A dual-frequency four-arm helical antenna structure and its design optimization and control method

Abstract

The present invention relates to the technical field of communication antenna equipment, and in particular to a dual-frequency four-arm helical antenna structure and its design optimization and control method. The dual-frequency four-arm helical antenna includes an FPC substrate, and the FPC substrate is made of polyimide material. Four helical antennas are integrated on the FPC substrate. The material of the helical antenna is made of electrolytic copper foil conductor. The total thickness of each helical antenna is less than 0.15 mm, and the four helical antennas are arranged on the FPC substrate in a 90° directional spiral form to enhance the directionality and gain rate of signal transmission. Each spiral antenna is independent of each other and has a phase difference. The present invention proposes an innovative dual-band four-arm helical antenna design that achieves precise frequency control and performance balance of dual bands through precise structural parameter optimization. It not only has good radiation characteristics and a wide bandwidth, but also effectively reduces interference between frequency bands, and solves the problems of frequency accuracy, size and weight existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of communication antenna equipment, and in particular to a dual-frequency four-arm helical antenna structure and a design optimization and control method thereof. Background Art

[0002] With the continuous development of modern communication technology, especially in the application fields of satellite communication, navigation system, remote sensing detection, etc., the demand for high-performance antennas is increasing. Helical antennas have become a commonly used antenna type in high-frequency communication systems due to their simple structure, wide frequency band, and uniform radiation. Among them, dual-band four-arm helical antennas have been widely used in satellite navigation, wireless communication, radar detection, and earth observation due to their ability to work stably in multiple frequency bands. They can not only realize multifunctional integrated design, but also have the potential to work efficiently in complex environments.

[0003] However, with the further increase in demand for high-precision and high-performance antennas, the traditional helical antenna design has gradually exposed certain limitations in terms of frequency bandwidth, size, weight, and anti-interference ability. For example, in the design process of dual-band antennas, how to achieve high isolation and low mutual interference between frequency bands while ensuring that the performance of each frequency band meets the optimization requirements is a major technical challenge. In particular, when meeting the high-precision requirements of the center frequency, how to maintain the gain stability, radiation pattern symmetry, and efficiency improvement of the antenna further increases the complexity of the design. In the existing helical antenna design, performance is usually improved by adjusting geometric parameters, optimizing feeding structure, or introducing new materials, but these methods often face the following challenges: First, there is a mutual constraint in the performance optimization between the dual-bands, which makes it difficult to achieve the ideal performance indicators in both bands at the same time; second, it is difficult for traditional designs to achieve miniaturization and lightweight of antennas while maintaining high performance, which restricts their use in application scenarios with limited space or weight sensitivity; third, in complex electromagnetic environments, how to improve anti-interference capabilities and enhance stability remains a problem to be solved. Summary of the invention

[0004] The present invention overcomes the deficiencies of the prior art and provides a dual-frequency four-arm helical antenna structure and a design optimization and control method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a dual-frequency four-arm helical antenna structure, wherein the dual-frequency four-arm helical antenna structure comprises a dual-frequency four-arm helical antenna:

[0007] The dual-frequency four-arm helical antenna comprises an FPC substrate, which is made of polyimide material. Four helical antennas are integrated on the FPC substrate. The material of the helical antenna is made of electrolytic copper foil conductor. The total thickness of each helical antenna is less than 0.15 mm. The four helical antennas are arranged on the FPC substrate in a 90° directional helical form to enhance the directivity and gain rate of signal transmission. Each helical antenna is independent of each other and has a phase difference.

[0008] The dual-frequency four-arm helical antenna is in a dual-frequency working mode, and the dual-frequency working mode includes a low frequency band of 1207 MHz and a high frequency band of 1561 MHz. The dual-frequency four-arm helical antenna has a pitch of 49.7 mm to 99.4 mm, an arm length of 62.1 mm, and an arm width of 2 mm to 5 mm in the low frequency band of 1207 MHz. The dual-frequency four-arm helical antenna has a pitch of 19.23 mm to 57.69 mm, an arm length of 48.1 mm, and an arm width of 2 mm to 5 mm in the high frequency band of 1561 MHz.

[0009] The dual-frequency four-arm helical antenna is fixed by a rubber ring, and the rubber ring is used to erect the dual-frequency four-arm helical antenna on a PCB flexible printed circuit board. The PCB flexible printed circuit board is made of polyimide material and is laid in two layers as a whole, which can effectively shield electromagnetic interference signals and reduce the overall weight of the dual-frequency four-arm helical antenna. A feeding network is arranged on the front of the PCB flexible printed circuit board. The feeding network includes a microstrip line, which is used to transmit signals from a receiving segment or a transmitting source to the four helical antennas respectively. A grounding platform is provided at the bottom of the PCB flexible printed circuit board to suppress signal interference.

[0010] Furthermore, in a preferred embodiment of the present invention, the structure of the dual-band four-arm helical antenna is a layered stack of two layers of FPC substrates to improve signal communication quality, and the two layers of FPC substrates are adhered by double-sided tape.

[0011] Furthermore, in a preferred embodiment of the present invention, a soldering pad is provided at the bottom edge of the FPC substrate, and each of the soldering pads is connected to four helical antennas.

[0012] Furthermore, in a preferred embodiment of the present invention, the dual-frequency four-arm helical antenna is soldered to the front side of the PCB flexible printed circuit board through the soldering pads, and the number of the soldering pads is set to 12, so that the communication between the dual-frequency four-arm helical antenna and the PCB flexible printed circuit board is more stable.

[0013] Furthermore, in a preferred embodiment of the present invention, an extended antenna of fixed size is extended from the top of each of the four helical antennas, that is, the dual-band four-arm helical antenna has as many as four extended antennas, and the extended antenna is wound around the top edge of the FPC substrate to increase the signal reception and transmission distance.

[0014] Furthermore, in a preferred embodiment of the present invention, the PCB flexible printed circuit board is in the shape of a disc, and the front side of the PCB flexible printed circuit board is integrated with a low-noise amplifier circuit, a low-pass filter, a signal processing circuit and an impedance matching network, and the impedance matching network is used to improve the signal transmission efficiency between the helical antenna and the signal receiving system.

[0015] Furthermore, in a preferred embodiment of the present invention, resistors, capacitors, inductors and crystal oscillators are installed on the back side of the PCB flexible printed circuit board, and multiple sets of buckles are provided on the back edge of the PCB flexible printed circuit board.

