CN117678122A - Dielectric lenses and antenna modules - Google Patents
Dielectric lenses and antenna modules Download PDFInfo
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- CN117678122A CN117678122A CN202280050742.8A CN202280050742A CN117678122A CN 117678122 A CN117678122 A CN 117678122A CN 202280050742 A CN202280050742 A CN 202280050742A CN 117678122 A CN117678122 A CN 117678122A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
- H01Q15/08—Refracting or diffracting devices, e.g. lens, prism formed of solid dielectric material
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Abstract
本公开提供一种能够在维持着是平面波的原状下变更为平面波的电磁波的特性的电介质透镜。电介质透镜(1)具有入射面(2)和处于与入射面(2)相反侧的出射面(3)。入射面(2)和出射面(3)各自是曲面，并且各自以假想直线(S)为中心旋转对称。入射面(2)和出射面(3)不是相互相同的形状。在使为平面波的电磁波在沿着假想直线(S)的方向行进而向入射面(2)入射的情况下，从出射面(3)出射为平面波的电磁波。
The present disclosure provides a dielectric lens that can change the characteristics of an electromagnetic wave into a plane wave while maintaining the original state of being a plane wave. A dielectric lens (1) has an incident surface (2) and an exit surface (3) on the opposite side to the incident surface (2). Each of the incident surface (2) and the emergent surface (3) is a curved surface, and each is rotationally symmetrical about an imaginary straight line (S). The entrance surface (2) and the exit surface (3) do not have the same shape as each other. When the electromagnetic wave which is a plane wave is made to travel in the direction along the imaginary straight line (S) and is incident on the incident surface (2), the electromagnetic wave which is a plane wave is emitted from the emission surface (3).
Description
Technical Field
The present disclosure relates to a dielectric lens and an antenna module, and more particularly, to a dielectric lens for converting an incident electromagnetic wave and emitting the converted electromagnetic wave, and an antenna module including the dielectric lens.
Background
Patent document 1 discloses an antenna array (array antenna) in which a plurality of microstrip line elements (element antennas) formed by etching a resin substrate are arranged.
Patent document 2 discloses a technique for transmitting electromagnetic waves emitted from 1 radiator through a dielectric lens to obtain only a desired radiation directivity by the dielectric lens.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2012-220418
Patent document 2: japanese patent laid-open No. 2002-246832
Disclosure of Invention
The subject of the present disclosure is to provide a dielectric lens capable of changing the characteristics of electromagnetic waves, which are plane waves, while maintaining the characteristics of electromagnetic waves, and an antenna module including the dielectric lens.
A dielectric lens according to an aspect of the present disclosure has an incident surface and an exit surface on the opposite side of the incident surface; the incident surface and the emission surface are each curved surfaces and are each rotationally symmetrical about an imaginary straight line intersecting with either one of the incident surface and the emission surface; the incident surface and the exit surface are not in the same shape; when an electromagnetic wave, which is a plane wave, is made to travel in a direction along the virtual straight line and is made to enter the incident surface, the electromagnetic wave is emitted as a plane wave from the emission surface.
An antenna module according to an aspect of the present disclosure includes: the dielectric lens; and a radiator that emits electromagnetic waves, which are plane waves, that travel in a direction along the virtual straight line and are incident on the incident surface.
Drawings
Fig. 1 is a schematic cross-sectional view of a dielectric lens and antenna module relating to an embodiment of the present disclosure.
Fig. 2 is an example of an optical model for deriving the shapes of the incident surface and the exit surface according to the present embodiment.
Fig. 3 is a graph showing the relative electromagnetic field intensity distribution of an incident wave set for specifically calculating the shape of a dielectric lens in the example of the present embodiment.
Fig. 4 is a graph showing the relative electromagnetic field intensity distribution of an incident wave set for specifically calculating the shape of a dielectric lens in the example of the present embodiment. A step of
Fig. 5 is a diagram showing the shape of the dielectric lens identified in the example of the present embodiment.
Fig. 6 is a diagram showing electromagnetic field simulation results in the case where electromagnetic waves pass through a dielectric lens in the example of the present embodiment.
Fig. 7 is a graph showing the relative electromagnetic field intensity distribution of the outgoing wave extracted from the electromagnetic field simulation result of fig. 6.
Fig. 8 is a graph showing the relative electromagnetic field intensity distribution of the incident wave extracted from the electromagnetic field simulation result of fig. 6.
Detailed Description
With the increase in the frequency of the use frequency band of the wireless communication system and the transition of the communication system, the practical use of a sensor system using electromagnetic waves, and the like, antenna characteristics such as directivity required for electromagnetic waves emitted from an antenna module have been diversified. Since electromagnetic waves have high directivity, it is required that electromagnetic waves are plane waves. In addition, the directivity of electromagnetic waves is affected by the beam diameter of the electromagnetic waves and the electromagnetic field intensity distribution.
Therefore, in order to change the directivity of the electromagnetic wave emitted from the antenna module, the design of the antenna module must be re-performed from the beginning, which consumes a lot of effort. For example, in the case of an array antenna as disclosed in patent document 1 (japanese patent application laid-open No. 2012-220418), the shape, number, arrangement, power supply output, and the like of element antennas must be redesigned so that electromagnetic waves have a desired beam diameter and electromagnetic field intensity distribution.
In order to solve the above problems, the inventors have conceived that a dielectric lens for converting a plane wave having a certain beam diameter and electromagnetic field intensity distribution into a desired beam diameter and electromagnetic field intensity distribution is provided.
