A dual-band dual-polarized electromagnetic lens antenna based on a wideband tight coupling structure

Abstract

This invention discloses an electromagnetic lens based on a broadband tightly coupled structure and its dual-frequency dual-polarized lens antenna, belonging to the field of mobile communication. It includes an electromagnetic lens array and a dual-frequency dual-polarized feed antenna placed at the focal point of the lens array. The electromagnetic lens is positioned above the feed of the dual-frequency dual-polarized antenna. The broadband tightly coupled unit consists of two dipoles, two pairs of delay lines, a metal pillar, two metasurface matching layers, and a reflector; the overall structure is mirror-symmetrical about the reflector. This invention controls the phase of the control unit by adjusting the length of the phase delay lines of the broadband tightly coupled unit, performing phase compensation at different positions on the lens array, thereby realizing the design of the electromagnetic lens. This invention effectively avoids the narrow bandwidth defect of traditional dual-frequency metasurface lenses, achieving excellent dual-polarization and high-gain performance in both target frequency bands.

Description

Technical Field

[0001] This invention belongs to the field of mobile communications, and particularly relates to a dual-frequency dual-polarized electromagnetic lens antenna based on a broadband tightly coupled structure. Background Technology

[0002] With the rapid development of mobile communication technology, the explosive growth of high-quality data services has placed higher demands on network coverage capabilities. In the Sub-6GHz band, especially in high-speed mobile scenarios such as high-speed rail, signals face multiple challenges, including Doppler shift, high penetration loss, and weak coverage in complex environments. To address these challenges, antenna technology that combines high gain, multi-band operation, and dual polarization has become a research hotspot. Lens antennas, as one of the effective means to achieve high gain, mainly include traditional dielectric lenses (such as Luneburg lenses) and emerging metasurface lenses. Traditional dielectric lenses are often bulky in low-frequency bands, while metasurface lenses, with their inherent advantages of low profile and easy integration, show great application potential.

[0003] However, existing metasurface lens technology still has significant limitations when applied to Sub-6GHz dual-band applications. Most designs are optimized only for a single frequency band, making it difficult to achieve precise wavefront phase modulation simultaneously across two separate frequency bands. Although there has been research on dual-band frequency-selective metasurface elements, their phase modulation capabilities and bandwidth performance are often insufficient, resulting in limited gain and bandwidth for lens antennas constructed from them. This makes it impossible to simultaneously meet the urgent requirements of practical communication frequency bands such as 1710-2170MHz and 3300-3800MHz for wide bandwidth, high gain, and stable dual-polarization performance. Therefore, designing an electromagnetic element and electromagnetic lens antenna that can possess wide bandwidth response, high transmission efficiency, and effective phase modulation capabilities in both frequency bands is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a dual-frequency, dual-polarized electromagnetic lens antenna based on a broadband tightly coupled structure, comprising: An electromagnetic lens array, wherein the electromagnetic lens array is composed of multiple broadband tightly coupled units arranged periodically; A dual-frequency dual-polarization feed antenna, wherein the feed antenna is disposed at the focal point of the electromagnetic lens array, for generating and radiating dual-polarized waves in two separate operating frequency bands; The electromagnetic lens array receives electromagnetic waves from the feed antenna and converts them into collimated high-gain beam outputs based on the phase modulation effect of the broadband tightly coupled unit.

[0005] Optionally, the broadband tightly coupled unit is a three-dimensional multilayer structure, comprising: A central metal layer; A receiving layer and a transmitting layer are respectively located on both sides of the central metal layer and are mirror-symmetrical about the central metal layer. Each of the receiving layer and the transmitting layer contains a pair of orthogonal, tapered, tightly coupled dipoles. Two pairs of phase delay lines, each pair of phase delay lines being perpendicularly connected to the graded tightly coupled dipoles at corresponding positions on the receiving layer and the transmitting layer, and passing through the central metal layer; An interconnecting metal pillar is disposed at the center of the unit and penetrates the central metal layer, and is vertically connected to the gradient tightly coupled dipoles on the receiving layer and the transmitting layer, respectively; Two metasurface matching layers are located outside the receiving layer and the transmitting layer, respectively.

