Anti-interference frequency reconfigurable antenna for low-altitude aircraft

Abstract

The invention relates to an anti-interference frequency reconfigurable antenna for a low-altitude aircraft, which belongs to the technical field of wireless energy transmission and comprises a bottom-layer metal floor, a middle-layer dielectric substrate, an upper-layer metal floor, a biasing circuit and a feed column. The bottom-layer metal floor is arranged on the lower surface of the middle-layer dielectric substrate; the upper-layer metal floor is arranged on the upper surface of the middle-layer dielectric substrate; two pairs of parallel rectangular short grooves and a pair of rectangular long grooves perpendicular to the rectangular short grooves are etched in the upper layer metal floor. A varactor is arranged in the rectangular long groove; the biasing circuit is arranged on the upper surface of the middle-layer dielectric substrate; and the feed column penetrates through the bottom layer metal floor, the middle layer dielectric substrate and the upper layer metal floor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic field and microwave, and relates to an anti-interference frequency reconfigurable antenna for a low-altitude aircraft. BACKGROUND

[0002] With the rapid development of low-altitude aircraft, its communication system faces severe challenges in a complex low-altitude electromagnetic environment, including dense heterogeneous interference, limited spectrum resources and dynamic channel characteristics. Traditional fixed-frequency or wide-band antennas lack the ability to actively avoid interference, and multi-antenna switching systems have problems of volume and mutual coupling.

[0003] Although frequency reconfigurable antennas can dynamically tune frequencies and provide potential for anti-interference, existing designs still have obvious deficiencies when applied to low-altitude aircraft. Firstly, the reconfiguration performance and reliability are often difficult to balance, and the complex tuning structure lacks stability in harsh working conditions. Secondly, there is a lack of deep integration with intelligent anti-interference strategies, and the antenna as an execution unit cannot achieve fast and accurate frequency band switching. Thirdly, the structure often does not fully consider the aerodynamic conformal requirements of the aircraft platform. Therefore, there is an urgent need in the field for an antenna solution that can be deeply integrated with low-altitude aircraft, has reliable reconfiguration capability, intelligent anti-interference mechanism and good platform compatibility, to fundamentally improve its communication resilience and survivability in a complex electromagnetic environment. SUMMARY

[0004] Therefore, the purpose of the present application is to provide an anti-interference frequency reconfigurable antenna for a low-altitude aircraft. The antenna adopts a single-layer structure, obtains sharp frequency selectivity and good out-of-band suppression capability by introducing two radiation zeros, and effectively filters out out-of-band interference. At the same time, the antenna has good operating bandwidth to ensure communication quality. The innovation lies in that only one set of control voltage is needed to realize fast reconfiguration of the operating frequency band, greatly simplifying the control system and improving the agility and reliability of frequency switching in a complex electromagnetic environment, solving the problems of complex control, slow response and insufficient stability in the prior art. Through analysis, design and optimization, a simple single-layer antenna structure is obtained, which is easy to process and manufacture and has a simple control method.

[0005] To achieve the above purpose, the present application provides the following technical solutions: The application discloses an anti-interference frequency reconfigurable antenna for low-altitude aircraft, which comprises a bottom metal floor, a middle dielectric substrate, an upper metal floor, a bias circuit and a feed column; the bottom metal floor is arranged on the lower surface of the middle dielectric substrate; the upper metal floor is arranged on the upper surface of the middle dielectric substrate; two pairs of parallel rectangular short grooves and one pair of rectangular long grooves perpendicular to the rectangular short grooves are etched on the upper metal floor; the rectangular long grooves are provided with varactor tubes; the bias circuit is arranged on the upper surface of the middle dielectric substrate; and the feed column penetrates through the bottom metal floor, the middle dielectric substrate and the upper metal floor.

[0006] Further, the one pair of rectangular long grooves are etched on two sides of the upper metal floor respectively; and each rectangular long groove is provided with three varactor tubes.

