Filtering-transmission array antenna and method for 5g millimeter wave system

Abstract

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

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and is particularly applicable to 5G millimeter-wave communication systems. It relates to a filtered transmission array unit, an antenna, and a design method thereof. Background Technology

[0002] Currently, wireless communication technology is developing rapidly, especially in 5G millimeter-wave communication systems, where the demand for antennas with strong anti-interference capabilities and high gain is particularly prominent in order to improve the performance of point-to-point communication. A 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 region of the feed, with numerous independently phase-tunable transmission array elements arranged regularly on its surface. Electromagnetic waves radiated from the phase center of the feed arrive at each element of the array as spherical waves. By precisely designing the phase distribution of the array elements, each element provides an appropriate phase shift, causing the array aperture to form a planar phase wavefront, thereby generating a high-gain beam in a specific direction. Integrating filtering functions into the transmission array antenna design allows the array elements to suppress electromagnetic signals outside the operating frequency band, effectively shielding against out-of-band interference and improving the signal-to-noise ratio and sensitivity of the wireless communication system.

[0003] Filtered transmission array antennas possess filtering characteristics and have advantages such as simple structure, low manufacturing cost, and no need for complex feeding networks, providing reliable technical support for advanced and low-cost wireless communication systems.

[0004] When designing filters, the main technical specifications to consider are: bandwidth, return loss, insertion loss, out-of-band rejection, and roll-off. The first three parameters are similar to those used in antenna design, while the latter two are not present in antenna design and therefore need to be considered when designing filter antennas. Current research indicates that the design methods for filter transmission array antennas can be mainly divided into three categories: 1) based on multi-layer frequency selective surfaces; 2) based on filter synthesis theory; and 3) fusion design. Each of these three design methods has its advantages and limitations, and the choice between them can be flexibly made for different application scenarios to meet specific performance requirements.

[0005] In 2023, Tian Hu et al. designed a filtered transmission array antenna operating at 5.8 GHz. They cascaded an interdigital filter with a microstrip patch antenna using a stacked PCB design, obtaining a filtered transmission array antenna element with 1-bit phase quantization. However, due to limitations in the filter structure itself, the antenna's operating bandwidth is very narrow, with a relative bandwidth of only 4.3%, and it only has 1-bit shift compensation capability. Therefore, after forming the antenna array, the measured gain of the antenna is 19.8 dBi, and the measured aperture efficiency is low, only 22%.

[0006] In 2021, Peng-Yu Feng et al. proposed a filtered transmission array antenna operating at 10 GHz, featuring high in-band gain and low out-of-band scattering characteristics. This filtered transmission array element consists of a dual-polarized resistive layer, a bandstop frequency selective surface (FSS), and an adjustable bandpass FSS acting as a phase shifter. This transmission array element exhibits transmission capability within the passband, with a measured transmission array gain of 25.3 dBi and a maximum aperture efficiency of 4.9%. In the stopband, the out-of-band suppression level is ≥25 dB, and the scattering cross section (SCS) decreases by approximately 8 dBi in the 4-7 GHz and 14-20 GHz ranges.

[0007] In 2022, Huawei's Lin proposed a 12 GHz dual-polarized magnetoelectric dipole frequency selective surface based on split-rings. This frequency selective surface structure uses four split-rings forming a magnetoelectric dipole, fed through a cross-shaped gap in the ground. The split-rings are introduced to create the upper sideband resonant zero, while the lower sideband resonant zero is controlled by the length and spacing of the metal pillars. By controlling these variables, a third-order dual-polarized frequency selective surface with an incident angle stability of 40° was achieved, with a measured insertion loss of 0.19 dB. Due to the introduction of split-rings, the element size needs to be minimized, resulting in a frequency selective surface period of only 0.12λ0. For higher frequency applications, this method may be impossible to fabricate, and this frequency selective surface lacks phase-shifting functionality. This work has also been applied to reflective array antennas, using FA1 as the reflective array antenna element to realize a 3-bit filtered reflective array antenna operating at 12 GHz.

