阅读说明：本技术 一种低剖面探地雷达天线 (Low-profile ground penetrating radar antenna ) 是由 张安学 崔嘉倩 师振盛 李建星 舒敏杰 于 2020-06-24 设计创作，主要内容包括：本发明公开一种低剖面探地雷达天线,包括馈电探针和辐射体,辐射体包括电偶极子和磁偶极子,U型金属板两个翼边端部均垂直连接有第一水平金属板,第一水平金属板的端部伸向U型金属板的对称轴,竖直金属板的端部垂直连接有第二水平金属板,两个第二水平金属板组成电偶极子；第二水平金属板的形状为轴对称的六边形或八边形,与竖直金属板连接；馈电探针设置于U型金属板内部,宽度不变部分和扇形短截线水平设置,宽度不变部分位于两竖直金属板的正下方,宽度不变部分的长度与两竖直金属板之间的距离相等,渐变微带线的部分水平延伸至距U型金属板其中一个翼边预设距离处并竖直向下弯折,其竖直部延伸至馈电端口。本发明天线带宽宽,时域特性良好。(The invention discloses a low-profile ground penetrating radar antenna, which comprises a feed probe and a radiator, wherein the radiator comprises an electric dipole and a magnetic dipole, the end parts of two wing edges of a U-shaped metal plate are vertically connected with a first horizontal metal plate, the end part of the first horizontal metal plate extends to the symmetry axis of the U-shaped metal plate, the end part of the vertical metal plate is vertically connected with a second horizontal metal plate, and the two second horizontal metal plates form the electric dipole; the second horizontal metal plate is in an axisymmetric hexagon or octagon shape and is connected with the vertical metal plate; the feeding probe is arranged in the U-shaped metal plate, the width-unchanged portion and the fan-shaped stub are horizontally arranged, the width-unchanged portion is located right below the two vertical metal plates, the length of the width-unchanged portion is equal to the distance between the two vertical metal plates, part of the horizontal portion of the gradient microstrip line extends to a position away from one wing edge of the U-shaped metal plate by a preset distance and is vertically bent downwards, and the vertical portion of the gradient microstrip line extends to the feeding port. The antenna has wide bandwidth and good time domain characteristics.)

1. The low-profile ground penetrating radar antenna is characterized by comprising a feed probe (1) and a radiator (2), wherein the radiator (2) comprises an electric dipole (201) and a magnetic dipole (202), the magnetic dipole (202) is of a symmetrical structure, the magnetic dipole (202) comprises a U-shaped metal plate (2021), a first horizontal metal plate (2022) and a vertical metal plate (2023), the end parts of two wing edges of the U-shaped metal plate (2021) are vertically connected with the first horizontal metal plate (2022), the end part of the first horizontal metal plate (2022) extends to the symmetrical axis of the U-shaped metal plate (2021), and the end part of the first horizontal metal plate (2022) is vertically connected with the vertical metal plate (2023); the end part of the vertical metal plate (2023) is vertically connected with a second horizontal metal plate (2011), and the two second horizontal metal plates (2011) form an electric dipole (201); the shape of the second horizontal metal plate (2011) is axisymmetric hexagon or octagon, one side of the second horizontal metal plate (2011) is connected with the vertical metal plate (2023), the length of the side of the second horizontal metal plate (2011) is equal to the width of the vertical metal plate (2023), and the widths of the first horizontal metal plate (2022) and the vertical metal plate (2023) are equal; the feed probe (1) is arranged inside the U-shaped metal plate (2021), and the feed probe (1) comprises a microstrip open-circuit fan-shaped stub (103), a width-invariable part (102) and a gradually-changed microstrip line part (101) which are sequentially connected; the width-unchanged part (102) and the fan-shaped stub (103) are horizontally arranged, the width-unchanged part (102) is positioned right below the two vertical metal plates (2023), the length of the width-unchanged part (102) is equal to the distance between the two vertical metal plates (2023), the part (101) of the gradient microstrip line horizontally extends to a preset distance away from one wing edge of the U-shaped metal plate (2021) and is vertically bent downwards, a feed port (20211) is formed in the bottom edge of the U-shaped metal plate (2021), and the vertical part of the part (101) of the gradient microstrip line extends to the feed port (20211); the distance between the horizontal part of the fan-shaped stub (103), the width-unchanged part (102) and the part (101) of the gradient microstrip line and the first horizontal metal plate (2022) is equal to the distance between the vertical part of the part (101) of the gradient microstrip line and the wing edge of the U-shaped metal plate (2021).

