station antenna is also supported by the dielectric plate, such as Figure 1 In addition, the support and body of the parasitic radiating element can be seen Figure 5 11 and 12 are supported by 3D printing medium material and copper clad plate etching; the base station antenna feed connection adopts SMA connector welding. Finally, all parts of the base station antenna are assembled to obtain the final dual-polarization quadrifilar helical antenna.

[0045] 2) Design aspect: The design method of the present invention comprises the following steps:

[0046] Step 1, using two pairs of orthogonally placed rhombus half-wavelength radiators, and feeding them respectively with two feeding balun structures 2, wherein the two pairs of rhombus half-wavelength radiators constitute a radiation unit 5; and forming a ±45° dual-linear polarization wave by virtue of their placement position;

[0047] Step 2, introducing the folded arm 4 and the parasitic patch unit 5 into the designed radiation unit, the introduction of the folded arm 4 and the parasitic patch unit 5 requires the size of the antenna to be adjusted again; miniaturization of the base station antenna is achieved with the help of the folded arm 2; broadband of the base station antenna is achieved with the help of the parasitic patch unit 5;

[0048] Step 3, introducing a parasitic radiation unit 12 at an appropriate position around the antenna, adjusting the amplitude and phase of the generated parasitic current by changing the structure and position of the parasitic radiation unit 12; and improving the cross-polarization discrimination rate by using the generated parasitic current;

[0049] Step 4: According to the cross-polarization situation at different frequencies, the winding wire is adjusted to be equivalent to inductance of different sizes, so that the parasitic elements show different trends with frequency changes, so as to better adapt to the change of the original cross-polarization discrimination rate with frequency. The specific structure can be seen Figure 6 ;

[0050] Step 5: Use a vector network and a microwave darkroom to test the above antenna, wherein the waveguide is designed and simulated using HFSS simulation software.

[0051] Specifically, the present invention provides a dual-polarized base station antenna loaded with a parasitic radiation unit, with a center frequency of 3.5 GHz. The base station antenna is mainly composed of a radiation unit and a loaded folding arm, a parasitic patch unit, etc. Its metal surface is bonded to a dielectric plate and supported by the dielectric plate. The parasitic radiation unit is prepared by etching a copper-clad plate, and its support structure is completed by 3D printing, and finally all parts are assembled to form a final antenna. The specific design steps are as follows:

[0052] For the original base station antenna structure, please refer to Figure 1 , Figure 1 The figure is a three-dimensional structural section diagram of a dual-polarization base station antenna. 1 in the figure is the connection between the SMA port and the antenna's feed balun structure, and the two are connected by welding;

[0053] 2 is a quarter-wavelength balun structure, which feeds the antenna through coupling, and the balun structure can be adjusted to adjust the input impedance of the antenna; 5 is the basic radiation unit of the antenna, which is composed of two pairs of half-wavelength rhombus radiators. By exciting the two pairs of radiators separately, two polarizations of ±45° can be achieved respectively; 4 is the folding arm of the antenna, which is formed by folding the two ends of the rhombus radiator. This structure can well reduce the size of the antenna and also adjust the cross-polarization of the antenna; 6 is the parasitic patch unit of the antenna, and the bandwidth of the antenna can be greatly improved by loading a parasitic patch above the antenna; all of the above units are attached to the dielectric plate as shown in 3, and the dielectric plate is used as the support of the antenna.

[0054] See also Figure 2 , Figure 2 The three-dimensional structure of the original dual-polarization base station antenna is Figure 1 After the various parts of the base station antenna shown are assembled, the resulting base station antenna structure is shown in the figure.

[0055] See also Figure 3-Figure 4 , Figure 3 and Figure 4 It is a side view of the original base station antenna, where 7 and 9 represent two ports, and 8 and 10 represent two feeding baluns.

[0056] See also Figure 5 , Figure 5The dual-polarized base station antenna loaded with parasitic radiation units has a structure as follows: Figure 1 As shown, the parasitic radiation unit 12 is fixed at an appropriate position around the antenna by a 3D printed support structure 11.

[0057] See also Figure 6 , Figure 6 It is the structure of the parasitic radiation unit. The parasitic radiation element can be obtained by etching the copper clad board. Figures 13 and 14 show the metal surface and the dielectric, respectively. In order to make the induced current generated by the parasitic radiation element have different performances as the frequency changes, we used the winding wire shown in 15 as the equivalent inductance when designing the component.

[0058] For antenna performance graphs, see Figure 7 -Figure 9.

