Dipole-fed structure with controllable electric field angle distribution in the near-field region

Abstract

This invention relates to the field of antenna technology and proposes a dipole-feed structure with controllable electric field angle distribution in the near-field region. The structure includes: a dipole radiator for radiating electromagnetic waves; a microstrip line connected to the dipole radiator for transmitting and converting the feed signal; a metal reflector disposed below the dipole radiator; and two metal baffles vertically fixed to the metal reflector and symmetrically disposed on both sides of the dipole radiator. The electric field angle distribution in the near-field region of the dipole-feed structure can be controlled by adjusting the horizontal distance between the two metal baffles and the dipole radiator or by adjusting the length of the two metal baffles. This invention overcomes the shortcomings of existing planar Luneburg lens antenna feed structures, such as uncontrollable electric field angle distribution, poor broadband matching, and low energy utilization. It achieves efficient energy coupling for planar Luneburg lenses with different focal lengths, simplifies antenna system design, and improves overall gain and aperture efficiency.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and more specifically, to a dipole-fed structure with controllable electric field angular distribution in the near-field region. Background Technology

[0002] As wireless communication technology evolves towards 5G / 6G, the millimeter-wave band (20-30GHz) has become a core band for achieving high-speed, low-latency communication due to its abundant bandwidth resources. Parallel-plate Luneburg lens antennas, with their characteristic of "gradient refractive index achieving spherical wave-to-plane wave conversion," offer both high gain and low cost advantages, making them a commonly used antenna in millimeter-wave communication systems. The feeding structure, as the "energy input end" of the lens antenna, directly determines the aperture efficiency and gain stability of the lens.

[0003] The feed source of a lens antenna typically needs to be placed at the focal point of the lens. This focal point depends on the design requirements and may be close to the edge of the lens structure or at a certain distance from the edge. Therefore, the energy distribution of the electromagnetic waves radiated by the feed source (the electric field angular distribution in the near-field region) needs to be adapted to the lens according to the relative position of the focal length to achieve the highest radiation efficiency and gain for the entire antenna. If the electric field angular distribution is too wide, some energy will overflow beyond the effective aperture of the lens, resulting in waste; if the electric field angular distribution is too narrow, the lens structure cannot be fully utilized, leading to a reduction in antenna aperture efficiency. Existing parallel-plate Luneburg lens antenna feeding schemes still suffer from poor compatibility between the feed source electric field angular distribution and the lens structure. The root cause lies in the fact that the dimensions of commonly used feed sources (such as rectangular waveguides, tapered slot antennas, TSAs, etc.) are closely related to the required operating frequency band, and these dimensions directly determine the electric field angular distribution. Furthermore, these feed structures inherently possess directional radiation characteristics, making it difficult to control the electric field angular distribution by adding additional modulation structures.

[0004] Therefore, there is an urgent need to propose a feeding structure that can achieve independent control of the operating frequency band and electric field angle distribution during the design phase, so as to adapt to the feed electric field angle distribution required by various planar lens antennas and obtain the maximum aperture efficiency and antenna gain. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of existing flat-plate Luneburg lens antenna feeding structures, such as "uncontrollable electric field angle distribution, poor broadband matching, and low energy utilization," and to provide a dipole feeding structure with controllable electric field angle distribution, thereby achieving efficient energy coupling for flat-plate Luneburg lenses with different focal lengths, simplifying antenna system design, and improving overall gain and aperture efficiency.

[0006] To achieve the above objectives, this invention proposes a dipole-fed structure with controllable electric field angle distribution in the near-field region, comprising: A dipole radiator is used to radiate electromagnetic waves. A microstrip line, connected to the dipole radiator, is used to transmit and convert the feed signal; A metal reflector is disposed below the dipole radiator; And two metal baffles, vertically fixed to the metal reflector, and symmetrically arranged on both sides of the dipole radiator; The electric field angular distribution of the dipole-fed structure in the near-field region can be controlled by adjusting the horizontal distance between the two metal baffles and the dipole radiator or by adjusting the length of the two metal baffles.

[0007] Furthermore, the dipole radiator is a symmetrical metal oscillator structure made of brass or gold-plated copper foil, and the length of the oscillator is half the wavelength corresponding to the center frequency of the operating frequency band.