For example, in the technique described in patent document 2 (japanese patent application laid-open No. 2002-246832), electromagnetic waves emitted from the 1 st radiator are converted using a dielectric lens to impart directivity, but the directivity of the antenna device that emits plane waves is not changed.
Accordingly, the present inventors have completed the present disclosure by developing a dielectric lens capable of changing the characteristics of electromagnetic waves, which are plane waves, while maintaining the characteristics of electromagnetic waves, which are plane waves. In addition, the source of this development is not limiting of the disclosure.
The dielectric lens 1 and the antenna module 10 according to the present embodiment will be described with reference to fig. 1. The broken line in fig. 1 indicates the direction in which the electromagnetic wave travels and the electromagnetic field intensity distribution of the electromagnetic wave.
The dielectric lens 1 has an incident surface 2 and an exit surface 3 on the opposite side of the incident surface 2. The incident surface 2 and the exit surface 3 are curved surfaces, and are rotationally symmetrical about an imaginary straight line S intersecting both the incident surface 2 and the exit surface 3. The entrance face 2 and the exit face 3 are not of mutually identical shape. When an electromagnetic wave (hereinafter also referred to as an incident wave I) that is a plane wave is caused to travel in a direction along the virtual straight line S and is incident on the incident surface 2, the electromagnetic wave (hereinafter also referred to as an outgoing wave E) that is a plane wave is emitted from the emission surface 3. That is, although the shape of the incident surface 2 and the shape of the emission surface 3 are not the same, when the incident wave I is made to enter the incident surface 2 while traveling in the direction of the virtual straight line S, each of the incident surface 2 and the emission surface 3 is formed in such a shape that the emission wave E is emitted as a plane wave from the emission surface 3.
In the present embodiment, the electromagnetic wave is a plane wave, and can be confirmed by the following method. The vibration component of the electromagnetic wave at the frequency f is extracted from the fluctuation electromagnetic field component at a certain point in the space through which the electromagnetic wave at the frequency f passes, and the vibration phase is measured. The plane formed by the set of points where the vibration phases extracted in this way are equal is referred to as a phase plane. The electromagnetic wave is assumed to be a plane wave when the predetermined phase plane is included between two virtual planes orthogonal to the virtual straight line S and spaced apart by a spacing position of (1/4) ×λ. λ is the wavelength of electromagnetic waves in vacuum, and is defined by the equation of λ=c/f according to the frequency f of electromagnetic waves and the speed c of light in vacuum.
In the present embodiment, the focal distance of the plane wave is infinity, or may be considered infinity.
According to the present embodiment, the incident wave I, which is a plane wave, can be converted into the outgoing wave E, which is a plane wave, by the dielectric lens 1. Since the incident surface 2 and the outgoing surface 3 are not in the same shape, the electromagnetic field distribution of the incident wave I and the electromagnetic field distribution of the outgoing wave E can be made different, and the beam radius of the incident wave I and the beam radius of the outgoing wave E can be made different. Therefore, only the dielectric lens 1 can convert an incident wave I, which is a plane wave, into an outgoing wave E, which is a plane wave having characteristics different from those of the incident wave I. That is, the dielectric lens 1 can change the characteristics of electromagnetic waves converted into plane waves while maintaining the original state of the plane waves.
The dielectric lens 1 is preferably made of isotropic dielectric. Isotropic dielectrics are substances whose dielectric constant tensor only has the value of the diagonal component and they have the same value. Specific examples of the isotropic dielectric include glass having no internal stress, low dielectric constant resins such as fluororesin having no internal stress, water and air. The dielectric lens 1 is made of glass or a low dielectric constant resin, for example. The relative permittivity of the dielectric lens 1 is, for example, 1.8 to 6.5. The relative permittivity of the dielectric lens 1 may not necessarily be in the above range, and may be appropriately designed according to the application or the like.
As described above, the dielectric lens 1 has the incident surface 2 and the exit surface 3. The incident surface 2 and the emission surface 3 are arranged in a direction along an imaginary straight line S intersecting both the incident surface 2 and the emission surface 3. The incident surface 2 is directed to the side opposite to the emission surface 3 side with respect to the incident surface 2, and the emission surface 3 is directed to the side opposite to the incident surface 2 side with respect to the emission surface 3. The incident surface 2 and the exit surface 3 are rotationally symmetrical about an imaginary straight line S. Therefore, the virtual straight line S may be a line intersecting the incident surface 2 at the center of the incident surface 2 and intersecting the emission surface 3 at the center of the emission surface 3. Furthermore, the shape of the entrance surface 2 is different from the shape of the exit surface 3. Thus, the electromagnetic field distribution of the incident wave I can be made different from the electromagnetic field distribution of the outgoing wave E, or the beam radius of the incident wave I can also be made different from the beam radius of the outgoing wave E.
As described above, the incident wave I and the outgoing wave E preferably have mutually different electromagnetic field intensity distributions. This makes it possible to make the characteristics of the outgoing wave E different from those of the incoming wave I.
