High-precision planar spiral active GNSS antenna device

Abstract

The invention relates to the technical field of sensor calibration, in particular to a high-precision planar spiral active GNSS antenna device, which comprises an antenna radiation main body and a radio frequency front-end circuit which are integrally arranged, the antenna radiation main body comprises a dielectric substrate and is processed by adopting a PCB (Printed Circuit Board) one-step forming process, a planar spiral radiation arm is arranged on the dielectric substrate, and the radio frequency front-end circuit is connected with the planar spiral radiation arm. The back surface of the dielectric substrate is provided with a *-shaped hollow coupling structure. The radio frequency front-end circuit is integrated with a dielectric substrate of the antenna radiation main body and is used for filtering, amplifying, shunting, gain adjusting and combining satellite signals received by the antenna radiation main body; the antenna radiation main body is configured to couple electromagnetic energy through a spiral structure of the planar spiral radiation arm to form broadband radiation, a coupling gap is generated in cooperation with a star-shaped hollow coupling structure on the back face of the dielectric substrate to expand gain bandwidth, bandwidth expansion is achieved through the synergistic effect of the broadband radiation and the dielectric substrate, and the broadband radiation is formed by combining shunt filtering processing of the radio frequency front-end circuit. And the requirements of light weight and integration of the automatic driving vehicle-mounted terminal can be met.

Description

Technical Field

[0001] This invention relates to the field of sensor calibration technology, and in particular to a high-precision planar spiral active GNSS antenna device. Background Technology

[0002] With the rapid development of Global Navigation Satellite Systems (GNSS), fields such as autonomous driving, UAV mapping, and high-precision measurement are placing increasingly stringent demands on the accuracy, reliability, and adaptability of navigation and positioning. In particular, antenna devices need to possess multi-constellation, multi-frequency signal reception capabilities to ensure positioning stability in complex scenarios. Currently, mainstream high-precision GNSS antennas need to cover multiple frequency bands, including GPS (L1, L2, L5), GLONASS (G1), and BD (B1I, B2A), while also meeting the design requirements of miniaturization, lightweighting, and low cost for terminal equipment.

[0003] However, existing GNSS antenna technology still suffers from many insurmountable defects, hindering its application in high-precision miniaturized terminals. Traditional high-precision GNSS antennas generally employ a ceramic-layered microstrip antenna structure, using two layers of ceramic dielectric to receive signals in the high-frequency (L1) and low-frequency (L2, L5) bands respectively: the L1 band uses one layer of ceramic dielectric substrate, while the L2 and L5 bands use another layer of ceramic dielectric substrate, and the two layers are stacked and packaged to form a complete antenna. This structural design directly results in a bulky and heavy antenna, making it extremely difficult to install and adapt to miniaturized equipment such as autonomous driving vehicle terminals and lightweight drones, and failing to meet the integrated design requirements of the terminal.

[0004] In terms of cost control, the shortcomings of traditional ceramic stacked antennas are more prominent. On the one hand, the material cost of a double-layer ceramic dielectric substrate is much higher than that of a single-layer substrate, usually more than twice the cost of a single-layer dielectric substrate. On the other hand, to achieve coupled output of high and low frequency signals, this type of antenna requires a multi-feed design, with at least two feed points on each dielectric substrate, which in turn requires at least three phase-shifting bridges to achieve signal synthesis, significantly increasing the material cost and design complexity of the circuit. At the same time, the feeding method of ceramic dielectric antennas often adopts a coaxial transmission structure composed of pins and insulators, which not only further increases the material cost but also has the problem of complex assembly process—the assembly process of pins and insulators is cumbersome and prone to quality problems such as omissions and assembly deviations, resulting in a decrease in antenna yield and indirectly increasing production and manufacturing costs.

