High-gain ultra-wideband cavity-backed butterfly antenna based on electric loading

Abstract

The invention belongs to the technical field of antennas, and provides a high-gain ultra-wideband cavity-backed butterfly antenna based on electric loading, which is used for reducing return loss while ensuring that the butterfly antenna meets the requirements of broadband and high gain characteristics. The antenna comprises a radiator and a back cavity, the back cavity is a semi-closed resonant cavity, the back cavity is arranged below the radiator, and the radiator is located at an opening in the top end of the back cavity; the radiating body comprises a dielectric substrate, and a semi-elliptical annular radiating arm, a semicircular parasitic patch, a strip-shaped metal branch knot and a loading capacitor which are arranged on the upper surface of the dielectric substrate; according to the invention, the semi-elliptical curvature gradient radiation arm structure is provided, the field angle is increased under the condition that the compact electric size is maintained, and the broadband matching characteristic is remarkably improved; meanwhile, the impedance characteristic is cooperatively optimized through capacitance loading and a composite electromagnetic coupling mechanism of a parasitic unit, and broadband matching of the butterfly antenna is effectively achieved; and moreover, a symmetrical back cavity resonance structure is introduced, so that the gain of the antenna is effectively improved on the premise of maintaining low return loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and specifically provides a high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading. Background Art

[0002] In the mid-20th century, with the development of radio communication technology, especially the growing demand for broadband antennas that can cover a wide frequency range in the fields of radar and satellite communications, scientific researchers began to explore new antenna designs. Based on the basic principles of the biconical antenna, researchers proposed the design concept of the butterfly antenna, which forms a shape similar to butterfly wings by extending the biconical antenna arms in order to achieve a wider operating frequency band. At the same time, electromagnetic field theory was applied to analyze the radiation characteristics and working mechanism of the butterfly antenna; using Maxwell's equations and their solutions, such as the method of moments (MoM), the finite element method (FEM) and other numerical methods, scientists were able to accurately simulate the electromagnetic field distribution inside and around the butterfly antenna, providing a theoretical basis for understanding how the butterfly antenna supports multi-mode operation through its unique geometric structure.

[0003] Since the 21st century, the application of new materials and advancements in microfabrication technology have further optimized the design of butterfly antennas. For example, the use of low-loss dielectric materials as substrates can effectively reduce the energy loss of the antenna itself. Advanced printed circuit board (PCB) and flexible electronics technologies have enabled butterfly antennas to be fabricated not only on traditional rigid materials but also integrated into wearable devices or other applications requiring flexibility. Furthermore, the emergence of metamaterials has opened up new possibilities for butterfly antennas, enabling them to enhance or customize antenna performance by designing artificial structures with specialized electromagnetic properties.

[0004] Therefore, in practical applications, butterfly antennas must meet both broadband and high-gain requirements. However, to achieve this broadband performance, resistors are typically added to the antenna's ends or along the edges of the tapered slots. The mechanism by which these resistors absorb reflected current is to absorb the remaining unradiated current through ohmic losses, reducing reflections and suppressing standing waves. However, this also introduces ohmic losses, which reduces radiation efficiency to a certain extent. To address this issue, the present invention provides a novel, high-gain, ultra-wideband, cavity-backed butterfly antenna based on electrical loading. Summary of the Invention

[0005] The present invention aims to provide a high-gain, ultra-wideband, cavity-backed butterfly antenna based on electrical loading, designed to reduce return loss while ensuring the antenna meets broadband and high-gain requirements. This invention creatively introduces a loading capacitor and a matching parasitic structure to optimize antenna current distribution and synergistically reduce return loss, significantly increasing the antenna's operating bandwidth. Simultaneously, the introduction of a cavity backing effectively increases the antenna's gain within the operating bandwidth (particularly at high frequencies) while ensuring low return loss.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading, characterized by comprising: a radiator and a cavity-backed antenna;

[0008] The radiator includes: a dielectric substrate and a semi-elliptical ring radiating arm provided on its upper surface, a semi-circular parasitic patch, a strip metal branch and a loading capacitor. The radiator adopts an axially symmetrical structure and is rectangular. The two semi-elliptical ring radiating arms are provided back to back and the long axis of the semi-elliptical ring radiating arm coincides with the long side of the radiator. The two semi-circular parasitic patches are respectively provided at the center of the semi-elliptical ring radiating arm and the straight edges of the semi-circular parasitic patch coincide with the long side of the radiator. The strip metal branch is provided along the short axis of the semi-elliptical ring radiating arm and the two ends connect the semi-elliptical ring radiating arm and the semi-circular parasitic patch. At the same time, the semi-circular parasitic patch and the slot at the end of the semi-elliptical ring radiating arm are respectively provided with loading capacitors.

