Broadband artificial magnetic conductor capable of regulating and controlling working frequency through thickness of metal circuit layer

Abstract

The invention discloses a broadband artificial magnetic conductor capable of regulating and controlling the working frequency through the thickness of a metal circuit layer. The broadband artificial magnetic conductor comprises the metal circuit layer with the adjustable thickness, a dielectric substrate and a floor. The thickness-adjustable metal circuit layer is arranged on the upper surface of the dielectric substrate, and a floor is arranged on the lower surface of the dielectric substrate to form an artificial magnetic conductor unit; the metal circuit layer is centrosymmetric and variable in thickness. The design of regulating and controlling the working frequency is achieved by changing the thickness of the metal circuit layer, and the problem that the working frequency needs to be regulated by designing a complex metal circuit layer structure in a time-consuming and labor-consuming mode is solved. Under the condition that a complex structure does not need to be designed, only by changing the thickness of the metal circuit layer, the artificial magnetic conductor can be suitable for different working frequency bands, and the stable broadband in-phase reflection characteristic of the artificial magnetic conductor can be kept. The artificial magnetic conductor unit can realize in-phase and efficient energy reflection of incident plane electromagnetic waves in a working frequency band, and the power reflection coefficient of the artificial magnetic conductor unit is kept above 98% under different metal layer thicknesses.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave metamaterial (metasurface) artificial magnetic conductors, and specifically relates to a broadband artificial magnetic conductor whose operating frequency is regulated by the thickness of a metal circuit layer. Background Art

[0002] Artificial magnetic conductors (AMCs) are electromagnetic metamaterials constructed with subwavelength periodic structures. Their core characteristic lies in their in-phase reflection within specific frequency bands—electromagnetic waves reflect with a phase close to zero, in stark contrast to the 180° phase shift observed on traditional metal surfaces. This characteristic stems from the equivalent magnetic resonance response of the unit structure. By optimizing the geometric parameters and material properties of the periodic units, the operating frequency band and phase bandwidth can be precisely controlled. In antenna engineering, AMCs, as reflective ground planes, can overcome the quarter-wavelength spacing limitations of traditional metal ground planes, reducing antenna profile thickness to λ / 10 or even lower while suppressing surface wave losses and improving radiation efficiency and gain. For example, integrating an AMC reflective layer into a microstrip antenna can reduce structural thickness by over 60%, while enabling multi-band and beam steering capabilities. This provides a key technical path for lightweight and thin RF systems for applications such as 5G communications and satellite payloads.

[0003] Wideband AMC design has always been a hot topic in AMC design research, as well as a technical challenge. Enabling AMCs to maintain near-zero reflection phase across a wide operating frequency band remains an extremely challenging task. Traditional AMC designs typically optimize the metal circuit layer's shape and structure, once the dielectric substrate material is selected. Current AMC metal circuit layer design typically involves selecting a basic shape based on the performance requirements of auxiliary components and adjusting the metal circuit layer structure based on preliminary optimization results. Adjusting the metal circuit layer structure based on preliminary optimization results often requires significant time and effort, and complex structural adjustments, such as slotting, adding parasitic components, creating interlayer vias, and multi-layer cascade design, increase the difficulty and cost of AMC manufacturing, hindering its practical application. Furthermore, in AMC design, the metal circuit layer's shape and structure often struggle to balance broadband characteristics with operating frequency, resulting in either a wider bandwidth but a higher operating frequency shift, or a narrower bandwidth but a lower operating frequency shift. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a broadband artificial magnetic conductor whose operating frequency is regulated by the thickness of the metal circuit layer.

[0005] The technical solution of the present invention is: a broadband artificial magnetic conductor whose operating frequency is regulated by the thickness of a metal circuit layer comprises a metal circuit layer with adjustable thickness, a dielectric substrate and a floor; A metal circuit layer with adjustable thickness is arranged on the upper surface of a dielectric substrate, and a floor layer is arranged on the lower surface of the dielectric substrate to form an artificial magnetic conductor unit; the metal circuit layer is centrally symmetrical and has variable thickness.

[0006] Furthermore, when the thickness of the metal circuit layer changes by 10%, its resonant frequency changes by 5-10%, achieving the purpose of frequency modulation; its in-phase reflection relative bandwidth remains basically unchanged, maintaining bandwidth stability.

[0007] Furthermore, the shape of the metal circuit layer with adjustable thickness is a simple centrally symmetrical pattern.

[0008] Furthermore, the dielectric substrate has a rectangular structure.

[0009] Furthermore, the thickness of the dielectric substrate is 0.01λ~0.05λ, and the length and width thereof are 0.08λ~0.12λ. Furthermore, the material of the floor is conductive metal or conductive material.