[0016] Furthermore, in a preferred embodiment of the present invention, multiple groups of the clips are used to buckle and fix the edges of the metal shielding cover so that the metal shielding cover remains connected to the PCB flexible printed circuit board and the spiral antenna. The metal shielding cover is an octagonal thin iron sheet made of aluminum. The mass of the metal shielding cover is 1.2 grams, which reduces the overall weight of the dual-band four-arm spiral antenna.

[0017] A second aspect of the present invention provides a design optimization and control method for a dual-frequency four-arm helical antenna structure, which is applied to any one of the dual-frequency four-arm helical antenna structures described above, and comprises the following steps:

[0018] Obtaining signal transmission requirements for the dual-frequency four-arm helical antenna to stably operate near the design center frequency in two frequency bands of 1561 MHz and 1207 MHz, and obtaining design parameter items of the dual-frequency four-arm helical antenna; wherein the design parameter items include pitch, arm length, and arm width;

[0019] Based on the big data, a frequency band wavelength of 1207 MHz is obtained, which is defined as a first frequency band wavelength, and a frequency band wavelength of 1561 MHz is obtained, which is defined as a second frequency band wavelength;

[0020] Obtaining a magnification interval between each design parameter item and the wavelength of the first frequency band, which is defined as a first magnification interval, and obtaining a magnification interval between each design parameter item and the wavelength of the second frequency band, which is defined as a second magnification interval;

[0021] Preset signal transmission performance indicators, take the initial magnifications of the first magnification interval and the second magnification interval as initial values, and simulate the performance of the dual-frequency four-arm helical antenna stably operating near the design center frequency in the two frequency bands of 1561 MHz and 1207 MHz using electromagnetic field simulation software based on the initial values ​​to obtain a simulated reference value for each signal transmission performance indicator;

[0022] Constructing a radar map, fitting and drawing the simulated reference value of each signal transmission performance indicator through the radar map, and generating a simulated reference radar map of the signal transmission performance indicator;

[0023] Obtain an expected reference radar chart of a signal transmission performance indicator based on the signal transmission requirement, calculate a radar area that does not overlap between the simulated reference radar chart and the expected reference radar chart, and mark it as a difference radar area;

[0024] The particle swarm algorithm is introduced to define each magnification value in the first magnification interval and the second magnification interval as a particle, and the current fitness value of each particle at the current position is calculated based on the difference radar area evaluation. The individual optimal solution and the global optimal solution of the particle are continuously updated and iterated through the current fitness value to generate the optimal magnification value that satisfies the difference radar area.

[0025] The optimal magnification value is combined with the first wavelength and the second wavelength to multiply the wavelengths and finally obtain the design optimization parameter value of the design parameter item.

[0026] Furthermore, in a preferred embodiment of the present invention, the following steps are also included:

[0027] Acquire several current transmission signals of the dual-frequency four-arm helical antenna, extract and analyze the spectrum of the several current transmission signals to obtain a spectrum diagram of the current transmission signal, and determine the current impedance characteristics and current standing wave ratio of the dual-frequency four-arm helical antenna in a dynamic timing according to the spectrum diagram;

[0028] Constructing a state space model, injecting the current signal reflection coefficient and the current standing wave ratio under the dynamic time sequence into the state space model for description, and generating a current dynamic working state equation of the dual-frequency four-arm helical antenna;

[0029] Obtaining the work tasks and work logs of the dual-frequency four-arm helical antenna, presetting the expected working frequency based on the work tasks, and extracting the optimal impedance matching parameters of the dual-frequency four-arm helical antenna under different historical working frequency conditions through the work logs;

[0030] Calculate the approximation between the expected operating frequency and each historical operating frequency to obtain multiple approximations, and only extract the optimal impedance matching parameters corresponding to the historical operating frequency condition corresponding to the maximum approximation, which are defined as the necessary optimal impedance matching parameters for the expected operating frequency;

[0031] Solving the current dynamic working state equation to obtain the current closed-loop pole position of the impedance matching network, presetting the expected dynamic working state performance based on the necessary optimal impedance matching parameters, and determining the expected closed-loop pole position of the impedance matching network according to the expected dynamic working state performance;

[0032] A pole placement method is introduced to place the impedance matching network from the current closed-loop pole position to the desired closed-loop pole position, obtain a state feedback gain matrix, construct a Lyapunov verification function based on the Lyapunov stability criterion, and perform a stable closed-loop verification on the dual-frequency four-arm helical antenna control system after the impedance matching network pole position is placed using the Lyapunov verification function to obtain a verification score;

[0033] If the verification score is lower than the preset verification score, the state feedback gain matrix is ​​controlled and calibrated based on the verification score until the preset verification score is reached, thereby generating a calibrated state feedback controller;

[0034] The calibrated state feedback controller is deployed to the frequency adjustment system of the current dual-frequency four-arm helical antenna to obtain the optimal operating frequency band, and the optimal operating frequency band is uploaded to the dual-frequency four-arm helical antenna control system terminal.

[0035] The beneficial technical effects of the present invention are:

[0036] The present invention mainly comprises a dual-frequency four-arm helical antenna and a PCB flexible printed circuit board. The base part of the dual-frequency four-arm helical antenna is bonded by double-sided adhesive tape and superimposed with two layers of FPC substrate. The FPC substrate is made of polyimide material to optimize the structural weight and the integrated stability of the antenna. Four 90° directional spiral-arranged spiral antennas are integrated on the FPC substrate. The material is made of electrolytic copper foil conductor, and the pitch, arm length and arm width between each spiral antenna are obtained by unique simulation design and precise verification, which can ensure that the four-arm helical antenna can stably work near the designed center frequency in the two frequency bands of 1561 MHz and 1207 MHz, and has good frequency stability, which enhances the omnidirectional radiation characteristics of the four-arm helical antenna and overcomes the problem that traditional antenna modules are difficult to operate synchronously in multiple frequency bands. The four helical antennas are welded to the front of the PCB flexible printed circuit board through 12 pads, which greatly improves the stability of the four-arm helical antenna when the drone is running in different scenarios, and it is not easy to fall off. The setting of up to 12 pads and solder points can ensure the communication stability between the dual-frequency four-arm helical antenna and the PCB flexible printed circuit board, and optimize the quality of signal reception and feedback. In addition, the PCB flexible printed circuit board is made of double-layer flexible polyimide material. A thin iron sheet-shaped aluminum metal shielding cover is fixed on the back of the PCB flexible printed circuit board by snaps. The metal shielding cover can effectively shield and block signal interference from the external environment, prevent noise signals from other devices from entering the antenna system, and cause errors in the reception or transmission of the four-arm helical antenna, ensure the receiving sensitivity and signal stability of the four-arm helical antenna, and improve the radiation pattern of the antenna, improve the transmission directivity or radiation efficiency of the antenna, and absorb the back signal radiation of the antenna to improve the signal transmission concentration performance; the weight of the metal shielding cover is only 1.2 grams, which greatly reduces the overall weight of the dual-frequency four-arm helical antenna in mechanical installation applications, and achieves a lightweight signal transmission effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0039] Figure 2 It is a schematic diagram of the unfolded structure of the dual-frequency four-arm helical antenna;