[0008] Furthermore, a rotatable connecting shaft is provided at the connection between the dipole radiator and the microstrip line, enabling the dipole radiator to finely adjust the radiation angle within a preset angle range.

[0009] Furthermore, the microstrip line forms a microstrip broadband balun with a characteristic impedance of 50Ω, used to convert unbalanced signals to balanced signals.

[0010] Furthermore, the metal reflector is made of brass with a thickness of 1-2 mm and has multiple positioning grooves on its surface to accommodate flat lenses with different focal lengths and adjust the installation position of the power supply structure.

[0011] Furthermore, the metal baffles on both sides are made of brass, and the groove lengths of the two baffles are different, corresponding to the major and minor axes of the rectangular lens respectively. By adjusting the spacing of one side baffle individually, asymmetrical beamwidth control can be achieved to adapt to the differences in the major and minor axis dimensions of the rectangular lens.

[0012] Furthermore, the top of each of the two metal baffles on both sides is provided with a detachable extension section for adjusting the energy distribution of the electromagnetic waves radiated by the feed source.

[0013] Furthermore, the dipole-fed structure operates in a frequency band covering 22.90 GHz to 28.31 GHz, and has a reflection coefficient of less than -10 dB.

[0014] Furthermore, by adjusting the metal baffles on both sides, the near-field electric field angle distribution of the feeding structure can be controlled within the range of 30° to 60°.

[0015] Furthermore, the overall dimensions of the power supply structure are 20mm in length, 15mm in width, and 5mm in height.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The electric field angle distribution in the near-field region is controllable and highly adaptable: By finely adjusting the distance between the metal baffles on both sides and the dipole, as well as the length of the metal baffles on both sides, the electric field angle distribution in the near-field region can be adjusted from 30° to 60°. It can adapt to parallel plate Luneburg lenses of different sizes (diameter 5.2λ0-9.5λ0, where λ0 is the free space wavelength of the center frequency), avoiding energy overflow or insufficient lens excitation, and ultimately achieving a high aperture efficiency of 78%-92%, far exceeding the traditional fixed beam feeding structure (26-66.5%).

[0017] 2. Excellent broadband performance, covering the core millimeter-wave frequency band: The broadband characteristics of the dipole radiator combined with the impedance matching design of the microstrip balun result in a high reflection coefficient |S0| within the 22.90-28.31GHz frequency band (relative bandwidth 21.13%). 11 |Always less than -10dB, energy transmission loss|S 12 |≈0dB, ensuring stable energy input to the lens across the entire frequency band, with gain fluctuation of only ±0.85dBi (measured gain 14.87-16.57dBi).

[0018] 3. High energy efficiency and compact structure: The metal reflector can recover about 80% of the back radiation energy of the dipole without the need for an additional matching network, reducing energy loss by 20%-30% compared to traditional feeding structures; the overall feeding structure size is only 20mm×15mm×5mm (length×width×height), which is easy to integrate with flat lens and meets the "miniaturization" requirements of millimeter wave systems.

[0019] 4. Simplified design and low cost: There is no need to design a complex three-level architecture of "feeder-matching network-lens". It can be directly assembled with parallel plate Luneburg lenses, reducing the R&D cycle; core components (dipole, baffle, reflector) can be processed by CNC or laser cutting, and the mass production cost is lower than that of traditional waveguide feeding structures. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is an exploded view of the dipole-fed structure with controllable electric field angle distribution in the near-field region in an embodiment of the present invention. Figure 2 This is a front view of the dipole-fed structure with controllable electric field angle distribution in the near-field region, as described in an embodiment of the present invention. Figure 3 The above are the electrical simulation results of the dipole-fed structure in the electromagnetic simulation design software in the embodiments of the present invention; Figure 4 The electric field angular distribution on the near-field observation line is obtained by electrical simulation of the Luneburg lens antenna using the dipole-fed structure of this invention. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] This invention has multiple implementations, and its typical representative structure is as follows: Figure 1 , Figure 2 As shown, it specifically includes: 1. Dipole radiator: It adopts a symmetrical metal oscillator structure (made of brass or gold-plated copper foil). The length of the oscillator is 1 / 2 of the wavelength corresponding to the center frequency of the working frequency band (25.6GHz) (approximately 5.86mm). It is used to radiate the balanced signal transmitted by the balun to the surface of the flat Lombard lens in the form of a spherical wave, and has natural broadband radiation characteristics.