When the electromagnetic field intensity distribution is made different between the incident wave I and the outgoing wave E, the electromagnetic field intensity distribution of the outgoing wave E is preferably more sparse as the electromagnetic field intensity distribution of the incident wave I is farther from the virtual straight line S in a case where the electromagnetic field intensity distribution is uniform in a direction orthogonal to the virtual straight line S. The electromagnetic wave emitted from the outer edge of the emission surface 3 is likely to be a spherical wave, which is likely to cause unwanted electromagnetic waves such as side lobes to be generated by interference. However, if the electromagnetic field intensity distribution of the outgoing wave E becomes more sparse as it is farther from the virtual straight line S, the electromagnetic field intensity distribution of the electromagnetic wave outgoing from the outer edge of the outgoing surface 3 becomes lower, and therefore side lobes are less likely to occur.
As described above, the beam radius of the incident wave I and the beam radius of the outgoing wave E are preferably different from each other. This makes it possible to make the directivity of the outgoing wave E different from that of the incoming wave I. That is, if the beam radius of the outgoing wave E is larger than the beam radius of the incoming wave I, the directivity of the outgoing wave E can be improved than the incoming wave I, and if the beam radius of the outgoing wave E is smaller than the beam radius of the incoming wave I, the directivity of the outgoing wave E can be made lower than the incoming wave I.
An example of specific shapes of the entrance surface 2 and the exit surface 3 of the dielectric lens 1 will be described.
Let the refractive index of the dielectric lens 1 be n. A coordinate plane is defined in which the z axis is the axis passing through the virtual straight line S and the x axis is the arbitrary axis orthogonal to the z axis. Let z-axis coordinate value of intersection point of z-axis and incidence plane 2 be z c1 And the z-axis coordinate value of the intersection point of the z-axis and the emission surface 3 is z c2 。
Preferably, the coordinate (z) on the incident surface 2 when the x-axis coordinate value in the coordinate plane is r 1 (R), R) and the coordinates (z) on the emission surface 3 when the x coordinate value is R 2 (R), R) satisfies the following formula. Coordinate (z) 1 (r), r) and coordinates (z 2 (R), R) has an incidence-to-coordinate (z) in the incident wave I 1 The part in (r), r) is derived from the coordinates (z 2 (R), R is a relation of partial emission of the emission wave E, and R is represented by R (R) as a function of R.
[ number 1]
(wherein,)
as shown in the optical model of FIG. 2, z in the above formula c1 Is the z-axis coordinate value of the intersection point of the z-axis and the incident surface 2, z c2 Is the z-axis coordinate value of the intersection of the z-axis and the exit surface 3. P (P) 1 (r) is the electromagnetic field intensity representing the incident wave I at the position where the x-axis coordinate value on the coordinate plane is rFunction of distribution, P 2 (R) is a function representing the electromagnetic field intensity distribution of the outgoing wave E at the position where the x-axis coordinate value on the coordinate plane is R. Wherein 0 r max And 0.ltoreq.Rr.ltoreq.Rr max . I.e. r max Is the radius of the incident surface 2, R max Is the radius of the exit face 3. In addition, r max And R is max It is preferable to multiply the wavelength of the incident wave I under vacuum by a value of 2 times or more.Is an auxiliary variable which is a function representing the refraction angle of the incident wave I when the incident wave I is incident into the dielectric lens 1 from the incident plane 2 at the position of the coordinate plane where the x-axis coordinate value is r, and +.>Is 0. In addition, the optical model of fig. 2 is not an optical model that accurately represents the shape of the dielectric lens 1.
The above [ number type 1]]The 4 equations shown in (a) are derived independently by the inventors by expressing the law of refraction of the incident surface 2 and the outgoing surface 3 (Snell's law), the law of conservation of energy for electromagnetic waves, and the law of constant optical path length in the form of geometrical optics by using the above-mentioned coordinate system and the respective amounts expressed in the coordinate system. If the shape z of the incident surface 2 is to be 1 (r) and shape z of the exit face 3 2 (R) is set as an indeterminate function, then due to the law of refraction, the refractive index is determined by z 1 (r) and z 2 The first-order differential equation of (R) is expressed so long as z 1 (r) and z 2 The respective quantities other than (R) are given as initial conditions, so that the uncertainty function z can be determined from 4 independent equations 1 (r)、z 2 (R)。
The inventors confirmed that the above formula is reasonable by a numerical verification experiment shown in the column of examples.
For the above [ formula 1]]The predetermined shape of the entrance surface 2 and the predetermined shape of the exit surface 3 allow dimensional errors that may occur in general. For example, when the relative dielectric constant is ε r Is used for the dielectric lens 1 of (a)When the incident wave I having the wavelength lambda in vacuum is converted, at least, -lambda/16/epsilon is allowed in the z-axis direction (direction along the virtual straight line S) for each of the shape of the incident surface 2 and the shape of the outgoing surface 3 r 1/2 The lambda/16/epsilon r 1/2 The following dimensional errors. Specifically, in the case where the material of the dielectric lens 1 is a fluororesin (polytetrafluoroethylene) having a relative permittivity of 2.0, and the dielectric lens 1 is used for converting an incident wave I having a frequency of 79GHz (i.e., a wavelength of 3.8mm in vacuum) suitable for an automotive anti-collision radar, the shape of the incident surface 2 and the shape of the outgoing surface 3 are allowed to be-3.8/16/2.0 in a direction along the virtual straight line S 1/2 3.8/16/2.0 mm above 1/2 Dimensional errors of less than or equal to mm, i.e., -0.17mm to 0.17 mm.
