CN111427013A - Radar device with main beam wave width reducing and side beam inhibiting function - Google Patents
Radar device with main beam wave width reducing and side beam inhibiting function Download PDFInfo
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- CN111427013A CN111427013A CN201910018310.9A CN201910018310A CN111427013A CN 111427013 A CN111427013 A CN 111427013A CN 201910018310 A CN201910018310 A CN 201910018310A CN 111427013 A CN111427013 A CN 111427013A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
- G01S7/032—Constructional details for solid-state radar subsystems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/36—Means for anti-jamming, e.g. ECCM, i.e. electronic counter-counter measures
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Abstract
A radar device with main beam wave width reduction, energy enhancement and side beam suppression functions comprises an antenna cover, an antenna component and a metamaterial component. The antenna assembly is arranged in the antenna housing and comprises an antenna substrate and an antenna arranged on one surface of the antenna substrate. The metamaterial assembly is arranged in the antenna housing, adhered or integrated with the antenna housing, and separated from the antenna assembly by a distance, and comprises a fixed substrate, a first metamaterial array and a second metamaterial array. The radar wave emitted by the antenna component is along an emission direction towards the metamaterial component, and the spacing is a multiple of half of the wavelength of the working frequency band of the radar wave in the air. The radar apparatus can reduce the wave width of the main beam, enhance the energy of the main beam and restrain the side beam.
Description
Technical Field
The present invention relates to a radar apparatus, and more particularly, to a radar apparatus, which enhances focusing of a main beam in a transmitting direction of a radar wave and suppresses side beams on both sides of the transmitting direction of the radar wave, so that the radar apparatus can well detect a forward object and avoid interference from the objects on both sides.
Background
The radar device is widely applied to vehicles, and the radar device is arranged at the head or the tail of the vehicle, so that the vehicle has the function of detecting front or rear objects, and the vehicle is prevented from accidentally impacting or running over the objects during driving or backing.
Referring to fig. 1, fig. 1 is a graph illustrating a beam pattern at a horizontal angle position (solid line curve connecting a plurality of points) and a beam pattern at a horizontal angle position (dotted line curve) after a radome is added to a conventional radar apparatus. The conventional radar device mainly reduces the antenna beam width by increasing the number of array antennas in the radar device, so as to improve the detection performance of the radar. However, although the aforementioned method of increasing the number of array antennas reduces the wave width of the Main beam (Main lobe), the energy of the Side wave (Side lobe) increases, which increases the echo signals on both sides of the radar apparatus, and causes the radar apparatus to be interfered by the reflected noise of trees and buildings on both sides, and if the Side wave suppression (taping) is performed by controlling impedance or phase, the energy of the Side beam can be reduced a lot, but for the waterproof design of the radar apparatus, a radar apparatus cover must be added for close assembly, and the energy of the antenna part of the original Side beam is increased by covering the radar apparatus cover with different materials and thicknesses, as shown in fig. 1. This causes the original field pattern (solid curve connected by a plurality of points) in which the main side wave has been suppressed to be much larger (dotted curve) after being reflected by the radome. Therefore, when the radar device is installed at the front end or the rear end of a vehicle, the reflected noise waves of the trees and buildings on the two sides enter the measurement spectrum of the radar device again, and the interference of the near-end reflection is caused.
In short, although the main side wave suppression of the array antenna can be reduced by the conventional side wave suppression (Tapering), the side wave suppression (Tapering) characteristics are destroyed by the near-field reflection of the antenna housing. Each set of radar system cannot use a bare board as a finished product, and the radome is required to be protected against water and the like, so how to improve the influence of the radome on the microwave radiation field pattern needs to be considered.
Disclosure of Invention
The present invention provides a radar apparatus with main beam enhancement and side beam suppression functions, which is invented in view of the shortcomings of the conventional radar apparatus in the main beam enhancement and side beam suppression of radar waves, resulting in the defects of insufficient functions of detecting objects in front and rear of a vehicle and easily suffering from the defects of interference of detection results by other objects on the side of the vehicle.
