A full-band dual-polarized direction-finding antenna array

Abstract

The application discloses a full-band dual-polarized direction-finding antenna array and belongs to the technical field of radio monitoring. The antenna array comprises a double-layer coaxial antenna array, an integrated main cavity and a signal processing link component. The double-layer coaxial antenna array is coaxially arranged by a low-frequency subarray and a high-frequency subarray, each of which contains 8 dual-polarized directional antenna elements. Each antenna element integrates horizontal and vertical polarization dipoles and is provided with a special-shaped reflection cavity. The integrated main cavity is made of 6061 aluminum alloy and is internally provided with a signal processing link. The overall height is less than or equal to 250 mm, and the overall weight is less than or equal to 15 kg. The signal processing link realizes 1.3GHz-9GHz full-band dual-polarized direction finding through low-noise amplification, frequency band / polarization switching, frequency conversion and MUSIC algorithm. The direction finding error RMS is less than or equal to 2°, and the horizontal coverage is 360° and the vertical coverage is ±35°. The application fills the domestic high-frequency horizontal polarization direction finding blank and is suitable for fixed stations, portable and movable direction finding stations.

Description

Technical Field

[0001] This invention relates to the field of radio monitoring technology, and specifically to a full-band dual-polarized direction-finding antenna array. Background Technology

[0002] Currently, radio monitoring and direction finding equipment is mainly divided into two categories: fixed and portable. It is widely used in electromagnetic environment monitoring, signal tracing, and other scenarios. However, existing technologies have three major drawbacks in high-frequency (>1.3GHz) applications:

[0003] 1. Deterioration of direction finding accuracy in high-frequency bands: Fixed station direction finding arrays need to be erected on high-speed rail towers and equipped with lightning rods to ensure safety. However, when the monitoring frequency exceeds 1.3GHz, the shielding effect of the lightning rod's metal structure and transmission cables is significantly enhanced, resulting in the direction finding error of traditional equipment in the 1.3GHz-9GHz frequency band generally being ≥5°RMS, and direction finding singularities are prone to occur, which cannot meet the requirements of high-precision monitoring.

[0004] 2. Low equipment integration and poor portability: The horizontal and vertical polarization antennas of existing equipment are mostly designed with independent layers. The overall height often exceeds 350mm and the weight of the whole machine is usually >20kg, which makes it difficult to adapt to the lightweight installation requirements of portable and relocatable direction finding stations.

[0005] 3. Gap in high-frequency horizontal polarization direction finding: Existing mature solutions in China can only achieve horizontal polarization direction finding in the 40MHz-1300MHz frequency band. However, due to technical bottlenecks such as lightning rod obstruction and cable phase interference, there is no integrated solution that can take into account both dual polarization monitoring and high-precision direction finding in the 1.3GHz-9GHz high-frequency band, which cannot meet the actual needs of wide-band electromagnetic environment monitoring.

[0006] In summary, existing technologies urgently need to overcome the technical bottlenecks of "anti-high frequency obstruction, high integration, and wide-band dual polarization" and develop a full-band dual polarization direction-finding antenna array that is suitable for multiple scenarios. Summary of the Invention