[0010] The beneficial effects of the present invention are as follows: The present invention proposes an innovative design for achieving operating frequency tuning by regulating the thickness of the metal circuit layer, solving the high design complexity and manufacturing cost issues associated with traditional broadband artificial magnetic conductors, which rely on complex metal circuit layer structures. Specifically, without requiring a complex structural design, the present invention allows the artificial magnetic conductor to be adapted to different operating frequency bands while maintaining its in-phase reflection relative bandwidth stable at approximately 24%. Furthermore, the artificial magnetic conductor unit can achieve in-phase and efficient energy reflection of incident plane electromagnetic waves within the operating frequency band, with its power reflection coefficient remaining above 98% for various metal layer thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a side view of an artificial magnetic conductor unit in which the metal circuit layer structure is a square as an example in an embodiment of the present invention; Figure 2 is a top view of an artificial magnetic conductor unit in which the metal circuit layer structure is a square as an example in an embodiment of the present invention; Figure 3 is a top view of an artificial magnetic conductor unit in which the metal circuit layer structure is circular as an example in an embodiment of the present invention; Figure 4 is a top view of an artificial magnetic conductor unit in an embodiment of the present invention, taking a square with a circular groove as an example of a metal circuit layer structure; Figure 5 is a reflection phase curve diagram of an artificial magnetic conductor unit taking a square metal circuit layer structure as an example according to an embodiment of the present invention as the thickness of the metal circuit layer changes; Figure 6is a line graph of the resonant frequency of an artificial magnetic conductor unit as the thickness of the metal circuit layer changes, taking the metal circuit layer structure as an example in an embodiment of the present invention as a square; Figure 7 is a line graph of the relative bandwidth of the in-phase reflection of the artificial magnetic conductor unit as the thickness of the metal circuit layer changes, taking the metal circuit layer structure as an example in the embodiment of the present invention as a square; Figure 8 is a graph showing a power reflection coefficient of an artificial magnetic conductor unit taking a square metal circuit layer structure as an example according to an embodiment of the present invention as the thickness of the metal circuit layer varies; In the figure, 1-metal circuit layer; 2-dielectric substrate; 3-floor. DETAILED DESCRIPTION

[0012] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0013] like Figure 1 As shown, the present invention provides a broadband artificial magnetic conductor with an operating frequency regulated by the thickness of a metal circuit layer, comprising a metal circuit layer 1 with adjustable thickness, a dielectric substrate 2 and a floor 3; A metal circuit layer 1 with adjustable thickness is arranged on the upper surface of a dielectric substrate 2, and a floor layer 3 is provided on the lower surface of the dielectric substrate 2, forming an artificial magnetic conductor unit; the metal circuit layer 1 is centrally symmetrical and has variable thickness.

[0014] In the embodiment of the present invention, when the thickness of the metal circuit layer changes by 10%, its resonant frequency changes by 5-10%, achieving the purpose of frequency modulation; its in-phase reflection relative bandwidth remains basically unchanged, maintaining bandwidth stability.

[0015] In the embodiment of the present invention, the dielectric substrate 2 is made of semiconductor, ceramic, hard circuit board or plastic.

[0016] In the embodiment of the present invention, the material of the floor 3 can be conductive metal or conductive material such as copper, iron, steel, alloy, aluminum, tin, etc.

[0017] In the embodiment of the present invention, Figure 1 As shown, the thickness of the metal circuit layer 1 provided on the dielectric substrate 2 is variable.

[0018] In the embodiment of the present invention, Figure 1 As shown, the thickness of the dielectric substrate 2 is 0.01λ~0.05λ, and the length and width thereof are 0.08λ~0.12λ.

[0019] In the embodiment of the present invention, Figure 2 As shown, the dielectric substrate 2 has a rectangular structure.

[0020] In the embodiment of the present invention, Figure 2 、 Figure 3、 Figure 4 As shown, the shape of the metal circuit layer 1 with adjustable thickness is a simple centrosymmetrical figure, which can be a square, circle, diamond, square ring, circular ring, cross, etc. By designing these simple figures and only changing their thickness, it is possible to avoid wasting a lot of time and effort on designing some complex structures to meet the requirements of broadband artificial magnetic conductors within the corresponding frequency band.

[0021] When designing a basic artificial magnetic conductor unit, there are some optimization steps. The specific optimization steps of the present invention are as follows: 1. First, select the required frequency bandwidth range. The present invention uses the X-band. 2. Select a suitable dielectric substrate and set its size and structural parameters. A simple metal circuit layer structure with adjustable thickness is designed on the dielectric substrate. This structure and the dielectric substrate together form an artificial magnetic conductor unit. By setting boundary conditions, the characteristics of an infinite periodic structure can be simulated, so that only an artificial magnetic conductor unit structure needs to be established. In order to ensure the excitation effect of the wave port, the distance between the wave port and the unit surface is set to be greater than a quarter wavelength, and the reference plane of the wave port is ensured to be located on the unit surface to avoid the path difference generated when the electromagnetic wave propagates in free space. 3. Set periodic boundary conditions. The present invention adopts unitcell periodic boundary conditions. 4. Continuously optimize the unit structure size so that the phase of the S parameter becomes as wide as possible within the frequency range from -90° to 90°.