[0008] Based on the above analysis, the problems and shortcomings of the existing technology 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 elements. The design that takes both into account is complex and difficult.

[0010] (2) The oblique incidence effect caused by the feeding method of the transmission array, the slotting or adding too many parasitic branches on the patch surface, will lead to high cross polarization and large phase error, making it difficult to realize the design concept of this type of filter antenna in the design of filter transmission array.

[0011] (3) There is little research on the N257 band of filtering transmission arrays in 5G communication systems, and the phase shift range of linearly polarized transmission array antennas is small.

[0012] (4) Existing wide phase-shifting range filter transmission array antenna elements often require high profiles, which is not conducive to integration into miniaturized communication systems. Summary of the Invention

[0013] To address the problems existing in the prior art, this invention provides a filtered transmission array element, an antenna, and a design method thereof.

[0014] First, this invention is implemented as follows: For the filter transmission array unit, the filter transmission array unit includes a transmitting layer and a receiving layer, with a filter phase-shifting layer between the transmitting and receiving layers; the antenna unit achieves phase shifting by rotating the transmitting antenna in conjunction with changing the size of the phase delay line. For the filter transmission array antenna, the arrangement of the antenna units and the rotation angle of the receiving antenna are determined according to the required array phase distribution at the center frequency point of the receiving antenna's operating frequency band, and the size of the phase delay line is also determined, thereby determining the final complete structure of the filter transmission array antenna.

[0015] Secondly, the transmitting layer consists of a first metal layer, a first dielectric layer, a first adhesive layer, and metal holes; the receiving layer consists of a fifth metal layer, a fourth dielectric layer, a third adhesive layer, and a fourth metal layer.

[0016] The transmitting layer and the filter / phase-shifting layer share a second metal layer as the ground plane. The receiving layer and the filter / phase-shifting layer share a fourth metal layer. The radiating structure of the transmitting layer is located at the bottom of the first dielectric layer and is composed of the first metal layer; the radiating structure of the receiving layer is located at the bottom of the fourth dielectric layer and is composed of a fifth metal layer. These two metal layers form a microstrip patch antenna with double T-shaped stubs. By introducing the T-shaped stubs, a pair of reverse currents are introduced, disrupting the basic TM01 operating mode of the microstrip antenna, thus preventing radiation from occurring near this frequency point and generating a transmission null. The receiving and transmitting patches use filter microstrip patches, introducing a lower sideband transmission null, ensuring stable oblique incidence performance within a certain range while possessing filtering characteristics, thereby achieving a high-efficiency filter transmission array antenna.

[0017] Furthermore, the filter phase-shifting layer consists of a second metal layer, a second dielectric layer, a second adhesive layer, a third dielectric layer, a third adhesive layer, a fourth metal layer, a third metal layer, and metal pins. The position of the metal pins is specially designed to ensure the stability of the upper sideband transmission zero. The upper sideband transmission zero, obtained using the SIW resonant cavity structure and the phase delay line structure, is used to fill in the phase as much as possible during filtering, thereby increasing the phase quantization bit depth.

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

[0019] Furthermore, the linearly polarized feed source adopts a broadband corrugated horn antenna, and the radiation direction of the linearly polarized feed source is directed towards the filter transmission array unit.

[0020] Another object of the present invention is to provide a design method for 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. The rotation generates two quantized phases of 0° and 180°, each with a 1-bit value.

[0022] Step two involves adjusting the size of the phase delay line in the filter transmission array unit to generate a continuous phase shift from 0° to 135°. Step two, combined with step one, achieves a 3-bit phase shift.

[0023] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0024] First, by utilizing the upper sideband transmission nulls obtained from the SICL structure with filtering capabilities, phase is padded as much as possible while filtering, thereby increasing the phase quantization bit depth. Simultaneously, the receiver and transmitter patches employ filtering microstrip patches, introducing lower sideband transmission nulls. This ensures stable oblique incidence performance within a certain range while maintaining filtering characteristics, thus achieving a high-efficiency filtered transmission array antenna. The phase shift of the transmission array elements in this invention is achieved through changes in the phase delay line size. Combining these two methods for phase modulation not only simplifies the element design process and reduces the difficulty of element structure design but also enables a transmission array antenna with stable filtering characteristics and high aperture efficiency.