[0007] This invention aims to solve the problems of low high-frequency direction finding accuracy, poor integration, and lack of horizontal polarization direction finding in the prior art, and provides a full-band dual-polarization direction finding antenna array.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A full-band dual-polarized direction-finding antenna array, comprising a dual-layer coaxial antenna array, an integrated host cavity, and a signal processing link assembly. The dual-layer coaxial antenna array includes a low-frequency subarray and a high-frequency subarray arranged coaxially. The low-frequency subarray covers the 1.3GHz-3.3GHz frequency band and consists of eight dual-polarized directional antenna elements evenly distributed along a circle with a diameter of 280mm. The high-frequency subarray covers the 3.3GHz-9GHz frequency band and consists of eight dual-polarized directional antenna elements evenly distributed along a circle with a diameter of 120mm. Each dual-polarized directional antenna element is orthogonally integrated with a horizontally polarized dipole and a vertically polarized dipole at a 90° angle on the same printed circuit board substrate, and its rear end is matched with an irregularly shaped reflective cavity. The integrated host cavity is made of 6061 aluminum alloy, with a lightning rod installation interface reserved at the top center. The interior is divided by metal partitions with a thickness of ≥2mm to accommodate signal processing link components and cables. The interior of the integrated host cavity is completely isolated from the outside. Cable routing is achieved through flange connectors. The external network port and power interface use aviation-grade sealed connectors and are located at the bottom of the cavity. The overall height of the integrated host cavity after assembly with the dual-layer coaxial antenna array is ≤250mm. The signal processing link components include a preamplifier, an antenna switching module, a dual-channel receiver, and a central processing unit (CPU). The preamplifier is designed for the 3.3GHz-9GHz frequency band and provides a fixed gain of 15dB. The antenna switching module supports 1.3-3.3GHz / 3.3-9GHz frequency band switching, horizontal / vertical polarization switching, and link phase calibration, outputting two target antenna signals. The dual-channel receiver amplifies the RF signal into two 80MHz intermediate frequency signals and generates a 1.3GHz-9GHz calibration signal to be fed back to the antenna switching module. The CPU has a built-in 14-bit ADC chip, supports correlation interferometer algorithms and spatial spectrum MUSIC direction finding algorithms, and can achieve 360° horizontal and ±35° vertical direction finding of incoming waves, with a direction finding error RMS≤2° within the 1.3GHz-9GHz frequency band.

[0009] Furthermore, the irregularly shaped reflective cavity is made of aluminum alloy to optimize the signal reception direction, so that the horizontal beamwidth of each dual-polarized directional antenna element is ≥45° and the vertical beamwidth is ≥70° in the 1.3GHz-9GHz frequency band.

[0010] Furthermore, the weight of a single dual-polarized directional antenna element is ≤100g, and the weight of the entire unit consisting of the dual-layer coaxial antenna array and the integrated host cavity is ≤15kg, supporting independent disassembly, debugging, and maintenance.

[0011] Furthermore, the noise figure of the preamplifier is ≤1.5dB, and the frequency band switching time of the antenna switching module is ≤100ns.

[0012] Furthermore, the amplitude flatness of the two 80MHz intermediate frequency signals output by the dual-channel receiver is ≤±0.5dB, and the frequency of the calibration signal covers 1.3GHz-9GHz with a frequency step of 1kHz and an attenuation step of 1dB.

[0013] Furthermore, the sampling rate of the ADC chip of the central processing unit is ≥250MSps, the computation delay of the MUSIC direction finding algorithm is ≤3ms, and the horizontal step size of the direction finding range is 0.5° and the vertical step size is 1°.

[0014] Furthermore, the shielding effectiveness of the integrated host cavity is ≥80dB, and the external interface protection level is IP67.

[0015] Furthermore, the direction-finding antenna array can be combined with a 20MHz-1300MHz direction-finding array to form a full-band radio monitoring system covering 20MHz-9GHz.

[0016] The beneficial effects of this invention include:

[0017] 1. Significantly improved direction finding accuracy: Through dual-layer coaxial and phase calibration technology, the direction finding error in the 1.3GHz-9GHz band is ≤2° (RMS), eliminating direction finding singularities, which is superior to the accuracy level of traditional equipment ≥5° (RMS);

[0018] 2. Filling a technological gap: For the first time, dual-polarization synchronous direction finding in the 1.3GHz-9GHz frequency band has been achieved, solving the problem of the lack of horizontal polarization direction finding in this frequency band in China;

[0019] 3. High integration and practicality: Overall height ≤250mm, total weight ≤15kg, supports multi-scenario deployment and modular maintenance;

[0020] 4. Excellent electromagnetic compatibility: The integrated cavity and irregularly shaped reflective cavity design provide shielding effectiveness ≥80dB, strong anti-interference capability, and improved direction finding accuracy. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the working principle of a full-band dual-polarized direction-finding antenna array according to the present invention.

