A tree antenna and its adaptive frequency sweeping method

Abstract

This invention discloses a tree antenna and its adaptive frequency sweeping method, comprising a tree-mounted body and a curved conformal Vivaldi radiator. One or more conformal Vivaldi radiators are attached to any position on the surface of the tree-mounted body and are in contact with it. The surface of the conformal Vivaldi radiators is covered with a shell of the same color as the tree-mounted body. Based on the principle of dielectric rod antennas, this tree antenna utilizes trees to enhance electromagnetic field radiation and gain. Combined with adaptive frequency sweeping technology, it adaptively adjusts the transmission frequency band of electromagnetic signals for different trees, achieving efficient electromagnetic signal transmission and reception. The structure is simple, economical, and environmentally friendly, and has application value in agriculture, forestry, and other fields.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, and more specifically to a tree antenna and its adaptive frequency sweeping method. Background Technology

[0002] Electronic communication and monitoring in jungles are often easily blocked by trees, causing them to malfunction. Using trees directly as antennas for signal transmission and reception can avoid this obstruction problem.

[0003] Current research on tree antennas often requires damaging the tree, such as inserting conductors or altering its growth conditions. Furthermore, the uncertainties surrounding plant size and material make them difficult to use for wireless communication requiring precise frequencies. Therefore, the electromagnetic radiation characteristics of plants have not yet been effectively utilized.

[0004] Patent application CN107248536A discloses a plant antenna, including a carrier plant with two spaced-apart cavities filled with liquid metal that remains liquid at room temperature. It also includes connecting wires; the connecting wires are radio frequency (RF) wires, each with two connectors at one end, which are respectively connected to the liquid metal in the two cavities; the connecting wires are also conductors, with both ends connected to the liquid metal in the two cavities, and a balancer is provided on the conductors; However, this invention has several drawbacks. First, the liquid metal used is expensive and unsuitable for large-scale application. Second, injecting liquid metal into plants is detrimental to ecological protection and may lead to water and soil pollution. Third, if the liquid metal is absorbed by the plant and gradually accumulates in the food chain, it may ultimately affect the health of animals and humans.

[0005] Patent application CN85103804A discloses an antenna device for receiving or transmitting electromagnetic waves. Its key feature is that a plant is planted in the center of a conductive layer container, and a magnetic ring induction coil is installed under the plant's crown. Radio frequency energy from the plant is obtained using the conductive layer and the magnetic ring induction coil. This antenna design requires an arc-shaped metal layer to be installed at the plant's roots, making it suitable only for small potted plants and unsuitable for large trees in forests. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a tree antenna based on a conformal Vivaldi radiator.

[0007] The technical solution adopted in this invention is as follows:

[0008] The present invention includes a tree loading body and a curved conformal Vivaldi radiator, wherein one or more conformal Vivaldi radiators are attached to any position on the surface of the tree loading body and are in contact with the tree loading body.

[0009] It also includes a housing, the surface of which is covered with a housing of the same color as the tree loading body.

[0010] The operating mode of the tree antenna is determined by the tree loading body, and the relationship between the operating mode of the tree antenna and the tree loading body is set according to the following formula:

[0011]

[0012] Where ζ and ξ are real numbers, representing the propagation constants β and β, respectively. z , β is the product of the diameter b of the tree loading body. z and β d All of these are propagation constants within the tree loading body. β represents the propagation constant outside the tree loading body. ρ and β z They represent β respectively d In the tangential ρ component and longitudinal z component of the tree loading body, ε d and ε c μ represents the relative permittivity inside and outside the tree loading body, respectively. d and μ c The values ​​χ represent the relative permeability inside and outside the tree loading body, respectively, and the eigenvalue χ represents the electromagnetic wave transmission mode of the tree loading body.

[0013] When the tree antenna transmits only the main mode, the diameter of the tree loading body is set according to the following formula:

[0014]

[0015] Where b represents the diameter of the tree loading body, χ 01 λ represents the eigenvalue of the dominant mode, λ0 is the operating wavelength in the dominant mode state, and ε d and ε c μ represents the relative permittivity inside and outside the tree loading body, respectively. d and μ c These represent the relative magnetic permeability inside and outside the tree loading body, respectively.