[0005] Furthermore, there is room for optimization in the design of the RF front-end circuit of traditional GNSS antennas. Existing antennas often use integrated devices for their RF front-end filters. These integrated filters are not only expensive but also space-consuming, contradicting the trend towards antenna miniaturization. At the same time, some integrated filters have narrow bandwidths, making them unsuitable for multi-frequency signal reception, and they also suffer from high insertion loss, limited out-of-band rejection, and are susceptible to external interference signals, thus reducing the antenna's positioning accuracy. Summary of the Invention

[0006] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0007] A high-precision planar spiral active GNSS antenna device includes an integrated antenna radiating body and an RF front-end circuit. The antenna radiating body includes a dielectric substrate and is manufactured using a PCB one-time molding process. A planar spiral radiating arm is provided on the dielectric substrate, and a meter-shaped hollow coupling structure is provided on the back of the dielectric substrate. The RF front-end circuit is integrated with the dielectric substrate of the antenna radiating body and is used to filter, amplify, split, adjust the gain, and combine the satellite signals received by the antenna radiating body. The antenna radiating body is configured to couple electromagnetic energy through the spiral structure of the planar spiral radiating arm to form broadband radiation. The coupling gap generated by the meter-shaped hollow coupling structure on the back of the dielectric substrate expands the gain bandwidth. The two work together to achieve bandwidth expansion. Combined with the splitting and filtering processing of the RF front-end circuit, the antenna device can receive multi-constellation multi-frequency satellite signals, including GPS: L1, L2, L5, GLONASS: G1, and BD: B1I, B2A band signals.

[0008] Preferably, the dielectric substrate of the antenna radiating body is made of FR4 material, the dielectric constant of the dielectric substrate is 4.4, and the thickness is 1 mm.

[0009] Preferably, the front side of the dielectric substrate of the antenna radiating body is provided with a radiating feed point; the radiating feed point is a circular pad with a diameter of 1.5mm, and the radiating feed point adopts a coaxial feeding method; the planar spiral radiating arm is an Archimedean spiral structure with a line width of 0.8mm and a length set to an even multiple of a quarter wavelength of the center frequency.

[0010] Preferably, a microstrip line is provided between the radiating feed point and the starting point of the planar spiral radiating arm. The length of the microstrip line is one-eighth of the center frequency wavelength. Impedance matching is achieved by adjusting the length and width of the microstrip line, so that the antenna resonates at the center frequency.

[0011] Preferably, the end of the planar spiral radiating arm is provided with a resistance matching structure, which is configured as an impedance matching structure adapted to the linewidth and length of the radiating arm.

[0012] Preferably, a square grounding pad is provided on the front side of the dielectric substrate of the antenna radiating body and next to the radiating feed point; the square grounding pad is connected to the ground layer on the back side of the dielectric substrate through a metallized via; a metric-shaped hollow coupling structure is provided on the ground layer, the gap width of the metric-shaped hollow coupling structure is 1.5mm, and the end of the metric-shaped hollow coupling structure is provided with an arc-shaped gap.

[0013] Preferably, the RF front-end circuit includes an input interface, a pre-filter amplification module, a high-low frequency splitting processing module, and a combining amplification output module, which are connected in sequence; the passive signal of the antenna radiating body is transmitted to the input interface of the RF front-end circuit through a copper coaxial cable.