[0022] By designing a basic artificial magnetic conductor unit, the operating frequency band can be controlled by changing the thickness of its metal circuit layer. Figure 5 A reflection phase curve for an artificial magnetic conductor unit with a square metal circuit layer is shown as the thickness of the metal circuit layer changes. The graph shows that the operating frequency band changes significantly with the thickness of the metal circuit layer, while the bandwidth remains stable. Figure 6 This is a line graph of the resonant frequency of an artificial magnetic conductor unit with a square metal circuit layer structure as an example, showing how the thickness of the metal circuit layer changes. It can be seen more clearly that the resonant frequency decreases as the thickness of the metal circuit layer increases. This not only achieves the purpose of frequency modulation, but also facilitates the miniaturization of the artificial magnetic conductor unit. Figure 7 Taking a square metal circuit layer structure as an example, the in-phase reflection relative bandwidth of an artificial magnetic conductor unit as the thickness of its metal circuit layer changes is shown in the line graph. It can be seen more clearly that the in-phase reflection relative bandwidth maintains its bandwidth stability as the thickness of the metal circuit layer increases, and even shows an upward trend. Figure 8 This is a graph showing the power reflection coefficient of an artificial magnetic conductor unit with a square metal circuit layer structure as an example. It can be easily seen that the power reflection coefficient remains above 98% at different metal circuit layer thicknesses.

[0023] The working principle of the present invention is as follows: According to the skin effect, the current is concentrated on the surface of the conductor at high frequencies. Increasing the thickness will reduce the effective resistance of the current path, but more significantly, it will reduce the internal inductance (determined by the energy storage of the magnetic field inside the conductor). The greater the thickness, the smaller the skin depth, the less energy the internal magnetic field will have, and the equivalent inductance will decrease. The in-phase reflection bandwidth is inversely proportional to the quality factor (Q value) of the resonant frequency, that is, the reduction of the equivalent inductance can widen the bandwidth. When the thickness of the metal circuit layer increases by 10%, its resonant frequency decreases by 8%, achieving the purpose of frequency modulation; its in-phase reflection relative bandwidth will increase by 5%, maintaining the stability of the bandwidth. The present invention provides the following beneficial effects: It proposes an innovative design for adjusting the operating frequency by varying the thickness of the metal circuit layer, resolving the time-consuming and labor-intensive design of complex metal circuit layer structures required for designing broadband artificial magnetic conductors. Specifically, without requiring complex structural design, the present invention enables artificial magnetic conductors to operate in different frequency bands while maintaining broadband stability simply by varying the thickness of the metal circuit layer.

[0024] Those skilled in the art will appreciate that the embodiments described herein are merely examples to help readers understand the principles of the present invention and are not intended to limit the scope of protection of the present invention to these specific descriptions and embodiments. Those skilled in the art may, based on the disclosure of the present invention and in combination with its technical implications, make various modifications and combinations, and such modifications and combinations shall still fall within the scope of protection of the present invention.

Claims

1. A broadband artificial magnetic conductor with an operating frequency controlled by the thickness of a metal circuit layer, characterized in that: It includes a metal circuit layer (1) with adjustable thickness, a dielectric substrate (2) and a floor (3); The thickness-adjustable metal circuit layer (1) is arranged on the upper surface of a dielectric substrate (2), and a floor layer (3) is provided on the lower surface of the dielectric substrate (2); the thickness-adjustable metal circuit layer (1) is centrally symmetrical and has a variable thickness.

2. The broadband artificial magnetic conductor with operating frequency controlled by thickness of metal circuit layer according to claim 1, characterized in that: When the thickness of the metal circuit layer changes by 10%, its resonant frequency changes by 5-10%, achieving the purpose of frequency modulation; Its in-phase reflection relative bandwidth remains basically unchanged, maintaining the stability of the bandwidth.

3. The broadband artificial magnetic conductor with operating frequency controlled by thickness of metal circuit layer according to claim 1, characterized in that: The metal circuit layer (1) with adjustable thickness is in the shape of a simple centrally symmetrical figure.

4. The broadband artificial magnetic conductor with operating frequency controlled by thickness of metal circuit layer according to claim 1, characterized in that: The dielectric substrate (2) has a rectangular structure.

5. The broadband artificial magnetic conductor with operating frequency controlled by thickness of metal circuit layer according to claim 1, characterized in that: The thickness of the dielectric substrate (2) is 0.01λ~0.05λ, and the length and width thereof are 0.08λ~0.12λ.

6. The broadband artificial magnetic conductor with operating frequency controlled by thickness of metal circuit layer according to claim 1, characterized in that: The material of the floor (3) is conductive metal or conductive material.

Images