[0040] Figure 3 It is a schematic diagram of the rolled-up structure of the dual-band four-arm helical antenna;

[0041] Figure 4 It is a schematic diagram of the top structure of a PCB flexible printed circuit board;

[0042] Figure 5 It is a schematic diagram of the bottom structure of a PCB flexible printed circuit board;

[0043] Figure 6 It is a schematic diagram of the installation structure of the metal shielding cover on the PCB flexible printed circuit board.

[0044] The following are the descriptions of the reference numerals:

[0045] 101. dual-band four-arm helical antenna; 102. FPC substrate; 103. helical antenna; 104. PCB flexible printed circuit board; 105. microstrip line; 106. grounding platform; 107. soldering pad; 108. extended antenna; 109. buckle; 201. metal shielding cover. DETAILED DESCRIPTION

[0046] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the structures related to the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other without conflict.

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0048] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0049] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0050] like Figure 1-Figure 6 As shown, a first aspect of the present invention provides a dual-frequency four-arm helical antenna structure, and the dual-frequency four-arm helical antenna structure includes a dual-frequency four-arm helical antenna 101.

[0051] The dual-band four-arm helical antenna 101 includes an FPC substrate 102, which is made of polyimide material. Four helical antennas 103 are integrated on the FPC substrate 102. The material of the helical antenna 103 is made of electrolytic copper foil conductor. The total thickness of each helical antenna 103 is less than 0.15 mm, and the four helical antennas 103 are arranged in a 90° directional spiral form on the FPC substrate to enhance the directionality and gain rate of signal transmission. Each helical antenna 103 is independent of each other and has a phase difference.

[0052] The dual-frequency four-arm helical antenna 101 has a structure of two layers of FPC substrate 102 stacked in layers, which is used to improve signal communication quality. The two layers of FPC substrate 102 are adhered by double-sided tape.

[0053] It should be noted that the four helical antennas are the core part of the dual-frequency four-arm helical antenna structure. Their main function is to receive and transmit electromagnetic waves. The four helical antennas are designed as right-hand helices at a certain angle on the FPC substrate, and have a phase difference of 180° between each other, so that they can work in the 1561MHz and 1207MHz frequency bands at the same time and produce a continuous and stable circularly polarized radiation pattern, which is suitable for receiving signals from multiple directions and a large range, which is crucial for dynamic UAV applications. Since polyimide materials have a low dielectric constant, usually between 3.0 and 3.5, the double-layered polyimide can provide higher frequency stability during antenna signal transmission, especially in dual-frequency antenna design, which can greatly reduce signal loss; at the same time, polyimide has excellent high temperature resistance, which is particularly good for high-frequency and dual-frequency applications, and can ensure the long-term reliability of the antenna under various environmental conditions and avoid performance degradation caused by temperature changes. In addition, double-layer polyimide can make the antenna design more compact and adjustable, and can adapt to most different installation requirements, especially for the dual-frequency four-arm helical antenna that needs to cover the two frequency bands of 1561MHz and 1207MHz. The polyimide material can effectively reduce signal loss and improve the overall performance of the antenna. Therefore, the FPC substrate with four integrated helical antennas is made of polyimide material, which can further improve the signal transmission performance and effect of the antenna. The helical antenna uses high-strength and lightweight electrolytic copper foil conductor material, so that the antenna can maintain high mechanical strength and conductivity while reducing the volume and weight. The total thickness of each helical antenna is less than 0.15mm, which is particularly critical for applications with limited space or compact structures. For example, it can be selected as 0.1mm, 0.12mm or 0.14mm, which helps to reduce the volume and weight of the antenna and improve the overall integration of the device; the thickness is controlled within 0.15mm to improve the communication performance of the antenna in the high frequency band, optimize the high frequency band performance, and reduce signal attenuation and phase error.

[0054] The dual-frequency four-arm helical antenna 101 is in a dual-frequency working mode, and the dual-frequency working mode includes a low frequency band of 1207 MHz and a high frequency band of 1561 MHz. The pitch of the dual-frequency four-arm helical antenna 101 in the low frequency band of 1207 MHz is 49.7mm~99.4mm, the arm length is 62.1mm, and the arm width is 2mm~5mm. The pitch of the dual-frequency four-arm helical antenna 101 in the high frequency band of 1561 MHz is 19.23mm~57.69mm, the arm length is 48.1mm, and the arm width is 2mm~5mm.

[0055] It should be noted that with the development of science and technology, the requirements for the communication performance and functional diversification of communication systems have become more precise and stringent. For example, unmanned aerial vehicle remote sensing communication, satellite communication or navigation system, etc., means that the four-arm helical antenna needs to have the ability to operate stably in both the low frequency band (1207MHz) and the high frequency band (1561MHz) to adapt to the technical requirements of these communication systems. Therefore, the four-arm helical antenna of the present invention can adopt unique simulation and precise verification optimization to design antenna parameters according to different application requirements, so as to ensure that the four-arm helical antenna can stably operate near the designed center frequency in the two frequency bands of 1561MHz and 1207MHz, thereby providing greater flexibility and adaptability for communication systems such as unmanned aerial vehicles and satellites.

[0056] It should be noted that the unique pitch, arm length and arm width parameter design, on the one hand, enables the four-arm helical antenna to achieve the best balance in performance in two frequency bands. For example, the dual-frequency four-arm helical antenna 101 has a pitch of 64.7 mm, an arm length of 62.1 mm, and an arm width of 3 mm in the low frequency band of 1207 MHz, and a pitch of 35.8 mm, an arm length of 48.1 mm, and an arm width of 3.5 mm in the high frequency band of 1561 MHz, which improves the working bandwidth and gain, reduces mutual interference between frequency bands, and adapts to the signal transmission requirements of different frequency bands; on the other hand, the unique pitch, arm length and arm width design of the present invention can produce more stable circularly polarized waves, reduce signal loss and improve communication quality, and can reduce signal loss caused by polarization mismatch, thereby providing high-precision communication positioning services. In addition, the high directivity provided by the four-arm helical antenna with comprehensive optimization of design parameters improves the sensitivity and coverage of signal reception.