The main objective of the present invention is to provide a radar apparatus with main beam enhancement and side beam suppression functions, comprising:
an antenna housing, in which an accommodation space is formed;
the antenna assembly is arranged in the accommodating space of the antenna housing and comprises an antenna substrate and an antenna arranged on one surface of the antenna substrate, wherein the antenna is used for transmitting radar waves for detecting objects in the external environment; and
the metamaterial assembly is arranged in the accommodating space and is separated from the antenna assembly by a distance, and the metamaterial assembly comprises a fixed substrate, a first metamaterial array and a second metamaterial array; the fixed substrate is attached to the inner surface of the accommodating space of the antenna housing or integrated in the antenna housing; the first metamaterial array is arranged on one of two opposite surfaces of the fixed substrate and comprises a plurality of first metamaterial units; the second metamaterial array is arranged on the other surface of the fixed substrate and comprises a plurality of second metamaterial units, and the plurality of second metamaterial units respectively correspond to and are aligned with the plurality of first metamaterial units;
the radar wave emitted by the antenna component is along an emission direction facing the metamaterial component, and the spacing is a multiple of one half of the wavelength of the radar wave in the air.
In an embodiment of the present invention, the at least one antenna is an array antenna.
In an embodiment of the invention, the thickness of the radome is a multiple of one-half of the wavelength of the radar wave at the radome material.
In an embodiment of the present invention, a thickness of a portion of the radome penetrated by the radar wave is a multiple of one-half of a wavelength of the radar wave at the radome material.
In an embodiment of the invention, the thickness of the metamaterial element is a multiple of one half of the wavelength of the radar wave at the metamaterial element.
In an embodiment of the invention, each first metamaterial unit has a first rectangular outer frame and a first spiral part located in the first rectangular outer frame and connected with the first rectangular outer frame; each second metamaterial unit is provided with a second rectangular outer frame and a second spiral part which is positioned in the second rectangular outer frame and connected with the second rectangular outer frame; the fixed substrate is provided with a plurality of through holes plated with metal conductors in a penetrating mode, the through holes correspond to the first metamaterial units and the second metamaterial units in number, and each through hole is connected with the corresponding first metamaterial unit and the corresponding second metamaterial unit respectively.
In one embodiment of the present invention, the metamaterial element has a negative refractive index.
In an embodiment of the invention, the radome has a positive refractive index.
In an embodiment of the invention, the absolute value of the negative refractive index of the metamaterial element is larger than the absolute value of the positive refractive index of the antenna housing.
The radar device with main beam wave width reduction, energy enhancement and side beam suppression functions has at least the following advantages.
1. Based on the design principle that the thickness of the antenna housing is a multiple of one-half of the wavelength of the radar wave in the antenna housing, the antenna housing with proper material and thickness can be selected, and further, the antenna beam pattern is prevented from being seriously distorted.
2. For the application of the medium-long distance detection radar, even though the material and the thickness of the antenna cover are no matter, the metamaterial assembly has the functions of reducing the wave width of a main wave beam, enhancing the energy of the main wave beam and reducing the energy of a side wave beam.
3. Generally, an antenna field with extremely narrow beams needs to be designed, more antennas are required to be connected in parallel, the area of a circuit board is increased, the number of side-wave beams of the antenna field is increased, the energy is increased, and if a metamaterial assembly is matched with a narrow-beam antenna with a small array to replace a large-scale extremely narrow-beam antenna with a large array, the same effects of reducing the beams, increasing the energy and reducing the area of the antenna and the energy of the side-wave beams can be achieved.
4. The invention can fix the shape and size of the antenna and can be used for controlling different antenna patterns by using different metamaterial components (different negative refractive indexes).
Drawings
Fig. 1 is a curve diagram of a beam pattern at a horizontal angle position (solid line curve connected by a plurality of points) where no radome is added and a beam pattern at a horizontal angle position (dotted line curve) where a radome is added in a conventional radar apparatus.
Fig. 2 is a perspective view of a radar apparatus with main beam enhancement and side beam suppression according to the present invention.
Fig. 3 is a perspective, largely exploded view of a radar apparatus according to the present invention.
Fig. 4 is a side sectional view of the radar apparatus of the present invention.
Fig. 5 is a schematic diagram of the relative relationship of incident, reflected and refracted angles of Snell's L aw.
FIG. 6A is a graph illustrating the effect of thin medium thickness on the angle of refraction of a wave.
FIG. 6B is a graph illustrating the effect of thick medium thickness on the angle of refraction of a wave.
Fig. 7 is a plan view of an antenna assembly of the present invention.