[0023] As a preferred embodiment, the dipole radiator maintains the basic structure of a symmetrical double oscillator and is additionally provided with an "angle fine-tuning structure": a rotatable connecting shaft is provided at the docking point of the oscillator and the balun, which can finely adjust the radiation angle of the dipole (within ±5°) around the shaft to ensure that the radiation energy can accurately cover the long axis and short axis range of the rectangular lens.

[0024] 2. Microstrip line: It forms a microstrip broadband balun with an impedance design of 50Ω (matching the external coaxial line feeder). One end is connected to the inner conductor of the coaxial line to receive unbalanced signals, and the other end is connected to the two oscillators of the dipole radiator to realize the "unbalanced-balanced" signal conversion, while suppressing common-mode current and ensuring broadband impedance matching.

[0025] 3. Metal reflector: A rectangular metal plate (made of brass, 1-2mm thick) is horizontally positioned directly below the dipole radiator to reflect the energy radiated from the back of the dipole, reducing energy loss and improving the energy utilization rate of the feeding structure.

[0026] In a preferred embodiment, the metal reflector is a rectangular flat plate structure, with its length and width adapted to the major and minor axis dimensions of the rectangular lens, respectively, to avoid wasting installation space caused by the reflector extending beyond the lens edge; it has a "multi-focal positioning structure": the surface is provided with multiple sets of positioning grooves, corresponding to the focal points of the rectangular lens at different positions, and the installation position of the power supply structure can be adjusted according to the actual focal length requirements of the lens to adapt to rectangular lenses with different focal lengths.

[0027] 4. Two metal baffles: These are two symmetrical rectangular metal plates (made of the same material as the reflector), which are vertically fixed to the metal reflector and located on both sides of the dipole radiator. By finely adjusting the horizontal distance between the baffle and the dipole or the length of the two baffles, the electromagnetic field distribution around the dipole can be changed, thereby precisely controlling the electric field angular distribution in the near field region to ensure a perfect match with the effective aperture of the parallel plate Luneburg lens.

[0028] In a preferred embodiment, the two metal baffles have a rectangular flat plate shape and additionally possess an "asymmetric adjustment structure": the two baffles have different groove lengths, corresponding to the major and minor axes of the rectangular lens respectively, allowing for individual adjustment of the spacing of one side baffle to achieve asymmetric beamwidth control and adapt to the differences in the major and minor axis dimensions of the rectangular lens; the top of the baffle is provided with a "detachable extension section": connected to the baffle body by a buckle, the extension section can be increased according to the thickness of the rectangular lens to further constrain the electromagnetic field in the vertical direction and avoid energy waste.

[0029] In summary, the near-field region electric field angle distribution controllable dipole-fed structure of the present invention achieves efficient adaptation with different parallel plate Lomborg lenses through the synergistic effect of the dipole radiator, microstrip line, metal reflector, and metal baffles on both sides.

[0030] Figure 3 As shown Figure 1 An electrical simulation result in electromagnetic simulation design software is presented for a beamwidth-adjustable dipole-fed structure of a parallel-plate Luneburg lens antenna suitable for the millimeter-wave band (22.90-28.31 GHz). Figure 2 It can be seen that the reflection coefficient |S11| of this feeding structure is less than -10 dB in the 22.90-28.31 GHz frequency band.

[0031] Figure 4 As shown Figure 1 The electric field angular distribution on the near-field observation line of a parallel-plate Luneburg lens antenna suitable for the millimeter-wave band (22.90-28.31 GHz) was obtained through electrical simulation using electromagnetic simulation design software. (The data is derived from...) Figure 4As can be seen, the structure of the present invention can adjust the length of the electromagnetic wave energy on the near-field line by finely adjusting the horizontal distance (W) between the baffle and the dipole or the length (L) of the two baffles, which means that the energy distribution of the electromagnetic wave around the dipole can be changed because the near-field line is an arc, thereby precisely controlling the electric field angle distribution in the near-field region.

