Resonance type artificial metamaterial structure and microstrip antenna

Abstract

The invention discloses a resonance type artificial metamaterial structure and a microstrip antenna, and relates to the technical field of microstrip antenna design, the resonance type artificial metamaterial structure comprises a plurality of branch knots with unequal widths and a wafer, the plurality of branch knots are connected end to end according to a spiral shape, the gaps between the parallel branch knots are different, and the wafer is arranged on the branch knots. The tail end of the innermost branch knot is connected with a wafer, and the resonance type artificial metamaterial structure is a left-handed metamaterial and has strong inductance and capacitance characteristics; a plurality of resonance type artificial metamaterial structures form an array form, are arranged on the surface of a dielectric substrate and are symmetrically distributed about the midpoint of the dielectric substrate, and the array formed by the resonance type artificial metamaterial structures can regulate and control the overall dielectric constant and magnetic conductivity of the microstrip antenna so as to generate a new radiation mode and resonance frequency points. And the problem that the microstrip antenna is difficult to realize multi-frequency and multi-mode is well solved.

Description

Technical Field

[0001] The present application relates to the technical field of microstrip antenna design, and in particular to a resonant artificial metamaterial structure and a microstrip antenna. Background Art

[0002] Microstrip antennas play a vital role in the field of antenna applications. They have gained widespread application due to their significant advantages, including small size, light weight, low profile, easy conformal design, high cost-effectiveness, and ease of circuit integration. Despite this, microstrip antennas also face some inherent challenges: their narrow frequency band, limited relative bandwidth, and high Q value, all of which limit their potential in broadband applications. In addition, traditional microstrip antenna designs typically only support single multi-frequency or multi-mode characteristics. Currently, the theoretical system for achieving multi-frequency and multi-mode characteristics of microstrip antennas is not yet fully mature, and the existing antenna structure design is relatively complex. Generally speaking, metamaterials rarely have strong inductance and capacitance characteristics, and they do not have resonant characteristics themselves, making it difficult to introduce new radiation modes and resonant frequencies, making it difficult to realize multi-frequency and multi-mode microstrip antennas.

[0003] In contrast, artificial metamaterials, due to their unique electromagnetic properties, offer broad application prospects in a variety of fields, including communications, radar, medical imaging, and energy conversion. Artificial metamaterials have attracted considerable attention due to their dual negativity, where both the dielectric constant (ε) and magnetic permeability (μ) are simultaneously negative within a specific frequency range. These materials are also known as dual-negative or left-handed materials because, during electromagnetic wave propagation, the electric field (E), magnetic field (H), and wave vector (k) follow the left-handed helical rule, as opposed to the right-handed helical rule for conventional materials (right-handed materials, where both the dielectric constant and magnetic permeability are positive). Therefore, by combining the strong inductance and unique left-handed electromagnetic properties of resonant artificial metamaterial units, it is expected that multiple radiation modes and resonant frequencies can be introduced into microstrip antennas, thereby addressing the difficulty of achieving multi-frequency and multi-mode microstrip antennas. Summary of the Invention

[0004] The purpose of this application is to provide a resonant artificial metamaterial structure and a microstrip antenna, which can introduce multiple radiation modes and multiple resonant frequencies into the microstrip antenna.

[0005] To achieve the above objectives, this application provides the following solutions: In the first aspect, the present application provides a resonant artificial metamaterial structure, comprising: a plurality of branches of unequal widths and a disc, wherein the plurality of branches are connected end to end in a spiral shape, the gaps between mutually parallel branches are different, and the ends of the innermost branches are connected to the disc; the resonant artificial metamaterial structure is a left-handed metamaterial, and the electric field, magnetic field and wave vector of the resonant artificial metamaterial structure follow the left-handed spiral rule; the resonant artificial metamaterial structure has strong inductance and capacitance characteristics.

[0006] Optionally, the widths of a group of mutually parallel branches in the resonant artificial metamaterial structure are 0.5 mm, 0.1 mm and 0.15 mm respectively.

[0007] Optionally, the radius of the disc is 0.17 mm.

[0008] In a second aspect, the present application provides a microstrip antenna comprising: a plurality of resonant artificial metamaterial structures, a dielectric substrate, and a feeding structure as described above; the plurality of resonant artificial metamaterial structures are arranged in an array form, arranged on the surface of the dielectric substrate and symmetrically distributed about the midpoint of the dielectric substrate; the feeding structure is used to provide feeding and thereby excite the resonant artificial metamaterial structure to radiate.