2. A low-profile ground penetrating radar antenna according to claim 1, wherein a medium for stabilizing the relative positions of the feed probe (1) and the radiator (2) is filled between the feed probe (1) and the radiator (2).

3. The low-profile ground penetrating radar antenna as claimed in claim 2, wherein the dielectric filling part is a PCB, and the PCB is a double-sided copper clad laminate.

4. A low-profile ground penetrating radar antenna according to claim 2, wherein the width w of the tapered microstrip line portion (101) at both ends is dependent on the impedance Z_cDetermination of the impedance Z_cThe following were used:

wherein the content of the first and second substances,_eand w is the width of the part (101) of the gradient microstrip line and d is the distance between the feed probe (1) and the metal plate of the radiation part, wherein the effective dielectric constant is W.

5. The low-profile ground penetrating radar antenna as recited in claim 1, wherein the end of the second horizontal metal plate (2011) is bent downwards to form a bent part (2012).

6. The antenna of any one of claims 1-5, wherein the low-profile ground penetrating radar antenna has an operating frequency of 100MHz and an overall external dimension of 0.07_l×0.4λ_l×0.1λ_lWherein λ is_lThe wavelength corresponding to the operating frequency of 100 MHz.

Technical Field

The invention belongs to the technical field of electromagnetic fields and microwaves, and relates to a ground penetrating radar antenna.

Background

The ground penetrating radar system has important application in geological detection, mineral exploration, life detection and other aspects. Besides the requirement of meeting the system bandwidth and directional diagram, the ground penetrating radar antenna is critical to radiate and receive pulse signals without distortion. Dispersion is an important factor causing distortion of the radiated pulses of the antenna, and therefore the design goals of the pulse antenna are ultra-wideband, low dispersion, high efficiency and high directivity.

The ground penetrating radar system generally determines the center frequency of operation according to the requirement of detection distance, and the system frequency is generally lower than 5GHz in consideration of loss. Antennas operating at low frequencies are generally of a large size and, in order to increase the flexibility of the detection system, the size and weight of the antenna must be reduced. However, miniaturization of the antenna means a reduction in bandwidth and a reduction in efficiency, resulting in deterioration of time domain performance. At present, the miniaturization design of a ground penetrating radar antenna with excellent time domain performance is lacked in the field.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to provide a low-profile ground penetrating radar antenna, which expands the bandwidth of the antenna while realizing the miniaturization of the antenna, enables the antenna to have good time domain characteristics and solves the problems in the prior art.

The technical scheme adopted by the invention is as follows:

a low-profile ground penetrating radar antenna comprises a feed probe and a radiating body, wherein the radiating body comprises an electric dipole and a magnetic dipole, the magnetic dipole is of a symmetrical structure and comprises a U-shaped metal plate, a first horizontal metal plate and a vertical metal plate, the end parts of two wing edges of the U-shaped metal plate are vertically connected with the first horizontal metal plate, the end part of the first horizontal metal plate extends to the symmetrical axis of the U-shaped metal plate, and the end part of the first horizontal metal plate is vertically connected with the vertical metal plate; the end part of the vertical metal plate is vertically connected with a second horizontal metal plate, and the two second horizontal metal plates form an electric dipole; the shape of the second horizontal metal plate is an axisymmetric hexagon or octagon, one side of the second horizontal metal plate is connected with the vertical metal plate, the length of the side of the second horizontal metal plate is equal to the width of the vertical metal plate, and the widths of the first horizontal metal plate and the vertical metal plate are equal; the feeding probe is arranged inside the U-shaped metal plate and comprises a fan-shaped stub, a width-unchanged part and a part of a gradually-changed microstrip line which are sequentially connected; the width-unchanged part and the fan-shaped stub are horizontally arranged, the width-unchanged part is positioned right below the two vertical metal plates, the length of the width-unchanged part is equal to the distance between the two vertical metal plates, part of the gradually-changed microstrip line horizontally extends to a position away from one wing edge of the U-shaped metal plate by a preset distance and is vertically bent downwards, a feed port is formed in the bottom edge of the U-shaped metal plate, and the vertical part of the gradually-changed microstrip line extends to the feed port; the distance between the fan-shaped stub, the width-unchanged part and part of the horizontal part of the gradual change microstrip line and the first horizontal metal plate is equal to the distance between part of the vertical part of the gradual change microstrip line and the wing edge of the U-shaped metal plate.

