Filtering transmission array antenna and method for 5G millimeter wave system

Abstract

The invention belongs to the technical field of wireless communication, and discloses a filtering transmission array unit, an antenna and a design method thereof. The array unit comprises a receiving layer, a phase shift layer and a transmitting layer, the receiving layer and the transmitting layer are connected through the phase shift layer, the array antenna comprises a linear polarization feed source and a filtering transmission array unit, and the linear polarization feed source is located above the center of the transmission array unit; the design method comprises the following steps of: obtaining an upper sideband transmission zero point by using an SICL structure with a filtering function; meanwhile, a receiving and transmitting patch adopts a filtering micro-strip patch, and a lower sideband transmission zero point is introduced, so that the stable oblique incidence performance within a certain range is ensured while the filtering characteristic is realized, and the high-efficiency filtering transmission array antenna is realized. Then, a receiving antenna of the transmission array unit is rotated by 180 degrees, and 1-bit 0-degree and 180-degree quantization phases are generated before and after rotation; meanwhile, the size of a phase delay line in the phase shift layer is adjusted, and the 3-bit phase shift range is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communication technology, and is particularly applicable to 5G millimeter wave communication systems, and relates to a filtering transmission array unit, an antenna, and a design method thereof. Background Art

[0002] At present, wireless communication technology is developing rapidly, especially in 5G millimeter wave communication systems. In order to improve the performance of point-to-point communication, the demand for antennas with strong anti-interference ability and high gain is particularly prominent. The transmission array antenna is a high-gain antenna consisting of a feed horn and a transmission array. The transmission array is located in the far field area of ​​the feed, and a large number of independently phase-adjustable transmission array units are regularly arranged on the surface. The phase center of the feed radiates electromagnetic waves, which arrive at each unit of the array as a spherical wave. By accurately designing the phase distribution of the array unit, each unit provides an appropriate phase shift, so that the array aperture forms a plane phase wavefront, thereby generating a high-gain beam in a specific direction. The filtering function is integrated into the transmission array antenna design, so that the array unit can suppress electromagnetic signals outside the working frequency band, thereby effectively shielding the interference of out-of-band signals and improving the signal-to-noise ratio and sensitivity of the wireless communication system.

[0003] The filtered transmission array antenna has filtering characteristics and has the advantages of simple structure, low manufacturing cost, and no need for complex feeding network. It provides reliable technical support for advanced and low-cost wireless communication systems.

[0004] When designing a filter, the main technical indicators for reference are: bandwidth, return loss, insertion loss, out-of-band suppression level, and transition band roll-off level. The first three parameters are similar to the antenna reference technical indicators, while the last two indicators are not included in the antenna design, so they also need to be considered when designing a filter antenna. From the current research results, the design methods of filtered transmission array antennas are mainly divided into three categories: 1) based on multi-layer frequency selective surfaces 2) based on filter synthesis theory design method 3) fusion design. The above three design methods each have their own advantages and limitations. In different application scenarios, these methods can be flexibly selected to meet specific indicator requirements.

[0005] In 2023, Tian Hu and others designed a filter transmission array antenna operating at 5.8GHz. Through a laminated PCB design, the interdigital filter and the microstrip patch antenna were cascaded to obtain a 1-bit phase quantized filter transmission array antenna unit. However, due to the limitations of the filter structure itself, the working bandwidth of the antenna is very narrow, with a relative bandwidth of only 4.3%, and only 1-bit shift compensation capability. Therefore, after forming the antenna array, the measured gain of the antenna is 19.8dBi, and the measured aperture efficiency is low, only 22%.

[0006] In 2021, Peng-Yu Feng et al. proposed a filtering transmission array antenna operating at 10 GHz with high in-band gain and low out-of-band scattering characteristics. The filtering transmission array unit consists of a dual-polarization resistor layer, a band-stop frequency selective surface (FSS), and an adjustable bandpass FSS as a phase shifter. The transmission array unit has a transmission function within the passband, the measured transmission array gain is 25.3dBi, and the maximum aperture efficiency of the antenna is 4.9%. The out-of-band suppression level in the stopband is ≥25dB, and the scattering cross section (SCS) is reduced by about 8dBi in the 4-7GHz and 14-20GHz ranges.