[0014] Compared with the prior art, the beneficial effects of the present invention are: Through the collaborative design of planar spiral radiating arms and rice-shaped hollow coupling structure, combined with the integrated application of FR4 substrate and PCB one-time molding process, and the refined processing architecture of RF front-end pre-filtering amplification, high and low frequency splitting, secondary filtering, independent gain adjustment, and combined amplification output, compared with traditional vehicle GNSS antennas, it effectively solves the contradiction between miniaturization and multi-band coverage of traditional multi-frequency antennas. The single PCB substrate integrated design allows the device size to be further reduced, making it much smaller than traditional stacked ceramic antennas, which can meet the lightweight and integrated requirements of autonomous driving vehicle terminals. At the same time, a single antenna can stably cover GPS: L1, L2, L5, GLONASS: G1, BD: B1I, B2A band signals. The high-precision planar spiral active GNSS antenna device can also reduce costs and process complexity. FR4 material replaces expensive ceramic substrates, and the one-time PCB molding process avoids the complex stacking and pin feeding assembly of ceramic antennas, further reducing material costs and improving yield, which meets the needs of large-scale mass production in vehicles. It can significantly improve the adaptability to complex vehicle environments. Through the dual optimization of the resistance matching structure and the Mi-type coupling structure, the antenna axis ratio is ≤1.5dB and the circular polarization purity is higher. It can effectively resist the signal polarization distortion caused by the metal body. Combined with the front filter, it can reduce the interference signal to less than one ten-thousandth of the original at the 2GHz frequency point. The shunt circuit can suppress the crosstalk between high and low frequency signals to less than one percent of the original. It can efficiently filter out electromagnetic interference from vehicle motors, millimeter-wave radar, etc. It can still ensure centimeter-level positioning accuracy within ±2cm in complex scenarios such as urban canyons and tunnel entrances.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the front structure of the antenna radiating body in this invention; Figure 2 This is a schematic diagram of the rear structure of the antenna radiating body in this invention; Figure 3 This is a schematic diagram of the overall structure of the antenna radiating body in this invention; Figure 4 This is a circuit diagram of the first half of the radio frequency front-end circuit in this invention; Figure 5 This is a circuit schematic diagram of the latter half of the radio frequency front-end circuit in this invention; Figure 6 This is a circuit module connection block diagram of the radio frequency front-end circuit in this invention.

[0018] The reference numerals and names in the figure are as follows: 1. Dielectric substrate; 2. Radiation feed point; 4. Planar spiral radiation arm start point; 5. Microstrip line; 6. Planar spiral radiation arm; 7. Resistor matching structure; 8. Grounding pad; 9. Meter-shaped hollow coupling structure; 10. Curved line gap; 11. Input interface; 12. Pre-filter amplification module; 13. High and low frequency split processing module; and 14. Combined amplification output module. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1-6 This embodiment proposes a high-precision planar spiral active GNSS antenna device, capable of receiving multi-constellation, multi-frequency GPS (L1, L2, L5), GLONASS (G1), and BD (B1I, B2A) satellite signals. Taking the high-precision positioning system of an autonomous vehicle as an application scenario, this high-precision planar spiral active GNSS antenna device is integrated into the roof-mounted communication module of the autonomous vehicle. The specific implementation is as follows: Fabrication of the antenna radiating body: FR4 (glass fiber reinforced epoxy resin) material with a dielectric constant of 4.4 and a thickness of 1mm was selected as the dielectric substrate 1. The dielectric substrate 1 was processed using a PCB one-time molding process. A planar spiral radiating arm 6 was printed on the front side of the dielectric substrate 1. The planar spiral radiating arm 6 is an Archimedean spiral structure with a linewidth of 0.8mm and a length of twice the quarter wavelength corresponding to the center frequency of 1575.42MHz in the L1 band. At the same time, a circular radiating feed point 2 with a diameter of 1.5mm was formed on the front side of the dielectric substrate 1. This feed point serves as the signal transmission interface between the antenna radiating body and the RF front-end circuit. Its core function is to efficiently export the multi-frequency GNSS electromagnetic signals coupled and received by the planar spiral radiating arm 6 to the subsequent microstrip line 5 and RF front-end. The 1.5mm diameter design is based on the adaptation requirements of coaxial cable feeding: on the one hand, this size can stably support the welding and fixing of the inner conductor of the coaxial cable, ensuring the mechanical reliability of the feeding connection and avoiding poor contact under vehicle bumps and vibrations; on the other hand, the circular structure can make the current distribution uniform, reduce radiation loss during signal transmission, and match the transmission characteristics of GNSS multi-frequency signals, reducing the reflection coefficient of the feeding port. This radiating feed point 2 adopts coaxial cable feeding, which can utilize the shielding layer of the coaxial cable to isolate electromagnetic interference in the vehicle environment, prevent interference signals from entering the feeding link, ensure the purity of the target GNSS signal, and at the same time, the low loss characteristics of the coaxial cable can reduce signal attenuation in the feeding link.