[0006] Optionally, an interdigitated capacitor structure is loaded on the gradient-type tightly coupled dipole, and the gradient-type tightly coupled dipole achieves broadband transmission through coupling with the central metal layer; Optionally, a through hole is provided at the center of the central metal layer for the interconnecting metal pillar to pass through, and a concave semi-circular structure is provided at the midpoint of the four sides of the central metal layer, through which the phase delay line passes; Optionally, the transmission phase of the broadband tightly coupled unit can be controlled by adjusting the physical length of the phase delay line to compensate for the spatial phase difference between the feed antenna and the units at different positions on the electromagnetic lens array. Optionally, based on the preset focal length and the position coordinates of each broadband tightly coupled unit in the electromagnetic lens array, the required phase compensation amount for each unit is calculated, and the target length of the corresponding phase delay line is determined. Optionally, the interconnecting metal pillars are used to change the transmission path of current in the broadband tightly coupled unit to optimize the transmission performance of the unit under oblique electromagnetic wave incidence conditions. Optionally, the metasurface matching layer is used to achieve impedance matching, thereby reducing the insertion loss of the broadband tightly coupled unit and increasing the transmission amplitude; Optionally, the dual-frequency dual-polarized feed antenna is a stacked structure, and the width of its radiation beam covers the entire electromagnetic lens array.

[0007] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a dual-frequency, dual-polarized electromagnetic lens antenna based on a broadband tightly coupled structure, effectively overcoming the shortcomings of existing dual-frequency metasurface lenses, such as narrow bandwidth and insufficient phase modulation capability. Through an innovative design of a three-dimensional tightly coupled unit with a gradient tightly coupled dipole, phase delay line, central metal pillar, and matching layer, this unit achieves a high transmission coefficient (0.85) and a phase modulation range exceeding 180° in a wide frequency range of 1710-3800MHz and beyond, while significantly improving oblique incidence performance. The unit is arranged using a frequency-independent equivalent distance delay phase compensation method, enabling a single lens array to achieve effective phase convergence of dual-polarized electromagnetic waves simultaneously in two octave intervals: 1710-2170MHz and 3300-3800MHz. This results in stable high gains of 14-16.1 dBi and 17.6-18.6 dBi, respectively, with low sidelobe and cross-polarization levels. While maintaining a low profile, this invention successfully achieves high-gain radiation with dual frequency bands, dual polarization, and wide bandwidth, significantly improving the coverage performance and signal quality of lens antennas in complex mobile communication scenarios. Attached Figure Description

[0008] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of an electromagnetic lens structure based on a broadband tightly coupled structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall and side view of the lens feed source according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the broadband tightly coupled unit structure of an electromagnetic lens based on a broadband tightly coupled structure according to an embodiment of the present invention; Figure 4 This is a side view of the broadband tightly coupled unit structure of the dual-frequency dual-polarized electromagnetic lens antenna based on a broadband tightly coupled unit according to an embodiment of the present invention. Figure 5 The broadband tightly coupled unit of the dual-frequency dual-polarized electromagnetic lens antenna based on the broadband tightly coupled unit in this embodiment of the invention is used in different... Transmission amplitude and transmission phase diagrams at values, where (a) is the transmission amplitude diagram and (b) is the transmission phase diagram; Figure 6 The broadband tightly coupled element of the dual-frequency dual-polarized electromagnetic lens antenna based on the broadband tightly coupled element in this embodiment of the invention is suitable for different incident angles. Transmission amplitude diagrams of TE polarization and TM polarization at 2.5mm, where (a) is the TE polarization diagram and (b) is the TM polarization transmission amplitude diagram. Figure 7 The broadband tightly coupled unit phase shift line of the dual-frequency dual-polarized electromagnetic lens antenna based on the broadband tightly coupled unit is shown in this embodiment of the invention. Distribution of values ​​on the lens array surface; Figure 8 The above are comparison diagrams of the gain direction of the dual-frequency dual-polarization electromagnetic lens antenna based on the broadband tightly coupled structure in this embodiment of the invention, with and without the lens at 2GHz and 3.5GHz. Among them, (a) is the comparison diagram of the gain direction of the +45° polarization horizontal plane with and without the lens at 2GHz, and (b) is the comparison diagram of the gain direction of the +45° polarization horizontal plane with and without the lens at 3.5GHz. Figure 9 The +45° polarization normalized radiation pattern of the dual-frequency dual-polarization electromagnetic lens antenna based on a broadband tightly coupled structure in an embodiment of the present invention is shown in the low-frequency and high-frequency bands, where (a) is the +45° polarization normalized radiation pattern in the low-frequency band and (b) is the +45° polarization normalized radiation pattern in the high-frequency band. Figure 10 The diagram shows the gain variation of the dual-frequency dual-polarized lens antenna based on a broadband tightly coupled structure in the low-frequency and high-frequency bands according to an embodiment of the present invention. (a) is the gain variation diagram in the low-frequency band, and (b) is the gain variation diagram in the high-frequency band. Detailed Implementation It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0009] Example 1 This embodiment provides a dual-frequency dual-polarized electromagnetic lens antenna based on a broadband tightly coupled structure, including: An electromagnetic lens based on a broadband tightly coupled structure and a dual-frequency dual-polarization lens feed.