[0007] In 2022, Huawei Lin proposed a dual-polarized magnetoelectric dipole frequency selective surface based on a split ring operating at 12 GHz. In this frequency selective surface structure, four split rings form a magnetoelectric dipole, which is fed through a cross gap in the ground. The purpose of introducing the split ring is to create a resonant zero point in the upper sideband, while the resonant zero point in the lower sideband is controlled by the length and spacing of the metal column. By controlling these variables, a third-order dual-polarized frequency selective surface with an incident angle stability of 40° and a measured insertion loss of 0.19 dB was achieved. Due to the introduction of the split ring, the unit needs to be made as small as possible, so the period of the frequency selective surface is only 0.12λ0. For higher frequency applications, this method is likely to make it impossible to process, and this frequency selective surface has no phase shifting function. This work has also been used in reflectarray antennas. FA1 is used as a reflectarray antenna unit to realize a 3-bit filtered reflectarray antenna operating at 12 GHz.

[0008] Through the above analysis, the problems and defects of the prior art are as follows:

[0009] (1) When designing a transmission array antenna, it is necessary to consider both the filtering performance and the phase shift of the transmission array antenna unit. However, it is complex and difficult to design both.

[0010] (2) The oblique incidence effect brought by the feeding method of the transmission array, grooving on the patch surface or adding too many parasitic branches will lead to high cross-polarization and large phase error, making the design ideas of this type of filtering antenna difficult to implement in the design of the transmission array.

[0011] (3) There is little research on the filter transmission array in the N257 frequency band in 5G communication systems, and the phase shift range of linear polarization transmission array antennas is small.

[0012] (4) Existing wide phase shift range filtering transmission array antenna units often require a high profile, which is not conducive to integration into miniaturized communication systems. Summary of the invention

[0013] In view of the problems existing in the prior art, the present invention provides a filtering transmission array unit, an antenna and a design method thereof.

[0014] First, the present invention is implemented as follows: for the filter transmission array unit, the filter transmission array unit includes a transmitting layer and a receiving layer, and there is a filter phase shift layer between the transmitting layer and the receiving layer; the antenna unit realizes phase shift by rotating the transmitting antenna in combination with changing the size of the phase delay line. For the filter transmission array antenna, according to the array surface phase distribution required by the center frequency point of the working frequency band of the receiving antenna, the arrangement of the antenna unit and the rotation angle of the receiving antenna are determined, and the size of the phase delay line is determined, thereby determining the complete structure of the final filter transmission array antenna.

[0015] Secondly, the transmitting layer is composed of the first metal layer, the first dielectric layer, the first bonding layer, and the metal hole; the receiving layer is composed of the fifth metal layer, the fourth dielectric layer, the third bonding layer, and the fourth metal layer;

[0016] The transmitting layer and the filtering phase shifting layer share the second metal layer as the floor. The receiving layer and the filtering phase shifting layer share the fourth metal layer. The radiation structure of the transmitting layer is located at the bottom of the first dielectric layer and is composed of the first metal layer; the radiation structure of the receiving layer is at the bottom of the fourth dielectric layer and is composed of the fifth metal layer. The two metal layers are a microstrip patch antenna with double T-shaped branches. By introducing the T-shaped branches, a pair of reverse currents are introduced, which destroys the basic TM01 working mode of the microstrip antenna, making it impossible to generate radiation near this frequency point, thereby generating a transmission zero point. The receiving and transmitting patch adopts a filtering microstrip patch and introduces a lower sideband transmission zero point. While having filtering characteristics, it ensures the stability of the oblique incidence performance within a certain range, thereby realizing a high-efficiency filtering transmission array antenna.

[0017] Furthermore, the filtering phase shifting layer is composed of a second metal layer, a second dielectric layer, a second bonding layer, a third dielectric layer, a third bonding layer, a fourth metal layer, a third metal layer and metal pins. The positions of the metal pins are specially designed to ensure the stability of the upper sideband transmission zero point. The upper sideband transmission zero point obtained by using the SIW resonant cavity structure and the phase delay line structure can fill the phase as much as possible during filtering and increase the phase quantization bit number.