[0022] Figure 2 This invention relates to a side-view of a full-band dual-polarized direction-finding antenna array. Figure 1 ;

[0023] Figure 3 This is a top view of a full-band dual-polarized direction-finding antenna array according to the present invention;

[0024] Figure 4 This invention relates to a side-view of a full-band dual-polarized direction-finding antenna array. Figure 2 ;

[0025] Figure 5 This is a schematic diagram of the dual-polarized antenna element structure of the present invention;

[0026] Figure 6 This is a direction finding accuracy curve for the 1.3GHz-3.3GHz range of the present invention;

[0027] Figure 7 This is a direction finding accuracy curve for the 3.3GHz-9GHz range of the present invention;

[0028] In the diagram, 1-lightning rod, 2-high frequency antenna, 3-reflecting cavity, 4-main body cavity, 5-low frequency antenna, 6-pre-amplifier low noise amplifier, 7-central processing unit, 8-dual-channel receiver, 9-antenna switching module, 10-printed board, 11-irregularly shaped reflecting cavity, 12-horizontally polarized antenna array element, 13-vertically polarized antenna array element, 14-printed board substrate. Detailed Implementation

[0029] The following is in conjunction with the attached diagram ( Figure 1 - Figure 7 The specific embodiments of the present invention will be described in detail below to make the advantages and features of the present invention easier to understand. The scope of protection of the present invention is not limited to the following embodiments:

[0030] Example 1

[0031] A full-band dual-polarized direction-finding antenna array includes a dual-layer coaxial antenna array, an integrated host cavity, and signal processing link components.

[0032] See Figure 1 - Figure 5 As shown, the connection relationships of each component are as follows:

[0033] The high-frequency antenna 2 is mounted on the top of the main unit cavity 4 along a circumference with a diameter of 120mm. The reflector cavity 3 is a component of the high-frequency antenna 2. The low-frequency antenna 5 is mounted on the lower layer along a circumference with a diameter of 280mm. The printed circuit board 10 is a component of the low-frequency antenna 5. The lightning rod 1 is fixed through the central interface at the top of the main unit cavity 4, and its axis coincides with the center of the two sub-arrays. The pre-amplifier 6, antenna switching module 9, dual-channel receiver 8, and central processing unit 7 are installed inside the main unit cavity 4 through metal partitions. The cables are connected through flange connectors. The external network port and power interface are located at the bottom of the cavity. The vertically polarized antenna array element 13 and the horizontally polarized antenna array element 12 are integrated on the printed circuit board substrate 14, and the rear end is matched with the irregularly shaped reflector cavity 11.

[0034] The dual-layer coaxial antenna array function is achieved through coaxially arranged low-frequency and high-frequency subarrays: the low-frequency subarray covers the 1.3GHz-3.3GHz frequency band and consists of 8 dual-polarized directional antenna elements (i.e., low-frequency antenna 5) evenly distributed along a circumference with a diameter of 280mm. The high-frequency subarray covers the 3.3GHz-9GHz frequency band and consists of 8 dual-polarized directional antenna elements (i.e., high-frequency antenna 2) evenly distributed along a circumference with a diameter of 120mm. Each dual-polarized directional antenna element is orthogonally integrated with a horizontally polarized dipole and a vertically polarized dipole at a 90° angle on the same printed circuit board substrate (e.g., F4B material), and its rear end is matched with an irregularly shaped reflective cavity.

[0035] The integrated host housing is constructed from a single piece of 6061 aluminum alloy, with a pre-installed lightning rod mounting interface at the top center for installing lightning rod 1. Internally, it is divided into four areas by metal partitions with a thickness of ≥2mm: a pre-amplifier area, a switching module area, a dual-channel receiver area, and a central processing unit area. Flange connector interfaces (for internal cable routing) are located on the side walls of the housing, and a sealed interface is located at the bottom. After assembly with the dual-layer coaxial antenna array, the total height is 245mm (meeting the ≤250mm requirement).

[0036] The signal processing link components function through a preamplifier low-noise amplifier, an antenna switching module, a dual-channel receiver, and a central processing unit (CPU). The preamplifier uses an ADL5565 chip, operating in the 3.3GHz-9GHz band with a gain of 15dB, and connects to the high-frequency subarray antenna element via a flange connector. The antenna switching module uses an HMC472 chip, supporting 1.3-3.3GHz / 3.3-9GHz band switching and horizontal / vertical polarization switching. It has a built-in phase calibration circuit and outputs two RF signals to the dual-channel receiver. The dual-channel receiver uses an AD9361 chip to convert the RF signal to an 80MHz intermediate frequency signal and simultaneously generates a 1.3GHz-9GHz calibration signal via a DDS module, which is fed back to the antenna switching module. The CPU has a built-in 14-bit ADC chip, supporting correlation interferometer algorithms and spatial spectrum MUSIC direction finding algorithms. It can achieve 360° horizontal and ±35° vertical direction finding of incoming waves, with a direction finding error RMS≤2° within the 1.3GHz-9GHz band.

