WO2014139067A1 - 一种柱状电磁波隐身器件 - Google Patents
一种柱状电磁波隐身器件 Download PDFInfo
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- WO2014139067A1 WO2014139067A1 PCT/CN2013/072376 CN2013072376W WO2014139067A1 WO 2014139067 A1 WO2014139067 A1 WO 2014139067A1 CN 2013072376 W CN2013072376 W CN 2013072376W WO 2014139067 A1 WO2014139067 A1 WO 2014139067A1
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- unit
- side wall
- dielectric
- medium unit
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Classifications
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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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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/12—Beam splitting or combining systems operating by refraction only
- G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
- F41H3/00—Camouflage, i.e. means or methods for concealment or disguise
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/02—Catoptric systems, e.g. image erecting and reversing system
- G02B17/023—Catoptric systems, e.g. image erecting and reversing system for extending or folding an optical path, e.g. delay lines
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/02—Catoptric systems, e.g. image erecting and reversing system
- G02B17/04—Catoptric systems, e.g. image erecting and reversing system using prisms only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/04—Prisms
- G02B5/045—Prism arrays
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/04—Prisms
- G02B5/06—Fluid-filled or evacuated prisms
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
Definitions
- the invention relates to a columnar electromagnetic wave stealth device, belonging to the field of electromagnetic wave stealth.
- Electromagnetic wave stealth has always been a long-standing dream of centuries, but it has not been realized.
- Electromagnetic waves are waves that are transmitted by energy and momentum in the form of periodic fluctuations in the space by an electric field and a magnetic field that oscillate in phase and are perpendicular to each other.
- the electromagnetic spectrum includes all possible frequencies of electromagnetic radiation, and the frequency of the electromagnetic spectrum is classified as radio waves, microwaves, infrared rays, visible rays, ultraviolet rays, X-rays, and gamma rays, from low to high.
- the electromagnetic spectrum is infinite and continuous. Generally, when electromagnetic waves are irradiated onto an object, they cannot completely propagate to the back of the object, but will scatter on the object.
- the electromagnetic wave when the electromagnetic wave is irradiated on the object, a shadow is generated behind the object, and the object behind the shadow is in the shadow area.
- the background is blocked by the object and cannot be detected.
- the ideal electromagnetic wave stealth technology can make electromagnetic waves bypass the hidden object and exit on the other side of the object according to the original path, so that no shadow is generated behind the object, and the background or other objects behind the object will not be front.
- the object is blocked.
- the electromagnetic wave does not illuminate the object, which is equivalent to the absence of the object, that is, the object is perfectly invisible.
- stealth technologies such as stealth aircraft
- stealth technology instead of eliminating the shadow of the aircraft under radar radiation.
- the surface of the object is coated with a material that absorbs radar waves to minimize the electromagnetic waves reflected back.
- This technique is not really stealth.
- This technology works mainly in the microwave band and can only be hidden from the single base station radar, but not the dual base station radar, so it is easily detected by the dual base station radar.
- the existing stealth technology is mainly military camouflage, etc.
- this technology will no longer have a stealth effect, so this is just a camouflage technique, rather than really disappearing from sight. .
- Pendry et al. published an article in the 2006 Science Journal [Science 312, 1780 (2006)] Stealth technology method. They used the method of transforming optics to design a stealth device with dielectric constant and permeability parameter varying with space, and experimentally verified it in the microwave band. In the experimental verification, they are realized by a metamaterial material: a metal pattern array is used to construct an anisotropic medium with equivalent dielectric constant and equivalent permeability parameter. The cylindrical stealth device is realized by placing these equivalent media in a cylindrical coordinate system according to certain requirements.
- this method of constructing a stealth device using a metal pattern array has a complicated construction method, and the above method can basically be used only for microwave or far infrared frequency bands due to the large loss of metal in the optical frequency band and the difficulty in processing after the scale is small. .
- Pendry et al. they used a lot of approximations, so in reality their stealth device reduced the scattering cross section of the object by only 24%, and did not reach the full stealth effect.
- the stealth device implemented by Pendry et al. does not completely eliminate the shadow of the object under electromagnetic radiation, the stealth device reduces the shadow behind the object to a certain extent, so it can be said to be an effective stealth device.
- the electromagnetic spectrum referred to in the present invention includes all possible frequencies of electromagnetic radiation, and the electromagnetic spectrum frequency is classified into radio waves, microwaves, infrared rays, visible rays, ultraviolet rays, X-rays, and gamma rays from low to high, and the electromagnetic spectrum is infinite, and It is continuous.
- the refractive index of an object refers to the ratio of the speed at which electromagnetic waves propagate in air to the speed at which the object propagates. When electromagnetic waves pass through two media of different refractive indices, they refract at the interface, which causes the electromagnetic waves to shift.