[0018] Another object of the present invention is to provide an antenna based on the filtering transmission array unit, the antenna comprising a linearly polarized feed source and a filtering transmission array unit, the linearly polarized feed source being located above the center of the filtering transmission array unit, the filtering transmission array antenna being composed of N×N filtering transmission array units, N≥2 and being an integer.

[0019] Furthermore, the linear polarization feed source adopts a broadband corrugated horn antenna, and the radiation direction of the linear polarization feed source is toward the filtering transmission array unit.

[0020] Another object of the present invention is to provide a method for designing the antenna, the method comprising the following steps:

[0021] Step 1: Rotate the receiving antenna in the transmission array unit by 180° to obtain state 0 and state 1, and generate two quantized phases of 0° and 180° of 1-bit before and after the rotation;

[0022] Step 2: adjust the size of the phase delay line in the filter transmission array unit to generate a continuous phase shift of 0°-135°. Step 2 is combined with step 1 to achieve a 3-bit phase shift.

[0023] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0024] First, the upper sideband transmission zero point is obtained by using the SICL structure with filtering function to fill the phase as much as possible while filtering, thereby increasing the number of phase quantization bits. At the same time, the receiving and transmitting patches use filtering microstrip patches to introduce lower sideband transmission zero points. While having filtering characteristics, the oblique incidence performance within a certain range is guaranteed to be stable, thereby realizing a high-efficiency filtering transmission array antenna. The phase shift of the transmission array unit in the present invention is achieved by changing the size of the phase delay line. The combination of these two methods with phase modulation not only simplifies the unit design process and reduces the difficulty of unit structure design, but also can realize a transmission array antenna with stable filtering characteristics and high aperture efficiency.

[0025] The present invention uses only one transmission array unit with the same structure, and the profile is low, which is 0.139λ 28 (λ 28 Indicates the wavelength of an electromagnetic wave with a frequency of 28 GHz); the present invention realizes filtering characteristics, and the working frequency band of the antenna is 27-29.5 GHz, which can meet the requirements of 5G millimeter wave frequency band communication technology in this frequency band and has strong application value. The gain of the antenna of the present invention at 28 GHz is 25.9 dBi, and the aperture efficiency is 62.13%. Both are higher than the above-mentioned designs, which improves the communication quality.

[0026] Second, the present invention proposes a filtering transmission array antenna. Compared with the existing wide phase shift range filtering transmission array antenna, the antenna array of the present invention has a low profile and only uses one unit to form the array, so that the transmission array antenna can achieve the filtering function; compared with the 2-bit filtering transmission array antenna, the present invention achieves a 3-bit phase shift range while ensuring the filtering performance, reduces the phase error caused by the quantized phase of the 2-bit transmission array antenna, and improves the aperture efficiency of the filtering transmission array antenna. The present invention has the advantages of low cost and high aperture efficiency, higher performance and better applicability, and has a wide range of application scenarios in the field of high-performance communications in the 5G millimeter wave frequency band.

[0027] Third, the technical solution of the present invention fills the technical gaps in the industry at home and abroad: 1) In the same industry at home and abroad, there are patents and papers that propose antennas with transmission characteristics with filtering performance. In order to ensure the filtering performance, the units of these antennas adopt a method of combining filtering structure with receiving and transmitting antennas, but this type of method leads to a small unit phase shift range, which in turn leads to low aperture efficiency of the antenna, which is not conducive to the performance of actual products. There are also studies using the cut-off characteristics of waveguides to make filtering transmission array antennas, but this method will lead to the disadvantage of high profile. The filtering transmission array antenna proposed in the present invention is arranged according to the phase distribution of the center frequency point, and 3bit phase shift is achieved by rotating the transmitting antenna and changing the size of the phase delay line. In addition, the working mode of double-sideband filtering is realized by only one unit, without the need for additional unit design. The phase compensation strategy and antenna unit structure proposed in the present invention have filled the current technical gap in the industry. 2) For the current filtering transmission array antenna, there is little research in the millimeter wave frequency band. The transmission array antenna designed by the present invention has an operating frequency of 28.5GHz, which is sufficient to meet the needs of 5G millimeter wave frequency band communication technology in this frequency band, filling the current gap in this regard in the industry.