[0010] The electromagnetic lens is composed of multiple broadband tightly coupled units arranged in a single configuration. Furthermore, the broadband tightly coupled unit is a three-dimensional structure, including two tightly coupled dipoles as a receiving layer and a transmitting monolayer, a metal layer, two pairs of phase delay lines, an interconnecting metal pillar, and two metasurface matching layers, and the upper and lower halves of the unit are symmetrical about the metal layer. Furthermore, an opening is designed in the metal layer at the exact midpoint between the transmitting and receiving layers to allow phase delay lines to pass through. Two pairs of delay lines are perpendicularly connected to the tightly coupled dipoles of the transmitting and receiving layers. The two orthogonal tightly coupled dipoles of the transmitting and receiving layers are designed with a gradient shape and loaded with interdigital capacitors. The broadband transmission effect is achieved through coupling with the metal reflector. Furthermore, a metal pillar is introduced at the center of the metasurface unit, which improves the oblique incidence transmission performance of the metasurface unit by reducing the current transmission path. Furthermore, the metasurface unit introduces two metasurface matching layers to improve transmission amplitude and reduce insertion loss; Furthermore, the transmission phase of the broadband tightly coupled unit is controlled to compensate for the spatial phase difference between the feed antenna and the units at different positions on the electromagnetic lens array. Furthermore, based on the preset focal length and the position coordinates of each broadband tightly coupled unit in the electromagnetic lens array, the required phase compensation amount for each unit is calculated, and the target length of the corresponding phase delay line is determined. Furthermore, the lens feed source employs a stacked dual-frequency dual-polarized antenna.

[0011] Specifically: This embodiment presents an electromagnetic lens and its dual-frequency dual-polarization lens antenna based on a broadband tightly coupled structure, comprising an electromagnetic lens and a dual-frequency dual-polarization feed antenna placed at the focal point of the lens array. The electromagnetic lens and its broadband tightly coupled unit are as follows: Figure 1 , Figure 3 and Figure 4 As shown, it consists of 13×13 broadband tightly coupled elements, with an overall size of 2.15λ1×2.15λ1×0.23λ1 (where λ1 is the free-space wavelength at 1.7 GHz, i.e., 380mm×380mm×40mm), an element period of 30mm, and the entire structure has been rotated 45° and chamfered. The electromagnetic lens is placed above the dual-frequency dual-polarized antenna feed, with a focal diameter ratio f / d of 0.5, meaning the distance from the feed radiating surface to the center of the lens is 190mm.