[0025] This invention uses only one type of transmission array element with the same structure, and has a low profile of 0.139λ. 28 (λ 28 (This refers to the wavelength of an electromagnetic wave with a frequency of 28 GHz). This invention achieves filtering characteristics, and the antenna operates in the 27-29.5 GHz frequency band, meeting the requirements of 5G millimeter-wave communication technology in this band and possessing strong application value. The antenna of this invention has a gain of 25.9 dBi and an aperture efficiency of 62.13% at 28 GHz, both higher than the designs mentioned above, thus improving communication quality.

[0026] Secondly, this invention proposes a filtered transmission array antenna. Compared to existing wide-phase-shift range filtered transmission array antennas, this invention features a lower antenna array profile and uses only one type of element to form the array, enabling the transmission array antenna to achieve filtering functionality. Compared to a 2-bit filtered transmission array antenna, this invention achieves a 3-bit phase-shift range while maintaining filtering performance, reducing the phase error caused by quantization phase in the 2-bit transmission array antenna and improving the aperture efficiency of the filtered transmission array antenna. This invention offers advantages such as low cost and high aperture efficiency, higher performance, and better applicability, making it suitable for a wide range of applications in high-performance communication in the 5G millimeter-wave band.

[0027] Third, the technical solution of this invention fills a technological gap in the domestic and international industry: 1) In the domestic and international industry, patents and papers have proposed antennas with transmission characteristics and filtering performance. To ensure filtering performance, these antennas use a combination of filtering structures and receiving / transmitting antennas. However, this approach results in a small phase shift range for the elements, leading to low antenna aperture efficiency, which is detrimental to the performance of actual products. Some studies have also used the cutoff characteristics of waveguides to fabricate filtering transmission array antennas, but this approach results in a high profile. The filtering transmission array antenna proposed in this invention is arranged according to the phase distribution at the center frequency point, achieving 3-bit phase shift by rotating the transmitting antenna and changing the size of the phase delay line. Furthermore, the double-sideband filtering operation mode is implemented by only one element, eliminating the need for additional element design. The phase compensation strategy and antenna element structure proposed in this invention have filled a current technological gap in the industry. 2) There is limited research on filtering transmission array antennas in the millimeter-wave band. The transmission array antenna designed in this invention operates at 28.5 GHz, which is sufficient to meet the requirements of 5G millimeter-wave band communication technology in this frequency range, filling a current gap in the industry in this area.

[0028] Fourth, regarding the significant technological advancements in the filtered transmission array unit and antenna:

[0029] 1) Phase modulation flexibility: By changing the size of the phase delay line and rotating the transmitting antenna, this design can achieve more flexible phase modulation, resulting in concentrated pen tip beam 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 point of the upper and lower sidebands while shifting the phase, thus achieving 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. Attached Figure Description

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

[0033] Figure 2The layers in (a) are: 1. First metal layer; 2. Metal hole; 3. First dielectric layer; 4. First adhesive layer; 5. Second metal layer; 6. Second dielectric layer; 7. Second adhesive layer; 8. Third dielectric layer; 9. Third adhesive layer; 10. Fourth metal layer; 11. Third metal layer; 12. Metal pin; 13. Fourth dielectric layer; 14. Metal hole; 15. Fifth metal layer. There is a ring 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 the 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 These are simulation results of the transmission amplitude and transmission phase of the filter transmission array unit provided in this embodiment of the invention at different lengths L2; ​​where (a) is the simulation result of the transmission amplitude and (b) is the simulation result of the transmission phase.