- the columnar electromagnetic wave stealth device of the present invention comprises six first medium units and six second medium units, the first medium unit and the second medium unit being transparent to incident electromagnetic waves, and the refractive index of the first medium unit is greater than the second
- the refractive index of the dielectric unit, the first dielectric unit is a cylinder having an isosceles triangle in cross section, and the second dielectric unit is either isosceles in cross section An angular cylinder or a cylinder having an isosceles trapezoidal cross section;
- the apex angle of the cross section of each of the first medium units is a first apex angle
- the two waists of the cross section of each of the first dielectric units are the first waist
- the bottom side of the cross section of each of the first dielectric units is the first a side wall
- a side wall of the first medium unit of the first medium unit is a first side wall
- a side wall of the first medium unit of the first medium unit is a third side wall
- the apex angle of the cross section of the second dielectric unit is the second apex angle
- the two waists are the second waist
- the bottom edge is the second bottom edge
- the sidewall of the second waist is the second sidewall
- the sidewall of the second bottom of the second dielectric unit is the fourth sidewall
- the angle formed by the extension lines of the two waist portions of the cross section of the second dielectric unit is the third angle
- the two waists of the cross section of the second dielectric unit are the third
- the waist and the bottom edge are a third bottom edge
- the upper bottom edge is a fourth bottom edge
- the sidewall of the second medium unit where the third waist is located is a fifth sidewall
- the third bottom of the second dielectric unit The sidewall on which the edge is located is a sixth sidewall
- the sidewall on which the fourth bottom edge of the second dielectric unit is located is a seventh sidewall;
- a second medium unit is disposed between each two adjacent first medium units, and the adjacent second side wall and the first side wall are opposite each other.
- the fourth sidewall of the second dielectric unit faces the background medium, and the third sidewall of each of the first dielectric units faces the invisible region;
- the cross section of the second medium unit is an isosceles triangle, if the first medium unit and the second medium unit are both solid, then the adjacent first side wall and the second side wall are in contact, or adjacent a side wall and a second side wall are separated by a second solid partition and both the first side wall and the second side wall are in contact with the corresponding second solid partition;
- the fourth side wall of the second medium unit is separated from the background medium by the first solid Separated from each other, the upper end and the lower end of the second medium unit are separated from the background medium by a fourth solid partition, respectively; and, or the adjacent first side wall and the second side wall are in contact, or the adjacent first side wall Separating from the second side wall by the second solid partition and contacting both the first side wall and the second side wall with the corresponding second solid partition;
- the cross section of the second medium unit is an isosceles triangle
- the first medium unit is a fluid and the second medium unit is a solid
- the upper end and the lower end of the first medium unit are separated from the background medium by a fourth solid
- the third side wall of the first medium unit is separated from the stealth area by the third solid partition; and, or the adjacent first side wall and the second side wall are in contact, or the adjacent first side wall Separating from the second side wall by the second solid partition and contacting both the first side wall and the second side wall with the corresponding second solid partition;
- the cross section of the second medium unit is an isosceles triangle
- the adjacent first side wall and the second side wall are separated by a second solid
- the first side wall and the second side wall are respectively in contact with the corresponding second solid partition
- the fourth side wall of the second medium unit is separated from the background medium by the first solid partition
- the first medium unit The third side wall and the stealth area are separated by a third solid partition
- the first medium unit The upper end, the lower end and the background medium are respectively separated by a fourth solid partition
- the upper end and the lower end of the second medium unit are separated from the background medium by a fourth solid partition;
- a second medium unit is disposed between each two adjacent first medium units, and the adjacent fifth side wall and the first side wall are opposite each other.
- the sixth sidewall of the second dielectric unit faces the background medium
- the seventh sidewall of each of the second dielectric units faces the invisible region
- the third sidewall of each of the first dielectric units faces the invisible region;
- the cross section of the second medium unit is an isosceles trapezoid
- the adjacent first side wall and the fifth side wall are in contact, or adjacent ones a side wall and a fifth side wall are separated by a second solid partition and both the first side wall and the fifth side wall are in contact with the corresponding second solid partition;
- the cross section of the second medium unit is an isosceles trapezoid
- the first medium unit is a solid and the second medium unit is a fluid
- the sixth side wall of the second medium unit is separated from the background medium by the first solid
- the seventh side wall of the second medium unit is separated from the stealth area by a third solid partition
- the upper end and the lower end of the second medium unit are separated from the background medium by a fourth solid partition
- Adjacent first and fifth side walls are in contact, or adjacent first and fifth side walls are separated by a second solid partition and the first side wall and the fifth side wall are respectively associated with Contacting the second solid partition;
- the cross section of the second medium unit is an isosceles trapezoid
- the first medium unit is a fluid and the second medium unit is a solid
- the upper end and the lower end of the first medium unit are separated from the background medium by a fourth solid
- the third side wall of the first medium unit is separated from the stealth area by the third solid partition; and, or the adjacent first side wall and the fifth side wall are in contact, or the adjacent first side wall And the fifth side wall are separated by the second solid partition and the first side wall and the fifth side wall are both in contact with the corresponding second solid partition;
- the cross section of the second medium unit is an isosceles trapezoid
- the adjacent first and fifth side walls are separated by a second solid
- the first side wall and the fifth side wall are respectively in contact with the corresponding second solid partition
- the sixth side wall of the second medium unit is separated from the background medium by the first solid partition
- the second medium unit The seventh side wall and the stealth area are separated by a third solid partition
- the third side wall of the first medium unit and the stealth area are separated by a third solid partition, the upper end and the lower end of the first medium unit and the background medium Separated by a fourth solid partition, respectively; the upper end and the lower end of the second medium unit are separated from the background medium by a fourth solid partition;
- the first solid partition, the second solid partition, and the fourth solid partition are transparent to incident electromagnetic waves, and a refractive index of the first solid partition is greater than or equal to a refractive index of the second dielectric unit, and the second solid partition
- the refractive index is greater than or equal to the refractive index of the second dielectric unit, and the thickness of the first solid partition, the thickness of the second solid partition, and the length of the first bottom side of the first dielectric unit satisfy the following formula (1)
- w 1 +7.04xw 2 ⁇ 2A (1)
- ⁇ represents the thickness of the first solid partition
- ⁇ represents the thickness of the second solid partition
- A represents the length of the first bottom side of the first medium unit .