[0012] Furthermore, the broadband tightly coupled unit includes two tightly coupled dipoles as receiving and transmitting units, a metal layer, two pairs of phase delay lines, an interconnecting metal pillar, and two metasurface matching layers. The overall structure is mirror-symmetrical about the metal layer. The tightly coupled dipoles are printed on the transmitting and receiving layers. The metasurface matching layers are formed by circular patches with a period of 10 mm and a radius of 3 mm printed on a second dielectric substrate. The dielectric substrate is ROC4003 with a thickness of 0.813 mm, a relative permittivity of 3.55, and a loss of 0.0027. The vertical distance between the tightly coupled dipoles and the metal layer is 18 mm, and the vertical distance between the metasurface matching layers and the metal layer is 20 mm. The metal layer is located in the middle of the transmitting and receiving layers, with an opening designed to allow the phase delay lines to pass through without contacting them. The emitter and receiver layers have two orthogonal, tightly coupled dipoles designed with a gradient shape and loaded with interdigital capacitors. A metal pillar with a radius of 0.5 mm and a height of 36 mm runs through the center of the metasurface unit. Considering periodicity and symmetry, a pair of phase delay lines are printed on a dielectric substrate with the same thickness and material as the emitter and receiver layers. Another pair of phase delay lines are printed on the same dielectric substrate. The phase delay lines are perpendicularly connected to the tightly coupled dipoles of the emitter and receiver layers. The phase delay line width is 0.2 mm, and the total length is 40 mm + 16 × 10⁻⁶ mm. The phase of the control unit is controlled by adjusting the length of the phase delay line, and different The changes in the transmission amplitude and phase of the vertically incident wave at the specified value are as follows: Figure 5 As shown in (a) and (b) in the figure. When the length When the thickness is increased from 0.2 mm to 4.2 mm, the metasurface element exhibits a transmission amplitude greater than 0.9 in the broadband range above 1.7 GHz to 4 GHz, and a phase change exceeding 187° at the lowest frequency, representing a significant improvement in bandwidth performance compared to commonly used lens antenna elements based on frequency-selective surfaces. Furthermore, the transmission amplitudes of the metasurface element under different incident angles for TE and TM polarizations are as follows: Figure 6 As shown in (a) and (b), the introduction of interconnect metal pillars changes the current transmitted from the delay line and shortens the current path. The matching layer plays the role of impedance matching. The introduction of metal pillars and metasurface matching layer significantly improves the oblique incidence transmission performance of the two frequency bands. When the oblique incidence angle reaches 30°, the transmission coefficient of TE and TM polarization in the two frequency bands is still greater than 0.85.

[0013] Furthermore, by calculating the corresponding phase compensation amount, the phase shift line of the metasurface unit is further calculated. The distribution of values ​​on the lens array surface, such as Figure 7 As shown.

[0014] Furthermore, a stacked dual-band dual-polarized feed antenna is employed, with an operating frequency band covering 1710MHz-2170MHz and 3400MHz-3800MHz, such as... Figure 2 As shown, the low-frequency antenna consists of a parasitic radiating element, a feed patch, a vertically tapered feed line, a microstrip filter structure, a reflector ground plane, and 180° phase-shift power dividers 1 and 2. The parasitic radiating element comprises four trapezoidal patches printed on dielectric substrate 1; a triangular feed patch printed on dielectric substrate 2 drives the parasitic radiating element to adjust its matching bandwidth; the vertically tapered feed line connects the feed patch and the microstrip filter structure, printed on a vertical dielectric substrate; the microstrip filter structure is printed on a 2mm thick dielectric substrate 4; the reflector ground plane is located between dielectric substrates 4 and 5; 180° phase-shift power dividers 1 and 2 are printed on dielectric substrate 5; metal vias connect the microstrip filter structure and the 180° phase-shift power dividers. The relative permittivity of the material is 4.4, the loss is 0.005, and the thickness of dielectric substrates 1, 2, 5, and the vertical dielectric substrate is 0.8mm. The high-frequency antenna adopts a common planar dipole form, printed on a 0.5mm dielectric substrate 3, and placed at a suitable height to achieve matching and radiation performance.