[0036] Figure 4 This is a simulation result diagram of the transmission amplitude and transmission phase of the filtered transmission array antenna unit provided in the embodiment of the present invention with 180° phase quantization;

[0037] Figure 5 The above are simulation results of the transmission amplitude and transmission phase of the transmitting antenna of the filter transmission array unit provided in the embodiment of the present invention at different angles;

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

[0039] Figure 7 These are top views of the linearly polarized feed, antenna array model, and each layer structure provided in the embodiments of the present invention; wherein, (a) is an array structure diagram, and 13 is a linearly polarized feed; (b) is a top view of the third metal layer of the transmission array element with phase compensation correction; (c) is a top view of the second metal layer of the transmission array element; (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; and (f) is a top view of the fifth metal layer of the array after phase compensation rotation.

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

[0041] Figure 9 These are simulation results of antenna gain and aperture efficiency provided in the embodiments of the present invention;

[0042] Figure 10 The above are simulated radiation patterns of the antenna at 28 GHz provided in this embodiment of the invention; wherein, (a) is the simulated normalized radiation pattern of the antenna in the E plane at 28 GHz; and (b) is the simulated normalized radiation pattern of the antenna in the H plane at 28 GHz. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

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

[0045] Example 1: High-efficiency filtered transmission array antenna based on linearly polarized feed

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

[0047] 2. Design parameters:

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

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

[0050] Array size: 15×15 units;

[0051] Feed source: Broadband linearly polarized horn antenna.

[0052] 3. Implementation process:

[0053] By introducing double-T stubs in the transmitting and receiving layer antennas and disrupting the TM01 operating mode, a transmission null point is introduced at 24GHz, achieving efficient and stable filtering characteristics.

[0054] The phase-shifting layer employs a SIW resonant cavity and phase delay line structure, combined with a metal pin design, to introduce an upper sideband transmission zero at 31 GHz, achieving upper sideband filtering performance. Through this combination of methods, the designed filter transmission array unit exhibits double-sideband suppression performance.

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

[0056] 4. Simulation performance:

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

[0058] The array exhibits a gain exceeding 25 dB at all operating frequencies, providing wide coverage and stable beam direction. Furthermore, the calculated selectivity (SE) is 1.55, with a maximum lower sideband suppression of 26.8 dB and a maximum upper sideband suppression of 26.18 dB, demonstrating the stability and practicality of this designed filtered transmission array antenna.

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

[0060] like Figure 1 and Figure 2 As shown, the filtered transmission array unit provided in this embodiment of the invention includes an emitting layer, a filtered phase-shifting layer, and a receiving layer. The emitting layer of the filtered transmission array unit is composed of a first metal layer 1, a first dielectric layer 3, a first adhesive 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 adhesive layer 9, and a fourth metal layer 10.

[0061] The transmitting layer and the filter / phase-shifting layer share a second metal layer 5 as a ground plane. The receiving layer and the filter / phase-shifting layer share a fourth metal layer 10. The radiating structure of the transmitting layer is located on top of the first dielectric layer 3 and consists of the first metal layer 1; the radiating structure of the receiving layer is located at the bottom of the fourth dielectric layer and consists of a fifth metal layer 15. These two metal layers form a microstrip patch antenna with double T-shaped stubs. By introducing the T-shaped stubs, a pair of reverse currents are introduced, disrupting the basic TM01 operating mode of the microstrip antenna, thus preventing radiation from occurring near this frequency point and generating a transmission null.

[0062] The filter phase shifting layer consists of a second metal layer 5, a second dielectric layer 6, a second adhesive layer 7, a third dielectric layer 8, a third adhesive layer 9, a fourth metal layer 10, a third metal layer 11, and a metal pin 12.

[0063] The third metal layer 11 is located above the third dielectric layer. A ring of metal holes exists between the second and fourth metal layers for electromagnetic shielding and to introduce transmission nulls in the upper sideband. The receiving layer antenna receives electromagnetic waves from the feed source, which are then transmitted to the phase-shifting layer via metal pillar 14. After phase control via a phase delay transmission line, the waves are relayed to the transmitting layer by metal pillar 2, where they radiate into free space via the microstrip patch antenna. The use of metal pins 12 ensures stability of the resonant point and low insertion loss during phase shifting, facilitating overall optimization after connecting the transmitting and receiving sections. Metal pins 12 connect the second and fourth metal layers, positioned between metal vias 2 and 14. The metal pins isolate the electric field between the two vias and provide impedance matching, effectively improving the transmission coefficient within the SICL passband.