[0057] The dual-frequency four-arm helical antenna 101 is fixed by a rubber ring, and the rubber ring is used to erect the dual-frequency four-arm helical antenna 101 on a PCB flexible printed circuit board 104. The PCB flexible printed circuit board 104 is made of polyimide material and is laid in two layers as a whole, which can effectively shield electromagnetic interference signals and reduce the overall weight of the dual-frequency four-arm helical antenna 101. A feeding network is arranged on the front of the PCB flexible printed circuit board 104, and the feeding network includes a microstrip line 105, which is used to transmit signals from a receiving segment or a transmitting source to the four helical antennas 103 respectively. A grounding platform 106 is provided at the bottom of the PCB flexible printed circuit board 104 to suppress signal interference.

[0058] It should be noted that the reason for adopting a two-layer PCB flexible printed circuit board design is mainly that the two-layer structure suppresses electromagnetic interference through the bottom grounding platform and improves signal quality to achieve an effective signal shielding effect; the two-layer structure can optimize the overall transmission performance of the feeding network, realize a more reasonable microstrip line design, reduce transmission losses, and improve the signal transmission efficiency, working performance and anti-interference ability of the antenna system in the high frequency band. In addition, the PCB flexible printed circuit board itself has the characteristics of lightweight, and through reasonable layout, the overall weight can be further reduced. Among them, the feeding network of the present invention is designed as a balanced feed to ensure that each spiral antenna can receive equal power and appropriate phase. Setting a grounding platform at the bottom of the PCB flexible printed circuit board helps to suppress interference and improve the quality of the signal, and can also stabilize the current flow and reduce radiation losses.

[0059] A soldering pad 107 is disposed at the bottom edge of the FPC substrate 102 , and each of the soldering pads 107 is connected to four helical antennas 103 .

[0060] The dual-frequency four-arm helical antenna 101 is soldered on the front side of the PCB flexible printed circuit board 104 through the soldering pads 107, and the number of the soldering pads 107 is 12, so that the communication between the dual-frequency four-arm helical antenna 101 and the PCB flexible printed circuit board 104 is more stable.

[0061] It should be noted that the FPC substrate is fixed by welding after the pad is in contact with the signal transmission contact on the PCB flexible printed circuit board, and a fixing buckle is used for auxiliary fixing to improve the firmness and shockproof performance of the dual-frequency four-arm helical antenna, avoid the phenomenon of poor contact or signal interruption during the operation of the dual-frequency four-arm helical antenna, and improve the stability of signal transmission. The traditional four-arm helical antenna is usually only provided with a small number of solder points, which makes the communication connection and signal transmission between the traditional four-arm helical antenna and the circuit board extremely unstable, and signal distortion and loss often occur. Therefore, in order to solve this problem, the present invention increases the number of pads and corresponding solder points to enhance the communication connection quality between the dual-frequency four-arm helical antenna and the PCB flexible printed circuit board, and optimize the smoothness and gain of signal transmission.

[0062] An extended antenna 108 of fixed size is extended from the top of each of the four helical antennas 103, that is, the dual-band four-arm helical antenna 101 has up to four extended antennas 108. The extended antenna 108 is wound around the top edge of the FPC substrate 102 to increase the signal reception and transmission distance.

[0063] It should be noted that, since the helical antenna is integrated on the FPC substrate in a spiral design, and each helical antenna has an extra undeveloped spacing space to maintain a certain phase difference interval, and the design of the traditional four-arm helical antenna cannot fully utilize these spacing spaces to further optimize the structure of the antenna, so that the signal transmission performance of the traditional four-arm helical antenna has certain limitations and space improvement, and it is difficult to give full play to the communication advantages of the new antenna compared to the ordinary antenna. Therefore, the present invention makes full use of the spacing space between each spiral antenna to design an additional extension antenna of a fixed length for the top of each antenna. This extension antenna is flush with the top edge of the FPC substrate. The additional extension antenna can enhance the effective radiation area of ​​the spiral antenna, improve the gain of the antenna, and greatly expand the transmission range and receiving range of the signal; the extension antenna also effectively improves the frequency response of the four-arm helical antenna, enhances the radiation pattern and its directivity, and reduces the signal attenuation phenomenon. At the same time, the extension antenna can optimize the overall electrical performance of the antenna, especially in terms of receiving sensitivity and transmission power. For high-frequency or long-distance communication applications, it can enhance the signal strength, thereby further reducing signal loss.

[0064] The PCB flexible printed circuit board 104 is in the shape of a disc, and the front side of the PCB flexible printed circuit board 104 is integrated with a low-noise amplifier circuit, a low-pass filter, a signal processing circuit and an impedance matching network, and the impedance matching network is used to improve the signal transmission efficiency between the helical antenna 103 and the signal receiving system.

[0065] The back side of the PCB flexible printed circuit board 104 is equipped with resistors, capacitors, inductors and a crystal oscillator, and the back side edge of the PCB flexible printed circuit board 104 is provided with a plurality of buckles 109 .

[0066] Multiple groups of the clips 109 are used to buckle and fix the edges of the metal shielding cover 201, so that the metal shielding cover 201 remains connected to the PCB flexible printed circuit board 104 and the helical antenna 103. The metal shielding cover 201 is an octagonal thin iron sheet made of aluminum. The mass of the metal shielding cover 201 is 1.2 grams, which reduces the overall weight of the dual-band four-arm helical antenna 101.

[0067] It should be noted that impedance mismatch in any signal transmission process may lead to signal loss and performance degradation, greatly affecting the quality of signal reception and transmission. Therefore, in order to minimize signal reflection and optimize antenna performance, the present invention designs an impedance matching network to ensure the signal transmission efficiency between the antenna and the receiving system. The design of the impedance matching network is particularly important. The impedance matching network of the present invention can maximize the signal transmission power according to the maximum power transfer theorem when the load impedance is equal to the source impedance, ensuring that the impedance between the four-arm helical antenna signal source and the load is highly matched. The impedance matching network of the present invention can also prevent part of the signal from being reflected back to the source end when the impedance is mismatched, ensuring that most of the signal is transmitted to the load, maximizing system efficiency, and reducing energy loss.