[0016] The conformal Vivaldi radiator includes a dielectric substrate, a metal ground plane, a slot, a circular resonant cavity, and a metal microstrip line. One side of the dielectric substrate is attached to the tree loading body and has the metal microstrip line. The other side has a metal ground plane attached to it. The metal ground plane has a slot and a circular hole that serves as the circular resonant cavity. The slot is arranged along the radiation direction and has a funnel-shaped opening. The circular hole is located at the narrow end of the funnel-shaped opening.

[0017] The groove lines on both sides of the slot are arranged symmetrically around the central axis of symmetry. The groove lines on each side are mainly composed of parallel groove lines and gradient groove lines. The parallel groove line is a line segment parallel to the axis of symmetry, and the gradient groove line is a curve. One end of the parallel groove line is connected to the gradient groove line, and the other end of the parallel groove line extends to the circular resonant cavity.

[0018] The metal microstrip line is mainly composed of vertical microstrip lines, horizontal microstrip lines and fan-shaped microstrip lines. One end of the vertical microstrip line extends away from the radiation direction to the edge of the dielectric substrate, and the other end of the vertical microstrip line is connected to one end of the horizontal microstrip line. The horizontal microstrip lines are arranged perpendicular to the radiation direction, and the end of the horizontal microstrip line away from the vertical microstrip line is connected to the fan-shaped microstrip line.

[0019] The dielectric substrate is made of PET dielectric material.

[0020] An adaptive frequency sweeping method for tree antennas includes the following steps:

[0021] S1. Set a signal with a preset frequency range as the excitation signal, perform ultra-wideband frequency sweep on the excitation signal, and divide the excitation signal into multiple excitation signals with different frequency bands.

[0022] S2. Input the excitation signals of different frequency bands into the metal microstrip line of the tree antenna in sequence. The excitation signal reflected back to the transmission direction is used as the reflected signal. The reflection coefficient of the tree antenna under different frequency bands is obtained by processing the excitation signal and the reflected signal. The frequency band with the lowest reflection coefficient is extracted as the optimal frequency band.

[0023] S3. Set a fixed time, during which the tree antenna transmits and receives signals using the optimal frequency band;

[0024] S4. After a fixed time has elapsed, return to S1 and repeat the cycle.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) This invention loads a conformal Vivaldi radiator onto a tree. Based on the dielectric rod theory, the tree guides electromagnetic radiation, and the changes in the tree's structure intercept the propagating surface waves, causing power radiation to be generated in the discontinuous parts of the tree's structure. This achieves the function of a tree antenna and realizes the effects of radiation enhancement and far-field gain adjustment. The tree antenna proposed in this invention has good concealment and ecological adaptability, and is simple in structure, economical and environmentally friendly, making it valuable for applications in agriculture, forestry and other fields.

[0027] (2) The tree antenna proposed in this invention can achieve omnidirectional electromagnetic radiation above the ground. By forming a terminal network through multiple tree antennas, it helps to cover dense electromagnetic fields in complex jungle environments, thereby realizing electromagnetic dynamic monitoring and data communication between terminals.

[0028] (3) This invention proposes an adaptive frequency sweeping technology suitable for tree antennas, namely, an electromagnetic signal transceiver architecture with adaptive frequency sweeping. By utilizing the reflection characteristics of radio frequency signals and the transmission characteristics of electromagnetic signals between trees, the problem of impedance mismatch and uncertain operating frequency is solved, avoiding the problem of uncertain operating frequency caused by differences in size and material between plants. At the same time, it can work effectively in different weather conditions.

[0029] This invention also proposes an adaptive frequency sweeping technique suitable for tree antennas to solve the problems of impedance mismatch and uncertain operating frequency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a tree antenna.