It is generally preferred that the output wave E is defined by P 2 The value of the electromagnetic field intensity distribution expressed by the function of (R) is defined as smaller as the value of R is larger. For example, by P 2 The electromagnetic field intensity distribution represented by the function of (R) preferably has a gaussian distribution. In this case, the electromagnetic field intensity distribution of the outgoing wave E becomes more sparse as it is farther from the virtual straight line S, and therefore side lobes are less likely to occur. In addition, due to P 1 (r)、P 2 Specifically, for example, by using an electromagnetic field intensity distribution having a predetermined side lobe value and having the most sharp directivity as represented by chebyshev distribution, the directivity (gain) can be improved while suppressing the side lobe.
R is as described above max The value of (2) and R max For example at r max <R max Is a relationship of (3). In this case, since the beam radius of the outgoing wave E is larger than that of the incoming wave I, the dielectric lens 1 can improve the directivity of the outgoing wave E, that is, the gain. r is (r) max The value of (2) and R max The value of (2) may also be r max >R max Is a relationship of (3). In this case, since the beam radius of the outgoing wave E is smaller than that of the incoming wave I, the dielectric lens 1 can reduce the directivity of the outgoing wave E.
The antenna module 10 according to the present embodiment will be described.
The antenna module 10 includes a dielectric lens 1 and a radiator 4. The radiator 4 emits electromagnetic waves, which are plane waves, and makes the electromagnetic waves travel in a direction along the virtual straight line S and enter the incident surface 2 of the dielectric lens 1. The electromagnetic wave emitted from the radiator 4 becomes the incident wave I.
The radiator 4 includes an antenna 5 that emits electromagnetic waves as plane waves. The antenna 5 is, for example, an array antenna including a plurality of element antennas. In addition, the structure of the antenna 5 is not limited to the array antenna.
The dielectric lens 1 is disposed such that, for example, the antenna 5 of the radiator 4 faces the incident surface 2 of the dielectric lens 1, and the central axis (optical axis) of the electromagnetic wave (incident wave I) emitted from the radiator 4 overlaps the virtual straight line S.
The entrance surface 2 and the exit surface 3 of the dielectric lens 1 have shapes specified by the above-described equations, for example. In this case, it is preferable that the electromagnetic field intensity distribution at the position where the x-axis coordinate value of the electromagnetic wave (incident wave I) emitted from the radiator 4 is r is defined by the above-mentioned P 1 (r) and the beam radius of the incident wave I is r max . In this case, the electromagnetic field intensity distribution at the position where the x-axis coordinate value of the outgoing wave E emitted from the dielectric lens 1 is R is defined by the above-mentioned P 1 (R) and the beam radius of the outgoing wave E is R max . In this way, the characteristics of the electromagnetic wave emitted from the radiator 4 as a plane wave can be changed by the dielectric lens 1 while the plane wave is maintained.
Therefore, according to the present embodiment, even when the same radiator 4 is used, the antenna module 10 that emits a plane wave having a desired characteristic can be realized by merely changing the shape of the dielectric lens 1. That is, in the present embodiment, in the antenna module 10 including the radiator 4 that emits the plane wave, the shape of the dielectric lens 1 may be designed so that the characteristics of the plane wave emitted from the antenna module 10 become desired, even if the antenna 5 of the radiator 4 is not separately designed.
In the present embodiment, the dielectric lens 1 may also serve as a radome. In this case, a function of changing the characteristics of electromagnetic waves, which are plane waves, can be provided to the radome that is originally a part of the housing. Further, by changing the shape of the radome, the antenna module 10 which emits a plane wave having a desired characteristic can be realized.
Examples
Hereinafter, a specific design result of the dielectric lens calculated using the expression shown in [ expression 1] of the present embodiment and a result of experimentally confirming whether or not the designed dielectric lens is correctly operated by an electromagnetic field simulator (finite element method) are shown. The present embodiment is not limited to the following.
First, in order to specifically calculate the shape of the dielectric lens using the expression expressed in [ equation 1], the following initial conditions are set.
Dielectric constant (. Epsilon.) of the substance constituting the dielectric lens r )：1.96
-shape of the entrance face: round shape
The aperture diameter of the incident face (2 xr max )：2
Shape of the exit face: round shape
The aperture diameter of the exit face (2X R max )：3.8
Distance between intersection of the imaginary straight line with the entrance face and intersection of the imaginary straight line with the exit face: 2.0
-electromagnetic field intensity distribution of incident waves: the uniform distribution shown in fig. 3. The distribution shown in fig. 3 is a distribution of relative electromagnetic field intensity, which is a value obtained by dividing the electromagnetic field intensity on the incident surface by the electromagnetic field intensity at the intersection point of the virtual straight line and the incident surface. The relative electromagnetic field strength is a dimensionless quantity, but the relative electromagnetic field strength shown in fig. 3 is expressed in dB, and therefore, the relative electromagnetic field strength on the imaginary straight line becomes 0dB.
Electromagnetic field intensity distribution of the outgoing wave: -30dB n=4 pseudo Taylor (pseudo Taylor) distribution shown in fig. 4. Fig. 4 is a distribution of relative electromagnetic field intensity, which is a value obtained by dividing the electromagnetic field intensity at the intersection of the virtual straight line on the emission surface 3 and the emission surface 3. The relative electromagnetic field strengths shown in fig. 4 are expressed in dB.
Design guidelines and various notes set when the initial conditions are selected are described.