[0028] Fourth, significant technological advances in filtering transmission array units and antennas:

[0029] 1) Flexibility in phase control: By changing the size of the phase delay line and rotating the transmitting antenna, this design can achieve more flexible phase control, and the resulting pen tip beam wave has concentrated energy, which is very useful for point-to-point communication systems.

[0030] 2) Stable filtering performance: This design maintains the stability of the transmission zero points of the upper and lower sidebands while shifting the phase, thereby achieving a more comprehensive and stable filtering performance.

[0031] 3) Wide phase compensation range: By modifying the size of the phase delay line and rotating the transmitting antenna, 3-bit phase compensation is achieved, avoiding the use of multiple units to achieve phase compensation, while reducing the size and weight of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a three-dimensional structure of a filtering transmission array unit provided in an embodiment of the present invention;

[0033] Figure 2The layers are: 1. First metal layer; 2. Metal holes; 3. First dielectric layer; 4. First bonding layer; 5. Second metal layer; 6. Second dielectric layer; 7. Second bonding layer; 8. Third dielectric layer; 9. Third bonding layer; 10. Fourth metal layer; 11. Third metal layer; 12. Metal pins; 13. Fourth dielectric layer; 14. Metal holes; 15. Fifth metal layer. There is a circle of metal holes between the second metal layer and the fourth metal layer.

[0034] Figure 2 In (b), 1 and 15 are two different states of the filter transmission array unit structure provided in an embodiment of the present invention; (1) is a top view of the filter transmission array unit in state 0; (b) is a top view of the filter transmission array unit in state 1; 5, 10 and 11 are top views of the second metal layer, the fourth and the fifth metal layer, respectively.

[0035] Figure 3 The filter transmission array unit provided by the embodiment of the present invention has different lengths L 2 When , the simulation results of transmission amplitude and transmission phase are shown; (a) is the simulation result of transmission amplitude, and (b) is the simulation result of transmission phase;

[0036] Figure 4 It is a simulation result diagram of the transmission amplitude and transmission phase of the filtering transmission array antenna unit provided by the embodiment of the present invention to achieve 180° phase quantization;

[0037] Figure 5 is a diagram showing simulation results of transmission amplitude and transmission phase of a filtering transmission array unit transmitting antenna at different angles provided by an embodiment of the present invention;

[0038] Figure 6 is a schematic diagram of phase compensation of an antenna array at 28.5 GHz provided by an embodiment of the present invention;

[0039] Figure 7 1 is a top view of a linear polarization feed, an antenna array model and each layer structure provided by an embodiment of the present invention; wherein, (a) is an array structure diagram, 13 is a linear polarization feed; (b) is a top view of the third metal layer of the transmission array unit with the size corrected according to phase compensation; (c) is a top view of the second metal layer of the transmission array unit; (d) is a top view of the fourth metal layer of the array antenna; (e) is a top view of the first metal layer of the array; (f) is a top view of the fifth metal layer of the array after rotation according to phase compensation;

[0040] Figure 8 is a diagram of antenna return loss simulation results provided by an embodiment of the present invention;

[0041] Fig. 9 is a diagram of antenna gain and aperture efficiency simulation results provided by an embodiment of the present invention;

[0042] Fig.10 It is the simulated radiation pattern of the antenna provided by an embodiment of the present invention at 28 GHz; wherein, (a) is the E-plane simulated normalized radiation pattern of the antenna at 28 GHz; (b) is the H-plane simulated normalized radiation pattern of the antenna at 28 GHz. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] The following is a specific embodiment of the filter transmission array antenna:

[0045] Embodiment 1: High-efficiency filtering transmission array antenna based on linear polarization feed

[0046] 1. Target application: Design a filter transmission array unit covering a wide frequency band of 27 GHz to 29.5 GHz for point-to-point communication systems with anti-interference characteristics.

[0047] 2. Design parameters:

[0048] Working frequency band: 27GHz~29.5GHz;

[0049] Transmission array unit structure: unit side length is 5mm;

[0050] Array size: 15×15 cells;

[0051] Feed: Broadband linearly polarized horn antenna.