Fig. 8 is a plan view of a metamaterial assembly in accordance with the present invention.
Fig. 9 is a partially enlarged plan view of one side of an embodiment 1 of a metamaterial assembly in accordance with the present invention.
Fig. 10 is a partial enlarged plan view of another side of an embodiment of a metamaterial assembly 1 of the present invention.
Fig. 11 is an enlarged partial side cross-sectional view of an embodiment 1 of a metamaterial assembly in accordance with the present invention.
Fig. 12 is a schematic diagram of a standing wave in which two identical sine waves, i.e., a right wave and a left wave (reflected wave), travel toward each other and interfere with each other to form a composite wave.
Fig. 13 is a schematic diagram of the refraction of the radar wave in the air and the general medium (solid line) and metamaterial (dotted line) according to the present invention.
Fig. 14 is a schematic view of the refraction of the radar wave in different media such as air, metamaterial components, and radomes.
Fig. 15 is a graph of antenna field patterns obtained by performing simulation analysis by using a 3D field theory and analyzing by replacing different antenna cover materials and adding a metamaterial in combination with the antenna cover according to the present invention.
Fig. 16 is a beam pattern graph of transmit/receive power measurements of fov (field of view) performed by radomes with different thicknesses in experiment 1 of the present invention.
Fig. 17 is a beam pattern curve diagram of the transmit/receive power measurement of the transmit/receive fov (field of view) by adding the metamaterial to the radome in experiment 2 of the present invention.
Fig. 18 is a beam pattern curve diagram of transmit/receive power measurement of fov (field of view) performed by the antenna housing with different thickness and material in experiment 3 of the present invention.
Fig. 19 is a beam pattern curve diagram of transmit/receive power measurements of fov (field of view) performed by adding metamaterials to the antenna covers with different thicknesses and materials in experiment 4 of the present invention.
Detailed Description
Referring to fig. 2 to 4, fig. 2 is a perspective view of a radar apparatus with main beam enhancement and side beam suppression functions according to the present invention. Fig. 3 is a perspective, largely exploded view of a radar apparatus according to the present invention, and fig. 4 is a side sectional view of the radar apparatus according to the present invention. The radar apparatus with main beam enhancement and side beam suppression of the present invention includes an antenna cover 10, an antenna assembly 20, and a Metamaterial (Metamaterial) assembly 30.
The radome 10 is a housing, which may be formed by two halves 11, 12 that are butt-jointed and fixed to each other. An accommodation space 100 is formed in the radome 10. The antenna assembly 20 is disposed in the accommodating space 100 of the antenna housing 10 and includes an antenna substrate 21 (circuit board) and at least one antenna 22 disposed on one side of the antenna substrate 21.
The at least one antenna 22 may be an array antenna 22 that emits radar waves for detecting objects in the external environment.
The metamaterial element 30 is disposed in the accommodating space 100 and separated from the antenna element 20 by a distance D1, and the metamaterial element 30 includes a fixed substrate 31, a first metamaterial array and a second metamaterial array. The fixed substrate 31 is an insulating, flexible film substrate, and the fixed substrate 31 is attached to the inner surface of the accommodating space 100 of the antenna cover 10. The first meta-material array is disposed on one of two opposite surfaces of the fixed substrate 31 and includes a plurality of first meta-material units 33. The plurality of second metamaterial units 35 respectively correspond to and are aligned with the plurality of first metamaterial units 33, that is, the central axis of each second metamaterial unit 35 is parallel to the normal of the fixed substrate 31, and the central axis of each second metamaterial unit 35 overlaps the central axis of each corresponding first metamaterial unit 33. In a preferred embodiment of the invention, the thickness of the metamaterial element 30 is a multiple of one half of the wavelength of the radar wave at the metamaterial element 30. The metamaterial component described in the invention is a layout structure of a metal or a circuit board, is not a material, and has the functions of reducing wave width of a wave beam, enhancing energy, suppressing a side wave beam and the like.