[0032] It is understood that the dipole-fed structure proposed in this embodiment has the following advantages: 1. The electric field angle distribution in the near-field region is controllable and highly adaptable: By finely adjusting the distance between the metal baffles on both sides and the dipole, the electric field angle distribution in the near-field region can be controlled from 30° to 60°. It can adapt to parallel plate Luneburg lenses of different sizes (diameter 5.2λ0-9.5λ0, where λ0 is the free space wavelength of the center frequency), avoiding energy overflow or insufficient lens excitation, and ultimately achieving a high aperture efficiency of 78%-92%, far exceeding the traditional fixed beam feeding structure (26-66.5%).

[0033] 2. Excellent wideband performance, covering the core millimeter-wave frequency band: The combination of the wideband characteristics of the dipole radiator and the impedance matching design of the microstrip balun ensures that the reflection coefficient |S11| is always less than -10dB and the energy transmission loss |S12|≈0dB within the 22.90-28.31GHz frequency band (relative bandwidth 21.13%), guaranteeing stable energy input to the lens across the entire frequency band, with gain fluctuation of only ±0.85dBi (measured gain 14.87-16.57dBi).

[0034] 3. High energy utilization and compact structure: The metal reflector can recover about 80% of the back radiation energy of the dipole without the need for an additional matching network, reducing energy loss by 20%-30% compared to traditional feeding structures; the overall feeding structure size is only 20mm×15mm×5mm (length×width×height), which is easy to integrate with flat lens and meets the "miniaturization" requirements of millimeter wave systems.

[0035] 4. Simplified design and low cost: There is no need to design a complex three-level architecture of "feeder-matching network-lens", and it can be directly assembled with parallel plate Luneburg lenses, reducing the R&D cycle; core components (dipole, baffle, reflector) can be processed by CNC or laser cutting, and the mass production cost is lower than that of traditional waveguide feeding structures.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A dipole-fed structure with controllable electric field angle distribution in the near-field region, characterized in that, include: A dipole radiator is used to radiate electromagnetic waves. A microstrip line, connected to the dipole radiator, is used to transmit and convert the feed signal; A metal reflector is disposed below the dipole radiator; And two metal baffles, vertically fixed to the metal reflector, and symmetrically arranged on both sides of the dipole radiator; The two metal baffles are made of brass, and the grooves of the two baffles are of different lengths, respectively corresponding to the major axis and minor axis of the rectangular lens. By adjusting the spacing of one side baffle, asymmetrical beamwidth control can be achieved to adapt to the differences in the major and minor axis dimensions of the rectangular lens. The electric field angular distribution of the dipole-fed structure in the near-field region can be controlled by adjusting the horizontal distance between the two metal baffles and the dipole radiator or by adjusting the length of the two metal baffles.

2. The dipole-fed structure according to claim 1, characterized in that, The dipole radiator is a symmetrical metal oscillator structure made of brass or gold-plated copper foil, and the length of the oscillator is half the wavelength corresponding to the center frequency of the operating frequency band.

3. The dipole-fed structure according to claim 1, characterized in that, The connection between the dipole radiator and the microstrip line is provided with a rotatable connecting shaft, which allows the dipole radiator to finely adjust the radiation angle within a preset angle range.

4. The dipole-fed structure according to claim 1, characterized in that, The microstrip line forms a microstrip broadband balun with a characteristic impedance of 50Ω, used to convert unbalanced signals to balanced signals.

5. The dipole-fed structure according to claim 1, characterized in that, The metal reflector is made of brass and is 1-2mm thick. It has multiple positioning grooves on its surface to accommodate flat lenses with different focal lengths and to adjust the installation position of the power supply structure.

6. The dipole-fed structure according to claim 1, characterized in that, The top of the two metal baffles on both sides is provided with a detachable extension section for adjusting the energy distribution of the electromagnetic waves radiated by the feed source.

7. The dipole-fed structure according to claim 1, characterized in that, The dipole-fed structure operates in a frequency band from 22.90 GHz to 28.31 GHz and has a reflection coefficient of less than -10 dB.

8. The dipole-fed structure according to claim 1, characterized in that, By adjusting the metal baffles on both sides, the near-field electric field angle distribution of the feeding structure can be controlled within the range of 30° to 60°.

9. The dipole-fed structure according to claim 1, characterized in that, The overall dimensions of the power supply structure are 20mm in length, 15mm in width, and 5mm in height.

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