[0031] Figure 2 This refers to the single conformal Vivaldi radiator structure in Example 1;

[0032] Figure 2 (a) is a front view of a single conformal Vivaldi radiator;

[0033] Figure 2 (b) is a schematic diagram of the metal microstrip line of a single conformal Vivaldi radiator;

[0034] Figure 3 Schematic diagram of a tree-loaded antenna based on a conformal Vivaldi radiator;

[0035] Figure 3 (a) A theoretical derivation model for surface waves using a conventional uniform continuous dielectric rod;

[0036] Figure 3 (b) The trunk structure of the tree loading body is simulated using a gradient medium rod;

[0037] Figure 4 This is a planar unfolded schematic diagram of a single conformal Vivaldi radiator in Example 1;

[0038] Figure 4 (a) shows the metal ground plane and slot lines of the Vivaldi radiator;

[0039] Figure 4 (b) is the metal microstrip line of the Vivaldi radiator;

[0040] Figure 5 The reflection coefficient S obtained by attaching a tree-loaded body to a single conformal Vivaldi radiator in Example 1 11 Simulation result diagram;

[0041] Figure 6 The image shows the simulation results of the far-field gain obtained by loading a tree onto a single conformal Vivaldi radiator in Example 1.

[0042] Figure 7 The ring-shaped Vivaldi radiator in Example 2 is composed of four conformal Vivaldi radiators.

[0043] Figure 8 The figures show the simulation results of the far-field radiation gain of the ring Vivaldi radiator and the ring Vivaldi radiator after loading trees in Example 2.

[0044] Figure 8 (a) Far-field radiation gain using only the ring Vivaldi radiator;

[0045] Figure 8 (b) Far-field radiation gain of the ring Vivaldi radiator after attaching a tree loading body;

[0046] Figure 9 This is a flowchart of the adaptive frequency sweeping technology applicable to the tree antenna operating mode in this invention.

[0047] Among them, 1. Tree loading body; 2. Conformal Vivaldi radiator; 3. Dielectric substrate; 4. Metal ground plane; 5. Slot; 6. Circular resonant cavity; 7. Metal microstrip line. Detailed Implementation

[0048] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0049] Tree antennas, for example Figure 1 As shown, it includes a tree loading body 1 and a curved conformal Vivaldi radiator 2, one or more conformal Vivaldi radiators 2 are attached to any position on the surface of the tree loading body 1 and are in contact with the tree loading body 1.

[0050] The tree loading body is the trunk of the tree, that is, the part of the trunk above the ground and below the branches.

[0051] The curvature of the conformal Vivaldi radiator 2 is primarily determined by the curvature of the tree loading body 1's bark. The conformal Vivaldi radiator 2 maintains the same arc shape as the trunk bark of the tree loading body 1 and is integrated with the trunk; that is, the conformal Vivaldi radiator 2 has the same radius of curvature as the trunk of the tree loading body 1. The conformal Vivaldi radiator 2 is attached to the above-ground portion of the trunk bark of the tree loading body 1 and secured with cable ties around the trunk.

[0052] The tree antenna also includes a shell. The surface of the conformal Vivaldi radiator 2 is covered with a shell of the same color as the tree loading body (1), which has good concealment and ecological adaptability.

[0053] A tree-loaded structure can be viewed as a combination of many dielectric materials, and the radiation of a tree antenna can be explained using the theory of dielectric rod antennas. Dielectric rod antennas utilize structural variations to truncate propagating surface waves, causing power radiation at the discontinuities in the dielectric rod; therefore, they are also called surface wave antennas. A dielectric rod antenna is a special case of a dielectric rod waveguide; a dielectric rod waveguide is a low-loss waveguide made of one or more layers of dielectric material. When the structure of a dielectric rod waveguide has discontinuities (i.e., bends, steps, and tapers exist), it will produce radiation. Tree-loaded structures, due to their growth, naturally possess structural discontinuities, making them suitable for surface wave propagation and serving as antennas for electromagnetic radiation.

[0054] The conformal Vivaldi radiator 2 generates electromagnetic radiation after receiving an input excitation signal, which excites the formation of an HEM field within the tree loading body 1 and conducts radiation along the trunk of the tree loading body 1.

[0055] like Figure 3 As shown, Figure 3 (a) is a theoretical derivation model for surface waves using a conventional homogeneous continuous dielectric rod. Figure 3 (b) To simulate the trunk structure of a tree-loaded structure using a gradient dielectric rod, taking a uniform continuous dielectric rod as an example, its waveguide has three layers: a core (μ i ,ε i ), outer dielectric (μ d ,ε d ) and outer cladding (μc ,ε c ).