- the stealth device of the present invention is placed in the background medium, and the relationship between the refractive index of the second dielectric unit and the refractive index of the background medium satisfies the following formula (2): : 11 (2) of formula (2), 3 ⁇ 4 represents a refractive index of the background medium, 3 ⁇ 4 two denotes a refractive index of the second media unit.
- the same electromagnetic wave beam incident from the background medium to the stealth device in a direction perpendicular to the third sidewall of one of the first dielectric units of the present invention can pass through the sequentially adjacent second dielectric units in sequence, The first medium unit, the second medium unit, the first medium unit, and the second medium unit are emitted into the background medium, and the same electromagnetic wave beam is on the same straight line as when incident.
- the cross section of the second dielectric unit of the present invention is an isosceles triangle
- the refractive index of the first dielectric unit, the refractive index of the second dielectric unit, the refractive index of the background medium, and the first top of the first dielectric unit The angle, the second apex angle of the second dielectric unit, the length of the first bottom side of the first dielectric unit, and the length of the second bottom side of the second dielectric unit satisfy each of the following equations (3) through (8) The relationship shown:
- the third corner of the dielectric unit, the length of the first bottom side of the first dielectric unit, and the length of the third bottom side of the second dielectric unit satisfy each of the above equations (3), (4), (7), and (8)
- 3 ⁇ 4 represents a refractive index of the first media unit
- two 3 ⁇ 4 denotes a refractive index of the second media unit
- /3 ⁇ 4 denotes the refractive index of the background medium
- ⁇ denotes the length of the first bottom side of the first dielectric unit
- ⁇ denotes the length of the second bottom side of the second dielectric unit
- ⁇ denotes the second apex angle
- C represents the length of the third bottom side of the second medium unit, indicating the third angle ⁇
- the beneficial effects of the present invention are:
- the first medium unit and the second medium unit are used as materials for constructing an electromagnetic wave stealth device.
- the trajectory of the beam is controlled by the medium with different refractive indexes, and the background medium is perpendicular to the stealth device.
- the direction of the third side wall of any one of the first dielectric units is incident, and sequentially passes through the sequentially adjacent second medium unit, the first medium unit, the second medium unit, the first medium unit, and the first unit constituting the stealth device of the present invention.
- the invention encloses the whole electromagnetic wave stealth device through the first medium unit and the second medium unit, does not need to utilize the metal pattern, but only utilizes materials which are easily available in nature, does not require a high process, and is easy to implement; works in a stealth device
- the first medium unit and the second medium unit are used to control the trajectory of the electromagnetic wave, the device does not need an external power supply and the like, and the performance is stable; compared with the existing technology that can only realize electromagnetic wave stealth in one polarization direction,
- the first medium unit and the second medium unit of the invention of the electromagnetic wave stealth device are isotropic and therefore insensitive to the polarization direction of the electromagnetic wave, especially in the visible light band, the natural light is incoherent and fully polarized, and the invention is in the visible light band.
- the invention has a very good stealth effect; the electromagnetic wave stealth device of the invention has a stealth effect in six directions and can be applied to the entire electromagnetic wave band.
- FIG. 1 is a schematic view of a first dielectric unit of an electromagnetic wave stealth device of the present invention
- FIG. 2 is a schematic view showing a second medium unit having an isosceles triangle in cross section of the electromagnetic wave stealth device of the present invention
- FIG. 3 is a schematic view showing the entire structure of a first embodiment of the electromagnetic wave stealth device of the present invention, wherein the second medium unit has an isosceles triangle in cross section and no solid partition exists;
- FIG. 4 is a schematic diagram showing the stealth effect of the electromagnetic beam passing through the electromagnetic wave stealth device shown in FIG. 3;
- Figure 5 is a trajectory diagram of the electromagnetic beam propagating in the electromagnetic wave stealth device shown in Figure 3;
- Figure 6 is a schematic view showing the refraction of electromagnetic waves as they pass through a parallel plate medium
- Figure 7 is a trajectory diagram of a second embodiment of an electromagnetic beam stealth device of the present invention, wherein the second dielectric unit has an isosceles triangle in cross section and a solid partition is present;
- Figure 8 is a schematic view showing a second medium unit having an isosceles trapezoidal cross section in the electromagnetic wave stealth device of the present invention.
- FIG. 9 is a schematic diagram showing the stealth effect of the electromagnetic beam passing through the third embodiment of the electromagnetic wave stealth device of the present invention, wherein the second medium unit has an isosceles trapezoidal cross section and no solid partition exists;
- Figure 10 is a trajectory diagram of electromagnetic beam propagation in a fourth embodiment of the electromagnetic wave stealth device of the present invention, wherein the second dielectric unit has an isosceles trapezoidal cross section and a solid partition is present;
- Figure 11 is a schematic view showing a shadow area generated behind an object when an electromagnetic beam is irradiated onto an object that is not in the stealth device; 12 is a schematic view showing the positional relationship between the upper end and the lower end of the first medium unit and the fourth solid partition in the electromagnetic wave stealth device of the present invention;
- Figure 13 is a view showing the positional relationship between the upper end and the lower end of the second medium unit having an isosceles triangle cross section and the fourth solid partition in the electromagnetic wave stealth device of the present invention
- Figure 14 is a view showing the positional relationship between the upper end and the lower end of the second medium unit having an isosceles trapezoidal cross section and the fourth solid partition in the electromagnetic wave stealth device of the present invention.