[0009] Optionally, the feeding structure is an L-shaped probe structure; the L-shaped probe structure includes an L-shaped metal patch and a coaxial probe located at the tail end of the L-shaped metal patch; the coaxial probe is used to provide feeding for the resonant artificial metamaterial structure, thereby generating radiation.

[0010] Optionally, an L-shaped metal patch is built into the middle of the dielectric substrate at a height of 1.17 mm. The L-shaped metal patch is formed by bending a long metal patch. One end of the L-shaped metal patch faces the bottom of the dielectric substrate and is connected to an external power supply as a feeding port. The length of the part of the L-shaped metal patch parallel to the dielectric substrate is 8.3 mm, and the height of the coaxial probe is 1.17 mm.

[0011] Optionally, the dielectric substrate is a Rogers 4003C square dielectric substrate with a dielectric constant of 3.55, a loss tangent of 0.0027, and a height of 2.34 mm.

[0012] Optionally, the distance between adjacent resonant-type artificial metamaterial structures is 0.1 mm, and the edge of the outermost resonant-type artificial metamaterial structure is 5 mm away from the edge of the dielectric substrate.

[0013] Optionally, the number of the resonant artificial metamaterial structures is 16, and the 16 resonant artificial metamaterial structures form a 4×4 array; the 16 resonant artificial metamaterial structures forming the 4×4 array introduce multiple new radiation modes to the microstrip antenna.

[0014] Optionally, the microstrip antenna generates a total of 6 resonant frequencies in the range of 3-8 GHz, namely 3.47 GHz, 5.02 GHz, 5.52 GHz, 6.42 GHz, 7.17 GHz and 7.66 GHz.

[0015] According to the specific embodiments provided in this application, this application discloses the following technical effects: The present application provides a resonant artificial metamaterial structure and a microstrip antenna. The resonant artificial metamaterial structure includes: a plurality of branches of unequal widths and a disc. The plurality of branches are connected end to end in a spiral shape. The gaps between mutually parallel branches are different. The ends of the innermost branches are connected to the disc. The resonant artificial metamaterial structure is a left-handed metamaterial with strong inductance and capacitance characteristics. The plurality of resonant artificial metamaterial structures are arranged in an array, disposed on the surface of a dielectric substrate and symmetrically distributed about the midpoint of the dielectric substrate. The array composed of the resonant artificial metamaterial structures can regulate the overall dielectric constant and magnetic permeability of the microstrip antenna, thereby generating new radiation modes and resonant frequencies. By introducing multiple radiation modes and multiple resonant frequencies into the microstrip antenna through this material structure, the problem that the microstrip antenna has difficulty in achieving multi-frequency and multi-mode is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A schematic diagram of a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0018] Figure 2 A top view of a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0019] Figure 3 This is an S-parameter diagram of a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0020] Figure 4 This is a graph of equivalent dielectric constant data for a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0021] Figure 5 This is a graph of magnetic permeability data of a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0022] Figure 6 This is a refractive index data diagram of a resonant artificial metamaterial structure provided in one embodiment of the present application.

[0023] Figure 7 A top view of a microstrip antenna provided in one embodiment of the present application.

[0024] Figure 8 A schematic diagram of the S11 parameter simulation results of a microstrip antenna provided in one embodiment of the present application.

[0025] Figure 9 This is a patch current distribution diagram of a microstrip antenna provided in one embodiment of the present application at a resonant frequency of 3.47 GHz.

[0026] Figure 10 This is a patch current distribution diagram of a microstrip antenna provided in one embodiment of the present application at a resonant frequency of 5.02 GHz.

[0027] Figure 11 This is a patch current distribution diagram of a microstrip antenna provided in one embodiment of the present application at a resonant frequency of 5.52 GHz.

[0028] Figure 12 This is an E-plane radiation pattern of a microstrip antenna provided in one embodiment of the present application at 5.52 GHz. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] The embodiment of the present application provides a resonant artificial metamaterial structure, such as Figure 1 As shown, it includes: several branches of unequal width and a disc, several branches are connected end to end in a spiral shape, the gaps between parallel branches are different, and the ends of the innermost branches are connected to the disc; the resonant artificial metamaterial structure is a left-handed metamaterial, and the electric field, magnetic field and wave vector of the resonant artificial metamaterial structure follow the left-handed spiral rule; the resonant artificial metamaterial structure has strong inductance and capacitance characteristics.