[0056] When the tree-loaded body is considered as a dielectric waveguide, according to Maxwell's equations and the boundary conditions of the dielectric waveguide, the HEM field expression in tree-loaded body 1 can be expressed as follows:

[0057]

[0058] in, and Let ε represent the propagation constants inside and outside the dielectric waveguide, respectively. d and ε c Let μ represent the relative permittivity inside and outside the dielectric waveguide, respectively. d and μ c Let represent the relative permeability inside and outside the dielectric waveguide, respectively; m represent the mode order; ω represent the frequency; and b represent the diameter of the dielectric rod. m and K m These are Bessel functions of order m, belonging to the first and second classes.

[0059] To evaluate the dielectric rod in an air environment, μ was used c =μ0 and ε c =ε0, and the relationship between the propagation constants is obtained based on the boundary conditions:

[0060]

[0061] ζ=β z b

[0062]

[0063] When the tree-loaded object is in an air environment, its distribution characteristics are obtained by solving the HEM field expression based on the boundary conditions and propagation constant relationship of the tree-loaded object. That is, the electrical radiation characteristics and operating mode of the tree antenna are determined by the tree-loaded object 1. The relationship between the electrical radiation characteristics and operating mode of the tree antenna and the tree-loaded object 1 is set according to the following formula:

[0064]

[0065] Where ζ and ξ are real numbers, representing the propagation constants β and β, respectively. z , The product of the diameter b of the tree loading body and the product of the diameter b are used to solve for the first kind of m-order Bessel function J. m The second kind of m-order Bessel function K m ,β z and β d All of these are propagation constants within the tree loading body. β represents the propagation constant outside the tree loading body. ρ and β z They represent β respectively d In the tangential ρ component and longitudinal z component of the tree loading body, ε d and ε c μ represents the relative permittivity inside and outside the tree-loaded body (1), respectively. d and μ c The relative permeability inside and outside the tree-loaded body (1), respectively, and the eigenvalues ​​χ, are given. This indicates the electromagnetic wave transmission mode of the tree-loaded body.

[0066] Operating modes refer to the dominant mode and m-th order higher-order modes in the electromagnetic wave transmission modes of the tree-loaded structure. The dominant mode has lower transmission loss; different modes correspond to different operating frequencies. Transmission modes refer to the shape and characteristics of electromagnetic waves propagating in a waveguide. They define the electric and magnetic field distributions as the signal propagates inside the tree-loaded structure. Different modes are often represented by different designations, such as TE. 01 Denotes the fundamental mode, TE mn (m>1, n>1) represents higher-order modes; the transmission mode is affected by the size and material of the tree loading body (specifically, the dielectric constant and magnetic permeability); different transmission modes correspond to different frequencies, and selecting a given operating frequency indicates that a specific mode is used to transmit electromagnetic waves.

[0067] The above formula only has practical significance when ξ remains a real number. The field outside the tree loading body will decay exponentially in the transverse direction, which is a necessary condition for the transmission of surface waves along the tree loading body.

[0068] For each value of m, there exists a finite number of eigenvalues ​​χ. mn This causes it to generate surface waves that propagate along the dielectric rod. For example, HEM 11 (HE 11 The eigenvalues ​​of the pattern are χ. 10 =0 represents the master mode. To maintain low-loss master mode transmission, χ 2 +ξ 2 It should be less than the square of the eigenvalues ​​of the second mode:

[0069] χ 2 +ξ 2 <χ 01 2

[0070] Therefore, the maximum diameter of the cylindrical dielectric rod under the condition of main mode transmission can be given, that is, when the tree antenna only transmits the main mode, the diameter of the tree loading body 1 is set according to the following formula:

[0071]

[0072] Where b represents the diameter of tree loading body 1, χ 01 λ0 represents the eigenvalue of the dominant mode, and λ0 is the operating wavelength in the dominant mode state.

[0073] The main mode is the mode with the lowest operating frequency.

[0074] These equations demonstrate that the diameter of the dielectric rod affects the electromagnetic radiation characteristics and operating mode of the dielectric rod antenna.