- the cross section of the second dielectric unit is isosceles a second apex angle when the triangle is triangular; ⁇ . a third angle of the cross section of the second dielectric unit is an isosceles trapezoid; 3. a first dielectric unit of the electromagnetic wave stealth device; 4. a first medium unit of the electromagnetic wave stealth device; a first medium unit of the electromagnetic wave stealth device; 6. a first medium unit of the electromagnetic wave stealth device; 7. a first medium unit of the electromagnetic wave stealth device; 8.
- Electromagnetic wave stealth device a second medium unit; 15. a second medium unit of the electromagnetic wave stealth device; 16. a region where the background medium is located; 17a. a track in the background medium before the electromagnetic beam is incident; 17b. electromagnetic wave a trajectory in the second medium unit; 17c. a trajectory of the electromagnetic beam in the first medium unit; 17d. a trajectory of the electromagnetic beam in the second medium unit; 17e.
- a trajectory of the electromagnetic beam in the first medium unit 17f.
- the trajectory of the electromagnetic beam in the second medium unit 17 g. the trajectory after the electromagnetic beam is emitted to the background medium; 18.
- the dielectric parallel plate having a thickness w and refractive index; a medium; 21a. a trajectory of the electromagnetic beam in the background medium before being incident on the electromagnetic wave stealth device of the present invention;
- 21b trajectory of the electromagnetic beam in the second medium unit
- 21c trajectory of the electromagnetic beam in the first medium unit
- 21d trajectory of the electromagnetic beam in the second medium unit
- 21e electromagnetic beam in the first medium unit Trajectory
- 21f Trajectory of the electromagnetic beam in the second medium unit
- 21g Trajectory after the electromagnetic beam exits to the background medium
- a second medium unit of the electromagnetic wave stealth device 30a. a trajectory of the electromagnetic beam incident on the background medium before the electromagnetic wave stealth device of the present invention; 30b. the electromagnetic beam is in the second medium unit Trajectory; 30c. Trajectory of the electromagnetic beam in the first medium unit; 30d. Trajectory of the electromagnetic beam in the second medium unit; 30e. Trajectory of the electromagnetic beam in the first medium unit 30f. trajectory of the electromagnetic beam in the second medium unit; 30g. trajectory after the electromagnetic beam is emitted to the background medium; 31a. trajectory of the electromagnetic beam before entering the electromagnetic wave stealth device of the invention in the background medium; 31b. electromagnetic beam at Two trajectories in the medium unit; 31c.
- Electromagnetic beam exit The trajectory after the background medium; 32. The object not directly placed in the stealth device and directly illuminated by the electromagnetic beam; 33. Under the electromagnetic beam illumination, the object not placed in the stealth device is in a plane perpendicular to the exit direction of the electromagnetic beam The width of the rectangular shadow produced thereon; 34. the fourth solid partition of the electromagnetic stealth device; 35. the second dielectric unit of the electromagnetic stealth device; 36. the second dielectric unit of the electromagnetic stealth device; 37.
- the second medium unit is an incident angle when the electromagnetic beam is incident from the background medium 16 to the first second medium unit 10 (ie, the angle between the incident beam and the interface normal); ⁇ is the electromagnetic beam from the background medium 16 is incident to the angle of refraction when the first second dielectric unit 10 is refracted (ie, the angle between the refracted beam and the interface normal); ⁇ is the electromagnetic beam from the first second medium
- the first unit 10 is incident to a first angle of incidence of the media unit 3 refraction;
- 2 is a second beam of electromagnetic waves from the first media unit 10 is incident on the first refraction angle when refraction occurs first media unit 3;
- ⁇ The incident angle is an incident angle when the electromagnetic beam is incident from the first first medium unit to the second second medium unit; the electromagnetic beam is incident from the first first medium unit 3 to the second second medium unit 11
- Electromagnetic waves are waves that are transmitted by energy and momentum in the form of periodic fluctuations of electric and magnetic fields that oscillate in phase and are perpendicular to each other in space.
- electromagnetic waves include radio waves, microwaves, infrared rays, visible light, ultraviolet light, X-rays and gamma rays, etc., which are acceptable to the human eye, with wavelengths between 380 and 780 nm. , called visible light.
- the propagation speed of electromagnetic waves varies. When the two media are compared, the medium with a large electromagnetic wave propagation velocity has a small refractive index, and the medium with a small electromagnetic wave propagation velocity has a large refractive index.
- the fluid referred to in the present invention is a generic term for liquids and gases.
- Figure 1 shows a first dielectric unit constituting the electromagnetic wave stealth device of the present invention, the first dielectric unit being a cylinder having an isosceles triangle in cross section.
- the apex angle of the cross section of each of the first dielectric units is the first apex angle ⁇
- the two waists are the first
- the waist and the bottom edge are the first bottom edge
- the sidewall of the first waist of the first dielectric unit is the first sidewall
- the sidewall of the first bottom edge of the first dielectric unit is the third sidewall 1 .
- Fig. 2 shows a structure of a second dielectric unit constituting the electromagnetic wave stealth device of the present invention.
- the second medium unit is a cylinder having an isosceles triangle in cross section.
- the apex angle of the cross section of the second medium unit is the second apex angle 3
- the two waists are the second waist
- the bottom edge is the second bottom edge
- the side of the second waist of the second medium unit is located.
- the wall is a second side wall
- the side wall of the second bottom side of the second dielectric unit is the fourth side wall 2.