[0064] The transmitting layer antenna transmits line-polarized electromagnetic waves, and the receiving layer antenna receives line-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-shifting layer, a continuous 3-bit phase shift range can be achieved. Rotating the receiving antenna 15 by 180° generates two quantized phases of 1-bit: 0° and 180°. Together with the above methods, a 3-bit phase shift range can be achieved, with minimal impact on filtering performance within the phase shift range.

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

[0066] The following is a detailed explanation of the working principle of the filter transmission array unit, divided into four sections:

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

[0068] The filter-transmission array unit comprises three parts: a transmitting layer, a phase-shifting layer, and a receiving layer. The antenna structure of the receiving layer receives linearly polarized electromagnetic waves emitted by the feed source. These waves are transmitted through metal pillars 14 in the receiving layer to the phase-shifting layer. In the phase-shifting layer, after precise phase control via a phase delay transmission line, the electromagnetic waves are then transmitted to the transmitting layer via metal pillars 2. The transmitting layer antenna re-radiates the modulated electromagnetic waves into free space, achieving efficient signal transmission. Through this multi-layered structure design, the unit can simultaneously perform electromagnetic wave reception, filtering, phase shifting, and transmission functions, achieving efficient control of electromagnetic waves.

[0069] 2. Filtering characteristics of a dual-T stub microstrip patch antenna

[0070] Both the transmitting and receiving microstrip patch antennas employ a design with double T-shaped stubs. This design, by introducing reverse current, effectively disrupts the antenna's TM01 operating mode, preventing electromagnetic radiation near specific frequencies and thus introducing a transmission null. The transmission null effectively suppresses unwanted frequency band signals through filtering, ensuring the spectral purity of the transmitted electromagnetic waves. Furthermore, the receiving patch antenna introduces a lower sideband transmission null, further improving the filtering effect and enhancing the stability of oblique incidence performance, ensuring high-efficiency operation even under electromagnetic wave incidence at different angles.

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

[0072] The filter phase-shifting layer consists of multiple layers, including a second, third, and fourth metal layer, and incorporates metal pins 12 to optimize electromagnetic characteristics. These metal pins, located between metal vias 2 and 14, serve for electric field isolation and impedance matching, significantly improving insertion loss during transmission while ensuring the transmission coefficient within the SICL passband. The filter phase-shifting layer also introduces upper sideband transmission zeros through a combination of SIW (Substrate Integrated Waveguide) resonant cavity and phase delay line structures. During phase shifting, the phase-shifting layer further stabilizes the upper sideband transmission zeros of the antenna, improving the filtering performance of the filter transmission array unit.

[0073] 4. Implementation of controllable phase shift function and 3-bit phase shift range

[0074] The receiving layer antenna can switch between states 0 and 1 after rotating 180°, corresponding to quantized phases of 0° and 180° respectively. Simultaneously, by adjusting the phase delay line size in the phase shift layer, continuous phase shifts from 0° to 135° can be achieved. Combining the rotation and phase delay line adjustment allows for phase shift control over a total range of 3 bits. Through optimized design, the filter-transmission array unit can provide high phase shift accuracy while minimizing the impact of the phase shift process on filtering performance, ensuring spectral purity and transmission efficiency. This design method, combining rotation and phase delay control, gives the array unit high flexibility and precise phase control capabilities.

[0075] The filtered transmission array unit achieves electromagnetic wave reception, filtering, phase shifting, and transmission functions through the rational design of the transmitting layer, phase shifting layer, and receiving layer. Utilizing the filtering characteristics of the dual-T stub microstrip antenna, the optimized phase shifting performance of the metal pins, and the efficient control capability of the 3-bit phase shift range, this unit maintains excellent performance even in complex electromagnetic environments, meeting the application requirements of high-efficiency filtered transmission array antennas.