[0015] Furthermore, due to the good symmetry of the dual-polarization feed, the gain and radiation pattern results of the two polarizations are similar. Figure 8 Only a comparison of the +45° polarization horizontal plane gain patterns of the dual-frequency dual-polarization lens antenna with and without lenses at 1.95GHz and 3.5GHz is given in the embodiments. Figure 8 As shown in (a) and (b), the feed gain is 7.8 dBi without a lens at 1.95 GHz and 15.4 dBi with a lens; the feed gain is 8.4 dBi without a lens at 1.95 GHz and 18.2 dBi with a lens. Figure 9 The +45° polarization normalized radiation patterns of the dual-frequency dual-polarization lens antenna in the embodiment are given, in the low-frequency and high-frequency bands, as follows: Figure 9 As shown in (a) and (b), it can be seen that the sidelobes in the low-frequency band are less than -14dB and the cross-polarization is less than -14dB, while the sidelobes in the high-frequency band are less than -14dB and the cross-polarization is less than -15dB. Figure 10 The gain variation diagrams of the dual-frequency dual-polarized lens antenna in the embodiment are given in the low-frequency and high-frequency bands, as follows: Figure 10 As shown in (a) and (b), the gain variation is 14-16.1 dBi in the low-frequency band and 17.6-18.6 dBi in the high-frequency band. Considering the influence of aperture efficiency and frequency on gain, the lens can achieve good focusing performance in both frequency bands.

[0016] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual-frequency, dual-polarized electromagnetic lens antenna based on a broadband tightly coupled structure, characterized in that, include: An electromagnetic lens array, wherein the electromagnetic lens array is composed of multiple broadband tightly coupled units arranged periodically; A dual-frequency dual-polarization feed antenna, wherein the feed antenna is disposed at the focal point of the electromagnetic lens array, for generating and radiating dual-polarized electromagnetic waves in two separate operating frequency bands; The electromagnetic lens array receives electromagnetic waves from the feed antenna and converts them into collimated high-gain beam outputs based on the phase modulation effect of the broadband tightly coupled unit.

2. The antenna according to claim 1, characterized in that, The broadband tightly coupled unit is a three-dimensional multi-layer structure, including: A central metal layer; A receiving layer and a transmitting layer are respectively located on both sides of the central metal layer and are mirror-symmetrical about the central metal layer. Each of the receiving layer and the transmitting layer contains a pair of orthogonal, tapered, tightly coupled dipoles. Two pairs of phase delay lines, each pair of phase delay lines being perpendicularly connected to the graded tightly coupled dipoles at corresponding positions on the receiving layer and the transmitting layer, and passing through the central metal layer; An interconnecting metal pillar is disposed at the center of the unit and penetrates the central metal layer, and is vertically connected to the gradient tightly coupled dipoles on the receiving layer and the transmitting layer, respectively; Two metasurface matching layers are located outside the receiving layer and the transmitting layer, respectively.

3. The antenna according to claim 2, characterized in that, The gradient-type tightly coupled dipole is loaded with an interdigitated capacitor structure, and the gradient-type tightly coupled dipole achieves broadband transmission through coupling with the central metal layer.

4. The antenna according to claim 2, characterized in that, The central metal layer has a through hole at its center for the interconnecting metal pillar to pass through, and the four sides of the central metal layer have a concave semicircular structure at their midpoints, through which the phase delay line passes.

5. The antenna according to claim 2, characterized in that, By adjusting the physical length of the phase delay line, the transmission phase of the broadband tightly coupled unit is controlled to compensate for the spatial phase difference between the feed antenna and the units at different positions on the electromagnetic lens array.

6. The antenna according to claim 5, characterized in that, Based on the preset focal length and the position coordinates of each broadband tightly coupled unit in the electromagnetic lens array, the phase compensation amount is calculated, and the target length of the corresponding phase delay line is determined.

7. The antenna according to claim 2, characterized in that, The interconnecting metal pillars are used to change the current transmission path in the broadband tightly coupled unit to optimize the transmission performance of the unit under oblique electromagnetic wave incidence conditions.

8. The antenna according to claim 2, characterized in that, The metasurface matching layer is used to achieve impedance matching, thereby reducing the insertion loss of the broadband tightly coupled unit and increasing the transmission amplitude.

9. The antenna according to claim 1, characterized in that, The dual-frequency dual-polarized feed antenna has a stacked structure, and the width of its radiation beam covers the entire electromagnetic lens array.

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