The radar wave emitted by the antenna component 20 is along an emission direction toward the metamaterial component 30, and when passing through the metamaterial component 30, the radar wave is refracted by the metamaterial component 30, so that a main beam of the radar wave is increased in the emission direction, and side beams of the radar wave located on two sides of the main beam are suppressed and decreased in the emission direction, and the radar wave passes through the metamaterial component 30, then passes through the radome 10, continues to be emitted to the external environment, and returns to the radar device after touching and bouncing off the object, thereby achieving the object detection effect. In addition, the distance D1 is a multiple of one-half of the wavelength of the radar wave in air. In the preferred embodiment of the present invention, the thickness D2 of the radome 10 is a multiple of one-half of the wavelength of the radar wave in the radome 10. In detail, the thickness D2 of the portion of the radome 10 penetrated by the radar wave is a multiple of one-half of the wavelength of the radar wave in the radome 10.
Before further describing the details of the components of the present invention, the design principle of the radar apparatus with main beam enhancement and side beam suppression according to the present invention is described as follows.
The thickness D2 and the material (dielectric constant) of the radome 10 of the present invention affect the field pattern change of the antenna 22. The influence objects of the thickness D2 of the radome 10 are respectively the node reflection of the standing wave and the refraction angle change of the field type, and the influence objects of the radome 10 material are related to the refraction angle change. In addition, the distance D1 between the antenna 22 and the radome 10 must be controlled, typically to be a multiple of one-half wavelength (the wavelength of the radar beam in the air medium), and the thickness D2 of the radome 10 must also be a multiple of one-half wavelength (the wavelength of the radar beam in the various radome 10 media).
To eliminate the effect of the thickness D2 of the radome 10, the thickness D2 of the radome 10 is controlled to be a multiple of one-half wavelength (the wavelength of the radar beam in various radomes 10 media), the one-half wavelength corresponding to each material is different, and the wavelength is calculated by comparing the velocity of the wave in the medium with that of the air, such as
Where v is the speed of wave travel in the medium and the speed of wave travel in air is
The antenna housing 10 is made of non-magnetic material. Is known as mur＝μ0Andr＝1 0where 1 is its relative permittivity, thus derived
At a certain operating frequency, the wavelength in the air medium is
The material of the antenna housing 10
Then
Therefore, at a frequency of 76.5GHz, the distance between the antenna substrate 21 (circuit board) and the radome 10 needs to be a multiple of one-half wavelength (air medium),
is a Polycarbonate (PC) material (dielectric constant)1) At 2.8, the thickness D2 of the radome 10 defines a multiple of one-half wavelength (radome 10 medium), i.e., is
Thus, it is possible to provide
If the thickness D2PC is not strong enough, the double thickness D22 × 1.195 is 2.39mm, so that the standing wave node effect can be eliminated and the distortion phenomenon of the radiation pattern can be reduced.
Referring to fig. 5, fig. 5 is a diagram showing the relative relationship between incident, reflection and refraction angles of Snell's L aw according to the design of the radome 10 itself, the thickness D2 and the material of the radome affect the microwave radiation field type, generally, when the antenna 22 radiates with a bare board, the radiation interface of the antenna 22 field type is air, the dielectric constant of which is about 1.0, and after the radome 10 is added, the radiation interface passes through the dielectric medium of the radome 10, the dielectric constant of which is about 2.8 if the radome 10 is made of PC material, and the dielectric constant of which is 3.8 if the radome 10 is made of Polybutylene terephthalate (PBT) material, as shown in fig. 2.
According to the Senell law, the incident angle and the refraction angle of the wave between two media are known to be theta1And theta2And the refractive index is n1And n2The relation is as follows:
n1·sin(θ1)＝n2·sin(θ2)
wherein v is2Representing the velocity of waves in the medium, f the radio frequency, c the speed of light
The following formula can be obtained:
from the relationship between Fresnel's Equation and permittivity, the following Equation is derived:
the greater the dielectric coefficient, the greater the radiation pattern change.
Referring to fig. 6A and 6B, fig. 6A is a schematic diagram illustrating an influence of a thin medium thickness D2 on a refraction angle of a wave, and fig. 6B is a schematic diagram illustrating an influence of a thick medium thickness D2 on a refraction angle of a wave.
From the above calculation, it can be found that the thicker the medium thickness D2 is, the larger the change in the radiation pattern is. However, the magnitude of the refraction of the radiation field pattern is proportional to the square root of the dielectric constant and proportional to the thickness of the medium D2.