[0075] The conformal Vivaldi radiator 2 includes a dielectric substrate 3, a metal ground plane 4, a slot 5, a circular resonant cavity 6, and a metal microstrip line 7. One side of the dielectric substrate 3 is attached to the tree loading body 1 and the metal microstrip line 7 is disposed on this surface. The other side is attached to the metal ground plane 4. The metal ground plane 4 is provided with a slot 5 and a circular hole serving as the circular resonant cavity 6. The slot 5 is arranged along the radiation direction and is configured as a funnel-shaped opening. The circular hole is opened at the end of the narrow end of the funnel-shaped opening and is connected to the circular hole.

[0076] The groove lines on both sides of the slot 5 are arranged symmetrically around the central axis of symmetry. The groove lines on each side are mainly composed of parallel groove lines and gradient groove lines. The parallel groove line is a line segment parallel to the axis of symmetry, and the gradient groove line is a curve. One end of the parallel groove line is connected to the gradient groove line. The gradient groove line gradually bends and extends to one end of the metal ground plate 4 in a direction away from the parallel groove line and away from the axis of symmetry. The other end of the parallel groove line extends to the circular resonant cavity 6.

[0077] The axis of symmetry is in the same direction as the radiation direction; the tapered slot line is responsible for guiding the electromagnetic waves radiated by the antenna, the parallel slot line is coupled to the metal microstrip line 7 and transmits electromagnetic waves, and the circular resonant cavity 6 is used to achieve impedance matching of the metal microstrip line 7.

[0078] The metal microstrip line 7 is mainly composed of vertical microstrip lines, horizontal microstrip lines and fan-shaped microstrip lines. The vertical microstrip lines are arranged vertically and one end extends away from the radiation direction to the edge of the dielectric substrate 3. The other end of the vertical microstrip line is connected to one end of the horizontal microstrip line. The horizontal microstrip lines are arranged perpendicular to the radiation direction and pointing towards the circular resonant cavity 6. The end of the horizontal microstrip line away from the vertical microstrip line is connected to the fan-shaped microstrip line, which is arranged near the circular resonant cavity 6.

[0079] The end of the metal microstrip line 7 has a fan-shaped structure, which is mainly used to achieve impedance matching; at the same time, the metal microstrip line 7 is coupled to the slot line 5 through the dielectric substrate 3.

[0080] The dielectric substrate 3 is made of flexible PET dielectric material with a dielectric constant of 2.9.

[0081] Tree-mounted antennas at different growth stages have varying diameters and dielectric parameters, making it difficult to determine their operating modes and frequencies. To address this issue, this invention proposes an adaptive frequency sweeping technique suitable for tree antennas. The key to this technique is its ability to automatically analyze the spectrum of interfering signals and, under complex conditions, automatically select the frequency band with the strongest radiation capability for transmission.

[0082] By leveraging the reflection characteristics of radio frequency signals and the transmission characteristics of electromagnetic signals between tree antennas, an ultra-wideband frequency sweep method is employed to obtain the optimal operating frequency band for tree antennas in the short term. Furthermore, the transmission frequency band of electromagnetic signals is adaptively adjusted for different tree antennas, achieving efficient electromagnetic signal transmission and reception. This adaptive frequency sweep method overcomes the problems of tree antennas being susceptible to the influence of tree growth conditions and weather changes, leading to impedance mismatch and uncertain operating frequencies.

[0083] The method includes the following steps:

[0084] S1. Set a signal with a certain frequency range as the excitation signal, perform ultra-wideband frequency sweep on the excitation signal, and divide the excitation signal into multiple excitation signals with different narrowband frequency bands;

[0085] S2. The excitation signals of different narrowband frequency bands are sequentially input into the metal microstrip line 7 of the tree antenna. Part of the excitation signal is radiated by the antenna, and the other part is reflected back to the transmission direction as the excitation signal because it is not effectively radiated due to the impedance characteristics of the antenna. The radiation efficiency and reflection coefficient of the tree antenna under different narrowband frequency bands are obtained by processing the excitation signal and the reflection signal. The narrowband frequency band with the highest radiation efficiency and the lowest reflection coefficient is extracted as the optimal frequency band.

[0086] S3. Set a fixed time, during which the tree antenna transmits and receives signals using the optimal frequency band;

[0087] S4. After a fixed time has elapsed, return to S1 and repeat the cycle.

[0088] Radiation efficiency represents an antenna's ability to effectively convert input power into electromagnetic waves for outward radiation; it is the ratio of radiated power to input power. Reflection coefficient represents the impedance matching of the signal at the antenna input; it measures how much of the input power is reflected back to the signal source; it is the ratio of reflected power to input power.