[0021] Furthermore, a microstrip line 5 is placed between the starting point of the radiating feed point 2 and the planar spiral radiating arm 6. The length of the microstrip line 5 is one-eighth of the wavelength of the center frequency point of the L1 band. By adjusting the linewidth of the microstrip line 5 to 0.5mm, 50Ω impedance matching between the radiating feed point 2 and the planar spiral radiating arm 6 is achieved, ensuring efficient signal transmission. From the perspective of impedance matching principles, the input impedance of the planar spiral radiating arm 6 differs from the 50Ω standard impedance of the radiating feed point 2 and the RF front-end circuit. Direct connection would cause signal reflection at the interface, resulting in signal loss and distortion. By designing the length of the microstrip line 5 to one-eighth of the wavelength of the center frequency point of the L1 band, approximately 24.1mm, and adjusting the linewidth by 0.5mm, the microstrip line 5 can form a specific impedance transformation network, accurately matching the input impedance of the planar spiral radiating arm 6 to 50Ω, minimizing the signal reflection coefficient. Ultimately, the signal transmission loss is ≤0.5dB, ensuring that the weak GNSS signal received by the planar spiral radiating arm 6 can be transmitted to the radio frequency front-end circuit to the maximum extent, providing a sufficient signal amplitude basis for subsequent signal amplification and filtering, and avoiding the decrease in positioning accuracy due to excessive signal loss. This is especially suitable for the stringent requirements of centimeter-level positioning for autonomous driving on the efficiency of weak signal transmission.

[0022] A resistor matching structure 7 is welded to the end of the planar spiral radiating arm 6. The resistance value of the resistor matching structure 7 is consistent with the equivalent impedance of the end of the planar spiral radiating arm 6. When the planar spiral radiating arm 6 is working, electromagnetic energy is transmitted along the spiral path. If the end of the radiating arm is suspended or the impedance is mismatched, some signal energy cannot be completely radiated, which will form a reflected current. This reflected current will be superimposed on the incident current, causing disordered current distribution on the radiating arm. This not only causes signal energy loss, but also damages the radiation characteristics of the antenna. Designing the resistance value of the resistor matching structure 7 to be consistent with the equivalent impedance of the end of the radiating arm allows the resistor to become a matching load at the end of the radiating arm, efficiently absorbing the remaining electromagnetic energy, avoiding the generation of reflected current, ensuring that the signal energy is radiated outward to the maximum extent, and reducing transmission loss. Furthermore, GNSS signals are circularly polarized waves, requiring the antenna to stably output circularly polarized radiation for efficient signal reception. While the planar helical radiating arm 6 naturally possesses wideband circular polarization characteristics, the reflected current at its end can induce stray polarization. These stray components interfere with normal circularly polarized radiation, leading to an increase in the antenna's axial ratio. The resistor matching structure 7 absorbs the reflected current, suppressing the generation of stray polarization components at the source, resulting in a purer circularly polarized wave output from the radiating arm, ultimately controlling the axial ratio to within 1.5 dB. In addition, the antenna in this embodiment needs to cover multiple frequency bands such as L1, L2, and L5, and the equivalent impedance of the radiating arm varies slightly across different frequency bands. The resistance value of the resistor matching structure 7 precisely matches the equivalent impedance at the end of the radiating arm, ensuring effective suppression of reflected current across the entire target frequency band. This prevents polarization performance degradation in a particular frequency band due to impedance mismatch, ensuring consistency in the reception of multi-constellation, multi-frequency signals.