[0009] The back cavity adopts a semi-closed resonant cavity, the back cavity is connected to the bottom of the radiator, and the radiator is located at the top opening of the back cavity.

[0010] Furthermore, the back cavity adopts an inverted tetrahedral structure, which is composed of a metal reflector located at the bottom and four groups of metal partitions located on the sides.

[0011] Furthermore, the outer contour of the semi-elliptical ring-shaped radiation arm is tangent to the short side of the radiator.

[0012] Furthermore, all loading capacitors have the same capacitance value.

[0013] Furthermore, the dielectric substrate adopts an FR4 dielectric substrate with a size of 265 mm×242 mm and a thickness of 2 mm.

[0014] Furthermore, the major axis of the outer contour of the semi-elliptical ring radiating arm is 265 mm and the minor axis is 153 mm, the major axis of the inner contour of the semi-elliptical ring radiating arm is 242 mm and the minor axis is 140 mm, and the thickness of the semi-elliptical ring radiating arm is 0.035 mm.

[0015] Furthermore, the radius of the semicircular parasitic patch is 10 mm and the thickness is 0.035 mm.

[0016] Furthermore, the length of the strip-shaped metal branch is 47 mm, the width is 2 mm, and the thickness is 0.035 mm.

[0017] Furthermore, the capacitance value of the loading capacitor is 1 pf.

[0018] Furthermore, the height of the back cavity is 35 mm, the size of the bottom of the back cavity is 242 mm×120 mm, the top size matches the dielectric substrate of the radiator, and the thickness of the metal reflector and the metal partition is 2 mm.

[0019] Based on the above technical solution, the beneficial effects of the present invention are:

[0020] In the traditional butterfly antenna design, its bandwidth is determined by the antenna's angle, and the lowest resonant frequency is determined by the antenna's length. The purpose of adjusting the bandwidth and the lowest resonant frequency can be achieved by adjusting the antenna's structural parameters. The larger the antenna's angle, the wider the impedance bandwidth. The longer the antenna length, the lower the operating frequency. Therefore, the present invention proposes a semi-elliptical curvature gradient radiation arm structure, which can increase the angle while maintaining a compact electrical size, significantly improving the broadband matching characteristics. At the same time, metal parasitic patches and capacitor loading technology are introduced. The introduced semicircular metal patch serves as a parasitic structure, which can couple with the radiating unit, thereby reconstructing the current distribution on the radiator surface, suppressing the arm end current reflection and compensating for the low-frequency reactance component. In addition, a metal reflector and a metal partition structure extended therefrom are loaded to form a back cavity, further utilizing the multi-mode coupling effect of the cavity to achieve directional convergence of electromagnetic energy, and the metal plate simultaneously plays a certain reflection role, thereby optimizing the antenna gain.

[0021] In summary, the present invention creatively proposes a new type of butterfly antenna, abandoning the traditional butterfly antenna design of reducing return loss by loading resistance but sacrificing antenna efficiency and gain, and synergistically optimizing impedance characteristics through the composite electromagnetic coupling mechanism of capacitor loading and parasitic units, thereby effectively achieving wide-band matching of the butterfly antenna; at the same time, on this basis, the symmetrical back cavity resonant structure is innovatively adopted, which effectively improves the gain of the antenna, especially the gain of the high-frequency part, while maintaining low return loss, breaking through the classic compromise relationship between the radiation efficiency and gain performance of the wide-band antenna, and has good practicality and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of the radiator of the electrically loaded high-gain ultra-wideband cavity-backed butterfly antenna in the present invention.

[0023] Figure 2 Schematic diagram of the back cavity structure of the high-gain ultra-wideband back cavity butterfly antenna based on electrical loading in the present invention.

[0024] Figure 3 This is a comparison chart of S11 between the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in the present invention and the butterfly antenna in the comparative example.

[0025] Figure 4 This is a gain comparison diagram of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in the present invention and the butterfly antenna in the comparative example.