- the electromagnetic wave stealth device is composed of six first dielectric units that are transparent to incident electromagnetic waves and six pairs of incident electromagnetic waves. It is a transparent second medium unit, wherein the first medium unit and the second medium unit are both solid.
- the cross sections of the six first medium units 3, 4, 5, 6, 7, and 8 are all isosceles triangles.
- the first dielectric units 3, 4, 5, 6, 7, and 8 are sequentially arranged in a clockwise direction and collectively define a stealth region 9, and the third side walls 1 of the six first dielectric units face the invisible region 9.
- the cross sections of the six second media units 10, 11, 12, 13, 14, and 15 are all isosceles triangles.
- Each second medium unit is located between two adjacent first medium units, that is, there is one second medium unit between every two adjacent first medium units, and the second medium unit is second.
- the sidewalls are respectively opposite and in contact with the first sidewall of the first dielectric unit adjacent thereto.
- the fourth side walls 2 of the six second dielectric units each face the background medium 16.
- the second medium unit 10 is located between the first medium unit 3 and the first medium unit 8, and correspondingly, the second medium units 11, 12, 13, 14, and 15 are sequentially located in the clockwise direction corresponding to two adjacent Between the first media units.
- the six first medium units are enclosed by a stealth area 9, the second medium unit 10 is located between the first medium unit 3 and the first medium unit 8, and the second medium unit 11 is located at the Between a medium unit 4 and the first medium unit 3, analogously, the second medium units 12, 13, 14, 15 are sequentially located in the clockwise direction between the respective two adjacent first medium units.
- the first medium unit 7, the second medium unit 15, the first medium unit 8, and the second medium unit 10 are sequentially arranged adjacent to each other in the clockwise direction to constitute an embodiment of the electromagnetic wave stealth device of the present invention.
- the fourth side wall 2 of the six second medium units faces the background medium 16
- the third side wall 1 of the six first medium units faces the stealth area 9, and the stealth area 9 is used to place the object that is hidden.
- the refraction of electromagnetic waves at the interface of anisotropic media is related to the direction of polarization of the incident electromagnetic waves.
- the first medium unit and the second medium unit used in the electromagnetic wave stealth device of the present invention are isotropic, and the refraction at the interface of the medium is independent of the polarization direction of the electromagnetic wave, so
- the stealth effect of the electromagnetic wave stealth device of the invention is independent of the polarization direction of the electromagnetic wave, and the stealthy body can be realized for the fully polarized electromagnetic wave.
- FIG. 4 it is assumed that the electromagnetic beam is incident in the background medium 16 from left to right in the horizontal direction to the electromagnetic wave stealth device of the present invention, at which time the electromagnetic beam is perpendicular to the third side wall 1 of the first dielectric unit 8.
- the propagation of the electromagnetic beam can be visually represented by many parallel rays.
- These rays represent the propagation characteristics of the electromagnetic beam at the location where the direction of the ray represents the direction of propagation of the energy of the electromagnetic beam at the location of the ray, ie the direction of the Poynting vector, and the ray can also be represented at the ray position.
- the propagation trajectory of the electromagnetic beam, the propagation of all these parallel rays also visually constitutes the propagation characteristics of the total electromagnetic beam.
- the direction of propagation (or referred to as "trajectory" in the background medium 16 before the electromagnetic beam is incident, that is, the parallel rays in the background medium 16 shown in FIG. 4) is perpendicular to the third side wall 1 of the first dielectric unit 8.
- the electromagnetic beam incident on the electromagnetic wave stealth device of the present invention will be divided into three parts: (1) at the "joining point” The beam of the above part (classified as electromagnetic beam I); (2) the beam of the following part at the "combination point” (classified as electromagnetic beam II); (3) the beam incident at the "combination point” (category Is the electromagnetic beam 111).
- the propagation of the electromagnetic beam in the electromagnetic wave stealth device of the present invention can also be represented by many parallel rays.
- the propagation trajectories of these parallel rays in various regions of the electromagnetic wave stealth device of the present invention also visually constitute the propagation trajectory of the entire electromagnetic beam in the corresponding region of the electromagnetic wave stealth device of the present invention.
- the electromagnetic beam 17 including the tracks 17a, 17b, 17c, 17d, 17e, 17f and 17g
- the propagation trajectories of the other parallel electromagnetic beams in the respective regions of the electromagnetic wave stealth device of the present invention are respectively related to the electromagnetic beam 17 in the electromagnetic wave stealth of the present invention.
- the propagation trajectories of the various regions of the device are parallel, so a similar analysis can be performed.
- the electromagnetic beam 17, 17a denotes a locus in the background medium before the electromagnetic beam is incident on the electromagnetic wave stealth device of the present invention, and the track 17a is perpendicular to the third side wall 1 of the first medium unit 8.
- electromagnetic waves are refracted at the interface of the background medium 16 and the second medium unit 10, and the electromagnetic beam 17 is offset within the second medium unit 10 as The position of track 17b.
- the electromagnetic beam 17 passes through the interface of the second medium unit 10 and the first medium unit 3
- the second refraction occurs, and the electromagnetic beam 17 is again shifted in the first medium unit 3 to the position where the track 17c is located.
- the third refraction occurs when the shifted electromagnetic beam 17 continues to pass through the interface between the first medium unit 3 and the second medium unit 11, and the electromagnetic beam 17 is offset in the second medium unit 11 to the position of the track 17d.
- the direction of the trajectory 17d where the electromagnetic beam 17 is located is just parallel to the direction of the trajectory 17a incident on the electromagnetic wave stealth device of the present invention but with a longitudinal displacement.