[0032] Specifically, strong inductance: The spiral structure of the resonant artificial metamaterial structure itself is similar to an inductor coil. When current passes through, a magnetic field is generated around it, thus exhibiting inductance characteristics. The design of unequal width further enhances this inductance effect. The change in width affects the distribution of current and the intensity of the magnetic field, thereby increasing the inductance. Strong capacitance: The designed spiral structure of unequal width forms a narrower metal wire gap, which is equivalent to a parallel capacitor, thereby increasing the overall capacitance of the structure. Compared with general metamaterial units, the spiral structure has a larger capacitance and inductance value, and is easier to control the transmission of electromagnetic waves on the surface. The spiral structure makes it easier to introduce new radiation modes of microstrip antennas and generate new resonant frequencies.

[0033] like Figure 2 The top view of the resonant metamaterial structure is shown. The side length of the resonant metamaterial is 2.1 mm. The widths of a set of parallel branches are w1 = 0.5 mm, w2 = 0.1 mm, and w3 = 0.15 mm, respectively, corresponding to the different characteristic impedances of the asymmetric stripline. The radius R of the disc is 0.17 mm.

[0034] By extracting the equivalent dielectric constant, equivalent magnetic permeability and refractive index of this resonant artificial metamaterial structure, it was found that it conforms to the left-handed material characteristics. This characteristic plays an important regulatory role in allowing microstrip antennas to broaden the frequency band and add new radiation modes.

[0035] like Figure 3 The figure shows the S parameter diagram of the resonant artificial metamaterial structure. Figure 3 It can be seen that the unit produces resonance in the working frequency band of 3-8GHz, which verifies that the above-mentioned resonant artificial metamaterial structure of this application itself has resonant characteristics. By obtaining the S11 parameter S(1,1) and S21 parameter S(2,1) of the structure, the S11 parameter is the transmission amplitude of the metamaterial, and the S21 parameter is the reflection amplitude of the metamaterial. Using the scattering parameter extraction method, the corresponding electromagnetic parameters of the metamaterial can be extracted. It is verified that the resonant metamaterial surface designed in this application is a left-handed metamaterial, and its refractive index is a negative refractive index. The equivalent dielectric constant and magnetic permeability must be satisfied to achieve double negative characteristics within the working frequency band. According to the relationship between the S parameter and the refractive index n shown in the following formula: .

[0036] in, n is the refractive index, k is the wave vector, d is the thickness of the loaded substrate, j is an imaginary unit. From this, the equivalent dielectric constant of the resonant metamaterial can be extracted ε and magnetic permeability μ , to verify whether it is a resonant left-handed material.

[0037] like Figure 4 As shown in the figure, according to the equivalent dielectric constant data extracted from the resonant artificial metamaterial structure designed in this application, it can be seen that it has a negative dielectric constant characteristic within the working frequency band and resonates at 6.42GHz. Figure 5 It can be seen from the figure that the real part of the structure is kept negative in the working frequency band, and the negative value characteristics of the equivalent dielectric constant data graph in the working frequency band are comprehensively extracted. Figure 6As shown in the figure, the refractive index data of the resonant artificial metamaterial structure designed by the present application is shown. The imaginary part of the refractive index represents the loss of the metamaterial, and it can be seen that the structure of the present application is a lossy material. Similarly, the refractive index fluctuates at the resonance point of 6.42 GHz, showing a negative refractive index effect, thereby verifying that the artificial metamaterial structure of the present application has resonance and left-handed characteristics, proving that loading the metamaterial structure can regulate the dielectric constant and magnetic permeability of the microstrip antenna as a whole, thereby generating new radiation modes and resonant frequencies.

[0038] During electromagnetic wave propagation in standard materials (right-handed materials), the electric field E, magnetic field H, and wave propagation direction k satisfy the right-hand rule. That is, if the four fingers of the right hand point in the direction of the electric field E, then bend the fingers so that they rotate through an angle less than 180° in the direction of the magnetic field H, the direction of the thumb will now correspond to the wave propagation direction k. However, in left-handed materials, these three relationships satisfy the left-hand relationship: the electric field E, magnetic field H, and wave propagation direction k satisfy the left-hand spiral rule. Left-handed materials have a larger propagation constant, and the aforementioned spiral structure of the present application increases the resonant path for the current, resulting in a new resonance point at 3.47 GHz for the antenna. Because the propagation phase direction of left-handed materials is opposite to the direction of electromagnetic wave propagation, the present application offers significant advantages in its ability to manipulate electromagnetic waves. The large propagation phase shift constant of the left-handed material of the present application can separate closely spaced resonance points, such as 5.02 GHz and 6.42 GHz. The multiple spiral arms of this spiral metamaterial structure generate different induced currents, resulting in different radiation capabilities.

