CN110994153A

CN110994153A - A broadband liquid antenna

Info

Publication number: CN110994153A
Application number: CN201911298122.2A
Authority: CN
Inventors: 安翔; 吕志清; 单孝通; 吕奇龙; 王英飞
Original assignee: Xidian University
Current assignee: Xidian University
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-10

Abstract

The invention provides a broadband liquid antenna, which mainly solves the problems of narrow frequency band and complex structure of the traditional liquid antenna. The device comprises a dielectric substrate (1), a feed probe (4) embedded in the center of the dielectric substrate, a dielectric shell (2) positioned on the upper part of the dielectric substrate, conductive liquid (3) injected into the dielectric shell and a circular conductor plate (5) positioned below the dielectric substrate; an annular groove (11) is carved on the upper surface of the dielectric substrate around the z axis, and a stepped through hole (12) is carved along the z axis and is respectively used for fixing the dielectric shell and the feed structure; a cylindrical groove (21) is carved in the medium shell along the z axis, and two layers of annular grooves (22, 23) are carved at equal intervals around the cylindrical groove; the medium shell (2), the medium substrate (1) and the feed probe (4) form a closed structure, so that conductive liquid can be contained conveniently. The invention has wide frequency band, stable impedance change in the pass band, good omnidirectional radiation characteristic, simple structure and easy maintenance, and can be used for a wireless communication system.

Description

Broadband liquid antenna

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a broadband liquid antenna taking conductive liquid as a radiating body, which can be used for a wireless communication system.

Background

With the rapid development of wireless communication technology, the application of the antenna is increasingly wide, the communication scene is more and more complex, the performance requirements of the communication system on the antenna are more and more strict, and the antenna designed by using novel materials has a wide prospect. The existing ultra-short wave frequency band antenna is mainly made of metal materials such as copper and aluminum, although the metal materials have excellent conductivity, the ultra-short wave frequency band antenna has the advantages of large volume, easy oxidation, high cost and difficult adaptation to complex geographical environments, can consume a large amount of natural resources in the metal smelting process, and can generate great pollution to the environment when the metal antenna is used in a large range.

The use of non-metallic materials as radiators for antennas has many advantages. For example, sea water can be used as a radiator of the antenna for marine communication, local materials are used, and the problem of sea water erosion is avoided. In an area with geological disasters, the traditional metal antenna cannot normally communicate after being bent, deformed and damaged, and muddy water, fruit and vegetable juice, salt water and the like are used as antenna radiators and can be easily found even under severe conditions. The liquid antenna has a reconfigurable characteristic that changes the shape of the antenna by utilizing the fluidity of the liquid, thereby changing the radiation characteristic of the antenna.

The mitsubishi electric corporation 2016 shows a spray water antenna named "seamaterial", which uses a high-pressure water pump to spray seawater into the air to form a stable water column, utilizes the conductivity of the seawater to transmit and receive space electromagnetic wave signals, can be used for marine short-wave and ultrashort-wave communication, can successfully perform digital television signal rebroadcasting experiments, and has the antenna efficiency as high as 70%. However, the water-jet antenna has the problems of narrow frequency band, large volume, large power consumption and easy influence of sea waves in practical application.

Researchers at the university of philips have designed a brine monopole antenna, which uses a rigid PVC pipe to contain seawater and is placed on a cylindrical dielectric substrate, a through hole is opened in the center of the dielectric substrate, and a metal probe penetrates into the brine from the bottom to feed a water column. The saline monopole antenna works stably, but has a narrow frequency band, and cannot perform self-adaptive reconstruction on the frequency band by utilizing the liquid mobility characteristic.

Disclosure of Invention

The invention aims to overcome the defects of the liquid antenna and provide a broadband liquid antenna so as to widen the bandwidth of the liquid antenna and improve the radiation efficiency of the antenna and the application capability in a complex scene.