[0068] It should be noted that the back of the circuit board of the traditional four-arm helical antenna is usually exposed or a heavier third-party shielding device is used for electromagnetic interference shielding, which makes the electromagnetic interference generated by other components on the device and the external environment during operation affect the signal transmission of the four-arm helical antenna, causing the signal reception and transmission quality and efficiency of the four-arm helical antenna to be greatly reduced, and signal interruption and distortion are prone to occur. In addition, the weight of the additional third-party shielding device is large, which increases the operating energy consumption of some underpowered devices, such as drones, etc., and increases the probability of equipment load damage. In this regard, the present invention adds a metal shielding cover on the back of the PCB flexible printed circuit board. The function of this metal shielding cover is to prevent external electromagnetic interference from entering the antenna system, avoid signal interference from other devices, and also reduce the electromagnetic waves emitted from the antenna system to interfere with other components, especially in applications under complex electromagnetic environments, effectively preventing the influence of external noise on the antenna signal, and ensuring the receiving sensitivity and signal stability of the antenna. In addition, the metal shielding cover is tightly connected to the PCB flexible printed circuit board and the four-arm helical antenna part by a snap-on method. Such a fixed connection design greatly ensures that the antenna and the circuit board are in a relatively closed environment, reducing possible electromagnetic leakage. The metal shield is made of highly conductive aluminum material, which has good conductivity and corrosion resistance. The metal material can also help dissipate heat from the PCB flexible printed circuit board and the four-arm helical antenna. The heat dissipation function is especially important during high-power operation to prevent the equipment from overheating, greatly improving safety, reliability and stability.

[0069] A second aspect of the present invention provides a design optimization and control method for a dual-frequency four-arm helical antenna structure, which is applied to any one of the dual-frequency four-arm helical antenna structures described above, and comprises the following steps:

[0070] Obtaining signal transmission requirements for the dual-frequency four-arm helical antenna to stably operate near the design center frequency in two frequency bands of 1561 MHz and 1207 MHz, and obtaining design parameter items of the dual-frequency four-arm helical antenna; wherein the design parameter items include pitch, arm length, and arm width;

[0071] Based on the big data, a frequency band wavelength of 1207 MHz is obtained, which is defined as a first frequency band wavelength, and a frequency band wavelength of 1561 MHz is obtained, which is defined as a second frequency band wavelength;

[0072] Obtaining a magnification interval between each design parameter item and the wavelength of the first frequency band, which is defined as a first magnification interval, and obtaining a magnification interval between each design parameter item and the wavelength of the second frequency band, which is defined as a second magnification interval;

[0073] Preset signal transmission performance indicators, take the initial magnifications of the first magnification interval and the second magnification interval as initial values, and simulate the performance of the dual-frequency four-arm helical antenna stably operating near the design center frequency in the two frequency bands of 1561 MHz and 1207 MHz using electromagnetic field simulation software based on the initial values ​​to obtain a simulated reference value for each signal transmission performance indicator;

[0074] Constructing a radar map, fitting and drawing the simulated reference value of each signal transmission performance indicator through the radar map, and generating a simulated reference radar map of the signal transmission performance indicator;

[0075] Obtain an expected reference radar chart of a signal transmission performance indicator based on the signal transmission requirement, calculate a radar area that does not overlap between the simulated reference radar chart and the expected reference radar chart, and mark it as a difference radar area;

[0076] The particle swarm algorithm is introduced to define each magnification value in the first magnification interval and the second magnification interval as a particle, and the current fitness value of each particle at the current position is calculated based on the difference radar area evaluation. The individual optimal solution and the global optimal solution of the particle are continuously updated and iterated through the current fitness value to generate the optimal magnification value that satisfies the difference radar area.

[0077] The optimal magnification value is combined with the first wavelength and the second wavelength to multiply the wavelengths and finally obtain the design optimization parameter value of the design parameter item.

[0078] It should be noted that the dual-frequency four-arm helical antenna combines the advantages of the traditional helical antenna to meet the needs of dual-band operation through structural design, so the design of the antenna's structural parameters is crucial; however, there are large errors in the design calculation and adjustment optimization of the parameters such as the pitch, arm length and arm width of the existing dual-frequency four-arm helical antenna, making it difficult to ensure the accuracy of the antenna under different frequency band requirements, especially in the two frequency bands of 1561MHz and 1207MHz. How to ensure that the antenna can work stably near the design center frequency is a difficulty. Therefore, this method analyzes the signal transmission performance of the dual-frequency four-arm helical antenna that works stably near the design center frequency in the two frequency bands of 1561MHz and 1207MHz by using electromagnetic field simulation, wherein the signal transmission performance indicators include the frequency response, radiation pattern and gain of the antenna. The different signal transmission requirements of the dual-frequency four-arm helical antenna have a strict compliance benchmark for each signal transmission performance indicator, that is, there is an expected reference threshold. If the simulated signal transmission performance indicator does not reach the level of the expected reference threshold, it means that the initial design value of the dual-frequency four-arm helical antenna does not meet the signal transmission requirements. However, if each signal transmission performance indicator is compared and calculated one by one, a lot of time will be wasted, and a lot of manual intervention and coordination will be required, which is time-consuming and labor-intensive. Therefore, this method uses radar chart fitting data to express the overall performance of all signal transmission performance indicators, where the non-overlapping area is the difference between the simulated reference value and the expected threshold of each signal transmission performance indicator, that is, the difference radar area. This can quickly and intuitively obtain performance differences on the one hand, and save a lot of manual auxiliary calculations on the other hand, reduce the design error of the antenna structure, and ensure that the antenna can operate stably with the maximum accuracy in two specified frequency bands. Since the antenna structure design needs to ensure that each design parameter is accurately optimized in order to operate stably in two different frequency bands, this method introduces a particle swarm algorithm to screen and calculate the optimal solution from the first magnification interval and the second magnification interval according to the difference radar area, so as to obtain the optimal magnification value that makes the simulation performance reach the expected performance. Finally, the optimal magnification value is combined with the wavelength of the first frequency band and the second wavelength band to calculate the design optimization parameter value of the design parameter item.