[0037] Example 2

[0038] This embodiment further constitutes a more optimized technical solution based on Embodiment 1.

[0039] In this embodiment, a trapezoidal groove structure is used for the low-frequency subarray antenna elements, while an arc-shaped groove structure is used for the high-frequency subarray. Anechoic chamber testing shows that within the 1.3GHz-9GHz frequency band, the horizontal beamwidth is 48°-60° (≥45°), and the vertical beamwidth is 72°-85° (≥70°), resulting in a 20% improvement in signal reception range compared to the basic solution.

[0040] The printed circuit board of the dual-polarized directional antenna element is made of ultra-thin F4B material, and the reflector cavity adopts a hollow design, reducing the weight of a single antenna element to 92g (≤100g); the dual-layer coaxial antenna array is fixed by a combination of "snap-on and screws", and the partition of the integrated main unit cavity adopts a quick-release structure, allowing each component to be disassembled independently, reducing the weight of the whole unit to 14.2kg (≤15kg).

[0041] The preamplifier uses the ADL5566 chip, reducing the noise figure to 1.3dB (≤1.5dB) and minimizing noise superposition of high-frequency signals; the frequency band switching time of the antenna switching module is optimized to 85ns (≤100ns), and the polarization switching is controlled by TTL level, with a switching phase error of ≤±6°, avoiding direction finding deviation caused by signal switching delay;

[0042] The dual-channel receiver adds an "amplitude equalization circuit," which adjusts the capacitor network to control the amplitude flatness of the two 80MHz intermediate frequency signals within ±0.4dB (≤±0.5dB). The calibration signal is generated by the AD9959DDS chip, covering a frequency range of 1.3GHz-9GHz with a frequency step of 1kHz. The attenuation is achieved in 1dB steps using the AD8370 digital attenuator, resulting in a 30% improvement in calibration accuracy compared to the basic solution.

[0043] The central processing unit uses a 14-bit, 250MSps ADC chip to realize functions such as data acquisition, central data analysis, spectrum analysis, and AOA direction finding. It also realizes data interaction and result display with external systems. The MUSIC algorithm is accelerated by FPGA, reducing the latency to 2.7ms (≤3ms). The horizontal step size of the direction finding range is 0.5° and the vertical step size is 1°.

[0044] The inner wall of the integrated host cavity is coated with conductive paint. After electromagnetic compatibility testing, the shielding effectiveness in the 30MHz-1GHz frequency band is 85dB (≥80dB). The external interface adopts IP67-level aviation plugs. After immersion and dust testing, the interface has no leakage and meets the requirements for use in harsh outdoor environments.

[0045] Example 3

[0046] This embodiment is based on the optimal solution of Embodiment 2. By combining it with an existing low-frequency band direction-finding array, it solves the problem of "full-band coverage" and forms a 20MHz-9GHz full-band radio monitoring system. The specific implementation is as follows:

[0047] The direction-finding antenna array of this invention (covering 1.3GHz-9GHz) connects to the SMA male connector of an existing 20MHz-1300MHz direction-finding array via an SMA female connector. Both share a central processing unit (based on an industrial-grade computer with a main frequency of 2.5GHz), and achieve data interaction via Ethernet. A time synchronization module (synchronization accuracy ≤1μs) is used to ensure that the signal sampling time of the two arrays is consistent, forming a full-band radio monitoring system covering 20MHz-9GHz, thereby meeting a wider range of broadband signal monitoring and direction-finding needs.

[0048] This combined system can be deployed at fixed monitoring stations or portable monitoring vehicles (weighing ≤30kg, compatible with vehicle-mounted brackets) to meet the full-band application needs of electromagnetic environment monitoring, illegal signal tracing, etc.

[0049] Example 4

[0050] This embodiment is based on the direction finding accuracy test of the product of the present invention, such as... Figure 6 As shown, in the 1.3GHz-3.3GHz frequency band, the direction finding error ranges from 0.2° to 1.8°, with an average error of 1.0°; Figure 7 As shown, in the 3.3GHz-9GHz frequency band, the direction finding error ranges from 0.5° to 2.0°, with an average error of 1.5°. The test results demonstrate that the direction finding error RMS meets the target of ≤2° across the entire frequency band, significantly outperforming traditional equipment.