In order to achieve the above purpose, the broadband liquid antenna of the present invention comprises a dielectric substrate, a dielectric housing, a feed probe and a circular conductor plate, wherein the dielectric housing is located at the upper part of the dielectric substrate and is filled with a conductive liquid;

an annular groove is carved on the upper surface of the medium substrate around the z axis, and a step-shaped through hole is carved along the z axis;

the medium shell is of a cylindrical structure, a cylindrical groove is formed in the medium shell along the z axis, two layers of annular grooves are formed in the medium shell around the cylindrical groove at equal intervals, the outer layer of the medium shell is embedded into the annular groove in the upper surface of the medium substrate, and a gap is reserved between the inner layer and the medium substrate.

Preferably, the medium substrate adopts a solid cubic structure.

Preferably, the conductive liquid is NaCl aqueous solution with the salinity of 3.5 percent, or fruit juice, muddy water or seawater.

Preferably, the feed probe is of a cylindrical structure, the bottom end of the feed probe is connected with the inner conductor of the coaxial connector, the top end of the feed probe is connected with a circular metal sheet, and the metal sheet is embedded into the stepped through hole of the medium substrate and is in contact with the conductive liquid.

Preferably, a through hole is formed in the center of the circular conductive plate, the inner conductor of the coaxial connector is connected to the feed probe through the through hole, and the outer conductor of the coaxial connector is connected to the circular conductive plate.

Compared with the prior art, the invention has the following advantages:

1. the invention designs a multilayer groove structure in the medium shell, a cylindrical groove is carved in the medium shell along the z axis and is equivalent to a main radiator of the antenna after being filled with liquid, and meanwhile, two layers of annular grooves are carved at equal intervals around the cylindrical groove and are equivalent to two layers of annular coupling water columns loaded at equal intervals around the antenna after being filled with liquid, thereby introducing electromagnetic coupling for the antenna and widening the bandwidth of the antenna.

2. In the invention, the gap is reserved between the inner layer of the medium shell and the medium substrate, so that the bottoms of water columns at different layers are communicated, the electromagnetic coupling between the water columns is enhanced, the current path is enlarged, the bandwidth is further enlarged, and compared with the existing liquid antenna, the liquid antenna with the structure has wider bandwidth.

3. According to the invention, the circular metal sheet is loaded on the top end of the feed probe, so that the contact area between the feed probe and the conductive liquid is increased, the current distribution is enlarged, the input impedance of the antenna is improved, and the heat loss of the antenna is reduced.

4. The antenna radiator adopts NaCl aqueous solution with the salinity of 3.5 percent, is environment-friendly, pollution-free and easy to obtain, has the salinity similar to that of offshore seawater, can be used for offshore communication, and has the advantage that the size of the antenna is greatly reduced compared with that of a traditional metal antenna due to the high dielectric constant of the saline.

5. The antenna assembly structure is simple in structure and easy to assemble and maintain, and the antenna assembly structure forms a closed structure after being assembled, so that the antenna assembly structure is more stable in use.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a broadband liquid antenna of the present invention;

FIG. 2 is a schematic view of a cross-sectional structure of a media substrate of the present invention;

FIG. 3 is a schematic cross-sectional view of a media housing of the present invention;

fig. 4 is a schematic diagram of an antenna feed structure in the present invention;

FIG. 5 is a schematic view of a circular conductor plate structure in the present invention;

FIG. 6 is a schematic diagram of a yoz cross-sectional structure of a broadband liquid antenna according to the present invention;

FIG. 7 is a graph of simulated reflection coefficients for a broadband liquid antenna of the present invention;

FIG. 8 is a simulated radiation efficiency plot for a broadband liquid antenna of the present invention;

FIG. 9 is an H-plane pattern simulated at 200MHz for a broadband liquid antenna of the present invention;

fig. 10 is an E-plane pattern simulated at 200MHz for a broadband liquid antenna of the present invention.

Detailed Description

Embodiments and effects of the present invention will be described in further detail below with reference to the accompanying drawings.

Example 1, the conductive liquid was a broadband antenna containing NaCl with a salinity of 3.5%.