Polytetrafluoroethylene was selected as the dielectric applied to the dielectric lens. Therefore, the relative permittivity ε of the dielectric material that will constitute the dielectric lens r Set to 1.96. In addition, attenuation of electromagnetic waves due to dielectric loss is often a problem in the high frequency band of millimeter wave or more, and polytetrafluoroethylene is often used as a dielectric lens material in the frequency band of millimeter wave or more because polytetrafluoroethylene has low dielectric loss.
In addition, in the present design, by combining an antenna which has a circular opening surface and emits electromagnetic waves having a uniform electromagnetic field intensity distribution with the dielectric lens of the present embodiment, the purpose of lowering side lobes of the electromagnetic waves (suppression of radiated electromagnetic waves is not required) and increasing gain (narrowing beam) is achieved.
By setting the above conditions, the relative permittivity intensity distribution in the emission surface is set. A circular aperture antenna having a uniform relative electromagnetic field intensity distribution is easy to design and manufacture, while it is necessary to generate side lobes (unnecessary electromagnetic waves other than the main beam) having a relative electromagnetic field intensity higher than-17.6 dB with reference to the maximum electromagnetic field intensity of the main beam (electromagnetic wave emitted in the optical axis direction). Therefore, in a communication system requiring no radiation suppression such that the relative electromagnetic field intensity of the side lobe is-17.6 dB or less (for example, in an automotive anti-collision radar requiring no radiation suppression such that the relative electromagnetic field intensity of the side lobe is-20 dB or less), an antenna that emits electromagnetic waves having a uniform relative electromagnetic field intensity cannot be used, and it is necessary to design an antenna that does not require higher radiation suppression, or to correct electromagnetic waves by combining the antenna with the dielectric lens of the present embodiment.
Based on the above design guidelines, in the present embodiment, a relative electromagnetic field intensity distribution (-30 dB n=4 pseudo Taylor distribution) on the emission surface, in which the relative electromagnetic field intensity of the side lobe of the emission wave is-30 dB or less, is set.
In the above initial conditions, the opening diameters of the incident surface and the emission surface and the distance between the incident surface and the emission surface are dimensionless times, but the design method using [ equation 1] is a method in a geometrical optical region having no frequency dependency, so that only the ratio of these 3 dimensions is important, and in the design stage based on [ equation 1], it is not necessary to set the actual dimensions as initial conditions. Therefore, the opening surface radius of the emission surface is set to 1 under the initial condition so that the ratio of the dimensions of each portion with respect to the opening diameter of the incident surface can be easily known. In addition, after each specification of the antenna having frequency correlation such as antenna gain actually required in the communication system is defined, the 3 sizes may be enlarged with an equal scale to be replaced with actual sizes.
Fig. 5 shows the shape of a dielectric lens given by applying the original condition described above to [ equation 1], and solving the simultaneous differential equation constituting [ equation 1] by using the ringe-Kutta (longge-Kutta) method. According to fig. 5, both the shape of the entrance surface and the shape of the exit surface are aspherical. Fig. 5 also shows the path of electromagnetic waves obtained by ray tracing based on the shapes of the incident surface and the exit surface. The electromagnetic wave is incident on the dielectric lens such that the optical axis thereof passes through the center of the incident surface and the center of the exit surface, that is, such that the optical axis of the electromagnetic wave overlaps the virtual straight line S. The path of the electromagnetic wave is represented by a plurality of lines indicating the traveling direction of the electromagnetic wave, and the density of the lines indicates the intensity of the electromagnetic wave. Since the incident wave set by the initial condition is a plane wave in which the electromagnetic field intensity is uniform in the entire area of the opening surface and travels in a direction parallel to the optical axis, the path of the incident wave in fig. 5 is represented by straight lines at equal intervals parallel to the optical axis. The electromagnetic wave is refracted while passing through the incident surface so that a position farther from the optical axis becomes farther from the optical axis, and thus the beam diameter of the electromagnetic wave is enlarged in the dielectric lens 1. The electromagnetic wave (outgoing wave) outgoing from the outgoing plane is represented by parallel lines parallel to the optical axis, and the interval of the parallel lines becomes larger as it is farther from the optical axis. This means that the outgoing wave is a plane wave traveling in a direction parallel to the optical axis, and the farther the relative electromagnetic field intensity of the outgoing wave is from the optical axis, the more attenuated.
In order to confirm the rationality of the design method using the dielectric lens of [ formula 1], it was confirmed by electromagnetic field simulation that plane waves having a uniform relative electromagnetic field intensity distribution were converted into plane waves having a relative electromagnetic field intensity distribution of-30 dB n=4 pseudo Taylor (pseudo Taylor) by passing through the dielectric lens designed as shown in fig. 5. The results are shown below.
Since the actual size is required for electromagnetic field simulation, the dielectric lens shown in fig. 5 is expanded in shape with an equal scale, and the size of the dielectric lens is set as follows.
Calculate frequency (frequency of electromagnetic waves): 79GHz (wavelength 3.80 mm)
Diameter of the entrance face: 19mm (5 times the wavelength of electromagnetic waves)
Diameter of the exit face: 36.1mm (9.5 times the wavelength of electromagnetic waves)
Distance of the entrance face from the exit face: 38mm (10 times the wavelength of electromagnetic waves)
-electromagnetic field simulator used: femto 2020.1.2 64bit
In addition, as long as the diameter of the incident surface is specified, the dimensions other than the diameter of the incident surface of the dielectric lens are also uniquely determined according to the initial conditions set in the design based on [ equation 1 ]. The diameter of the incident surface is selected as described above, taking into consideration the calculation time required for electromagnetic field simulation and the aperture diameter of the dielectric lens for which the geometrical optics underlying [ equation 1] are established. The larger the open diameter of the dielectric lens compared with the wavelength of the electromagnetic wave, the more consistent the geometrical optics and the actual dynamics of the electromagnetic wave. However, since the analysis region is large in the dielectric lens having such a large aperture, a large amount of time is required for electromagnetic field simulation. From these two opposite perspectives, the diameter of the incident surface is set.