In order to avoid the standing wave node effect and cause the serious deformation of the radiation field pattern of the antenna 22, the distance between the antenna 22 and the radome 10 is controlled to be designed to be a multiple of a half wavelength (air medium), and the thickness D2 of the radome 10 also needs to be designed to be a multiple of a half wavelength (radome 10 medium), so that the standing wave effect of the near-field antenna 22 can be reduced.
If the thickness D2 of the radome 10 is optimized, but the final field shape change is affected by the original antenna 22 field shape, the radome 10 material, and other factors, so the negative influence of the radome 10 on the antenna 22 field shape is further improved, and therefore, the negative influence of the radome 10 is improved by using the Metamaterial (Metamaterial) characteristic, because the Metamaterial has the characteristic that the refraction angle of the Metamaterial in the slanell's law generates a negative angle, and the negative influence of the radome 10 is mostly due to the positive angle influence of the refraction angle.
In the invention, in addition to controlling the distance between the antenna 22 and the radome 10 and the thickness D2 of the radome 10, an extremely thin plate is further applied, and a Printed Circuit Board (PCB) structure with Electromagnetic Band Gap (EBG) is used as a material of the metamaterial assembly 30 to improve the characteristic of the radome 10 for damaging the side wave suppression.
Referring to fig. 9-11, fig. 9 is a partially enlarged plan view of one side of a first embodiment of a metamaterial assembly 30 in accordance with the present invention, fig. 10 is a partially enlarged plan view of another side of the first embodiment of a metamaterial assembly 30 in accordance with the present invention, and fig. 11 is a partially enlarged side cross-sectional view of the first embodiment of a metamaterial assembly 30 in accordance with the present invention. Each first meta-material unit 33 has a first rectangular outer frame 331 and a first spiral portion 332 located inside the first rectangular outer frame 331 and connected to the first rectangular outer frame 331. Each second metamaterial unit 35 has a second rectangular outer frame 351 and a second spiral portion 352 located inside the second rectangular outer frame 351 and connected to the second rectangular outer frame 351. A plurality of through holes 310 plated with metal conductors are formed through the fixed substrate 31, the number of the through holes 310 corresponds to the plurality of first metamaterial units 33 and the plurality of second metamaterial units 35, and each through hole 310 is connected to the corresponding first metamaterial unit 33 and the corresponding second metamaterial unit 35. In the preferred embodiment, there is a space 330 between two adjacent first metamaterial units 33, and two adjacent second metamaterial units 35 are closely connected.
The metamaterial unit 30 of the present invention has the above embodiments with better radar wave main beam enhancement and side beam suppression effects. The metamaterial elements 30 of the present invention have a Slow wave (Slow wave) high impedance surface characteristic, and may also be referred to as Frequency Selective Surfaces (FSS). When the incident field passes through the metal surface of the structure, the metal surface will generate an induced current, and the induced current will generate a scattered field. The total field at any position in space is the sum of the reflected and transmitted fields caused by the interface between the induced current and the dielectric, which improves the radiation of the antenna 22.
In addition, the standing wave theory of the radar wave of the invention is as follows:
referring to fig. 12, fig. 12 is a schematic diagram of a Standing Wave (or Stationary Wave), in which two identical sine waves, i.e., a right Wave and a left Wave (reflected Wave), travel in opposite directions to interfere with each other to form a composite Wave (composite Wave). The standing wave is a composite wave formed by two sine waves with the same wavelength, cycle times, frequency and wave speed which are oppositely advanced and interfered. Unlike a traveling wave, the waveform of a standing wave cannot advance, and thus cannot propagate energy. When the standing wave passes, each mass point makes harmonic motion. Since the distance between the antenna 22 and the radome 10 from the thickness D2 of the radome 10 is fixed and in the near-field range, the incident wave and the reflected wave have the same intensity, period, and the like and have opposite directions, and the conditions for forming the standing wave are met, the incident wave and the reflected wave are set at the trough of the standing wave at the reflection Node (Node) of the radome 10, so that the near-field reflection energy is minimized.
The wave propagating in the opposite direction can be expressed by the following equation
y1＝y0sin(kx-ωt)
y2＝y0sin(kx+ωt)
Where y0 is the amplitude of the wave, ω is the angular velocity, ω is 2 π f, k is the wavenumber,
x and t are variables of distance and time, and the result after superposition of two waves is as follows:
y＝y0sin(kx-ωt)+y0sin(kx+ωt)
simplified to obtain y ═ 2y0cos(ωt)sin(kx)
From the above equation, 0, λ/2, λ, 3 λ/2, is the trough (a multiple of λ/2), whose amplitude is 0, and at λ/4, 3 λ/4, 5 λ/4.