[0007] Further, the bias circuit comprises six groups of resistors, inductors and metal columns; in each group, the inductor is connected with the resistor, the resistor is connected with the varactor tube, and the metal column penetrates through the bottom metal floor and the middle dielectric substrate and is connected with the inductor.

[0008] Further, the rectangular short groove is composed of a narrow rectangular groove and a wide rectangular groove; the wide rectangular groove is etched inside the upper metal floor, and the narrow rectangular groove penetrates through the rectangular long groove and is in communication with the edge of the upper metal floor.

[0009] Further, one pair of rectangular short grooves vertically penetrates through one rectangular long groove, and the other pair of rectangular short grooves vertically penetrates through the other rectangular long groove.

[0010] Further, the middle dielectric substrate is square-shaped; and the upper metal floor is square-shaped.

[0011] Further, the middle dielectric substrate has a relative dielectric constant of 2.2, a loss tangent angle of 0.001 and a side length of 41 mm.

[0012] Further, the upper metal floor has a side length of 26.5 mm; one pair of rectangular short grooves has a spacing of 9 mm, and the other pair of rectangular short grooves has a spacing of 13 mm; the narrow rectangular groove has a width of 0.2 mm and a length of 5 mm; the wide rectangular groove has a width of 1.65 mm and a length of 6.5 mm; and the rectangular long groove has a width of 0.5 mm and a length of 26.5 mm.

[0013] Further, the varactor tube has a capacitance control voltage of 0-17 V and a capacitance of 0.15-1.3 pF; the resistor has a resistance of 1 MΩ; and the inductor has an inductance of 30 nH.

[0014] The application has the following beneficial effects: (1) By adjusting the feeding position, the TM01 mode of the upper metal floor is excited, then two pairs of rectangular short slots are etched on both sides of the upper metal floor, so that the resonance frequencies of the high-order resonance modes TM20 and TM21 mode of the upper metal floor are moved to low frequencies, and a good working frequency band is formed with the original TM01 mode; at the same time, due to the introduction of the rectangular short slots, the rectangular short slots generate two sides of equal amplitude and opposite surface currents at high and low frequencies, realize far field radiation cancellation, form two radiation zeros, and control the two radiation zeros by changing the length of the rectangular short slot; on this basis, a pair of rectangular long slots are etched in the direction perpendicular to the rectangular short slot, and the entire upper metal floor is divided into two parts; the varactor tube is arranged between the two parts to connect the two parts into a whole; and six bias circuits are arranged on the outside, a set of DC bias voltage is used to control the capacitance of the six varactor tubes, so that the working frequency band and the radiation zero change synchronously without affecting the radiation performance and anti-interference ability. The two radiation zeros effectively suppress the interference signals outside the passband, and improve the anti-interference ability and communication quality of the system. The introduced rectangular short slot expands the bandwidth of the antenna, and in addition, it can be continuously tuned within the working frequency band, and the agility and reliability of frequency switching in a complex electromagnetic environment are improved.

[0015] (2) Select three states (0.15pF / 17V, 0.55pF / 5.5V and 1.3pF / 0V) as the working state of the antenna, the center frequencies are 3.69, 3.85 and 4.05GHz respectively, the tuning bandwidth is 18.3% (3.53-4.24GHz), and the peak gain in the working frequency band can be 6.9, 6.1 and 6.2dBi respectively.

[0016] (3) While realizing high performance, the stable side radiation characteristics of the antenna are also ensured, the cross-polarization levels of E-plane and H-plane at 3.69, 3.85 and 4.05GHz are greater than 35dB, and the profile height of the antenna is 0.03λ0. The antenna has superior performance, small size, simple structure, simple control mode, strong anti-interference and other characteristics, and has certain use value.