Preferably, a medium for stabilizing the relative positions of the feed probe and the radiator is filled between the feed probe and the radiator.

Preferably, the medium filling part is a PCB, and the PCB adopts a double-sided copper-clad plate.

Preferably, the width w of the two ends of the part of the gradual change microstrip line depends on the impedance Z_cDetermination of the impedance Z_cThe following were used:

wherein the content of the first and second substances,_eand w is the width of the part of the gradient microstrip line and d is the distance between the feed probe and the metal plate of the radiation part, which is the effective dielectric constant.

Preferably, the end of the second horizontal metal plate is bent downwards to form a bent part.

Preferably, the working frequency of the low-profile ground penetrating radar antenna is 100-300MHz, and the overall external dimension is 0.07 lambda_l×0.4λ_l×0.1λ_lWherein λ is_lThe wavelength corresponding to the operating frequency of 100 MHz.

The invention has the following beneficial effects:

the second horizontal metal plate of the low-profile ground penetrating radar antenna is in an axisymmetric hexagon or octagon shape, and is equivalent to a structure obtained by cutting corners of four vertex angles of a rectangle compared with the existing rectangular structure, so that the bandwidth of the antenna can be expanded. Compared with the existing U-shaped magnetic dipole, the magnetic dipole provided by the invention can greatly reduce the height of the magnetic dipole under the condition that the resonance frequency of the magnetic dipole is consistent with that of an electric dipole by making the bottom edge of the U-shaped metal plate longer and making the wing edge shorter under the condition that the total length meets the requirement, so that the size of the low-profile ground penetrating radar antenna in the height direction of the profile is smaller, and the miniaturization of the antenna is realized. The width of the feed probe is linearly gradually changed, and the tail end of the feed probe is a fan-shaped stub, so that the feed probe can be used for adjusting the input impedance of an antenna and realizing broadband matching. The invention relates to a magnetoelectric dipole antenna adopting probe coupling feed, wherein an electric dipole and a magnetic dipole both belong to electrically small antennas, and the magnetoelectric dipole antenna has smaller size, narrower bandwidth and omnidirectional radiation. According to the invention, the magnetoelectric dipole is combined with the magnetic dipole through the electric dipole, so that on one hand, the reactance energy is compensated with each other, the low-frequency cut-off frequency can be reduced, and the bandwidth of the antenna is increased; on the other hand, unidirectional radiation can be achieved by directional pattern superposition. In conclusion, the invention expands the bandwidth of the antenna while realizing the miniaturization of the antenna, so that the antenna has good time domain characteristics.

Furthermore, a medium for stabilizing the relative positions of the feed probe and the radiator is filled between the feed probe and the radiator, so that the stability of the low-profile ground penetrating radar antenna structure is improved.

Furthermore, the medium adopts a PCB (printed Circuit Board), and the double-sided copper-clad plate of the PCB can reduce the total mass and further improve the stability of the whole structure.

Furthermore, the end of the second horizontal metal plate is bent downwards to form a bent part, and the length of the low-profile ground penetrating radar antenna can be further reduced by the structure.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

fig. 2(a) is a first antenna structure diagram formed by filling a medium between a feed probe and a radiator, processing the medium by a PCB process, and assembling the medium and a metal aluminum plate according to the present invention;

fig. 2(b) is a second antenna structure diagram formed by filling a medium between a feed probe and a radiator, processing the medium by a PCB process, and assembling the medium and a metal aluminum plate according to the present invention;

FIG. 2(c) is a top view of a low-profile georadar antenna according to an embodiment of the present invention;

FIG. 2(d) is a left side view of a low-profile ground penetrating radar antenna according to an embodiment of the present invention;

FIG. 3 is a diagram of the results of actual measurement and simulation of S parameters of the antenna of the present invention;

FIG. 4(a) is a simulation result diagram (plane E) of the antenna pattern of the present invention; FIG. 4(b) is a graph (plane H) of simulation results of the antenna pattern of the present invention;

FIG. 5 is a graph of gain simulation results of the present invention;

FIG. 6 is a diagram of a group delay simulation result of the present invention;

FIG. 7 is a diagram of the time domain signal test results of the present invention.