In addition, the theory of the metamaterial is mainly applied to the application of Negative-index metamaterials (NIMs), and in a general medium structure, the refractive index (refractiveness) of the slanell law is positive, so that the radiation field divergence of the energy antenna 22 is reduced. Because of the refractive index n2＝μr rIf both μ and μ are less than 0, the time-harmonic plane wave equation of Maxwell's equation is represented in this structure as follows:
k×E＝ωμ0μH；
k×H＝-ω0E。
referring to fig. 13, fig. 13 is a schematic diagram showing the refraction of the radar wave between the air and different media such as the radome 10, the refractive index n must be negative when the vector is introduced into Maxwell's equation and Poynting, so that the new incident and refraction angle relationship of fig. 13 can be obtained by introducing the refractive index into the incident and refraction angle relationship of Snell L aw of fig. 5, which is conventionally obtained from the medium 1 (air, refractive index n)1) To medium 2 (radome 10, refractive index n)2) From the solid incident ray to the broken refracted ray, but with a negative index metamaterial, from the solid incident ray to the solid refracted ray, which is the same as the focusing way of an optical convex lens, has the functions of increasing the gain of the antenna 22 and reducing the side of each stepThe effect of the energy of the wave.
Referring to fig. 14, fig. 14 is a schematic diagram illustrating the refraction of radar waves between different media such as air, the metamaterial assembly 30, and the radome 10. Wherein the metamaterial component 30 of the present invention is attached to the radome 10, and comprises three dielectric layers, i.e. air (dielectric 1), metamaterial (dielectric 2) and radome 10 (dielectric 3) (refractive indexes n respectively)1、n2、n3) The layer structure is shown in fig. 14, the negative refractive index of the metamaterial must be greater than the positive refractive index of the radome 10 itself, so as to achieve the effects of suppressing the energy of the side beam and reducing the wave width of the main beam, because the thickness D2 of the radome 10 is thicker (much greater than the metamaterial), so that the gain effect of the antenna 22 is greatly reduced, how to increase the negative refractive index of the metamaterial can be greater than the refractive index of the radome 10, and the maximum way is to (i) adjust the side length of each unit of the metamaterial to be equal to one-half wavelength of the operating frequency, and (ii) increase the number of layers of the metamaterial, and change the metamaterial into a multilayer board to continuously increase the negative refractive index. However, the thickness of the PCB and the cost of the manufacturing process need to be considered, and after all, the invention is a consumer vehicle product and cannot increase excessive cost.
In a preferred embodiment of the invention, the metamaterial element has a negative refractive index and the radome has a positive refractive index, the absolute value of the negative refractive index of the metamaterial element being greater than the absolute value of the positive refractive index of the radome.
Referring to fig. 15, fig. 15 is a field pattern graph of the antenna 22 obtained by performing simulation analysis by using a 3D field theory, and performing analysis by changing different antenna Cover 10 materials and adding metamaterials, wherein the PC _ Cover _ EBG curve shows that after the metamaterials are added, the main beam is obviously narrowed, the energy of each side beam is reduced, and the gain is increased.
Experiments related to the invention
Referring to fig. 16, fig. 16 is a beam pattern graph of transmit/receive power measurements of transmit/receive fov (field of view) performed by the radome 10 with different thickness D2 in experiment 1 of the present invention. In experiment 1, each of the transmitting and receiving antennas is a single serial array antenna 22 made of PC materialDifferent radome 10 thicknesses D2 were made (1 ═ 2.8), where the thickness D2 determines the multiple of one-half wavelength (radome 10 medium), i.e., is
Referring to fig. 11, the transmit/receive power measurement of the transmit/receive fov (field of view) is performed with the radome 10 having different thickness D2, wherein (i) the solid line curve is a field without the radome 10, (ii) the dotted line curve has a thickness D21.15mm close to λ 1/2 ═ 1.195mm, and its field has compression but less distortion, (iii) the dotted line curve has a thickness D22.33mm close to 2 × (λ 1/2) ═ 2.39mm, and likewise its field has compression but less distortion, (iv) the dotted line curve has a thickness D22.0mm not λ 1/2 or its multiple, and the standing wave effect is generated to cause severe distortion of the field.