[0017] Other advantages, objects, and features of the present application will be in part apparent and in part pointed out hereinafter in the specification, and in part will be observed by persons skilled in the art upon examination of the following specification. The objects and other advantages of the present application can be realized and attained by the below description. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred detailed description of the present application will be combined with the drawings to make the objects, technical solutions and advantages of the present application clearer, wherein: Figure 1The anti-interference frequency reconfigurable antenna structure diagram for low-altitude aircraft according to the present application; Figure 2 The anti-interference frequency reconfigurable antenna size diagram for low-altitude aircraft according to the present application; Figure 3 The anti-interference frequency reconfigurable antenna parameter curve in three working states for low-altitude aircraft according to the present application, wherein (a) is the S 11 parameter, and (b) is the achievable gain; Figure 4 The anti-interference frequency reconfigurable antenna directivity diagram for low-altitude aircraft according to the present application, wherein (a) is the E-plane normalized directivity diagram of the antenna at the center frequency (3.69, 3.85 and 4.05 GHz) in three working states, and (b) is the H-plane normalized directivity diagram of the antenna at the center frequency (3.69, 3.85 and 4.05 GHz) in three working states; The figure mark: upper metal floor 1, bottom metal floor 2, middle layer dielectric substrate 3, feed column 4, rectangular short slot 5, rectangular long slot 6, inductance 7, resistance 8, varactor 9, metal column 10. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below with specific reference on the attached drawings. It is to be noted that other advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in the present specification. The present application can also be implemented or applied in other different embodiments, and the details in the present specification can be modified or changed in various ways based on different views and applications without departing from the spirit of the present application. It is to be noted that the figures provided in the following embodiments only schematically illustrate the basic concept of the present application, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0020] It is to be noted that the figures are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical figure, and cannot be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components in the figures can be omitted, enlarged or reduced, and do not represent the size of the actual product; it can be understood by those skilled in the art that some well-known structures and their descriptions in the figures can be omitted.

[0021] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", etc. are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0022] Embodiment 1 Referring to the accompanying Figure 1 The present application provides an anti-interference frequency reconfigurable antenna for low-altitude aircraft, which comprises an upper metal floor 1, a lower metal floor 2, a middle layer dielectric substrate 3, a feed column 4, a rectangular short slot 5, a rectangular long slot 6, an inductor 7, a resistor 8, a varactor 9, and a metal column 10. The upper surface of the middle layer dielectric substrate 3 is provided with the upper metal floor 1, and the lower surface is provided with the lower metal floor 2. Two pairs of rectangular short slots 5 composed of narrow rectangular slots and wide rectangular slots of different lengths are etched on the upper metal floor 1, rectangular long slots 6 are etched in a direction perpendicular to the rectangular short slots, and six identical varactors 9 are arranged in the rectangular long slots 6. The inductor 7 and the resistor 8 are arranged on the periphery of the upper metal floor 1, and the metal column 10 penetrates the lower metal floor 2, the middle layer dielectric substrate 3, and the inductor 7, the resistor 8, and the varactor 9 to form a complete bias circuit. The feed column 4 penetrates the lower metal floor 2, the middle layer dielectric substrate 3, and the upper metal floor 1.

[0023] Embodiment 2 In this embodiment, the lower metal floor and the dielectric substrate are the same size, and the side length is 41 mm. The shortest distance from the position of the feed column to the edge of the upper metal floor is 8.5 mm. Both pairs of rectangular short slots are composed of a narrow rectangular slot with a width of 0.2 mm and a length of 5 mm, and a wide rectangular slot with a width of 1.65 mm and a length of 6.5 mm. The narrow rectangular slot in the left pair of rectangular short slots has a spacing of 9 mm, and the wide rectangular slot in the right pair of rectangular short slots has a spacing of 13 mm. The rectangular long slot has a width of 26.5 mm, a length of 0.5 mm, and a spacing of 21.5 mm.

[0024] The side length of the upper metal floor is 26.5 mm, and the copper thickness of the upper metal floor and the lower metal floor is 0.017 mm, and the thickness of the dielectric substrate is 2.5 mm.

[0025] The material of the dielectric substrate is F4B, the relative dielectric constant is 2.2, and the loss tangent is 0.001.

[0026] The high-frequency electromagnetic simulation software HFSS2022 is used for simulating the differential feed filter antenna based on the substrate integrated waveguide, and the parameters after simulation optimization are shown in Table 1 (unit: mm).