Referring to fig. 1, the present embodiment includes a dielectric substrate 1, a dielectric housing 2, a feeding probe 4 and a circular conductive plate 5, the dielectric housing 2 is located on the upper portion of the dielectric substrate 1 and filled with a conductive liquid 3, the feeding probe 4 is embedded in the center of the dielectric substrate 1, and the circular conductive plate 5 is located under the dielectric substrate 1.

Referring to fig. 2, the dielectric substrate 1 is of a solid cubic structure, and an annular groove 11 is carved on the upper surface of the dielectric substrate around a z-axis, and a step-shaped through hole 12 is carved along the z-axis; height H of dielectric substrate 1₁₁Is 50mm, and has a length and a width equal to their dimensions W₁₄Is 180 mm; radius W of the annular groove 11₁₁Is 70mm, width W₁₃Is 2mm, depth H₁₃Is 10 mm; large hole radius W of step-shaped through hole 12₁₂Is 10mm, depth H₁₄Is 20mm, and the radius W of the small hole₁₅Is 1mm, depth H₁₂Is 30 mm.

Referring to fig. 3, the dielectric housing 2 is a cylindrical structure, which is engraved with a cylindrical groove 21 along the z-axis, and two layers of

annular grooves

22 and 23 equally spaced around the cylindrical groove; radius W of the media case 2₂₇Is 70mm, height H₂₁Is 410 mm; radius W of cylindrical recess 21₂₁Is 10mm, depth H₂₃Is 390 mm; width W of first layer annular groove 22₂₂Is 20mm, depth H₂₄Is 390 mm; width W of second layer annular groove 23₂₃Is 20mm, depth H₂₅Is 390 mm; the spacing W between the cylindrical recess 21 and the first layer annular recess 22₂₆10mm, of a first layer of annular grooves 22 and a second layer of annular grooves 23Spacing W₂₅Is 10 mm; top wall thickness H of dielectric housing 2₂₆Is 5mm, and the thickness W of the side wall of the media case 2₂₄Is 2 mm.

Referring to fig. 4 and 5, the feed probe 4 is a cylindrical structure, the bottom end of which is connected to the inner conductor of the coaxial connector, and the top end of which is connected to a circular metal sheet 41; a through hole 51 is formed in the center of the circular conductor plate 5, an inner conductor of the coaxial connector is connected with the feed probe 4 through the through hole 51, and an outer conductor of the coaxial connector is connected with the circular conductor plate 5; probe radius W of feed probe 4₄₂Is 1mm and has a height H₄₂30mm, radius W of top-loaded round metal sheet₄₁Is 10mm and has a thickness H₄₁1mm, radius W of the circular conductor plate 5₅₁2000mm and 5mm thick.

Referring to fig. 6, the outer layer of the dielectric housing 2 is embedded in the annular groove 11 on the upper surface of the dielectric substrate 1, and a gap is left between the inner layer and the dielectric substrate 1; the feed probe 4 is embedded into the stepped through hole 12 of the medium substrate 1 and is in contact with the conductive liquid 3; in order to ensure that the conductive liquid 3 injected into the medium housing 2 does not leak, the annular groove 11 for fixing the medium substrate 1 and the medium housing 2 is filled with sealant, and the feed probe 4 and the stepped through hole 12 are filled with sealant.

In this example, ε is used as the dielectric substrate 1_rHard Teflon material 2.1, epsilon is used for the dielectric housing 2_rAs the conductive liquid 3, a 3.5% NaCl aqueous solution was used as a radiator, the copper material was used for the feed probe 4, and the stainless steel material was used for the circular conductive plate 5, which is a hard transparent PMMA tube of 3.4.

Example 2 broadband antenna with seawater as conductive liquid

The structure of this example is the same as that of embodiment 1, except that the conductive liquid 3 is seawater, and the parameters of each part of the antenna are set as follows:

height H of dielectric substrate 1₁₁Is 40mm, and has a length and a width dimension W₁₄Is 170 mm;

radius W of the annular groove 11₁₁Is 50mm, width W₁₃Is 5mm, depth H₁₃Is 5 mm;

large hole radius W of step-shaped through hole 12₁₂Is 8mm, depth H₁₄Is 10mm, and the radius W of the small hole₁₅Is 1mm, depth H₁₂Is 30 mm.