Fig. 6 shows electromagnetic field simulation results in the case where electromagnetic waves pass through a dielectric lens under the above-described conditions. Fig. 6 shows a state in which an electromagnetic wave, which is a plane wave having parallel electric field vectors and having uniform electric field intensity distribution, enters a dielectric lens such that the optical axis of the electromagnetic wave passes through the center of the entrance surface and the center of the exit surface, that is, such that the optical axis overlaps the virtual straight line S, and is refracted at the entrance surface and then refracted at the exit surface. In addition, the optical axis coincides with the lower boundary of fig. 6. The shades in fig. 6 indicate the intensity of the electromagnetic field intensity, and the whiter indicates the stronger the electromagnetic field intensity. According to fig. 6, if an electromagnetic wave is incident on the incident surface from the left side of the incident surface, the electromagnetic wave traveling in the dielectric lens is substantially a plane wave in the vicinity of the optical axis, but spreads so as to become farther from the optical axis at a position farther from the optical axis. Then, if the electromagnetic wave passes through the exit surface, the electromagnetic wave becomes a plane wave again, but the electromagnetic field intensity becomes weaker as the position is farther from the optical axis. Further, if the interval between the fringes formed by the depths in fig. 6 is based on, a shortening (0.71 times) of the wavelength of the electromagnetic wave inversely proportional to the 1/2 th power of the relative dielectric constant (1.96) in the dielectric lens can be observed. From the above, it can be qualitatively confirmed that the dielectric lens design method according to [ equation 1] of the present embodiment functions correctly.
In the following, a result of examining whether or not the electric field intensity distribution of the outgoing wave calculated from the electromagnetic field simulation matches the pseudo Taylor distribution assumed at the time of design, i.e., -30dB n=4, is identical to the electromagnetic field intensity distribution quantitatively confirmed from the electromagnetic field intensity distribution shown in fig. 6.
Fig. 7 and 8 show the relative electromagnetic field intensity distribution extracted from the electromagnetic field simulation result of fig. 6. Fig. 7 shows the relative electromagnetic field intensity distribution of the outgoing wave along the axis of the right boundary of fig. 6, and fig. 8 shows the relative electromagnetic field intensity distribution of the incoming wave along the axis of the left boundary of fig. 6.
In fig. 7, the horizontal axis represents the distance from the optical axis when the radius of the emission surface is 1. The circular marks in fig. 7 represent the relative electromagnetic field strengths calculated by electromagnetic field simulation. The solid line in fig. 7 shows the relative electromagnetic field intensity distribution obtained by correcting the-30 dB n=4 pseudo Taylor (pseudo Taylor) distribution by the correction curved surface method in consideration of the respective reflection attenuations of the incident surface and the exit surface. The modified surface method is a dielectric lens design method according to the present embodiment using [ formula 1 ]. In this embodiment, the shapes of the incident surface and the exit surface are designed without considering the reflection attenuation of each of the incident surface and the exit surface, but for quantitative confirmation, the result of correcting the initial condition-30 dB n=4 pseudo Taylor (pseudo Taylor) distribution by considering the reflection attenuation should be compared with the relative electromagnetic field intensity calculated by electromagnetic field simulation.
In fig. 8, the horizontal axis represents the distance from the optical axis when the radius of the incident surface is 1. The circular marks in fig. 8 represent the relative electromagnetic field strengths calculated by electromagnetic field simulation. The solid line in fig. 8 represents the uniform relative electromagnetic field intensity distribution set as the initial condition.
From fig. 7, it can be seen that there is a difference of about 3dB or less in the vicinity of the optical axis and about 5dB in the periphery of the emission surface between the result of electromagnetic field simulation and the transmittance of the dielectric lens obtained by the modified surface method. However, according to fig. 8, since the difference in the relative electromagnetic field intensity of the electromagnetic wave on the incident surface side is at most 3dB, the difference in transmittance between the result of electromagnetic field simulation shown in fig. 7 and the dielectric lens obtained by the modified surface method is within a reasonable range, and it can be determined that the two are identical. The non-uniformity of the relative electromagnetic field intensity calculated by the electromagnetic field simulation shown in fig. 8 occurs because the analysis area (diameter of the incident surface) is small, and is not a cause of the electromagnetic field simulator used.
As is clear from the above-described embodiments, the dielectric lens (1) according to the first aspect of the present disclosure has an incident surface (2) and an exit surface (3) on the opposite side of the incident surface (2). The incident surface (2) and the emission surface (3) are each curved surfaces, and are each rotationally symmetrical about an imaginary straight line (S) intersecting either the incident surface (2) or the emission surface (3). The entrance surface (2) and the exit surface (3) are not of the same shape. When an electromagnetic wave, which is a plane wave, is made to enter the incident surface (2) while traveling in the direction of the virtual straight line (S), the electromagnetic wave, which is a plane wave, is emitted from the emission surface (3).