[0023] A square grounding pad 8 with dimensions of 2mm × 2mm is formed on the front side of the dielectric substrate 1 and 2mm to the side of the radiating feed point 2. The square grounding pad 8 is connected to the ground layer on the back side of the dielectric substrate 1 through a metallized via with a diameter of 0.3mm. It can provide a low impedance grounding path. The square grounding pad 8 serves as the front-end interface for antenna grounding. The metallized via enables the connection between the front and back sides and the overall grounding, allowing stray currents generated during antenna operation to be quickly conducted into the ground layer. This prevents stray currents from accumulating near the feed point, avoids interference with the signal transmission of the radiating feed point 2, and ensures the purity of the GNSS target signal. Furthermore, it can enhance electromagnetic shielding. The shielding structure formed by the grounding pad 8 and the back grounding layer can resist external electromagnetic interference generated by motors, radars and other equipment in the vehicle environment, reduce interference signals from entering the antenna radiation link through the feed point, and suppress the leakage of the antenna's own radiated signal to the surrounding circuits. In addition, it can ensure the reliability of structure and connection. The 2mm×2mm square size is suitable for PCB processing technology and can stably support the grounding connection or soldering fixation requirements. The 0.3mm diameter metallized via ensures the mechanical connection strength of the front and back grounding, and is suitable for long-term stable operation in the bumpy and vibrating environment of the vehicle, while improving the overall mechanical rigidity of the antenna.

[0024] A 1 / 4-shaped hollow coupling structure 9 is etched into the ground layer on the back of the dielectric substrate 1. The gap width of the 1 / 4-shaped hollow coupling structure 9 is set to 1.5 mm, and an arc line gap 10 with an arc radius of 2 mm is added at the end of the 1 / 4-shaped hollow coupling structure 9. This can eliminate the edge current concentration phenomenon caused by the right angle gap, avoid the spurious resonance peak caused by current concentration, ensure the smooth and stable gain curve in each target frequency band, reduce in-band insertion loss, and ensure the consistency of the antenna's receiving sensitivity across the entire frequency band. Through the synergistic effect of the 1 / 4-shaped hollow coupling structure 9 and the planar spiral radiating arm 6, the gain bandwidth of the antenna is expanded, so that the antenna's operating bandwidth covers target frequency bands such as L1 (1559-1591MHz), L2 (1215-1237MHz), and L5 (1176-1188MHz), solving the problem of high single-band gain and weak multi-band coverage capability of traditional planar spiral antennas.

[0025] Please refer to Figure 4-6 The radio frequency (RF) front-end circuit integrated with the antenna radiating body is fabricated by integrating the RF front-end circuit and the antenna radiating body onto the same PCB substrate. This RF front-end circuit includes an input interface 11, a pre-filter amplification module 12, a high- and low-frequency splitting processing module 13, and a combining amplification output module 14, all electrically connected in sequence. The passive signal from the antenna radiating body is transmitted to the input interface 11 of the RF front-end circuit via a copper coaxial cable. This achieves integrated and efficient processing of the antenna signal while also considering miniaturization, low loss, and anti-interference requirements. On the one hand, the PCB integration eliminates the need for external transmission cables between the antenna and the RF circuit, shortening the signal transmission path, reducing signal loss during transmission, and minimizing interference. The impact of vibration and bumps in the vehicle environment on signal connection stability enhances the overall mechanical reliability of the device, meeting the design requirements of integrated and lightweight vehicle terminals. On the other hand, the hierarchical serial module architecture can perform refined processing of the entire process of filtering, amplifying, splitting, purifying, combining, and adapting the weak multi-frequency passive GNSS signals received by the antenna. Input interface 11 serves as the signal receiving entry point, which is precisely connected to the feed point of the antenna radiating body through a copper coaxial cable to ensure lossless signal input. The subsequent hierarchical modules can specifically solve problems such as strong electromagnetic interference, multi-frequency signal mixing, and unstable amplitude in the vehicle environment, providing high-purity and high-stability GNSS signals for the positioning module.