[0026] Figure 5 This is a comparison diagram of the directional patterns of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in the present invention and the butterfly antenna in the comparative example. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Example 1

[0029] This embodiment provides a high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading, the structure of which is as follows: Figure 1 and Figure 2 As shown, it includes: a radiator and a back cavity; wherein:

[0030] The radiator includes: a dielectric substrate and a semi-elliptical ring radiating arm provided on its upper surface, a semi-circular parasitic patch, a strip metal branch and a loading capacitor. The radiator adopts an axially symmetrical structure and is rectangular. The two semi-elliptical ring radiating arms are provided back to back and the long axis of the semi-elliptical ring radiating arm coincides with the long side of the radiator. The two semi-circular parasitic patches P1 and P2 are respectively provided at the center of the semi-elliptical ring radiating arm and the straight edges of the semi-circular parasitic patches coincide with the long side of the radiator. The strip metal branch is provided along the short axis of the semi-elliptical ring radiating arm and the two ends connect the semi-elliptical ring radiating arm and the semi-circular parasitic patch. At the same time, the slots at the ends of the semi-elliptical ring radiating arm and the semi-elliptical ring radiating arm are respectively provided with loading capacitors C1 to C4.

[0031] The back cavity adopts an inverted tetrahedral structure, specifically a semi-closed resonant cavity consisting of a metal reflector at the bottom and four groups of metal partitions at the side; the back cavity is connected to the bottom of the radiator, and the radiator is located at the top opening of the back cavity.

[0032] Furthermore, the dielectric substrate adopts an FR4 dielectric substrate with a size of 265 mm×242 mm, a thickness of 2 mm, a dielectric constant of 4.3, and a loss tangent of 0.025.

[0033] Furthermore, the major axis of the outer contour of the semi-elliptical ring radiating arm is 265 mm and the minor axis is 153 mm, the major axis of the inner contour of the semi-elliptical ring radiating arm is 242 mm and the minor axis is 140 mm, and the thickness of the semi-elliptical ring radiating arm is 0.035 mm.

[0034] Furthermore, the radius of the semicircular parasitic patch is 10 mm and the thickness is 0.035 mm.

[0035] Furthermore, the length of the strip-shaped metal branch is 47 mm, the width is 2 mm, and the thickness is 0.035 mm.

[0036] Furthermore, the capacitance values ​​of the loading capacitors C1 to C4 are all 1 pf.

[0037] Furthermore, the height of the back cavity is 35 mm, the size of the bottom of the back cavity is 242 mm×120 mm, the top size matches the dielectric substrate of the radiator, and the thickness of the metal reflector and the metal partition is 2 mm.

[0038] The beneficial effects of the present invention are described in detail below in conjunction with simulation tests.

[0039] In order to more intuitively illustrate the beneficial effects of the present invention, the present invention provides three comparative examples; among them, comparative example 1: the butterfly antenna only includes a radiator, and the radiator is composed of a dielectric substrate and a semi-elliptical ring radiating arm arranged on its upper surface, and the structural relationship and size are the same as those in Example 1; comparative example 2: the butterfly antenna only includes a radiator, and the radiator is composed of a dielectric substrate and a semi-elliptical ring radiating arm arranged on its upper surface, a semicircular parasitic patch and a strip metal branch, and the structural relationship and size are the same as those in Example 1; comparative example 3: the butterfly antenna only includes a radiator, and the radiator includes: a dielectric substrate and a semi-elliptical ring radiating arm arranged on its upper surface, a semicircular parasitic patch, a strip metal branch and a loading capacitor, and the structural relationship and size are the same as those in Example 1.

[0040] like Figure 3 The figure shows the S of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in Example 1 and the butterfly antennas in Comparative Examples 1 to 3. 11 Comparison chart: As can be seen from the figure, when there is no loading, the S of the butterfly antenna in comparative example 1 is 11 In the frequency band of 0.6GHz-1.2GHz, it is higher than -10dB. In order to further broaden the working bandwidth of the antenna, a parasitic patch is introduced at the end of the antenna radiation arm. By introducing a new resonance point, the antenna can maintain good matching characteristics in a wider frequency band. 11 There are some improvements in the range of 1.1GHz-3GHz, but unnecessary resonance points are introduced in the range of 0.8GHz-1.0GHz, which affects the working bandwidth of the antenna. In order to further optimize the working bandwidth of the antenna, loading capacitors are introduced to improve the low frequency. After the loading capacitors are introduced, the butterfly antenna in comparative example 3 achieves S 11are all lower than -10dB. At this time, the relative bandwidth of the antenna reaches 185%. However, in the field of microwave imaging, the antenna also needs to have good gain within the working bandwidth. Therefore, it is considered to add a reflector directly below the antenna, and extend four sets of metal partitions based on the reflector to form a semi-closed resonant cavity through the multi-path electromagnetic coupling effect. With the help of cavity mode control and surface current coordinated distribution mechanism, the directional convergence of electromagnetic energy and radiation wavefront shaping are effectively achieved; In summary, in this embodiment, the high-gain ultra-wideband back-cavity butterfly antenna based on electrical loading, S 11 In the range of 0.3GHz-4GHz, the performance is lower than -10dB, the relative bandwidth reaches 185%, and the antenna matching performance is greatly optimized.