- the electromagnetic beam 17 passes forward through the first media sheet A fifth refraction occurs at the interface of the element 4 and the second dielectric unit 12, and the electromagnetic beam 17 is offset within the second medium unit 12 to the position of the track 17f.
- the sixth refraction occurs when the electromagnetic beam 17 passes forward through the interface of the second medium unit 12 and the background medium 16, and the direction in which the electromagnetic beam 17 exits to the trajectory 17g in the background medium 16 is the same as the direction of the trajectory 17a at the time of incidence. That is, the trajectory 17a of the electromagnetic beam 17 before entering the electromagnetic wave stealth device of the present invention is on the same straight line as the trajectory 17g at the time of exit.
- the propagation trajectories of the other electromagnetic beams in the respective regions of the electromagnetic wave stealth device of the present invention are respectively parallel to the propagation trajectories of the electromagnetic beams 17 in the respective regions of the electromagnetic wave stealth device of the present invention, they are incident on the trajectory and exit before the electromagnetic wave stealth device of the present invention.
- the respective trajectories are on the same straight line without any change. Therefore, the trajectory of the electromagnetic beam I before entering the electromagnetic wave stealth device of the present invention does not change as compared with the trajectory at the time of exit.
- the beam (electromagnetic beam I) of the upper portion of the electromagnetic wave at the "joining point" is analyzed by the above, and the background medium 16 is incident on the electromagnetic wave stealth device of the present invention in a direction perpendicular to the third side wall 1 of the first dielectric unit 8. Then, the tracks of the background medium 16 are sequentially emitted along the second medium unit 10, the first medium unit 3, the second medium unit 11, the first medium unit 4, and the second medium unit 12 which are sequentially adjacent to each other. Due to the symmetry, it is apparent that the lower half of the electromagnetic wave (ie, the electromagnetic beam ⁇ ) is incident on the electromagnetic wave stealth device of the present invention from the background medium 16, and then sequentially passes through the second medium unit 15 and the first medium that are sequentially adjacent.
- the lower half of the electromagnetic wave ie, the electromagnetic beam ⁇
- the unit 7, the second medium unit 14, the first medium unit 6, and the second medium unit 13 are finally emitted to the background medium 16. Therefore, when the electromagnetic beam is incident on the electromagnetic wave stealth device of the present invention, the beam of the upper half will be deflected upward, and the beam of the lower half will be deflected downward, thereby bypassing the stealth region 9 of the middle portion and returning to the original when exiting. On the path, the objects in the stealth area 9 are made invisible.
- the electromagnetic beam ie, the electromagnetic beam 111 where the electromagnetic wave is incident from the background medium to the "bonding point
- the area is infinitely small, That is, the total electromagnetic wave power (the product of the Poynting power per unit area and the area at the joint point) of the "bonding point" is 0, so the "bonding point" itself does not destroy the overall stealth effect of the device.
- the relationship between the structural parameters of the electromagnetic wave stealth device of the present invention and the refractive index of each dielectric unit will be exemplified below with reference to FIG.
- the refractive index of the first dielectric unit is 3 ⁇ 4
- the refractive index of the second dielectric unit is 3 ⁇ 4
- the refractive index of the background medium is 3 ⁇ 4
- the first apex angle of the first dielectric unit is “
- the apex angle is such that the length of the first bottom side of the first dielectric unit is the length of the second bottom side of the second second dielectric unit.
- the mass unit 10 is refracted at the interface, and the incident direction of the electromagnetic beam in the background medium 16 is perpendicular to the third side wall 1 of the first dielectric unit 8.
- the interface with 10 and the first medium unit 3 can be obtained: " ⁇ 2arcsin -60°.
- the electromagnetic beam of unit 3 can be incident on the interface between the first medium unit 3 and the second medium unit 11, and the following is obtained:
- the first apex angle of the first dielectric unit, the refractive index of the first dielectric unit, the refractive index of the second dielectric unit, and the third refractive index of the second dielectric unit may be set according to the refractive index of the background medium/3 ⁇ 4 3 ⁇ 4 . Any two of the variables yield values for the other variables.
- Figure 6 shows the electromagnetic wave incident from the medium 18 with refractive index to a parallel plate medium of thickness w and refractive index.
- the plate medium 19 is further propagated to the medium 20 having a refractive index of /3 ⁇ 4, and the direction of the electromagnetic waves emitted from the two to the medium 20 remains unchanged, and only a small displacement is generated, as shown in Fig. 6, by analysis and calculation.
- the distance of the displacement is:
- Fig. 7 is a schematic view showing a second embodiment of the electromagnetic wave stealth device of the present invention.
- the cross sections of the six first dielectric units 3, 4, 5, 6, 7, 8 are isosceles triangles, and the third side walls 1 of the six first dielectric units face Stealth area 9;
- the cross sections of the six second medium units 10, 11, 12, 13, 14, 15 are isosceles triangles, and are respectively located between two adjacent first medium units, six second medium units
- the fourth side wall 2 faces the background medium 16; the adjacent first side wall and the second side wall are separated by the second solid partition 23 and the first side wall and the second side wall are respectively associated with the second solid
- the partition 23 contacts, the fourth side wall 2 of the second medium unit is separated from the background medium 16 by the first solid partition 22, and the third side wall 1 of the first medium unit and the stealth area 9 are separated by a third solid.