According to the first aspect, the dielectric lens (1) can change the characteristics of electromagnetic waves converted into plane waves while maintaining the original state of the plane waves.
In a second aspect of the present disclosure, in the first aspect, the electromagnetic wave incident to the incident surface (2) and the electromagnetic wave emitted from the emission surface (3) have mutually different electromagnetic field intensity distributions.
According to the second aspect, the electromagnetic wave emitted from the emission surface (3) can be made different from the electromagnetic wave incident on the incidence surface (2).
In a third aspect of the present disclosure, in the first or second aspect, a beam radius of the electromagnetic wave incident on the incident surface (2) and a beam radius of the electromagnetic wave emitted from the emission surface (3) are different from each other.
According to the third aspect, the directivity of the electromagnetic wave emitted from the emission surface (3) can be made different from the directivity of the electromagnetic wave incident on the incidence surface (2).
In a fourth aspect of the present disclosure, in any one of the first to third aspects, when the electromagnetic field intensity distribution of the electromagnetic wave incident on the incident surface (2) is uniform in a direction orthogonal to the virtual straight line (S), the electromagnetic field intensity distribution of the electromagnetic wave emitted from the emission surface (3) becomes more sparse as the electromagnetic field intensity distribution is farther from the virtual straight line (S).
According to the fourth aspect, the electromagnetic field intensity distribution of the electromagnetic wave emitted from the outer edge of the emission surface (3) becomes low, and therefore side lobes are less likely to occur.
In a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the refractive index of the dielectric lens (1) is n, and if a coordinate plane is defined in which an axis passing through the virtual straight line (S) is a z-axis and an arbitrary axis orthogonal to the z-axis is an x-axis, the coordinate (z) on the incident surface (2) in which an x-axis coordinate value in the coordinate plane is r 1 (R), R) and the coordinates (z) on the exit face (3) where the x coordinate value is R 2 (R), R) satisfies the following formula. However, R is represented by R (R) which is a function of R.
[ number 2]
(wherein,)
in the formula, z c1 Is the z-axis coordinate value of the intersection point of the z-axis and the incident plane (2), z c2 Is the z-axis coordinate value of the intersection point of the z-axis and the emitting surface (3), P 1 (r) is a function representing the electromagnetic field intensity distribution of the electromagnetic wave incident on the incident surface (2) at the position where the x-axis coordinate value on the coordinate plane is r, P 2 (R) is a function representing the electromagnetic field intensity distribution of the electromagnetic wave emitted from the emission surface (3) at the position where the x-axis coordinate value on the coordinate plane is R, wherein 0 +.r +. max And 0.ltoreq.R.ltoreq.R max 。Is an auxiliary variable which is a function representing the refraction angle of an electromagnetic wave when the electromagnetic wave is incident into the dielectric lens (1) from the incident surface (2) at the position of the x-axis coordinate value r on the coordinate plane, and>is 0.
According to the fifth aspect, the dielectric lens (1) capable of changing the characteristics of the electromagnetic wave which is a plane wave to the electromagnetic wave of the plane wave while maintaining the original state of the plane wave can be realized.
An antenna module (10) pertaining to a sixth aspect of the present disclosure is provided with: a dielectric lens (1) relating to any one of the first to fifth aspects; and a radiator (4) which emits electromagnetic waves, which are plane waves, and which makes the electromagnetic waves travel in a direction along an imaginary straight line (S) and enter the incident surface (2).
According to the sixth aspect, the dielectric lens (1) can change the characteristics of electromagnetic waves, which are plane waves, emitted from the radiator (4) while maintaining the original state of the plane waves.
In a seventh aspect of the present disclosure, in the sixth aspect, the dielectric lens (1) doubles as a radome.
In the seventh aspect, a function of changing the characteristics of electromagnetic waves, which are plane waves, can be provided to the radome that is originally a part of the casing.
Description of the reference numerals
1. Dielectric lens
2. Incidence plane
3. Exit surface
4. Radioactive device
5. Antenna
Claims (8)
1. A dielectric lens, comprising a lens body and a lens body,
an exit surface having an entrance surface and an exit surface opposite to the entrance surface;
the incident surface and the emission surface are each curved surfaces and are each rotationally symmetrical about an imaginary straight line intersecting with either the incident surface or the emission surface;
the incident surface and the exit surface are not in the same shape;
when an electromagnetic wave, which is a plane wave, is made to travel in a direction along the virtual straight line and is made to enter the incident surface, the electromagnetic wave is emitted as a plane wave from the emission surface.
2. The dielectric lens of claim 1,
the electromagnetic wave incident on the incident surface and the electromagnetic wave emitted from the emission surface have mutually different electromagnetic field intensity distributions.
3. The dielectric lens of claim 1 or 2,
the beam radius of the electromagnetic wave incident on the incident surface and the beam radius of the electromagnetic wave emitted from the emission surface are different from each other.
4. The dielectric lens of claim 1 or 2,
when the electromagnetic field intensity distribution of the electromagnetic wave incident on the incident surface is uniform in a direction perpendicular to the virtual straight line, the electromagnetic field intensity distribution of the electromagnetic wave emitted from the emission surface becomes more sparse as the distance from the virtual straight line increases.
5. The dielectric lens of claim 3,
when the electromagnetic field intensity distribution of the electromagnetic wave incident on the incident surface is uniform in a direction perpendicular to the virtual straight line, the electromagnetic field intensity distribution of the electromagnetic wave emitted from the emission surface becomes more sparse as the distance from the virtual straight line increases.