[0026] In the aforementioned RF front-end circuit, the pre-filter amplification module 12 includes a pre-filter, coupling capacitor C5, and a first-stage amplifier U1. It performs anti-interference preprocessing and initial amplitude enhancement on the weak passive GNSS signal input from the antenna, laying a high-purity signal foundation for subsequent signal splitting and purification. The pre-filter is a multi-stage inductor and capacitor bandpass filter network, such as... Figure 4As shown, the pre-filter is composed of capacitor C1, inductor L1, capacitor C2, inductor L2, capacitor C3, inductor L3, capacitor C4, and inductor L4 connected together. This pre-filter is used to filter out unwanted signals and interference signals outside the operating frequency band from the antenna received signal. Its insertion loss does not exceed 1.5dB. While filtering out unwanted signals such as clutter and harmonics generated by equipment such as motors and millimeter-wave radar in the vehicle environment, it retains the target signal energy to the maximum extent. The out-of-band rejection is not less than 40dB at 2GHz, which can significantly attenuate strong interference signals outside the passband and prevent interference signals from intruding into the subsequent processing links. The pre-filter passes through... The overcoupling capacitor C5 is electrically connected to the input terminal of the first-stage amplifier U1. The coupling capacitor C5 performs the dual functions of DC blocking and signal coupling transmission. It can block the DC component of the front-end circuit from entering the amplifier U1 and causing its operating point to shift, and can also efficiently transmit the filtered AC GNSS signal. The gain of the first-stage amplifier U1 is set to 5dB to perform preliminary amplification of the filtered signal, raising the signal amplitude to the range that meets the working requirements of the high and low frequency split circuit. This solves the problem of low amplitude of GNSS passive signal and easy submersion by noise in subsequent circuits, ensuring the continuity and reliability of signal processing. The high-low frequency splitting processing module 13 includes a high-low frequency balun splitting circuit, a post-filtering module, and a gain adjustment module. It performs precise frequency band separation and secondary filtering purification on the pre-amplified multi-frequency mixed GNSS signal, eliminating mutual interference between high and low frequency signals and providing a high-purity single-band signal for subsequent gain adjustment and combining output. The high-low frequency balun splitting circuit consists of inductor L5, capacitor C6, inductor L6, capacitor C7, inductor L7, and capacitor C8. Figure 5 As shown, inductor L5, capacitor C6, and inductor L8 constitute a high-frequency splitter unit to separate the L1 frequency band signal. Capacitor C7, inductor L7, and capacitor C8 constitute a low-frequency splitter unit to separate the L2 and L5 frequency band signals. The isolation between the high-frequency and low-frequency splitter units is no less than 20dB to reduce mutual interference between high-frequency and low-frequency signals within the band, prevent harmonic components of high-frequency signals from mixing into the low-frequency link, and prevent spurious components of low-frequency signals from interfering with the high-frequency link, thus ensuring the independence and purity of the two signals. The post-filtering module includes an L1 filter and an L... Two filters are used: the center frequency of filter L1 is set to 1575MHz, and the center frequency of filter L2 is set to 1220MHz. They are connected to the output terminals of the high-frequency splitter and the low-frequency splitter, respectively, to perform secondary filtering and purification on the split signal. This further filters out the adjacent channel interference and noise remaining in the splitting process, significantly improving the signal-to-noise ratio of the output signal. This lays a high-quality signal foundation for subsequent gain adjustment and combining, ensuring that the signal finally output to the positioning module can accurately match the high-precision positioning requirements of multi-constellation and multi-frequency systems.

[0027] like Figure 5As shown, the gain adjustment module includes two independent Π-type resistor matching networks. One Π-type resistor matching network consists of resistors R2, R3, and R4, which is connected to the output of the L1 filter and used to adjust the gain of the L1 band signal. The other Π-type resistor matching network consists of resistors R6, R7, and R8, which is connected to the output of the L2 filter and used to adjust the gain of the L2 and L5 band signals. Independent amplitude calibration and gain adaptation are performed on the L1 band signal and the L2 and L5 band signals after splitting and secondary filtering to ensure that the output amplitudes of the two signals are consistent and match the input requirements of the subsequent combiner and positioning module. The two Π-type resistor matching networks are respectively connected to the outputs of the L1 and L2 filters, utilizing resistor voltage division and impedance... The dual characteristics of the matching feature enable precise gain adjustment from 0dB to 6dB. This not only compensates for the amplitude attenuation caused by filtering and splitting of signals from different frequency bands, but also avoids mutual interference between the two signals from a single gain adjustment link. At the same time, the Π-shaped topology can maintain a standard impedance matching of 50Ω while adjusting the gain, preventing signal reflection loss caused by gain adjustment and ensuring signal transmission efficiency. The design of two independent adjustments can adapt to the signal amplitude characteristics of the L1 band and the L2 and L5 bands respectively, solving the problem of amplitude imbalance caused by the frequency band difference of multi-frequency signals. This ensures that the amplitude of the two signals is consistent before merging, avoiding signal cancellation or distortion caused by amplitude difference during merging. Ultimately, it provides the positioning module with a stable and high-purity multi-frequency GNSS signal.