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

[0077] The linearly polarized feed 16 adopts a broadband corrugated horn antenna, and the radiation direction of the linearly polarized feed 13 is oriented towards the transmission array antenna.

[0078] This invention also provides a phase compensation method for a dual-frequency dual-circularly polarized transmission array antenna 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°, generating two quantized phases of 0° and 180° with a 1-bit value before and after the rotation;

[0080] Step 2: The transmission array antenna element of this invention uses a structure to achieve dual-band operation. The element needs to be considered when performing phase compensation.

[0081] Figure 3 The transmission amplitude and phase shift range of the antenna elements of this invention are presented when the total length L2 of the phase delay line is changed. When the transmission line length increases from 3.87 mm to 6.04 mm, it can be seen that the transmission coefficient is less than -1 dB in the passband, and the phase shift range is 0°-135°. During the phase shift, the null point of the lower sideband stabilizes at 24 GHz, while the upper sideband, due to the limitations of the phase shift structure, changes the internal spatial dimensions of the cavity, causing a certain degree of resonant frequency shift. Due to the special feeding structure of the transmission array, the feeding of the transmission array is equivalent to an amplitude weighting. The elements with a larger weight are distributed in the central part of the array. The phase distribution of the elements in the central part of the antenna is basically in the range of 0°-90°. During the phase shift, the transmission null point of the upper sideband of these elements is relatively stable at around 31 GHz. The weight of the remaining phase elements is relatively low, so their impact on the array performance is small. Therefore, it can be predicted that the null point of the upper sideband of the array will stably appear at 31 GHz.

[0082] Figure 4 The figure compares the transmission performance and phase change of the antenna element after the receiving antenna of the present invention is reversed by 180°. As can be seen from the figure, the transmission amplitude of the receiving antenna remains almost unchanged in both state 0 and state 1, while the phase difference is 180°. This yields 1-bit quantized phase at 0° and 180°. The transmission zero point in the upper sideband shifts slightly towards lower frequencies by 0.2 GHz, while the transmission zero point in the lower sideband remains unchanged.

[0083] Figure 5 The effects of different incident angles on the element under oblique incidence on the E-plane are presented. When the incident angle is less than 30°, the transmission performance of the element within the passband does not change significantly, while the transmission zero point of the lower sideband shifts slightly. The transmission zero point of the upper sideband is generated by the cavity of the transmission structure and therefore remains stable. From a phase perspective, the transmission phase within the passband hardly changes. Through analysis of... Figure 5 The analysis shows that the performance of this element's E-plane is very stable within the 30° oblique incidence range.

[0084] Figure 6 The phase distribution diagram required for the antenna array of this invention is provided. The arrangement of the antenna elements on the array surface can be obtained from the phase distribution diagram.

[0085] Figure 8 Simulation results of the return loss of the antenna of the present invention are shown. It can be seen that the return loss of the antenna of the present invention is greater than 10dB in the 26.5GHz-29.5GHz frequency band.

[0086] Figure 9 Simulation results for the antenna's aperture efficiency and gain are presented. The antenna's maximum gain is 25.9 dBi, and its maximum aperture efficiency is 62.13%. At this point, the upper sideband transmission null occurs at 31 GHz, proving... Figure 3 The predicted results were correct. Simultaneously, the calculated selectivity (SE) was 1.55, the maximum suppression level (PSL) of the lower sideband was 26.8 dB, and the maximum PSL of the upper sideband was 26.18 dB, demonstrating the stability and practicality of the designed filtered transmission array antenna. Furthermore, compared with the previously mentioned literature, the aperture efficiency of the antenna in this design is greater than that of the antennas proposed in the literature.