In the figure, 1 feeding probe, 101 tapered microstrip line portion, 102 width invariant portion, 103 fan-shaped stub, 2 radiator, 201 electric dipole, 2011 second horizontal metal plate, 2012 bent portion, 202 magnetic dipole, 2021U-shaped metal plate, 20211 feeding port, 2022 first horizontal metal plate, 2023 vertical metal plate, 3 coupling feeding portion.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, 2(a) and 2(b), the low-profile ground penetrating radar antenna of the present invention includes a feed probe 1 and a radiator 2, where the radiator 2 includes an electric dipole 201 and a magnetic dipole 202, the magnetic dipole 202 is a symmetric structure, the magnetic dipole 202 includes a U-shaped metal plate 2021, a first horizontal metal plate 2022 and a vertical metal plate 2023, the ends of two wings of the U-shaped metal plate 2021 are both vertically connected with the first horizontal metal plate 2022, one end of the first horizontal metal plate 2022 is connected with the end of the wing of the U-shaped metal plate 2021, the other end of the first horizontal metal plate 2022 extends to the symmetry axis of the U-shaped metal plate 2021, the ends of the two first horizontal metal plates 2022 extending to one end of the symmetry axis of the U-shaped metal plate 2021 are both vertically connected with the vertical metal plate 2023, and the lower end of the vertical metal plate 2023 is connected with the first horizontal metal plate 2022; the upper ends of the two vertical metal plates 2023 are vertically connected with second horizontal metal plates 2011, and the two second horizontal metal plates 2011 form an electric dipole 201; the second horizontal metal plate 2011 is in an axisymmetric hexagonal shape or an octagonal shape, one side of the second horizontal metal plate 2011, which is perpendicular to the symmetry axis of the second horizontal metal plate, is connected with the upper end of the vertical metal plate 2023, the width of the vertical metal plate 2023 is the same as the length of the side of the second horizontal metal plate 2011, which is connected with the vertical metal plate 2023, and the width of the first horizontal metal plate 2022 is the same as the width of the vertical metal plate 2023; the feeding probe 1 is arranged inside the U-shaped metal plate 2021, and the feeding probe 1 comprises a fan-shaped stub 103, a width-unchanged part 102 and a part 101 of a gradually-changed microstrip line which are sequentially connected; the width-unchanged portion 102 and the fan-shaped stub 103 are horizontally arranged, the width-unchanged portion 102 is located right below the two vertical metal plates 2023, the length of the width-unchanged portion 102 is equal to the distance between the two vertical metal plates 2023, the portion 101 of the gradient microstrip line horizontally extends to a preset distance from one wing edge of the U-shaped metal plate 2021 and is vertically bent downwards, a feed port 20211 is formed in the bottom edge of the U-shaped metal plate 2021, and the vertical portion of the portion 101 of the gradient microstrip line extends to the feed port 20211; the distance between the fan-shaped stub 103 and the first horizontal metal plate 2022, the distance between the width-unchanged portion 102 and the first horizontal metal plate 2022, the distance between the horizontal portion of the portion 101 of the tapered microstrip line and the first horizontal metal plate 2022, and the distance between the vertical portion of the portion 101 of the tapered microstrip line and the wing edge of the U-shaped metal plate 2021 are equal.

As a preferred embodiment of the present invention, a medium for stabilizing the relative positions of the feed probe 1 and the radiator 2 is filled between the feed probe 1 and the radiator 2, and the filled medium can ensure the stability of the antenna structure.

As the preferred embodiment of the invention, the medium filling part is realized by a PCB (printed Circuit Board), the PCB adopts a double-sided copper-clad plate, a top layer printed radiator and a bottom layer printed probe, and the low-profile ground penetrating radar antenna is formed by assembling a metal aluminum plate and the PCB, so the low-profile ground penetrating radar antenna has light overall weight and stable structure.