[0027] Table 1

[0028] Referring to the accompanying Figure 2 , L 1 and W 1 is the length of the upper metal floor, L 2 is the distance between the rectangular long slots, L 3 and L 4 are the lengths of the narrow rectangular slot and the wide rectangular slot respectively constituting the rectangular short slot, L 5 is the side length of the middle layer dielectric substrate and the lower metal floor, and W2 is the length of the rectangular long slot, W 3 and W 4 are the widths of the narrow rectangular slot and the wide rectangular slot respectively constituting the rectangular short slot, G 1 is the distance between the narrow rectangular slots in the left pair of rectangular short slots, G 2 is the distance between the wide rectangular slots in the right pair of rectangular short slots, H is the thickness of the middle layer dielectric substrate, D is the distance between the feeding column and the edge of the upper metal floor.

[0029] Figure 3 S 11 The parameters and the curve of the achievable gain varying with frequency are obtained by simulation. As shown in Figs. Figure 3 (a) and (b). The measured-10dB fractional impedance bandwidth is 18.3% (from 3.53GHz to 4.24GHz), and there are three obvious in-band resonances. Referring to the measured achievable gain curve, it shows good filtering capability, and there are two controllable radiation zeros in the stop band. The peak achievable gains in three states (0.15pF / 17V, 0.55pF / 5.5V and 1.3pF / 0V) are 6.9, 6.1 and 6.2dBi respectively, which are slightly lower than the simulation values. Figure 4 Figs.

[0030] Finally, it is to be explained that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions, and all should be covered in the scope of the claims of the present application.

Claims

1. An anti-interference frequency reconfigurable antenna for low-altitude aircraft, characterized in that: The device includes a bottom metal ground plane, a middle dielectric substrate, an upper metal ground plane, a bias circuit, and a power supply post. The bottom metal ground plane is disposed on the lower surface of the middle dielectric substrate. The upper metal ground plane is disposed on the upper surface of the middle dielectric substrate. Two pairs of parallel rectangular short slots and one pair of rectangular long slots perpendicular to the rectangular short slots are etched on the upper metal ground plane. A varactor tube is disposed in the rectangular long slot. The bias circuit is disposed on the upper surface of the middle dielectric substrate. The power supply post penetrates the bottom metal ground plane, the middle dielectric substrate, and the upper metal ground plane.

2. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The pair of rectangular slots are respectively etched on both sides of the upper metal floor; each rectangular slot contains 3 variable capacity tubes.

3. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The bias circuit includes six groups of resistors, inductors, and metal pillars; in each group, the inductor is connected to the resistor, the resistor is connected to the varactor, and the metal pillar penetrates the bottom metal ground plane and the middle dielectric substrate and is connected to the inductor.

4. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The rectangular short slot consists of a narrow rectangular slot and a wide rectangular slot, wherein the wide rectangular slot is etched inside the upper metal floor, and the narrow rectangular slot passes through the rectangular long slot and is connected to the edge of the upper metal floor.

5. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: One pair of rectangular short slots passes perpendicularly through a rectangular long slot, and another pair of rectangular short slots passes perpendicularly through another rectangular long slot.

6. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The middle dielectric substrate is square; the upper metal floor is square.

7. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The intermediate dielectric substrate has a relative permittivity of 2.2, a loss tangent of 0.001, and a side length of 41 mm.

8. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The upper metal floor has a side length of 26.5mm; one pair of rectangular short grooves has a spacing of 9mm, and the other pair of rectangular short grooves has a spacing of 13mm; the narrow rectangular groove has a width of 0.2mm and a length of 5mm; the wide rectangular groove has a width of 1.65mm and a length of 6.5mm; and the long rectangular groove has a width of 0.5mm and a length of 26.5mm.

9. The anti-interference frequency reconfigurable antenna for low-altitude aircraft according to claim 1, characterized in that: The variable capacitor tube has a capacitance control voltage of 0-17V and a capacitance value of 0.15-1.3pF; the resistor has a resistance value of 1MΩ; and the inductor has an inductance value of 30nH.

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