[0087] The array unit of this invention includes a receiving antenna and a transmitting antenna, which are connected by a filter phase-shifting layer. The array antenna includes a linearly polarized feed and a filter transmission array unit, with the linearly polarized feed located above the center of the transmission array unit. The design method involves rotating the receiving antenna of the transmission array unit by 180°, generating two quantized phases of 1-bit (0° and 180°) before and after the rotation. Simultaneously, the length of the phase delay line is adjusted; together, these methods achieve a 3-bit phase shift range. The filter transmission array antenna of this invention has the advantages of low profile, filtering capability, and high aperture efficiency, meeting the needs of millimeter-wave band communication development. This invention reduces the profile height of the filter transmission array antenna, resulting in a compact structure and improved antenna aperture efficiency, making it applicable to miniaturized and integrated communication systems.

[0088] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A filter transmission array unit, characterized in that, It includes a transmitter layer, a receiver layer, and a filter and phase shifter layer disposed between the transmitter and receiver layers. The transmitting layer comprises, from top to bottom, a first metal layer, a first dielectric layer, a first adhesive layer, and a second metal layer; the radiating structure of the transmitting layer is located on top of the first dielectric layer and is composed of the first metal layer; the second metal layer is at the bottom of the first dielectric layer and serves as the ground plane for the transmitting layer antenna; The receiving layer consists of a fifth metal layer, a fourth dielectric layer, and a fourth metal layer from bottom to top; the radiating structure of the receiving layer is located at the bottom of the fourth dielectric layer and is composed of the fifth metal layer; the fourth metal layer is located at the top of the fourth dielectric layer and serves as the ground plane for the receiving layer antenna. The filter phase shifting layer comprises, from top to bottom, a second metal layer, a second dielectric layer, a second adhesive layer, a third metal layer, a third dielectric layer, a third adhesive layer, and a fourth metal layer; The third metal layer is located on 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 in the middle of the two metal holes. The filter phase-shifting layer uses the SIW resonant cavity structure and phase delay line structure to introduce the upper sideband transmission zero. The position of the metal pin is optimized to ensure the stability of the upper sideband transmission zero. The upper sideband transmission zero is obtained using a SICL structure with filtering function; there is a ring of metal holes between the second and fourth metal layers for electromagnetic shielding and to introduce the upper sideband transmission zero. The transmitting layer and the filter phase-shifting layer share a second metal layer as a ground plane, and the receiving layer and the filter phase-shifting layer share a fourth metal layer as a ground plane.

2. The filter transmission array unit according to claim 1, characterized in that, The radiating structure of the transmitting layer is located at the bottom of the first dielectric layer and is composed of the first metal layer. The radiating structure of the receiving layer is located at the bottom of the fourth dielectric layer and is composed of the fifth metal layer. Both layers have microstrip patch antennas with double T-shaped stubs.

3. An antenna based on a filter transmission array element using the filter transmission array element described in any one of claims 1-2, characterized in that, It includes a linearly polarized feed source and a filter transmission array composed of N×N filter transmission array elements, where N≥2 and is an integer; The linearly polarized feed source is located above the center of the filter transmission array, and the radiation direction of the linearly polarized feed source is towards the filter transmission array.

4. The antenna according to claim 3, characterized in that, The linearly polarized feed source is a linearly polarized broadband corrugated horn antenna, which can achieve broadband linearly polarized radiation.

5. The antenna according to claim 3, 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 modulation functions.

6. The antenna according to claim 3, characterized in that, The antenna is designed with the array phase distribution required by the center frequency of the receiving antenna's operating frequency band, and the arrangement and size of the filtering and transmission array elements are determined accordingly.

7. An antenna design method based on a filtered transmission array element as described in any one of claims 3-6, characterized in that, Includes the following steps: Step 1: Rotate the receiving antenna in the transmission array unit by 180° to obtain state 0 and state 1 respectively, realizing 1-bit quantized phase at 0° and 180°; 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°.

8. The design method according to claim 7, characterized in that, By combining steps one and two, a 3-bit phase shift function is achieved, thereby meeting the antenna array phase distribution requirements.

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