As a preferred embodiment of the present invention, the end of the second horizontal metal plate 2011 is bent downward to form a bent portion 2012, and by this bending, the total length of the low-profile ground penetrating radar antenna of the present invention is further shortened while the performance of the antenna is not affected.

As a preferred embodiment of the present invention, the end of the second horizontal metal plate 2011 is bent vertically downward to form a bent portion 2012.

As a preferred embodiment of the invention, the working frequency of the low-profile ground penetrating radar antenna is 100-300MHz, and the overall external dimension is 0.07 lambda_l×0.4λ_l×0.1λ_lWherein λ is_lThe wavelength corresponding to the operating frequency of 100 MHz.

As a preferred embodiment of the present invention, the shape of the first horizontal metal plate 2022 is a hexagon or an octagon obtained by cutting four corners of a rectangle.

In the invention, the electric dipole and the magnetic dipole both belong to electrically small antennas, generally have smaller size but narrower bandwidth and radiate in all directions. However, the magnetoelectric dipole is combined with the magnetic dipole through the electric dipole, so that on one hand, the reactance energy is mutually compensated, the low-frequency cut-off frequency can be reduced, and the bandwidth of the antenna is increased; on the other hand, unidirectional radiation can be achieved by directional pattern superposition. The working frequency band of the magnetoelectric dipole is determined by the electric dipole and the magnetic dipole, and the bandwidth of the magnetoelectric dipole is mainly limited by the size of the height and the width of the antenna section. In the design, the magnetic dipole is folded in order to reduce the height of the section of the antenna (the magnetic dipole is arranged in the form of three parts, namely a U-shaped metal plate, a first horizontal metal plate and a vertical metal plate, the bottom edge of the U-shaped metal plate can be made longer, the wing edge can be made shorter, and the size in the height direction is reduced), but the total length of the U-shaped metal plate is kept unchanged, so that the resonance frequency of the U-shaped metal plate is ensured to be consistent with that of an electric dipole. The input impedance of the antenna can be adjusted at the feed end chamfer of the electric dipole, the current distribution can be changed at the tail end chamfer, the position of a resonance point is adjusted, and the bandwidth of the electric dipole can be improved by adjusting the sizes of the two chamfers (based on the fact, the first horizontal metal plate can be cut into a hexagon or an octagon according to needs). The width of the U-shaped metal plate of the magnetic dipole is increased as much as possible under the condition of meeting the size requirement, the Q value can be reduced, and the bandwidth of the magnetic dipole is improved.

The input resistance is increased due to the reduction of the height of the antenna section, the matching is difficult, the inverted-L-shaped probe with gradually changed width is designed according to the radiation structure to perform coupling feeding at the connection position of the magnetoelectric dipoles, and the width and the distance of the vertical metal plate 2023 mainly influence the input impedance at the coupling feeding part 3. The inverted L-shaped probe can excite an electric dipole and a magnetic dipole simultaneously and is a balun feed structure. The gradually changing part 101 of the probe and the metal plate of the radiation part (i.e. the U-shaped metal plate and the first horizontal metal plate) form a microstrip line structure, so that signal transmission and broadband impedance transformation are realized. The matching of the resistance can be realized by adjusting the line width of the end of the gradually changing microstrip line (the end connected to the constant width portion 102). The width-invariant portion 102 realizes feeding through electric field coupling, at this time, the magnetic dipole is equivalent to a parallel plate waveguide with a short-circuited end and is equivalent to inductance, the quarter-wavelength microstrip open-circuited sector stub 103 is equivalent to capacitance, and the reactance can be cancelled by adjusting the angle and the radius of the sector stub 103, so that impedance matching is realized. The low-profile ground penetrating radar antenna has the advantages that the profile height can be as small as possible, so that the low-profile ground penetrating radar antenna can adapt to a vehicle-mounted environment and expand the application range.

The portion 101 of tapered microstrip line achieves a gradual change in impedance from the feed port 50 Ω to the input impedance of the coupled feed portion (about 150 Ω), the dimensions of which can be determined according to the microstrip line impedance calculation:

in the formula:_efor the effective dielectric constant, w is the width of the portion 101 of the tapered microstrip line, and d is the distance between the probe and the radiating portion metal plate.