[0052] 3. Implementation process:

[0053] Double T-shaped branches are introduced in the transmitting and receiving antennas, and the transmission zero point is introduced at 24GHz by destroying the TM01 working mode to achieve efficient and stable filtering characteristics.

[0054] The phase shift layer adopts SIW resonant cavity and phase delay line structure, combined with metal pin design, to introduce upper sideband transmission zero at 31GHz to achieve upper sideband filtering performance. By combining the above two points, the designed filter transmission array unit has double sideband suppression performance.

[0055] The unit design achieves 1 bit (0° and 180°) of quantized phase by rotating the receiving antenna, and combines delay line adjustment to achieve an additional 2 bits of phase control, completing a total phase shift range of 3 bits.

[0056] 4. Simulation performance:

[0057] The insertion loss of the filter transmission array unit in the range of 27GHz to 29.5GHz is less than 1dB;

[0058] The gain of the array at each operating frequency is higher than 25dB, with a wide coverage and stable beam direction. At the same time, the selection performance SE is calculated to be 1.55, the maximum suppression of the lower sideband is 26.8dB, and the maximum suppression of the upper sideband is 26.18dB, which shows the stability and practicality of the design of the filter transmission array antenna.

[0059] Example 1 demonstrates the application of the filtered transmission array antenna in a point-to-point communication context, emphasizing the high efficiency and double-sideband filtering characteristics, and reflects the high performance characteristics and scenario applicability of this design.

[0060] like Figure 1 and Figure 2 As shown, the filter transmission array unit provided in the embodiment of the present invention includes an emission layer, a filter phase shift layer and a receiving layer. The emission layer of the filter transmission array unit is composed of a first metal layer 1, a first dielectric layer 3, a first bonding layer 5, and a metal hole 2; the receiving layer is composed of a fifth metal layer 15, a fourth dielectric layer 13, a third bonding layer 9, and a fourth metal layer 10;

[0061] The transmitting layer and the filtering phase shifting layer share the second metal layer 5 as the floor. The receiving layer and the filtering phase shifting layer share the fourth metal layer 10. The radiation structure of the transmitting layer is located on the top of the first dielectric layer 3 and is composed of the first metal layer 1; the radiation structure of the receiving layer is at the bottom of the fourth dielectric layer and is composed of the fifth metal layer 15. The two metal layers are a microstrip patch antenna with double T-shaped branches. By introducing the T-shaped branches, a pair of reverse currents are introduced, which destroys the basic TM01 working mode of the microstrip antenna, so that radiation cannot be generated near this frequency point, thereby generating a transmission zero point.

[0062] The filtering phase shifting layer is composed of a second metal layer 5 , a second dielectric layer 6 , a second bonding layer 7 , a third dielectric layer 8 , a third bonding layer 9 , a fourth metal layer 10 , a third metal layer 11 and metal pins 12 .

[0063] The third metal layer 11 is located above the third dielectric layer, and there is a circle of metal holes between the second metal layer and the fourth metal layer for electromagnetic shielding and introducing the transmission zero point of the upper sideband. The receiving layer antenna receives the electromagnetic wave of the feed source, transmits it to the phase shift layer through the metal column 14, and after the transmission phase is controlled by the phase delay transmission line, it is transferred to the transmitting layer by the metal column 2, and radiated to the free space by the microstrip patch antenna of the transmitting layer. By using the metal pin 12, the stability of the resonance point and the low insertion loss can be guaranteed as much as possible during the phase shift process, which is convenient for the overall optimization after connecting the transmitting and receiving parts. The metal pin 12 connects the second and fourth metal layers, and is located between the metal through hole 2 and the metal hole 14. The metal pin isolates the electric field between the two metal through holes and plays a role in impedance matching, which effectively improves the transmission coefficient in the SICL passband.

[0064] The transmitting layer antenna transmits linearly polarized electromagnetic waves, and the receiving layer antenna receives linearly polarized electromagnetic waves. The receiving layer antenna 15 has two states, state 0 and state 1. By adjusting the size of the phase delay line of the filter phase shift layer, a continuous 3-bit phase shift range can be achieved; the receiving antenna 15 is rotated 180°, and two 1-bit quantized phases of 0° and 180° can be generated before and after the rotation; together with the above method, a 3-bit phase shift range can be achieved, and the filtering performance is affected as little as possible within the phase shift range.