- the dividers 24 are spaced apart. If the first medium unit and the second medium unit are both solid, then the structure of the electromagnetic wave stealth device of the present invention is either as shown in FIGS. 3, 4 and 5, or equivalent to the first solid shown in FIG. The case of the partition 22 and the third solid partition 24. If the first medium unit is a solid and the second medium unit is a fluid, then, as shown in FIG. 13, the upper and lower ends of the second medium unit 10, 11, 12, 13, 14, 15 are respectively separated from the background medium 16 by The fourth solid partitions 34 are spaced apart. At this time, the structure of the electromagnetic wave stealth device of the present invention is equivalent to the case of the third solid partition 24 shown in FIG. 7 but not in FIG. 7, or equivalent to the one shown in FIG.
- the third solid partition 24 and the second solid partition 23 are in direct contact with the adjacent first and second side walls. If the first medium unit is a fluid and the second medium unit is a solid, then, as shown in FIG. 12, the upper end and the lower end of the first medium unit 3, 4, 5, 6, 7, 8 and the background medium 16 are respectively The fourth solid partitions 34 are spaced apart. At this time, the structure of the electromagnetic wave stealth device of the present invention is equivalent to the case of the first solid partition 22 shown in FIG. 7, but not equivalent to the first solid partition 22, or the same as shown in FIG. A solid partition 22 and a second solid partition 23 with adjacent first and second side walls in direct contact.
- first medium unit is a fluid and the second medium unit is a fluid
- first medium unit 3 4, 5, 6, 7, 8 and the background medium 16 are as shown in FIGS. 12 and 13 Separated by a fourth solid partition 34, respectively, the upper and lower ends of the second medium unit 10, 11, 12, 13, 14, 15 are separated from the background medium 16 by a fourth solid partition 34, respectively.
- the structure of the invention electromagnetic wave stealth device is shown in FIG.
- the electromagnetic beam 21 (including the tracks 21a, 21b, 21c, 21d, 21e, 21f, and 21g) incident on the electromagnetic wave stealth device of the present invention having the solid partition and the electromagnetic wave stealth device of the present invention having no solid partition are compared by the following.
- the trajectory of the electromagnetic beam 17 (including the trajectories 17a, 17b, 17c, 17d, lie, 17f and 17g) is used to analyze the effect of each solid partition on the stealth effect of the electromagnetic wave stealth device of the present invention. As shown in FIG. 7, the case where the influence of the solid partition on the electromagnetic beam is maximized is analyzed, that is, the case where the first solid partition 22, the second solid partition 23, and the third solid partition 24 are simultaneously present in the stealth device. .
- the trajectory 21d of the medium unit 11 has a direction unchanged as compared with the trajectory 17d, but in terms of displacement, the trajectory 21d increases the offset of ck with respect to the trajectory 17d, wherein the displacement of 4 is determined by the first medium unit 3 and Caused by the second solid partition 23 between the two dielectric units 11.
- the electromagnetic beam 21 passes through the second medium unit 11 and the second solid partition 23 between the second medium unit 11 and the first medium unit 4 and is incident on the first medium unit 4,
- the displacement caused by the second solid partition 23 between the second medium unit 11 and the first medium unit 4 is -k, that is, the trajectory 21e of the first medium unit 4 is compared with when there is no second solid partition 23
- the spacing between the tracks 17e is reduced by a shift of 4, but the direction remains unchanged;
- the electromagnetic beam 21 is passed by the first medium unit 4 through the second solid partition 23 between the first medium unit 4 and the second medium unit 12 and
- the second solid partition 23 between the first medium unit 4 and the second medium unit 12 will cause a displacement of - ⁇ , as compared with when there is no second solid partition 23
- the spacing between the track 21f of the two dielectric unit 1 and the track 17f is again reduced by a shift of 4, but the direction remains unchanged; the electromagnetic beam 21 is passed between the second medium unit 12 and the background medium
- the first solid partition 22 is incident on the background medium 16 Second dielectric unit 12 and a first solid background medium 16 between the spacer 22 due to the displacement - ⁇ , so that the final an incident electromagnetic beam in a background medium 16 in the direction of the track 21 g 17g same direction as the trajectory And the trajectories of the two coincide. Therefore, the electromagnetic beam 21 is emitted into the background medium 16 along the sequentially adjacent second medium unit 10, the first medium unit 3, the second medium unit 11, the first medium unit 4, and the second medium unit 12 in sequential order.
- the trajectory 21g is still the same as the direction of the trajectory 21a at the time of incidence, and is on the same straight line.
- Figure 11 is a schematic illustration of the object 32 being shaded directly under the electromagnetic beam illumination without being placed in the stealth device.
- the object 32 is a cylinder having a regular hexagonal cross section
- a shadow area is present behind the object under the irradiation of the electromagnetic beam.
- the shape of the shadow is a rectangle in a plane perpendicular to the direction of propagation of the electromagnetic wave beam, so the size of the shadow area can be quantized by the width 33 of the shadow on the plane of the beam direction of the vertical electromagnetic wave.
- the width of the shadow is reduced, thereby reducing the area of the shadow. The smaller the area of the shadow, the better the stealth effect.
- the stealth device can have a stealth effect. Since the refractive index of the first solid spacer is greater than or equal to the refractive index of the second dielectric unit, the refractive index of the second solid spacer is greater than or equal to the refractive index of the second dielectric unit, and thus is generated on a plane perpendicular to the direction in which the electromagnetic beam exits.