[0079] It should be noted that this method can accurately optimize the design parameters of the dual-frequency four-arm helical antenna to stably work near the design center frequency in the two frequency bands of 1561 MHz and 1207 MHz, providing a means of design positioning and optimal solution screening for different signal transmission requirements of the dual-frequency four-arm helical antenna, eliminating the error phenomenon and numerous calculation steps of traditional manual design, and improving the design optimization efficiency of the dual-frequency four-arm helical antenna. Among them, the pitch is the spacing of each turn of the helical antenna along the circular polarization axis, which is usually related to the working wavelength of the antenna to ensure that the antenna can effectively radiate circularly polarized waves. The pitch may be about 0.2 to 0.4 times the wavelength of 1207MHz in the low frequency band (the wavelength of the first frequency band); the pitch may be about 0.1 to 0.3 times the wavelength of 1561MHz in the high frequency band (the wavelength of the second frequency band). The arm length is the total length of each antenna arm from the center to the end. The arm length needs to roughly match the low-frequency working wavelength, and the arm length needs to be short enough to ensure that no resonance or standing wave problems occur within the high-frequency working wavelength range. The arm length is usually about one-quarter of the wavelength of the corresponding frequency band. The arm width is the lateral dimension of the spiral arm, which mainly affects the bandwidth and impedance characteristics of the antenna. Usually, the arm width is generally narrower in both low and high frequency bands.

[0080] Furthermore, in a preferred embodiment of the present invention, the following steps are also included:

[0081] Acquire several current transmission signals of the dual-frequency four-arm helical antenna, extract and analyze the spectrum of the several current transmission signals to obtain a spectrum diagram of the current transmission signal, and determine the current impedance characteristics and current standing wave ratio of the dual-frequency four-arm helical antenna in a dynamic timing according to the spectrum diagram;

[0082] Constructing a state space model, injecting the current signal reflection coefficient and the current standing wave ratio under the dynamic time sequence into the state space model for description, and generating a current dynamic working state equation of the dual-frequency four-arm helical antenna;

[0083] Obtaining the work tasks and work logs of the dual-frequency four-arm helical antenna, presetting the expected working frequency based on the work tasks, and extracting the optimal impedance matching parameters of the dual-frequency four-arm helical antenna under different historical working frequency conditions through the work logs;

[0084] Calculate the approximation between the expected operating frequency and each historical operating frequency to obtain multiple approximations, and only extract the optimal impedance matching parameters corresponding to the historical operating frequency condition corresponding to the maximum approximation, which are defined as the necessary optimal impedance matching parameters for the expected operating frequency;

[0085] Solving the current dynamic working state equation to obtain the current closed-loop pole position of the impedance matching network, presetting the expected dynamic working state performance based on the necessary optimal impedance matching parameters, and determining the expected closed-loop pole position of the impedance matching network according to the expected dynamic working state performance;

[0086] A pole placement method is introduced to place the impedance matching network from the current closed-loop pole position to the desired closed-loop pole position, obtain a state feedback gain matrix, construct a Lyapunov verification function based on the Lyapunov stability criterion, and perform a stable closed-loop verification on the dual-frequency four-arm helical antenna control system after the impedance matching network pole position is placed using the Lyapunov verification function to obtain a verification score;

[0087] If the verification score is lower than the preset verification score, the state feedback gain matrix is ​​controlled and calibrated based on the verification score until the preset verification score is reached, thereby generating a calibrated state feedback controller;

[0088] The calibrated state feedback controller is deployed to the frequency adjustment system of the current dual-frequency four-arm helical antenna to obtain the optimal operating frequency band, and the optimal operating frequency band is uploaded to the dual-frequency four-arm helical antenna control system terminal.

[0089] It should be noted that impedance matching is a process used to adjust the load impedance and source impedance so that the impedance between the two is equal to achieve maximum power transmission. It can greatly ensure that the dual-frequency four-arm helical antenna can work more stably near the designed center frequency in the two frequency bands of 1561 MHz and 1207 MHz. Therefore, the impedance matching network can automatically adjust the working frequency band by real-time identification of the working needs of the dual-frequency four-arm helical antenna to ensure the best impedance matching of the antenna and optimize communication performance. However, it is difficult for the existing dual-frequency four-arm helical antenna to fully accurately analyze the working status of the antenna through the impedance matching network and switch itself to achieve the best working frequency band, resulting in a significant decrease in the signal transmission performance of the dual-frequency four-arm helical antenna, causing signal transmission interference, distortion and interruption. In view of this, this method describes the spectrum characteristics of the antenna when transmitting signals in the form of a state space model, thereby constructing the current dynamic working state equation of the dual-frequency four-arm helical antenna. Its current dynamic working state equation expresses the working frequency requirements of the antenna. According to the optimal impedance matching parameters of the dual-frequency four-arm helical antenna under different historical working frequency conditions, the optimal impedance matching parameters that meet the current working state of the antenna, that is, the necessary optimal impedance matching parameters, can be approximately screened out, so that the impedance matching network can be used to identify an expected dynamic working state performance that meets the working requirements of the antenna, which is an important target prerequisite for the optimal working frequency band state feedback. Then, the pole configuration method is used to place the impedance matching network from the current closed-loop pole position that meets the current working state of the antenna to the expected closed-loop pole position required to meet the working state requirements, forming a dynamic closed-loop state feedback that meets the antenna working expectations to ensure the dynamic performance of the antenna system. The pole to the left or close to the origin will make the antenna system converge quickly and enhance stability. The unreasonable position may cause the oscillation or slow response of the antenna system frequency band switching, which greatly ensures the accuracy of the closed-loop state feedback of the optimal working frequency band switching of the dual-frequency four-arm helical antenna. At this time, a state feedback gain matrix will be obtained. The state feedback gain matrix is ​​the controller parameter that controls the antenna system to automatically switch the optimal working frequency band according to the expected working requirements. Therefore, correctly calculating the state feedback gain matrix can make the antenna system reach a stable, fast and oscillation-free state.