[0065] In the embodiment of the present invention, the outline of the filtering transmission array unit is rectangular.

[0066] The following is a detailed description of the working principle of the filter transmission array unit in four sections:

[0067] 1. Basic structure of filter transmission array unit and electromagnetic wave transmission path

[0068] The filtering transmission array unit includes three parts: the transmitting layer, the phase shifting layer and the receiving layer. The antenna structure of the receiving layer receives the linearly polarized electromagnetic waves emitted by the feed source, and the electromagnetic waves are transmitted to the phase shifting layer through the metal column 14 of the receiving layer. After precise phase control through the phase delay transmission line in the phase shifting layer, the electromagnetic waves are then transmitted to the transmitting layer by the metal column 2. The transmitting layer antenna re-radiates the regulated electromagnetic waves into the free space to achieve efficient signal transmission. Through this multi-layer structural design, the unit can simultaneously realize the reception, filtering, phase shifting and transmission functions of electromagnetic waves, and complete efficient control of electromagnetic waves.

[0069] 2. Filtering characteristics of double-T-shaped branch microstrip patch antenna

[0070] The microstrip patch antennas of both the transmitting and receiving layers are designed with double T-shaped branches. This design effectively destroys the TM01 working mode of the antenna foundation by introducing reverse current, making it impossible to generate electromagnetic radiation near a specific frequency point, thereby realizing the introduction of transmission zeros. The transmission zero effectively suppresses unnecessary frequency band signals through filtering function, ensuring the purity of the spectrum of electromagnetic wave transmission. On this basis, the receiving patch antenna also introduces the lower sideband transmission zero point, which further improves the filtering effect and enhances the stability of the oblique incidence performance, ensuring that it can still maintain high efficiency under electromagnetic wave incidence at different angles.

[0071] 3. Electromagnetic characteristics of the filter phase shift layer and upper sideband transmission zero point control

[0072] The filtering phase shifting layer is composed of a multilayer structure including a second metal layer, a third metal layer and a fourth metal layer, and a metal pin 12 is introduced to optimize the electromagnetic characteristics. The metal pin is located between the metal through hole 2 and the metal hole 14, and is used for electric field isolation and impedance matching, which significantly improves the insertion loss during the transmission process, while ensuring the transmission coefficient within the SICL passband. The filtering phase shifting layer also introduces the upper sideband transmission zero point by combining the SIW (substrate integrated waveguide) resonant cavity structure and the phase delay line structure. In the process of phase shifting, the phase shifting layer further stabilizes the upper sideband transmission zero point of the antenna and improves the filtering performance of the filtering transmission array unit.

[0073] 4. Controllable phase shift function and 3-bit phase shift range

[0074] After rotating 180°, the receiving layer antenna can switch to state 0 and state 1, corresponding to quantized phases of 0° and 180° respectively; at the same time, by adjusting the size of the phase delay line in the phase shift layer, a continuous phase shift of 0° to 135° can be achieved. Combining the above rotation and phase delay line adjustment, a total phase shift control range of 3 bits can be achieved. Through optimized design, the filter transmission array unit can provide high phase shift accuracy while minimizing the impact of the phase shift process on the filtering performance, ensuring spectrum purity and transmission efficiency. This design method that combines rotation and phase delay control gives the array unit high flexibility and precise phase control capabilities.

[0075] The filter transmission array unit realizes the reception, filtering, phase shifting and transmission functions of electromagnetic waves by rationally designing the transmitting layer, phase shifting layer and receiving layer. By utilizing the filtering characteristics of the double T-shaped branch microstrip antenna, the phase shifting performance optimized by the metal pins and the efficient control capability of the 3-bit phase shift range, the unit can still maintain excellent performance in complex electromagnetic environments and meet the application requirements of high-efficiency filter transmission array antennas.

[0076] The present invention provides an antenna for a filtering transmission array unit of a 5G millimeter wave communication system, comprising an antenna composed of a linearly polarized feed source 16 and a dual-frequency dual circularly polarized transmission array unit, wherein the linearly polarized feed source 16 is located above the center of the dual-frequency dual circularly polarized transmission array antenna, and the filtering transmission array antenna is composed of N×N filtering transmission array units, where N≥2 and is an integer. In this embodiment, the number of transmission arrays used is 15×15.