Experiment 2
Referring to fig. 17, fig. 17 is a beam pattern graph of the transceiving power measurement of the transceiving fov (field view) performed by adding the metamaterial to the radome 10 in the experiment 2 of the present invention. In experiment 2, four parallel serial array antennas 22 are used for transmission and four parallel serial array antennas 22 are used for reception, a PC material (1 ═ 2.8) is used for the radome 10 with a thickness of d22.0mm, and a metamaterial is added to measure the transmitting and receiving power of the transmitting and receiving fov (field of view), as shown in fig. 12, wherein (i) the solid curve is a field pattern without the radome 10, (ii) the dashed curve with a thickness of d22.0mm not being λ 1/2 or its fraction, a standing wave effect is generated to cause a severe distortion of the field pattern, (iii) the one-point chain curve with a thickness of d22.0mm is added with the metamaterial, not only the wave width of the Main beam (Main beam) is reduced and the energy of the Main beam is enhanced, but also the energy of the Side waves (Side beams) on both sides is reduced.
Experiment 3
Referring to fig. 18, fig. 18 is a beam pattern graph of transmit/receive power measurement of a transmit/receive fov (field of view) performed by the radome 10 with different thicknesses D2 and materials in experiment 3 of the present invention. In experiment 3, each of the transmitting and receiving antennas is a single serial array antenna 22, and the thickness D2 of the radome 10 is made of PC material (1 ═ 2.8) and PBT material (2 ═ 3.2), wherein the thickness D2 is defined as the multiple of one-half wavelength (dielectric of the radome 10), that is, the multiple of the one-half wavelength (dielectric of the radome 10)
Reference is made to fig. 13 for transceiver fov (field of view) measurements with radomes 10 of different thickness D2, where (i) the solid line curve is field type without radome 10, (ii) the dashed line curve thickness D21.15mm PC is close to λ 1/2 ═ 1.195mm, with field type compression but minimal distortion, (iii) the dotted line curve thickness D22.33mm PC is close to 2 × (λ 1/2) ═ 2.39mm, likewise with field type compression but less distortion but greater attenuation than PC 1.15mm, (iv) the one-point line curve thickness D22.33mm PC is not λ 1/2 or a multiple thereof, with standing wave effect resulting in severe distortion of field type, (v) the two-point line curve thickness D22.13mm PBT is not λ 2/2 or a multiple thereof, with field type severe distortion effect resulting (vi) the fine line curve thickness D22.26mm close to 2(λ 2/2) with PBT 2.5635 mm, with field type distortion being greater than the first dielectric constant refractive index D33 mm, with field type refractive index being proportional to the first dielectric index D26 mm.
Experiment 4
Referring to fig. 19, fig. 19 is a beam pattern graph of transmit/receive power measurement of fov (field of view) performed by the radome 10 with different thickness D2 and material in experiment 4 of the present invention. In experiment 4, a single serial array antenna 22 is transmitted and received, different radome 10 thicknesses D2 are made of PC materials (1 ═ 2.8), and meta-materials are added to be attached to the radome 10, referring to fig. 14, the radome 10 with different thicknesses D2 and the meta-materials are added to perform transmit and receive power measurement of fov (field of view), wherein (i) the solid line curve is the original field pattern without the radome 10, and (ii) the dotted line curve is the field pattern with the thickness D22.0mm PC which is not λ 1/2 or a multiple thereof, which generates a standing wave effect to cause severe distortion of the field pattern, and (iii) the dotted line curve is the field pattern with the thickness D22.0mm PC and the meta-materials, at this time, the original severely distorted field pattern (dotted line curve) is also subjected to wave width reduction, and the side wave reduction is improved, and the center of the main beam still has a slight recess, but the central energy is higher than that of the meta-. (iv) The one-point chain curve is that the thickness D21.15mm PC is close to lambda 1/2, the field type of the two-point chain curve has compression, but the two-point chain curve with the minimum distortion (v) is that after the metamaterial is added to the thickness D21.15mm PC, the wave width is reduced and the energy is enhanced, and the function of reducing the side wave is very obvious compared with the field type without the metamaterial. By analyzing the measurement data, no matter what the material of the radome 10 or the thickness D2 is λ 1/2 or its multiple, and the addition of the metamaterial has the functions of reducing the main beam width and reducing the side beam energy, so the radome is used for detecting radar in long distance in front of the automobile.