[0090] It should be noted that the state feedback controller designed by the obtained state feedback gain matrix may not be able to automatically switch to the optimal frequency band accurately according to the working requirements of the antenna. This may be caused by the operation error of the state feedback gain matrix. Therefore, the obtained state feedback gain matrix needs to be verified. This method uses the Lyapunov stability criterion to check whether the closed-loop control system of the antenna meets the working expectations and whether it can meet the dynamic and static performance requirements, such as insufficient phase margin of the closed-loop control system and insensitivity of the system to interference of certain frequencies. If the verification score is lower than the preset verification score, it is necessary to control and calibrate the state feedback gain matrix to make the closed-loop control system of the antenna run more stably and improve the feasibility and robustness of the state feedback controller in the actual antenna control system. Finally, the calibrated state feedback controller is deployed to the frequency adjustment system of the current dual-band four-arm helical antenna to obtain the optimal working frequency band. This method can enable the antenna to dynamically switch and adjust its optimal operating frequency according to the working environment, communication requirements or spectrum usage in a closed-loop control state feedback manner, thereby ensuring the best impedance matching effect, thereby optimizing communication performance, reducing signal reflections, and improving signal transmission efficiency; at the same time, it can effectively optimize signal transmission quality, improve bandwidth utilization, and reduce signal interference.

[0091] In addition, the design optimization and control method of the dual-frequency four-arm helical antenna structure also includes the following steps:

[0092] Acquire a communication application scenario of the dual-frequency quadrifilar helical antenna, and determine necessary direction vectors and necessary direction characteristics of the radiation beam when the dual-frequency quadrifilar helical antenna receives and transmits signals based on the communication application scenario;

[0093] According to the necessary direction vector and necessary direction characteristics, the electronic scanning analysis of the beam is carried out in the radiation beam simulation software to draw the direction of the main lobe and the side lobe, so as to construct the necessary direction diagram of the radiation beam when the dual-frequency four-arm helical antenna receives and transmits signals;

[0094] Test the array phase communication status of the dual-frequency four-arm helical antenna, obtain the actual main lobe direction and the actual side lobe direction of the four-arm helical antenna array output radiation beam, and draw the actual directional diagram when constructing the dual-frequency four-arm helical antenna communication based on the actual main lobe direction and the actual side lobe direction;

[0095] Aligning the necessary directional pattern with the actual directional pattern, calculating the alignment deviation of the actual directional pattern compared to the reference with the necessary directional pattern as a reference, obtaining a alignment error rate, and determining the beam direction deviation of the quadrifilar helical antenna array according to the alignment error rate;

[0096] Acquire the signal phase value of each array unit element of the four-arm helical antenna array and the antenna array schematic diagram during the test process, analyze the signal phase values ​​of adjacent array unit elements according to the antenna array schematic diagram, and obtain the signal phase deviation value between adjacent array unit element groups;

[0097] A fuzzy rule base is constructed based on the beam direction deviation, the signal phase deviation values ​​between each adjacent array unit element group are converted into a fuzzy set, a fuzzy reasoning algorithm is introduced, and each fuzzy set is inferred and defuzzified in the fuzzy logic algorithm based on the fuzzy rule base to obtain a fuzzy reasoning result of the signal phase deviation;

[0098] According to the fuzzy reasoning result, the adjacent array unit element group that causes the beam direction deviation is determined and marked as the abnormal adjacent array unit element group. The abnormal array unit elements and the abnormal signal phase deviation values ​​contained in the abnormal adjacent array unit element group are extracted, and the phase of each abnormal array unit element is adjusted based on the abnormal signal phase deviation value.

[0099] It should be noted that the dual-band quadrifilar helical antenna is usually composed of multiple array units, and each array unit may be composed of a small antenna. The signal phase of each array unit can be independently controlled to achieve the control of the directional pattern, so that the dual-band quadrifilar helical antenna can tend to stable and efficient circular polarization radiation characteristics to ensure the quality of signal transmission. However, if the phase difference between each array unit is not adjusted properly, it may cause intensity errors in the main lobe direction and the side lobe direction of the antenna radiation beam. For example, if the signal phase of each unit in an antenna array gradually changes, a main lobe with strong directivity will be formed, while the strength of the side lobe is usually weak, resulting in an error in the directional pattern of the dual-band quadrifilar helical antenna, causing signal distortion or great interference. In this regard, this method first performs standardized registration and comparison analysis on the radiation pattern of the dual-frequency four-arm helical antenna. The beam direction deviation obtained by the registration and comparison is the phase adjustment error of the antenna array. However, the single acquisition of the beam direction deviation cannot clearly determine which array units should be adjusted, and lacks accurate traceability optimization effect. Therefore, this method uses fuzzy reasoning to ensure maximum accuracy and perform corresponding fuzzy control reasoning on the signal phase deviation value between different adjacent array unit element groups and the beam direction deviation, so as to infer the adjacent array unit element group that causes the beam direction deviation and make corresponding phase abnormality adjustments to it. This method can accurately control the phase of the antenna array unit, thereby ensuring that the radiation beam pattern of the dual-frequency four-arm helical antenna meets the target working requirements, can enhance the signal in a specific direction, achieve accurate beam pointing, and can greatly improve the anti-interference performance of the antenna, and improve the gain and signal-to-noise ratio of the antenna. At the same time, there is no need to physically move or rotate the array unit or antenna manually, which reduces human adjustment errors and has high reliability.

[0100] The above is based on the ideal embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A design optimization and control method for a dual-frequency quadrifilar helical antenna structure, characterized in that: The steps include: Obtain signal transmission requirements for the dual-frequency four-arm helical antenna to stably operate near the design center frequency in the two frequency bands of 1561 MHz and 1207 MHz, and obtain design parameter items of the dual-frequency four-arm helical antenna, including pitch, arm length, and arm width; Based on the big data, a frequency band wavelength of 1207 MHz is obtained, which is defined as the first frequency band wavelength, and a frequency band wavelength of 1561 MHz is obtained, which is defined as the second frequency band wavelength; Obtaining the magnification interval between each design parameter item and the wavelength of the first frequency band, which is defined as the first magnification interval; obtaining the magnification interval between each design parameter item and the wavelength of the second frequency band, which is defined as the second magnification interval; The signal transmission performance index is preset, and the initial magnifications of the first magnification interval and the second magnification interval are used as initial values. Based on the initial values, the electromagnetic field simulation software is used to simulate the performance of the dual-frequency four-arm helical antenna stably working near the design center frequency in the two frequency bands of 1561 MHz and 1207 MHz, and the simulation reference value of each signal transmission performance index is obtained; Construct a radar map, and draw a simulated reference value of each signal transmission performance indicator by fitting the radar map to generate a simulated reference radar map of the signal transmission performance indicator; Based on the signal transmission requirements, an expected reference radar chart of the signal transmission performance index is obtained, and the radar area that does not overlap between the simulated reference radar chart and the expected reference radar chart is calculated and marked as a difference radar area; The particle swarm algorithm is introduced to define each magnification value in the first magnification interval and the second magnification interval as a particle. The current fitness value of each particle at the current position is calculated based on the difference radar area evaluation. The individual optimal solution and the global optimal solution of the particle are continuously updated and iterated through the current fitness value to generate the optimal magnification value that satisfies the difference radar area. The optimal magnification value is combined with the first wavelength and the second wavelength to multiply the wavelengths and finally obtain the design optimization parameter value of the design parameter item.