[0039] In another exemplary embodiment of the present application, Figure 7 As shown, a microstrip antenna is provided, comprising: a plurality of resonant artificial metamaterial structures, a dielectric substrate, and a feeding structure as described in the above embodiments; the plurality of resonant artificial metamaterial structures are arranged in an array, arranged on the surface of the dielectric substrate and symmetrically distributed about the midpoint of the dielectric substrate; the feeding structure is used to provide feeding and thereby excite the resonant artificial metamaterial structure to radiate.

[0040] As an exemplary embodiment, the feeding structure is an L-shaped probe structure; the L-shaped probe structure includes an L-shaped metal patch and a coaxial probe located at the end of the L-shaped metal patch. The coaxial probe is used to provide power feeding for the resonant artificial metamaterial structure, thereby generating radiation. The L-shaped metal patch is embedded in the middle of the dielectric substrate at a height of 1.17mm. The L-shaped metal patch is formed by bending a long metal patch. The end of the L-shaped metal patch facing the bottom of the dielectric substrate serves as a feeding port for connection to an external power source. The length of the portion of the L-shaped metal patch parallel to the dielectric substrate is 8.3mm, and the height of the coaxial probe is 1.17mm.

[0041] As an exemplary embodiment, the dielectric substrate is a Rogers 4003C square dielectric substrate with a dielectric constant of 3.55, a loss tangent of 0.0027, and a height of 2.34 mm. Specifically, in this embodiment, there are 16 resonant artificial metamaterial structures, forming a 4×4 array. These 16 resonant artificial metamaterial structures in this 4×4 array introduce multiple new radiation modes to the microstrip antenna. The spacing between adjacent resonant artificial metamaterial structures is 0.1 mm, and the edge of the outermost resonant artificial metamaterial structure is 5 mm from the edge of the dielectric substrate.

[0042] By forming a 4×4 array loaded on a microstrip antenna, it is verified whether it can control the multi-frequency and multi-mode of the microstrip antenna. Through simulation, it can be found that Figure 8 The S11 parameter simulation results of this embodiment are as follows: Figure 8 It can be seen that the structure generates a total of 6 resonant frequency points in the range of 3-8GHz. They are 3.47GHz, 5.02GHz, 5.52GHz, 6.42GHz, 7.17GHz, and 7.66GHz respectively. The antenna structure without the resonant metamaterial of the invention can only generate 2 resonant points. By loading the 4×4 array composed of the resonant artificial metamaterial structure of this application, an additional 4 new resonant frequency points are generated for the microstrip antenna. Unlike traditional microstrip antennas with fewer frequency points, the structure of this application is loaded on the microstrip antenna, realizing the multi-frequency operation of the microstrip antenna.

[0043] Figure 9 This is the patch current distribution diagram for a 4×4 array of this resonant metamaterial structure at the 3.47 GHz resonant frequency. As shown in the current distribution diagram, the induced currents in patches not participating in radiation are weak and have no impact on radiation. Patches participating in radiation can have upward-directed equivalent currents J1 and J2. The induced currents are concentrated on the inner spiral arms of the artificial metamaterial structure. Equivalent currents J1 and J2 form a resonant loop on these spiral arms. The radiation pattern at the 3.47 GHz resonant point is generated by the combined effects of the antenna's own TM10 mode and the equivalent currents J1 and J2 in the radiating patches.

[0044] Figure 10 The current distribution of the patches in a 4×4 array of resonant metamaterials at the 5.02 GHz resonant frequency is shown. At this resonant frequency, the induced currents in the gaps between the metamaterial patches on either side are the largest, representing equivalent currents J3 and J4. These equivalent currents, combined with the currents in the L-shaped feed patch, form a three-element array, generating the radiation pattern of the 5.02 GHz resonant frequency.

[0045] Figure 11This figure shows the patch current distribution at the 5.52 GHz resonant frequency of a 4×4 array of resonant metamaterials. As shown, the patches at the four corners generate the largest induced currents, concentrated at the opening of the spiral structure, forming a resonant loop. These currents are equivalent to currents J5, J6, J7, and J8. The four corner patches act as radiators. Because the induced currents generated by these patches are not equal, the radiation capabilities generated by these induced currents vary, which can easily cause a shift in the radiation pattern.