[0089] The specific embodiments 1 and 2 of the present invention are as follows:

[0090] Example 1

[0091] like Figure 4As shown, the length of the metal ground plane of a single conformal Vivaldi radiator 2 is H, and the width is W; the width of the rectangular portion of the slot 5 is GW, that is, the distance between the two parallel slot lines is GW, and the gradient slot line portion changes in the form of a natural exponential: 0.5GW × e rx r is the gradual rate of change, and x is the direction of extension;

[0092] The radius of the circular resonant cavity 6 is R1; the linewidth of the metal microstrip line 7 is MW, the line length is L1 and L2, and the radius of the fan-shaped end is R2;

[0093] A single conformal Vivaldi radiator 2, bent at 180° to form an arch shape, is positioned 15 mm apart and covers the surface of the branches of the tree loading body 1 for electromagnetic simulation. The tree loading body 1 is a traditional tree structure, with the dielectric constant (ε = 60, μ = 1) and conductivity (10 S / m) of salt water as used. The specific dimensions of a single conformal Vivaldi radiator 2 are shown in the table below:

[0094]

[0095] The simulation results are plotted as a spectrum curve. Analysis of the reflection coefficient S. 11 Simulation results, such as Figure 5 As shown, a single conformal Vivaldi radiator 2 in S after loading trees 11 The reflection coefficient is significantly reduced, with values ​​below -10dB in the frequency band below 2000MHz. However, the addition of trees produces a more pronounced resonance (valley). The far-field gain simulation results are presented as follows: Figure 6 As shown, in the 1500-2000MHz frequency band, compared to the unloaded case, the far-field gain of a single conformal Vivaldi radiator 2 is significantly enhanced after loading trees, and the reflection coefficient S... 11 There is a significant improvement; in addition, the gain is significantly enhanced at multiple resonant frequencies (peaks) after the trees are loaded.

[0096] In this embodiment, after the conformal Vivaldi radiator 2 is loaded with trees, the electromagnetic radiation is guided by the trees, thereby producing a radiation enhancement effect, especially for radiators with small electrical dimensions.

[0097] Example 2

[0098] like Figure 7As shown, the conformal Vivaldi radiator 2 is curved at 90° to form an arch shape. Four conformal Vivaldi radiators 2 are interconnected to form a ring-shaped Vivaldi radiator, which surrounds the trunk of the tree. The ring-shaped Vivaldi radiator surrounds the trunk of the tree loading body 1, while simultaneously stimulating the four conformal Vivaldi radiators to form a wide electromagnetic radiation range. The simultaneous action of the four conformal Vivaldi radiators sacrifices maximum gain to obtain omnidirectional radiation characteristics.

[0099] Electromagnetic simulations were performed using the structural parameters described in Example 1, simultaneously exciting four conformal Vivaldi radiators 2. The far-field gain patterns were compared with and without the loading of trees. The simulation results are as follows: Figure 8 As shown. Figure 8 (a) is the far-field radiation gain of the ring Vivaldi radiator (operating frequency of 752 MHz), where Phi = 0° and Phi = 90° represent the radiation patterns of two different vertical cross sections; Figure 8 (b) is the far-field radiation gain of the ring Vivaldi radiator after loading trees (800MHz operating frequency), where Phi = 48°, Phi = 78°, and Phi = 189° represent the radiation patterns of three different vertical sections.

[0100] After the trees were loaded, the maximum gain of the ring-shaped Vivaldi radiator dropped from 20 dBi to 6.05 dBi. This was mainly because the trees also guided the electromagnetic radiation in the horizontal direction, and the simultaneous action of the four radiators formed omnidirectional radiation in the vertical positive direction, which looked like a cone-shaped three-dimensional far-field gain map. After the energy was omnidirectionally radiated, the maximum gain inevitably decreased.

[0101] Furthermore, the omnidirectional radiation gain of multiple tree antennas helps to create a dense electromagnetic field in jungle areas, which is effective for communication in complex jungle environments. Additionally, each tree antenna can function as a transceiver terminal, and multiple terminals can form a sensor network, thereby enabling dynamic electromagnetic monitoring in jungle environments.