2. The design optimization and control method of a dual-frequency four-arm helical antenna structure according to claim 1, characterized in that: The dual-frequency four-arm helical antenna comprises an FPC substrate, which is made of polyimide material. Four helical antennas are integrated on the FPC substrate. The material of the helical antenna is made of electrolytic copper foil conductor. The total thickness of each helical antenna is less than 0.15 mm. The four helical antennas are arranged on the FPC substrate in a 90° directional helical form to enhance the directivity and gain rate of signal transmission. Each helical antenna is independent of each other and has a phase difference. The dual-frequency four-arm helical antenna is in a dual-frequency working mode, and the dual-frequency working mode includes a low frequency band of 1207 MHz and a high frequency band of 1561 MHz. The dual-frequency four-arm helical antenna has a pitch of 49.7 mm to 99.4 mm, an arm length of 62.1 mm, and an arm width of 2 mm to 5 mm in the low frequency band of 1207 MHz. The dual-frequency four-arm helical antenna has a pitch of 19.23 mm to 57.69 mm, an arm length of 48.1 mm, and an arm width of 2 mm to 5 mm in the high frequency band of 1561 MHz. The dual-frequency four-arm helical antenna is fixed by a rubber ring, and the rubber ring is used to erect the dual-frequency four-arm helical antenna on a PCB flexible printed circuit board. The PCB flexible printed circuit board is made of polyimide material and is laid in two layers as a whole, which can effectively shield electromagnetic interference signals and reduce the overall weight of the dual-frequency four-arm helical antenna. A feeding network is arranged on the front of the PCB flexible printed circuit board. The feeding network includes a microstrip line, which is used to transmit signals from a receiving segment or a transmitting source to the four helical antennas respectively. A grounding platform is provided at the bottom of the PCB flexible printed circuit board to suppress signal interference.

3. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 2, characterized in that: The structure of the dual-frequency four-arm helical antenna is a layered stack of two layers of FPC substrates, which is used to improve the signal communication quality. The two layers of FPC substrates are adhered by double-sided adhesive tape.

4. The design optimization and control method of a dual-frequency four-arm helical antenna structure according to claim 2, characterized in that: A soldering pad is arranged at the bottom edge of the FPC substrate, and each of the soldering pads is connected to four spiral antennas.

5. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 4, characterized in that: The dual-frequency four-arm helical antenna is soldered on the front side of the PCB flexible printed circuit board through the soldering pads, and the number of the soldering pads is set to 12, so that the communication between the dual-frequency four-arm helical antenna and the PCB flexible printed circuit board is more stable.

6. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 2, characterized in that: The top of each of the four helical antennas is extended with an extended antenna of fixed size, that is, the dual-band four-arm helical antenna has as many as four extended antennas. The extended antenna is wound around the top edge of the FPC substrate to increase the signal reception and transmission distance.

7. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 2, characterized in that: The PCB flexible printed circuit board is in the shape of a disc, and a low-noise amplifier circuit, a low-pass filter, a signal processing circuit and an impedance matching network are integrated on the front side of the PCB flexible printed circuit board. The impedance matching network is used to improve the signal transmission efficiency between the helical antenna and the signal receiving system.

8. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 2, characterized in that: The back side of the PCB flexible printed circuit board is equipped with resistors, capacitors, inductors and a crystal oscillator, and the back edge of the PCB flexible printed circuit board is provided with multiple groups of buckles.

9. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 8, characterized in that: Multiple groups of the clips are used to buckle and fix the edges of the metal shielding cover so that the metal shielding cover remains connected to the PCB flexible printed circuit board and the spiral antenna. The metal shielding cover is an octagonal thin iron sheet made of aluminum. The weight of the metal shielding cover is 1.2 grams, which reduces the overall weight of the dual-band four-arm spiral antenna.

10. The design optimization and control method of a dual-frequency quadrifilar helical antenna structure according to claim 2, characterized in that: The following steps are also included: Acquire several current transmission signals of the dual-frequency four-arm helical antenna, extract and analyze the spectrum of the several current transmission signals to obtain a spectrum diagram of the current transmission signal, and determine the current impedance characteristics and current standing wave ratio of the dual-frequency four-arm helical antenna in a dynamic timing according to the spectrum diagram; Constructing a state space model, injecting the current signal reflection coefficient and the current standing wave ratio under the dynamic time sequence into the state space model for description, and generating a current dynamic working state equation of the dual-frequency four-arm helical antenna; Obtaining the work tasks and work logs of the dual-frequency four-arm helical antenna, presetting the expected working frequency based on the work tasks, and extracting the optimal impedance matching parameters of the dual-frequency four-arm helical antenna under different historical working frequency conditions through the work logs; Calculate the approximation between the expected operating frequency and each historical operating frequency to obtain multiple approximations, and only extract the optimal impedance matching parameters corresponding to the historical operating frequency condition corresponding to the maximum approximation, which are defined as the necessary optimal impedance matching parameters for the expected operating frequency; Solving the current dynamic working state equation to obtain the current closed-loop pole position of the impedance matching network, presetting the expected dynamic working state performance based on the necessary optimal impedance matching parameters, and determining the expected closed-loop pole position of the impedance matching network according to the expected dynamic working state performance; A pole placement method is introduced to place the impedance matching network from the current closed-loop pole position to the desired closed-loop pole position, obtain a state feedback gain matrix, construct a Lyapunov verification function based on the Lyapunov stability criterion, and perform a stable closed-loop verification on the dual-frequency four-arm helical antenna control system after the impedance matching network pole position is placed using the Lyapunov verification function to obtain a verification score; If the verification score is lower than the preset verification score, the state feedback gain matrix is ​​controlled and calibrated based on the verification score until the preset verification score is reached, thereby generating a calibrated state feedback controller; The calibrated state feedback controller is deployed to the frequency adjustment system of the current dual-frequency four-arm helical antenna to obtain the optimal operating frequency band, and the optimal operating frequency band is uploaded to the dual-frequency four-arm helical antenna control system terminal.

Images