[0077] The linear polarization feed source 16 adopts a broadband corrugated horn antenna, and the radiation direction of the linear polarization feed source 13 is toward the transmission array antenna.

[0078] The present invention also provides a dual-frequency dual circular polarization transmission array antenna phase compensation method for a 5G millimeter wave communication system, comprising the following steps:

[0079] Step 1: Rotate the receiving antenna 2 in the dual-frequency dual circular polarization transmission array unit by 180°, and generate two 1-bit quantized phases of 0° and 180° before and after the rotation;

[0080] Step 2: The transmission array antenna unit of the present invention uses a structure to achieve dual-band operation, and the unit needs to be considered during phase compensation.

[0081] Figure 3 The total length L of the phase delay line of the antenna unit of the present invention is given. 2 The transmission amplitude and phase change range when the transmission line length increases from 3.87mm to 6.04mm can be seen that the transmission coefficient is less than -1dB in the passband, and the phase shift range is 0°-135°. During the phase shift process, the zero point of the lower sideband is stable at 24GHz, while the upper sideband changes the spatial dimensions inside the cavity due to the limitation of the phase shift structure, causing a certain degree of shift in the resonant frequency. Due to the special feeding structure of the transmission array, the feeding of the transmission array is equivalent to an amplitude weighting. The units with a larger weight ratio are distributed in the central part of the array. The unit phase distribution in the central part of the antenna is basically in the range of 0°-90°. During the phase shift process, the upper sideband transmission zero point of this part of the units is relatively stable at around 31GHz. The weight ratio of the remaining phase units is relatively low, so it has little impact on the performance of the array. Therefore, it can be predicted that the zero point of the upper sideband of the array will stably appear at 31GHz.

[0082] Figure 4 The comparison of the transmission performance and phase change of the antenna unit after the receiving antenna of the antenna unit of the present invention is given after the receiving antenna is reversed by 180°. It can be seen from the figure that the transmission amplitude of the receiving antenna is almost unchanged in the two states of state 0 and state 1, while the phase difference is 180°. That is, 1-bit quantized phases of 0° and 180° are obtained. The transmission zero point of the upper sideband is slightly moved by 0.2GHz to the low frequency, and the transmission zero point of the lower sideband remains unchanged.

[0083] Figure 5 The effects of different angles of incidence on the unit under oblique incidence on the E-plane are given. When the incident angle is less than 30°, there is no obvious change in the unit transmission performance within the passband, while the transmission zero point of the lower sideband is slightly offset. The upper sideband transmission zero point is generated by the cavity of the transmission structure, so it remains stable and does not move. From the phase point of view, the transmission phase within the passband hardly changes. Figure 5 From the analysis, it can be seen that the performance of this unit is very stable within the 30° oblique incidence range on the E plane.

[0084] Figure 6 The phase distribution diagram required by the antenna array of the present invention is given. Through the phase distribution diagram, the arrangement of antenna units on the array surface can be obtained.

[0085] Figure 8 The simulation result diagram of the return loss of the antenna of the present invention is given, and it can be seen that the return loss of the antenna of the present invention is greater than 10dB in the frequency band of 26.5GHz-29.5GHz.

[0086] Fig. 9 The simulation results of the antenna aperture efficiency and gain are given. The maximum gain of the antenna is 25.9dBi, and the maximum aperture efficiency of the antenna is 62.13%. At this time, the upper sideband transmission zero point appears at 31GHz, proving that Figure 3 The prediction result is correct. At the same time, the selection performance SE is calculated to be 1.55, the maximum suppression of the lower sideband is 26.8dB, and the maximum suppression of the upper sideband is 26.18dB, which shows the stability and practicality of the filtering transmission array antenna designed in this paper. In addition, compared with the literature mentioned above, the aperture efficiency of the antenna designed in this paper is greater than the antenna proposed in the literature.