6. The dielectric lens of claim 1,
the refractive index of the dielectric lens is n;
if a coordinate plane is defined in which the axis passing through the virtual straight line is the z-axis and any axis orthogonal to the z-axis is the x-axis,
the coordinate (z) on the incident surface at the x-axis coordinate value r in the coordinate plane 1 (R), R) and x coordinate values are R (z) 2 (R) satisfies the following formula, wherein R is represented by R (R) as a function of R,
[ number 1]
In the above-mentioned formula (i), the water,
z c1 is the z-axis coordinate value of the intersection point of the z-axis and the incident plane, z c2 A z-axis coordinate value which is the intersection point of the z-axis and the emission surface;
P 1 (r) is a function of electromagnetic field intensity distribution of electromagnetic waves incident on the incident surface at a position where the x-axis coordinate value on the coordinate plane is r, P 2 (R) is a function of electromagnetic field intensity distribution of electromagnetic waves emitted from the emission surface at a position where an x-axis coordinate value on the coordinate plane is R, wherein 0R max And 0.ltoreq.R.ltoreq.R max ；
Is an auxiliary variable which is a function of refraction angle representing an electromagnetic wave at a position where an x-axis coordinate value on the coordinate plane is r when the electromagnetic wave is incident into the dielectric lens from the incident surface, and>is 0.
7. An antenna module is provided, which is used for the antenna module,
the device is provided with:
the dielectric lens of claim 1 or 6; and
and a radiator which emits electromagnetic waves, which are plane waves, and which makes the electromagnetic waves travel in a direction along the virtual straight line and enter the incident surface.
8. The antenna module as claimed in claim 7,
the dielectric lens also serves as a radome.
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| JP2021-119123 | 2021-07-19 | ||
| JP2021119123 | 2021-07-19 | ||
| PCT/JP2022/024099 WO2023002784A1 (en) | 2021-07-19 | 2022-06-16 | Dielectric lens and antenna module |
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| CN117678122A true CN117678122A (en) | 2024-03-08 |
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| JP (1) | JP7825234B2 (en) |
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| CN116315708A (en) * | 2023-02-22 | 2023-06-23 | 太原理工大学 | A dual-wavelength beam-splitting structure |
| JP2025029857A (en) * | 2023-08-22 | 2025-03-07 | 電気興業株式会社 | Transparent metasurface-loaded antenna and transparent metasurface plate |
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|---|---|---|---|---|
| JPS60129703A (en) * | 1983-12-16 | 1985-07-11 | Toyota Central Res & Dev Lab Inc | Aspherical lens for optical device |
| JPH04362608A (en) * | 1991-06-11 | 1992-12-15 | Matsushita Electric Ind Co Ltd | Beam expander and optical head using it |
| TW583787B (en) * | 2002-03-07 | 2004-04-11 | Huan-Cheng Lien | The design method of the microwave concave lens antenna for converting omnidirectional radiation pattern into multi-beam with different beamwidth |
| JP2006081771A (en) * | 2004-09-17 | 2006-03-30 | Canon Inc | Method and apparatus for estimating information about living organisms using electromagnetic waves |
| JP2014206740A (en) * | 2013-04-11 | 2014-10-30 | アスフェリコン ゲゼルシャフト ミット ベシュレンクテル ハフツング | Refractive beam former |
| JP2020060484A (en) * | 2018-10-11 | 2020-04-16 | パナソニックＩｐマネジメント株式会社 | Radar equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3455212B2 (en) | 1990-08-27 | 2003-10-14 | オリンパス光学工業株式会社 | Imaging device |
| JP6440123B2 (en) | 2015-05-19 | 2018-12-19 | パナソニックＩｐマネジメント株式会社 | Antenna device, radio communication device, and radar device |
| JP6337171B1 (en) | 2017-03-23 | 2018-06-06 | パナソニック株式会社 | Antenna device |
-
2022
- 2022-06-16 JP JP2023536654A patent/JP7825234B2/en active Active
- 2022-06-16 WO PCT/JP2022/024099 patent/WO2023002784A1/en not_active Ceased
- 2022-06-16 CN CN202280050742.8A patent/CN117678122A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60129703A (en) * | 1983-12-16 | 1985-07-11 | Toyota Central Res & Dev Lab Inc | Aspherical lens for optical device |
| JPH04362608A (en) * | 1991-06-11 | 1992-12-15 | Matsushita Electric Ind Co Ltd | Beam expander and optical head using it |
| TW583787B (en) * | 2002-03-07 | 2004-04-11 | Huan-Cheng Lien | The design method of the microwave concave lens antenna for converting omnidirectional radiation pattern into multi-beam with different beamwidth |
| JP2006081771A (en) * | 2004-09-17 | 2006-03-30 | Canon Inc | Method and apparatus for estimating information about living organisms using electromagnetic waves |
| JP2014206740A (en) * | 2013-04-11 | 2014-10-30 | アスフェリコン ゲゼルシャフト ミット ベシュレンクテル ハフツング | Refractive beam former |
| JP2020060484A (en) * | 2018-10-11 | 2020-04-16 | パナソニックＩｐマネジメント株式会社 | Radar equipment |
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| WO2023002784A1 (en) | 2023-01-26 |
| JP7825234B2 (en) | 2026-03-06 |
| JPWO2023002784A1 (en) | 2023-01-26 |
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