Radius W of the media case 2₂₇Is 50mm, height H₂₁Is 505 mm;

radius W of cylindrical recess 21₂₁Is 10mm, depth H₂₃Is 490 mm;

width W of first layer annular groove 22₂₂Is 10mm, depth H₂₄Is 490 mm;

width W of second layer annular groove 23₂₃Is 10mm, depth H₂₅Is 490 mm;

the interval W between the first layer annular groove 22 and the second layer annular groove 23₂₅Is 10 mm;

the spacing W between the cylindrical recess 21 and the first layer annular recess 22₂₆Is 10 mm;

top wall thickness H of dielectric housing 2₂₆Is 2mm, and the thickness W of the side wall of the media case 2₂₄Is 5 mm;

probe radius W of feed probe 4₄₂Is 1mm and has a height H₄₂30mm, radius W of top-loaded round metal sheet₄₁Is 8mm and has a thickness H₄₁Is 1 mm;

radius W of circular conductor plate 5₅₁1000mm and 5mm in thickness.

EXAMPLE 3 broadband antenna with coconut water as conductive liquid

The structure of this example is the same as that of example 1, except that the conductive liquid 3 is coconut milk, and the parameters of the respective parts of the antenna are set as follows:

height H of dielectric substrate 1₁₁60mm, length and width dimensions W₁₄Is 250 mm;

radius W of the annular groove 11₁₁Is 100mm, width W₁₃Is 10mm, depth H₁₃Is 15 mm;

large hole radius W of step-shaped through hole 12₁₂Is 15mm, depth H₁₄Is 20mm, and the radius W of the small hole₁₅Is 1mm, depth H₁₂Is 40 mm.

Radius W of the media case 2₂₇Is 100mm and highDegree H₂₁Is 815 mm;

radius W of cylindrical recess 21₂₁Is 20mm, depth H₂₃790 mm;

width W of first layer annular groove 22₂₂Is 20mm, depth H₂₄790 mm;

width W of second layer annular groove 23₂₃Is 20mm, depth H₂₅790 mm;

the interval W between the first layer annular groove 22 and the second layer annular groove 23₂₅Is 20 mm;

the spacing W between the cylindrical recess 21 and the first layer annular recess 22₂₆Is 20 mm;

top wall thickness H of dielectric housing 2₂₆Is 5mm, and the thickness W of the side wall of the media case 2₂₄Is 10 mm;

probe radius W of feed probe 4₄₂Is 1mm and has a height H₄₂40mm, radius W of the top-loaded round metal piece₄₁Is 15mm and has a thickness H₄₁Is 1 mm;

radius W of circular conductor plate 5₅₁3000mm and 5mm thick.

The effects of the present invention can be further illustrated by the following simulations:

first, simulation condition

Example 1 of the invention was simulated using the commercial simulation software HFSS 15.0.

Second, simulation content

Simulation 1, the reflection coefficient of example 1 was simulated, and the result is shown in fig. 7.

As can be seen from FIG. 7, the frequency f at which the antenna reflection coefficient is less than-10 dB_L＝95MHz、f_H320MHz, the absolute bandwidth Δ f is calculated as f_H-f_L225MHz, relative bandwidth

The calculation results show that the relative bandwidth of the invention is far larger than 25% relative bandwidth required by a broadband antenna.

Simulation 2, the radiation efficiency of example 1 was simulated, and the result is shown in fig. 8.

As can be seen from fig. 8, the radiation efficiency of the antenna is between 50% and 70% at a frequency of 100MHz to 200MHz, and between 30% and 50% at a frequency of 200MHz to 300MHz, and the internal resistance loss of the antenna is increased at a high frequency band, which results in a decrease in the radiation efficiency.

Simulation 3, the H-plane pattern of example 1 was simulated, and the result is shown in fig. 9.