[0059] Figure 7 is a performance diagram of the proposed inventive antenna within the operating frequency band. Figure 7 It is the S parameter of the antenna. The impedance bandwidth below -10dB is 3.15-3.82GHz (19.2%), and the isolation within the band is less than -30dB.

[0060] Figure 8 The main polarization and cross-polarization E-plane radiation patterns (+45° linear polarization) of the original base station antenna at different frequencies when no parasitic radiation elements are loaded. As the frequency increases from 3.2GHz to 3.8GHz, the cross-polarization also increases significantly, which greatly affects the performance of the antenna. Since the antenna structure is roughly symmetrical, the H-plane radiation pattern of the antenna and the -45° linear polarization results are also similar to those in the figure.

[0061] Figure 9 is a comparison of the E-plane radiation patterns of the +45° linearly polarized antenna with and without loaded parasitic radiating elements at 3.2 GHz (Figure a), 3.5 GHz (Figure b), and 3.8 GHz (Figure c). It can be seen that due to the loading of the parasitic radiating element, the cross-polarization of the antenna is improved at different frequencies, especially at 3.8 GHz, where the cross-polarization of the antenna is significantly reduced by loading the parasitic radiating element.

[0062] See also Fig.10 , Fig.10 The application of the proposed dual-polarization base station antenna loaded with parasitic radiation units in the array is similar to the effect in a single antenna. After the parasitic radiation elements are loaded into the array, the cross-polarization discrimination rate of the array at different frequencies will also be improved.

[0063] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna, characterized in that: It includes a radiation unit, a folded arm, a parasitic patch unit, a feeding balun structure, an SMA connector, a parasitic radiation unit and a supporting structure; The radiation unit includes two pairs of orthogonally placed rhombus half-wavelength radiators, the radiation unit is supported by a dielectric plate and fed by a quarter-wavelength balun structure; The folded arm is produced by folding two ends of the rhombus half-wavelength radiator; The parasitic patch unit is a metal plane fixed by the dielectric plate and is placed above the radiation unit through the dielectric plate; The balun structure couples and feeds the radiation unit through the dielectric plate support, and the bottom end thereof passes through the metal floor and is connected to the inner conductor of the connector; the inner conductor of the SMA connector passes through the central circular hole of the metal bottom plate and is connected to the balun structure, and the outer conductor of the SMA connector is connected to the metal floor; The parasitic radiation unit is attached to the supporting structure and fixed around the antenna through the supporting structure.

2. The structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna according to claim 1, characterized in that: The base station antenna has two ports, each port excites a pair of rhombus half-wavelength radiators; The two pairs of rhombus-shaped half-wavelength radiators radiate ±45° dual-linear polarized waves.

3. The structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna according to claim 1, characterized in that: The input impedance of the feeding port can be changed by adjusting the balun structure.

4. The structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna according to claim 1, characterized in that: The parasitic radiation unit acts as a parasitic element to generate a parasitic current; By controlling the amplitude and phase of the parasitic current generated by the parasitic element, the cross-polarization discrimination rate is improved.

5. The structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna according to claim 4, characterized in that: The parasitic radiation unit is wound with equivalent inductance and introduces distributed capacitance at both ends, so that the amplitude of the parasitic current generated by the parasitic element can achieve the required size at different frequencies.

6. The structure for improving the cross-polarization discrimination rate of a dual-polarization base station antenna according to claim 4, characterized in that: The parasitic radiation unit is placed at a position that controls the phase of the parasitic current generated by the parasitic element.

7. A method for improving the cross-polarization discrimination rate of a dual-polarization base station antenna, characterized in that: The following steps are involved: Step 1, using two pairs of orthogonally placed rhombus half-wavelength radiators, and feeding them respectively with two feeding baluns, the two pairs of radiators constitute a radiating unit; and forming a ±45° dual-linear polarized wave by virtue of their placement positions; Step 2: introducing a folded arm and a parasitic patch unit into the designed radiation unit. The introduction of the folded arm and the parasitic patch unit requires adjusting the size of the antenna again. Step 3, introducing a parasitic radiating unit around the antenna, adjusting the amplitude and phase of the generated parasitic current by changing the structure and position of the parasitic radiating unit; and improving the cross-polarization discrimination rate by using the generated parasitic current; Step 4: According to the cross-polarization conditions at different frequencies, the winding wire is adjusted to be equivalent to inductances of different sizes, so that the parasitic elements show different trends with frequency changes; Step 5: Use vector network and microwave darkroom to test the above antenna.

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