[0087] The array unit of the present invention includes a receiving antenna and a transmitting antenna, and the receiving antenna and the transmitting antenna are connected through a filtering phase shift layer. The array antenna includes a linear polarization feed source and a filtering transmission array unit, and the linear polarization feed source is located above the center of the transmission array unit; the design method is: rotate the receiving antenna of the transmission array unit 180°, and generate 1-bit 0° and 180° two quantized phases before and after the rotation; at the same time, adjust the length of the phase delay line. The above method can achieve a 3-bit phase shift range. The filtering transmission array antenna of the present invention has the advantages of low profile, filtering, and high aperture efficiency. Such a filtering transmission array antenna can meet the development needs of millimeter wave frequency band communications. The present invention reduces the profile height of the filtering transmission array antenna, has a compact structure, and improves the antenna aperture efficiency. It can be applied to miniaturized and integrated communication systems.

[0088] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A filter transmission array unit, characterized in that: It includes a transmitting layer, a receiving layer and a filtering phase shifting layer arranged between the transmitting layer and the receiving layer. The transmitting layer is composed of a first metal layer, a first dielectric layer, a first bonding layer, a second metal layer and a metal hole; the radiation structure of the transmitting layer is located on the top of the first dielectric layer and is composed of the first metal layer 1; the second metal layer is at the bottom of the first dielectric layer and serves as the floor of the transmitting layer antenna; The receiving layer is composed of a fifth metal layer, a fourth dielectric layer, a third bonding layer, a metal hole and a fourth metal layer; the radiation structure of the receiving layer is at the bottom of the fourth dielectric layer and is composed of the fifth metal layer; The fourth metal layer is on top of the fourth dielectric layer and serves as the floor of the receiving layer antenna; The filtering phase shifting layer is composed of a second metal layer, a second dielectric layer, a second bonding layer, a third dielectric layer, a third bonding layer, a fourth metal layer, a third metal layer, metal holes and metal pins; The third metal layer is located on the top of the third dielectric layer and is a phase delay line; the phase delay line is connected to the first and fifth metal layers through two metal holes; the metal pin is connected to the second and fourth metal layers and is located between the two metal holes.

2. The filter transmission array unit according to claim 1, characterized in that: The transmitting layer and the phase shifting layer share the second metal layer as a floor, and the receiving layer and the phase shifting layer share the fourth metal layer as a floor.

3. The filter transmission array unit according to claim 1, characterized in that: The radiation structure of the transmitting layer is located at the bottom of the first dielectric layer and is composed of the first metal layer. The radiation structure of the receiving layer is located at the bottom of the fourth dielectric layer and is composed of the fifth metal layer. The radiation structures of the two layers are both microstrip patch antennas with double T-shaped branches.

4. The filter transmission array unit according to claim 1, characterized in that: The filtering phase shifting layer introduces an upper sideband transmission zero point by using a SIW resonant cavity structure and a phase delay line structure, and the position of the metal pin is optimized to ensure the stability of the upper sideband transmission zero point.

5. An antenna based on a filter transmission array unit, characterized in that: It includes a linear polarization feed source and a filter transmission array composed of N×N filter transmission array units, where N ≥ 2 and is an integer; The linear polarization feed source is located above the center of the filter transmission array, and the radiation direction of the linear polarization feed source is toward the filter transmission array.

6. The antenna according to claim 5, characterized in that The linear polarization feed source is a linear polarization broadband corrugated horn antenna, which can realize broadband linear polarization radiation.

7. The antenna according to claim 5, characterized in that: The filter transmission array unit achieves phase quantization compensation by adjusting the size of the phase delay line and the rotation angle of the receiving antenna, ensuring that the array has filtering and phase control functions.

8. The antenna according to claim 5, characterized in that: The antenna designs the arrangement and size of the filter transmission array units according to the array surface phase distribution required by the central frequency point of the working frequency band of the receiving antenna.

9. A design method for a filter transmission array antenna, characterized in that: The following steps are involved: Step 1: Rotate the receiving antenna in the transmission array unit by 180° to obtain state 0 and state 1, respectively, to achieve 1-bit quantized phase of 0° and 180°; Step 2: Adjust the size of the phase delay line in the filter transmission array unit to produce a continuous phase shift of 0°-135°.

10. The design method according to claim 9, characterized in that: By combining step one and step two, a 3-bit phase shift function is implemented to meet the antenna array phase distribution requirements.

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