Claims

1. A full-band dual-polarized direction-finding antenna array, characterized in that, Includes a dual-layer coaxial antenna array, an integrated main unit cavity, and signal processing link components; The dual-layer coaxial antenna array includes a low-frequency subarray and a high-frequency subarray arranged coaxially. The low-frequency subarray covers the 1.3GHz-3.3GHz frequency band and consists of eight dual-polarized directional antenna elements evenly distributed along a circle with a diameter of 280mm. The high-frequency subarray covers the 3.3GHz-9GHz frequency band and consists of eight dual-polarized directional antenna elements evenly distributed along a circle with a diameter of 120mm. Each dual-polarized directional antenna element is orthogonally integrated with a horizontally polarized dipole and a vertically polarized dipole at a 90° angle on the same printed circuit board substrate, and is matched with an irregularly shaped reflective cavity at its rear end. The integrated host cavity is made of 6061 aluminum alloy, with a lightning rod installation interface reserved at the top center. The interior is divided by metal partitions with a thickness of ≥2mm to accommodate the signal processing link components and cables. The interior of the integrated host cavity is completely isolated from the outside. The cable routing is converted through flange connectors. The external network port and power interface use aviation sealed connectors and are located at the bottom of the cavity. The overall height of the integrated host cavity after assembly with the double-layer coaxial antenna array is ≤250mm. The signal processing link components include a preamplifier, an antenna switching module, a dual-channel receiver, and a central processing unit (CPU). The preamplifier is designed for the 3.3GHz-9GHz frequency band and provides a fixed gain of 15dB. The antenna switching module supports 1.3-3.3GHz / 3.3-9GHz frequency band switching, horizontal / vertical polarization switching, and link phase calibration, outputting two target antenna signals. The dual-channel receiver amplifies the RF signal into two 80MHz intermediate frequency signals and generates a 1.3GHz-9GHz calibration signal, which is fed back to the antenna switching module. The CPU has a built-in 14-bit ADC chip, supports correlation interferometer algorithms and spatial spectrum MUSIC direction finding algorithms, and can achieve 360° horizontal and ±35° vertical direction finding of incoming waves, with a direction finding error RMS ≤ 2° within the 1.3GHz-9GHz frequency band.

2. The full-band dual-polarization direction-finding antenna array according to claim 1, characterized in that, The irregularly shaped reflective cavity is made of aluminum alloy and is used to optimize the signal reception direction, so that the horizontal beamwidth of each dual-polarized directional antenna element is ≥45° and the vertical beamwidth is ≥70° in the 1.3GHz-9GHz frequency band.

3. The full-band dual-polarized direction-finding antenna array according to claim 1, characterized in that, The weight of a single dual-polarized directional antenna element is ≤100g, and the weight of the entire unit consisting of the dual-layer coaxial antenna array and the integrated host cavity is ≤15kg, supporting independent disassembly, debugging and maintenance.

4. The full-band dual-polarized direction-finding antenna array according to claim 1, characterized in that, The noise figure of the preamplifier is ≤1.5dB, and the frequency band switching time of the antenna switching module is ≤100ns.

5. A full-band dual-polarized direction-finding antenna array according to claim 1, characterized in that, The amplitude flatness of the two 80MHz intermediate frequency signals output by the dual-channel receiver is ≤±0.5dB. The frequency of the calibration signal covers 1.3GHz-9GHz with a frequency step of 1kHz and an attenuation step of 1dB.

6. The full-band dual-polarized direction-finding antenna array according to claim 1, characterized in that, The central processing unit's ADC chip has a sampling rate of ≥250MSps, a MUSIC direction finding algorithm operation delay of ≤3ms, and a horizontal step size of 0.5° and a vertical step size of 1° for the direction finding range.

7. A full-band dual-polarized direction-finding antenna array according to claim 1, characterized in that, The shielding effectiveness of the integrated host cavity is ≥80dB, and the protection level of the external interface is IP67.

8. A full-band dual-polarized direction-finding antenna array according to any one of claims 1-7, characterized in that, The direction-finding antenna array can be combined with a 20MHz-1300MHz direction-finding array to form a full-band radio monitoring system covering 20MHz-9GHz.

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