[0041] like Figure 4 The figure shows the gain variation curve of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in Example 1 and the butterfly antennas in Comparative Examples 1 and 3 versus frequency. It can be seen from the figure that the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in this embodiment has a maximum gain of approximately 5.22dBi within the impedance bandwidth range. At the same time, the gain in the two frequency bands of 0.7GHz-1.5GHz and 3.5GHz-4GHz is higher than 3.2dBi, and the maximum gain improvement that can be achieved compared with the comparative example is 8.51dBi.

[0042] Finally, the time domain radiation pattern of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in Example 1 and the butterfly antenna in Comparative Example 1 is simulated. The input signal is a zero-order Gaussian signal. The E-plane radiation pattern of this embodiment and Comparative Example 1 is compared. Figure 5 As shown in the figure, it can be seen that the forward radiation of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in this embodiment is better, which is increased by 21.1%, and the backward radiation is also significantly improved. In the fields of point-to-point communication, radar detection or satellite communication, the directional advantages of the high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading in the present invention can significantly improve the performance and efficiency of the system.

[0043] In summary, the present invention provides a high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading, which effectively improves the gain and radiation pattern while ensuring a wide operating band; it can play an important role in ground-penetrating radar systems, greatly enhancing the system's detection capabilities and practicality in various complex environments.

[0044] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading, characterized in that: include: Radiator and back cavity; The radiator includes: a dielectric substrate and a semi-elliptical ring radiating arm provided on its upper surface, a semi-circular parasitic patch, a strip metal branch and a loading capacitor. The radiator adopts an axially symmetrical structure and is rectangular. The two semi-elliptical ring radiating arms are provided back to back and the long axis of the semi-elliptical ring radiating arm coincides with the long side of the radiator. The two semi-circular parasitic patches are respectively provided at the center of the semi-elliptical ring radiating arm and the straight edges of the semi-circular parasitic patch coincide with the long side of the radiator. The strip metal branch is provided along the short axis of the semi-elliptical ring radiating arm and the two ends connect the semi-elliptical ring radiating arm and the semi-circular parasitic patch. At the same time, the semi-circular parasitic patch and the slot at the end of the semi-elliptical ring radiating arm are respectively provided with loading capacitors. The back cavity adopts a semi-closed resonant cavity, the back cavity is connected to the bottom of the radiator, and the radiator is located at the top opening of the back cavity.

2. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The back cavity adopts an inverted quadrangular pyramid structure, which consists of a metal reflector at the bottom and four groups of metal partitions at the side.

3. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The outer contour of the semi-elliptical ring-shaped radiation arm is tangent to the short side of the radiator.

4. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: All load capacitors use the same capacitance value.

5. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The dielectric substrate adopts FR4 dielectric substrate with a size of 265mm×242mm and a thickness of 2mm.

6. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The major axis of the outer contour of the semi-elliptical ring radiating arm is 265 mm and the minor axis is 153 mm. The major axis of the inner contour of the semi-elliptical ring radiating arm is 242 mm and the minor axis is 140 mm. The thickness of the semi-elliptical ring radiating arm is 0.035 mm.

7. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The radius of the semicircular parasitic patch is 10 mm and the thickness is 0.035 mm.

8. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The length of the strip metal branch is 47 mm, the width is 2 mm, and the thickness is 0.035 mm.

9. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The capacitance value of the loading capacitor is 1pF.

10. The high-gain ultra-wideband cavity-backed butterfly antenna based on electrical loading according to claim 1, characterized in that: The height of the back cavity is 35 mm, the size of the bottom of the back cavity is 242 mm×120 mm, the top size matches the dielectric substrate of the radiator, and the thickness of the metal reflector and the metal partition is 2 mm.

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