As can be seen from fig. 9, the H-plane pattern is non-directional, with a difference of 40dB between the main polarization and the cross polarization, because the conductive liquid 3 in example 1 is rotationally symmetric about the z-axis, so the H-plane radiation characteristic is good.

Simulation 4, the E-plane pattern of example 1 was simulated, and the result is shown in fig. 10.

As can be seen from fig. 10, the maximum radiation direction of the E-plane pattern is about 40 degrees from the horizontal plane, and as can be seen from the H-plane pattern shown in fig. 9, the antenna has back diffraction due to the limited size of the circular conductive plate 5 in example 1, but the omnidirectional radiation characteristic of the broadband liquid antenna of the present invention is good in the case of using the limited size circular conductive plate 5.

Claims

1. A broadband liquid antenna, comprising a dielectric substrate (1), a dielectric housing (2), a feeding probe (4) and a circular conductor plate (5), the dielectric housing (2) being located on the upper part of the dielectric substrate (1) , which is filled with conductive liquid (3), the feeding probe (4) is embedded in the center of the dielectric substrate (1), and the circular conductor plate (5) is placed under the dielectric substrate (1), characterized in that;

The upper surface of the dielectric substrate (1) is engraved with an annular groove (11) around the z-axis, and a stepped through hole (12) is engraved along the z-axis;

The dielectric housing (2) adopts a cylindrical structure, which is engraved with a cylindrical groove (21) along the z-axis, and is engraved with two layers of annular grooves (22, 23) at equal intervals around the cylindrical groove. The layer is embedded in the annular groove (11) on the upper surface of the dielectric substrate (1), leaving a gap between the inner layer and the dielectric substrate (1).

2 . The antenna according to claim 1 , wherein the dielectric substrate ( 1 ) adopts a solid cube structure. 3 .

3 . The antenna according to claim 1 , wherein the conductive liquid ( 3 ) adopts a NaCl aqueous solution or fruit juice or mud water or sea water with a salinity of 3.5%. 4 .

4. The antenna according to claim 1, wherein the feeding probe (4) adopts a cylindrical structure, and its bottom end is connected with the inner conductor of the coaxial joint, and its top end is connected with a circular metal sheet (41 ), the metal sheet is embedded in the stepped through hole (12) of the dielectric substrate (1), and is in contact with the conductive liquid (3).

5. The antenna according to claim 1, characterized in that: a through hole (51) is provided at the center of the circular conductor plate (5), and the inner conductor of the coaxial joint passes through the through hole (51) and passes through the The feeding probe (4) is connected, and the outer conductor of the coaxial joint is connected with the circular conductor plate (5).

6. The antenna according to claim 1, characterized in that: the height of the dielectric substrate (1) is 40-60 mm, the length and width are 170-250 mm; the radius of the annular groove (11) is 50-100 mm, The width is 2mm-10mm, and the depth is 5mm-15mm; the large hole radius of the stepped through hole (12) is 8mm-15mm, the depth is 10mm-40mm, the small hole radius is 1mm, and the depth is 10mm-40mm.

7. The antenna according to claim 1, characterized in that: the radius of the dielectric housing (2) is 50mm～100mm, and the height is 300mm～900mm; the radius of the cylindrical groove (21) is 5mm～20mm, and the depth is 300mm～ 800mm; the widths of the two layers of annular grooves (22, 23) are both 10mm to 30mm, and the depths are both 300mm to 800mm; the interval between the cylindrical grooves (21) and the first layer of annular grooves (22) is 5mm to 20mm, The interval between the first-layer annular groove (22) and the second-layer annular groove (23) is 5 mm to 20 mm, the thickness of the top wall of the dielectric casing (2) is 2 mm to 10 mm, and the thickness of the side wall of the dielectric casing (2) is 2 mm to 2 mm 10mm.

8 . The antenna according to claim 1 , wherein the circular conductor plate ( 5 ) has a radius of 1000 mm to 3000 mm and a thickness of not less than 2 mm. 9 .