[0028] like Figure 5As shown, the combiner amplifier output module 14 includes a combiner, a final stage amplifier U2, and a Π-type matching network. It efficiently combines, enhances, and adapts the amplitude of two independent frequency band signals, providing a stable GNSS signal that meets accuracy requirements for the vehicle-mounted positioning module. The combiner is an inductor and capacitor bandpass combining network, composed of inductor L8, capacitor C9, inductor L9, capacitor C10, inductor L10, and capacitor C11. It combines the gain-adjusted L1 band signal with the L2 and L5 band signals, accurately combining them into one signal with low loss while avoiding mutual interference or energy cancellation at the combining node, ensuring the integrity of the multi-frequency signal. The output of the combiner is electrically connected to the input of the final stage amplifier U2. The gain of the final stage amplifier U2 is adjusted according to the vehicle-mounted positioning module. The positioning module is selected with a requirement of 10dB. The final stage amplifier U2 is used to enhance the amplitude of the combined signal, making up for the slight losses in the preceding splitting, filtering, and combining stages, and raising the signal amplitude to the standard range required by the vehicle positioning module. This solves the problem of decreased positioning sensitivity caused by signal amplitude attenuation after multi-frequency combining. The Π-type matching network consists of inductor L11, capacitor C12, and inductor L12. Its core function is to adjust the standing wave ratio (VSWR) of the output signal of the final stage amplifier and maintain a standard impedance matching of 50Ω. Controlling the VSWR within 1.8 can significantly reduce signal reflection loss and ensure that the signal is transmitted to the positioning module through the output port with the highest efficiency. Finally, it realizes closed-loop processing of multi-frequency signal combining, amplitude enhancement, and efficient transmission, ensuring the high purity and high stability of the active antenna output signal, and providing core signal support for centimeter-level high-precision positioning of autonomous driving.

[0029] The high-precision planar spiral active GNSS antenna device proposed in this technical solution, through the collaborative design of the planar spiral radiating arm 6 and the meter-shaped hollow coupling structure 9, combined with the integrated application of FR4 substrate and PCB one-time molding process, and the refined processing architecture of RF front-end pre-filtering amplification, high and low frequency splitting, secondary filtering, independent gain adjustment, and combined amplification output, effectively solves the contradiction between miniaturization and multi-band coverage of traditional vehicle-mounted GNSS antennas compared with traditional multi-frequency antennas. The single PCB substrate integrated design allows the device size to be further reduced, making it much smaller than traditional stacked ceramic antennas, which can meet the lightweight and integrated requirements of autonomous driving vehicle terminals. At the same time, a single antenna can stably cover GPS: L1, L2, L5, GLONASS: G1, BD: B1I, B2A band signals. Furthermore, the high-precision planar spiral active GNSS antenna device can reduce costs and process complexity. FR4 material replaces expensive ceramic substrates, and the one-time PCB molding process avoids the complex stacking and pin feeding assembly of ceramic antennas, further reducing material costs and increasing yield, which meets the needs of large-scale mass production in vehicles. Furthermore, it significantly improves adaptability to complex vehicle environments. Through the dual optimization of the resistance matching structure 7 and the meter-shaped hollow coupling structure 9, the antenna axis ratio is ≤1.5dB, and the circular polarization purity is higher. It can effectively resist signal polarization distortion caused by metal body obstruction. Combined with the front filter, it can reduce the interference signal to less than one ten-thousandth of the original at the 2GHz frequency point, and the shunt circuit can suppress the crosstalk between high and low frequency signals to less than one percent of the original, achieving a high isolation effect. It can efficiently filter out electromagnetic interference from vehicle motors, millimeter-wave radar, etc., and can still ensure centimeter-level positioning accuracy within ±2cm in complex scenarios such as urban canyons and tunnel entrances.