[0046] In addition, the resonant artificial metamaterial structure array designed in this application is loaded on the microstrip antenna, which introduces multiple new radiation modes for the microstrip antenna. Specifically, Figure 9 , this mode is mainly generated by the inner ring induced current of the spiral metamaterial structure. Figure 10 , this pattern is generated by the induced current generated at both ends of the 4×4 metamaterial patch and the current on the L-shaped feeding patch, which constitutes an equivalent three-element electric dipole array. Figure 11 As shown in the figure, this pattern is generated by induced currents of varying magnitude around the metamaterial array patch. The varying magnitudes of the induced currents produce varying radiation capabilities, causing the antenna's main radiation direction to deviate by 15 degrees from the axial direction. This pattern can be used for tilted beam scanning.

[0047] like Figure 12 Figure 2 shows the E-plane radiation pattern of the microstrip antenna structure of this embodiment at 5.52 GHz. Unlike the original antenna structure, where the main beam has a Theta angle of 0°, the radiation pattern at this point exhibits a beam offset of approximately 15°. This is due to the difference in induced current magnitude. The radiation pattern confirms that the radiation pattern at this resonant point exhibits a 15° beam offset, demonstrating the practicality of beam offset control for microstrip antennas.

[0048] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A resonant artificial metamaterial structure, characterized in that: include: A plurality of branches of unequal widths and a disc, wherein the plurality of branches are connected end to end in a spiral shape, the gaps between mutually parallel branches are different, and the ends of the innermost branches are connected to the disc; the resonant artificial metamaterial structure is a left-handed metamaterial, and the electric field, magnetic field and wave vector of the resonant artificial metamaterial structure follow the left-handed spiral rule; the resonant artificial metamaterial structure has strong inductance and capacitance characteristics.

2. The resonant artificial metamaterial structure according to claim 1, characterized in that: The widths of a group of mutually parallel branches in the resonant artificial metamaterial structure are 0.5 mm, 0.1 mm and 0.15 mm respectively.

3. The resonant artificial metamaterial structure according to claim 1, characterized in that: The radius of the disc is 0.17 mm.

4. A microstrip antenna, characterized in that: include: Several resonant artificial metamaterial structures, dielectric substrates, and feeding structures according to any one of claims 1 to 3; several of the resonant artificial metamaterial structures are arranged in an array, arranged on the surface of the dielectric substrate and symmetrically distributed about the midpoint of the dielectric substrate; the feeding structure is used to provide feeding and thereby excite the resonant artificial metamaterial structure to radiate.

5. The microstrip antenna according to claim 4, characterized in that The feeding structure is an L-shaped probe structure; the L-shaped probe structure includes an L-shaped metal patch and a coaxial probe located at the tail end of the L-shaped metal patch; the coaxial probe is used to provide feeding for the resonant artificial metamaterial structure, thereby generating radiation.

6. The microstrip antenna according to claim 5, characterized in that The L-shaped metal patch is built into the middle of the dielectric substrate at a height of 1.17 mm. The L-shaped metal patch is formed by bending a long metal patch. The end of the L-shaped metal patch facing the bottom of the dielectric substrate serves as a feeding port connected to an external power supply. The length of the portion of the L-shaped metal patch parallel to the dielectric substrate is 8.3 mm, and the height of the coaxial probe is 1.17 mm.

7. The microstrip antenna according to claim 4, characterized in that: The dielectric substrate is a Rogers 4003C square dielectric substrate with a dielectric constant of 3.55, a loss tangent of 0.0027, and a height of 2.34 mm.

8. The microstrip antenna according to claim 4, wherein: The distance between adjacent resonant-type artificial metamaterial structures is 0.1 mm, and the edge of the outermost resonant-type artificial metamaterial structure is 5 mm away from the edge of the dielectric substrate.

9. The microstrip antenna according to claim 4, characterized in that: The number of the resonant artificial metamaterial structures is 16, and the 16 resonant artificial metamaterial structures form a 4×4 array; the 16 resonant artificial metamaterial structures forming the 4×4 array introduce multiple new radiation modes to the microstrip antenna.

10. The microstrip antenna according to claim 4, characterized in that: The microstrip antenna generates a total of 6 resonant frequencies in the range of 3-8 GHz, namely 3.47 GHz, 5.02 GHz, 5.52 GHz, 6.42 GHz, 7.17 GHz and 7.66 GHz.

Images