The radar device with main beam energy enhancement, wave width reduction and side beam suppression functions has at least the following advantages.
1. Based on the design principle that the thickness D2 of the radome 10 of the present invention is a multiple of one-half of the wavelength of the radar wave in the radome 10, the radome 10 with a suitable material and thickness D2 may be selected, thereby avoiding a severe distortion of the beam pattern of the antenna 22.
2. For mid-and-long-distance detection radar applications, even though the material and thickness D2 of the radome 10 are not the same, the metamaterial element 30 can have the functions of reducing the main beam width and reducing the side beam energy.
3. Generally, to design the field of the antenna 22 with very narrow beams, more antennas 22 are required to be connected in parallel, which results in an increase in the area of the circuit board, and an increase in the number of side-wave beams and energy of the field of the antenna 22, and if the combination of the metamaterial assembly 30 and a general narrow-beam antenna can replace the very narrow-beam antenna 22, the effect of reducing the area of the antenna 22 and the energy of the side-wave beams can be achieved.
4. The present invention can fix the type size of the antenna 22 and can be used to control different antenna 22 patterns by using different metamaterial elements 30 (different negative refractive indexes).
Claims (9)
1. A radar device with main beam wave width reduction, energy enhancement and side beam suppression functions is characterized in that: the radar apparatus includes:
an antenna housing, in which an accommodation space is formed;
the antenna assembly is arranged in the accommodating space of the antenna housing and comprises an antenna substrate and an antenna arranged on one surface of the antenna substrate, and the antenna is used for transmitting radar waves to detect objects in the external environment; and
the metamaterial assembly is arranged in the accommodating space and is separated from the antenna assembly by a distance, and the metamaterial assembly comprises a fixed substrate, a first metamaterial array and a second metamaterial array; the fixed substrate is attached to the inner surface of the accommodating space of the antenna housing or is integrated in the antenna housing; the first metamaterial array is arranged on one of two opposite surfaces of the fixed substrate and comprises a plurality of first metamaterial units; the second metamaterial array is arranged on the other surface of the fixed substrate and comprises a plurality of second metamaterial units, and the plurality of second metamaterial units respectively correspond to and are aligned with the plurality of first metamaterial units;
the radar wave emitted by the antenna component is along an emission direction facing the metamaterial component, and the spacing is a multiple of one half of the wavelength of the radar wave in the air.
2. The radar apparatus according to claim 1, wherein: the thickness of the radome is a multiple of one-half of the wavelength of the radar wave at the radome material.
3. The radar apparatus according to claim 2, wherein: the thickness of the portion of the radome penetrated by the radar wave is a multiple of one-half of the wavelength of the radar wave at the radome material.
4. The radar apparatus according to any one of claims 1 to 3, wherein: the thickness of the metamaterial component is a multiple of one-half of the wavelength of the radar wave at the metamaterial component.
5. The radar apparatus according to any one of claims 1 to 3, wherein: the antenna is an array antenna.
6. The radar apparatus according to any one of claims 1 to 3, wherein: each first metamaterial unit is provided with a first rectangular outer frame and a first spiral part which is positioned in the first rectangular outer frame and connected with the first rectangular outer frame; each second metamaterial unit is provided with a second rectangular outer frame and a second spiral part which is positioned in the second rectangular outer frame and connected with the second rectangular outer frame; the fixed substrate is provided with a plurality of through holes plated with metal conductors in a penetrating mode, the number of the through holes corresponds to the first metamaterial units and the second metamaterial units, and each through hole is connected with the corresponding first metamaterial unit and the corresponding second metamaterial unit respectively.
7. The radar apparatus according to any one of claims 1 to 3, wherein: the metamaterial element has a negative refractive index.
8. The radar apparatus according to any one of claims 1 to 3, wherein: the radome has a positive refractive index.
9. The radar apparatus according to any one of claims 1 to 3, wherein: the absolute value of the negative refractive index of the metamaterial assembly is larger than the absolute value of the positive refractive index of the radome.
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| CN201910018310.9A CN111427013A (en) | 2019-01-09 | 2019-01-09 | Radar device with main beam wave width reducing and side beam inhibiting function |
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