[0030] Through the above implementation methods, this device can be adapted to the in-vehicle environment of autonomous vehicles, realize the reception of multi-constellation and multi-frequency satellite signals, ensure centimeter-level positioning accuracy, and meet the requirements of miniaturization, low cost, and high reliability.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A high-precision planar spiral active GNSS antenna device, characterized in that, The antenna radiating body and the radio frequency front-end circuit are integrated. The antenna radiating body includes a dielectric substrate (1) and is manufactured using a PCB one-time molding process. A planar spiral radiating arm (6) is provided on the dielectric substrate (1), and a meter-shaped hollow coupling structure (9) is provided on the back of the dielectric substrate (1). The radio frequency front-end circuit is integrated with the dielectric substrate (1) of the antenna radiating body and is used to filter, amplify, split, adjust the gain and combine the satellite signals received by the antenna radiating body. The antenna radiating body is configured to couple electromagnetic energy through the spiral structure of the planar spiral radiating arm (6) to form broadband radiation. The coupling gap generated by the meter-shaped hollow coupling structure (9) on the back of the dielectric substrate (1) expands the gain bandwidth. The two work together to achieve bandwidth expansion. Combined with the splitting and filtering processing of the radio frequency front-end circuit, the antenna device can receive multi-constellation multi-frequency satellite signals. The multi-constellation multi-frequency satellite signals include GPS: L1, L2, L5, GLONASS: G1, BD: B1I, B2A band signals.

2. The high-precision planar spiral active GNSS antenna device according to claim 1, characterized in that, The dielectric substrate (1) of the antenna radiating body is made of FR4 material, with a dielectric constant of 4.4 and a thickness of 1 mm.

3. The high-precision planar spiral active GNSS antenna device according to claim 1, characterized in that, The dielectric substrate (1) of the antenna radiating body has a radiating feed point (2) on the front side; the radiating feed point (2) is a circular pad with a diameter of 1.5 mm, and the radiating feed point (2) adopts a coaxial feeding method; the planar spiral radiating arm (6) is an Archimedean spiral structure with a line width of 0.8 mm and a length set to an even multiple of a quarter wavelength of the center frequency.

4. A high-precision planar spiral active GNSS antenna device according to claim 3, characterized in that, A microstrip line (5) is provided between the radiating feed point (2) and the starting point (4) of the planar spiral radiating arm. The length of the microstrip line (5) is one-eighth of the center frequency wavelength. Impedance matching is achieved by adjusting the length and width of the microstrip line (5) so that the antenna resonates at the center frequency.

5. A high-precision planar spiral active GNSS antenna device according to claim 3, characterized in that, The end of the planar spiral radiating arm is provided with a resistance matching structure (7), which is set as an impedance matching structure adapted to the line width and length of the radiating arm.

6. A high-precision planar spiral active GNSS antenna device according to claim 1, characterized in that, A square grounding pad (8) is provided on the front side of the dielectric substrate (1) of the antenna radiating body and on the side of the radiation feed point (2); the back side of the dielectric substrate (1) has a grounding layer, and the square grounding pad (8) is connected to the grounding layer on the back side of the dielectric substrate (1) through a metallized via. The rice-shaped hollow coupling structure (9) is set on the grounding layer. The gap width of the rice-shaped hollow coupling structure (9) is 1.5mm, and the end of the rice-shaped hollow coupling structure (9) is provided with an arc-shaped line gap (10).

7. A high-precision planar spiral active GNSS antenna device according to claim 1, characterized in that, The radio frequency front-end circuit includes an input interface (11), a pre-filter amplification module (12), a high-low frequency splitting processing module (13), and a combined amplification output module (14) connected in sequence; the passive signal of the antenna radiating body is transmitted to the input interface (11) of the radio frequency front-end circuit through a copper coaxial cable.

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