[0102] The above are merely embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A tree antenna, characterized in that: Includes a tree loading body (1) and a curved conformal Vivaldi radiator (2), one or more conformal Vivaldi radiators (2) are attached to any position on the surface of the tree loading body (1) and are in contact with the tree loading body (1); The operating mode of the tree antenna is determined by the tree loading body (1), and the relationship between the operating mode of the tree antenna and the tree loading body (1) is set according to the following formula: Where ζ and ξ are real numbers, representing the propagation constants β and β, respectively. z , β is the product of the diameter b of the tree loading body. z and β d All of these are propagation constants within the tree loading body. β represents the propagation constant outside the tree loading body. ρ and β z They represent β respectively d In the tangential ρ component and longitudinal z component of the tree loading body, ε d and ε c μ represents the relative permittivity inside and outside the tree-loaded body (1), respectively. d and μ c The relative permeability inside and outside the tree loading body (1) are respectively represented, and the eigenvalue X represents the electromagnetic wave transmission mode of the tree loading body. m and K m These are Bessel functions of order m, belonging to the first and second classes; When the tree antenna transmits only the main mode, the diameter of the tree loading body (1) is set according to the following formula: Where b represents the diameter of the tree loading body (1), X 01 λ represents the eigenvalue of the dominant mode, λ0 is the operating wavelength in the dominant mode state, and ε d and ε c μ represents the relative permittivity inside and outside the tree-loaded body (1), respectively. d and μ c These represent the relative magnetic permeability inside and outside the tree loading body (1), respectively; The tree antenna employs an adaptive frequency sweeping method, which includes the following steps: S1. Set a signal with a preset frequency range as the excitation signal, perform ultra-wideband frequency sweep on the excitation signal, and divide the excitation signal into multiple excitation signals with different frequency bands. S2. Input the excitation signals of different frequency bands into the metal microstrip line (7) of the tree antenna in sequence. The excitation signal reflected back to the transmission direction is used as the reflection signal. The reflection coefficient of the tree antenna under different frequency bands is obtained by processing the excitation signal and the reflection signal. The frequency band with the lowest reflection coefficient is extracted as the optimal frequency band. S3. Set a fixed time, during which the tree antenna transmits and receives signals using the optimal frequency band; S4. After a fixed time has elapsed, return to S1 and repeat the cycle.

2. The tree antenna according to claim 1, characterized in that: It also includes a housing, the surface of which is covered with a housing of the same color as the tree load (1).

3. A tree antenna according to claim 1, characterized in that: The conformal Vivaldi radiator (2) includes a dielectric substrate (3), a metal ground plane (4), a slot (5), a circular resonant cavity (6), and a metal microstrip line (7). One side of the dielectric substrate (3) is attached to the tree loading body (1) and is provided with the metal microstrip line (7). The other side is attached with the metal ground plane (4). The metal ground plane (4) is provided with a slot (5) and a circular hole as the circular resonant cavity (6). The slot (5) is arranged along the radiation direction. The slot (5) is set in the shape of a horn-shaped opening. The circular hole is opened at the end of the narrow end of the horn-shaped opening.

4. A tree antenna according to claim 3, characterized in that: The groove lines on both sides of the slot (5) are arranged symmetrically around the central axis of symmetry. The groove lines on each side are mainly composed of parallel groove lines and gradient groove lines. The parallel groove line is a line segment parallel to the axis of symmetry, and the gradient groove line is a curve. One end of the parallel groove line is connected to the gradient groove line, and the other end of the parallel groove line extends to the circular resonant cavity (6).

5. A tree antenna according to claim 3, characterized in that: The metal microstrip line (7) is mainly composed of vertical microstrip lines, horizontal microstrip lines and fan-shaped microstrip lines. One end of the vertical microstrip line extends away from the radiation direction to the edge of the dielectric substrate (3). The other end of the vertical microstrip line is connected to one end of the horizontal microstrip line. The horizontal microstrip line is arranged perpendicular to the radiation direction. The end of the horizontal microstrip line that is far away from the vertical microstrip line is connected to the fan-shaped microstrip line.

6. A tree antenna according to claim 3, characterized in that: The dielectric substrate (3) is made of PET dielectric material.

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