- the width of the rectangular shadow generated by the object under the electromagnetic wave irradiation on a plane perpendicular to the exit direction of the electromagnetic beam is H. It is possible to calculate H ⁇ 2A, where A is the length of the first base of the first dielectric unit. Therefore, as long as ⁇ ⁇ 1, that is, in the case of + 7.04 > ⁇ ⁇ 2 ⁇ 2 ⁇
- the electromagnetic wave stealth device of the invention can effectively reduce the shadow area generated by the object, so that the width L of the shadow generated when the object having the same shape and size of the stealth region of the stealth device is placed in the stealth device is always smaller than the object is not placed.
- the width H of the shadow produced during the stealth device always has a certain stealth effect.
- the formula for the maximum width L of the resulting shadow is given above, wherein the thinner the thickness of the first solid partition or the second solid partition, the smaller the width of the shadow.
- a corresponding first solid partition or second solid partition may not be required.
- the width of the shadow L 0, at which point complete stealth can be achieved.
- Fig. 8 shows another second medium unit constituting the electromagnetic wave stealth device of the present invention, the second medium unit being a cylinder having an isosceles trapezoidal cross section.
- Fig. 9 is a schematic view showing a third embodiment of the electromagnetic wave stealth device of the present invention. In FIG.
- the six first medium units 3, 4, 5, 6, 7, 8 are all isosceles triangles, and are sequentially arranged in a clockwise direction and collectively enclose a stealth area 9, which is six
- the third side wall 1 of the first medium unit 3, 4, 5, 6, 7, 8 faces the stealth area 9
- the cross sections of the six second medium units 27, 28, 29, 35, 36, 37 are all isosceles a trapezoid, and respectively located between two adjacent first medium units, that is, a second medium unit between each two adjacent first medium units, and a fifth side wall of each second medium unit Contacting the first side wall of the first medium unit adjacent thereto, the sixth side wall 25 of the six second medium units 27, 28, 29, 35, 36, 37 facing the background medium 16, six second medium
- the seventh side wall 26 of the unit 27, 28, 29, 35, 36, 37 faces the invisible area 9.
- the electromagnetic beam 30 is taken as an example to further illustrate the following:
- the electromagnetic beam 30 is incident in a direction perpendicular to the third side wall 1 of the first medium unit 8, and sequentially passes through the adjacent second medium unit 27, the first medium unit 3, the second medium unit 28, and the first medium.
- the trajectory 30g that is emitted from the unit 4 and the second medium unit 29 into the background medium 16 is the same as the direction of the trajectory 30a at the time of incidence and is on the same straight line, and does not pass through the intermediate stealth area.
- the propagation trajectories of the other parallel incident electromagnetic beams in the respective regions of the electromagnetic wave stealth device of the present invention are respectively parallel to the propagation trajectories of the electromagnetic beams 30 in the respective regions of the electromagnetic wave stealth device of the present invention, they are incident on the trajectory before the electromagnetic wave stealth device of the present invention.
- the respective trajectories are on the same line as the exit, no Any change occurs, and the same electromagnetic wave beam incident from the background medium to the stealth device is sequentially passed through the second medium unit, the first medium unit, the second medium unit, the first medium unit, and the second medium. After the cell exits into the background medium, according to Snell's law and the analysis with reference to Fig.
- the refractive index of the first dielectric unit is 3 ⁇ 4
- the refractive index of the second dielectric unit is 3 ⁇ 4
- the refraction of the background medium The rate is 3 ⁇ 4
- the first apex angle of the first dielectric unit satisfies the relationship shown in the following equation:
- the base angle of the isosceles trapezoidal cross section of the second medium unit is 90° - , depending on the geometry
- A represents the length of the first bottom side of the first medium unit
- C represents the length of the third bottom side of the second medium unit.
- a o can be seen, satisfying ⁇ ⁇ :- + ⁇ ⁇ , the second medium unit sin ( «/2 sin ( «/2 four base length) is greater than or equal to 0, and when) is equal to 0, is the second medium unit cross section is isosceles triangle Case.
- Fig. 10 is a schematic view showing a fourth embodiment of the electromagnetic wave stealth device of the present invention.
- the cross sections of the six first medium units 3, 4, 5, 6, 7, 8 are isosceles triangles, and the first of the six first medium units 3, 4, 5, 6, 7, 8
- the three side walls 1 face the stealth area 9;
- the six second medium units 27, 28, 29, 35, 36, 37 have an isosceles trapezoidal cross section and are respectively located between the respective adjacent two first medium units
- the sixth side wall 25 of the six second medium units 27, 28, 29, 35, 36, 37 faces the background medium 16, the seventh side of the six second medium units 27, 28, 29, 35, 36, 37
- the wall 26 faces the invisible area 9, and the adjacent first and fifth side walls are separated by a second solid partition and the first side wall and the fifth side wall are both in contact with the corresponding second solid partition 23,
- the sixth side wall 25 of the second medium unit is separated from the background medium 16 by the first solid partition 22, and the seventh side wall 26 of the second medium unit and the stealth area 9 are
- the electromagnetic wave stealth device structure of the present invention is either as shown in FIG. 9 or equivalent to the first solid partition 22 and the third solid partition in FIG. 24 situation. If the first medium unit is a solid and the second medium unit is a fluid, then, as shown in FIG. 14, the upper end and the lower end of the second medium unit 27, 28, 29, 35, 36, 37 and the background medium 16 are respectively The fourth solid partitions 34 are spaced apart, at this time, the structure of the electromagnetic wave stealth device of the present invention is equivalent to the case of the third solid partition 24 between the first medium unit and the stealth region 9 shown in FIG. 10, or Corresponding to the second solid partition 23 shown in FIG.
- first medium unit is a fluid and the second medium unit is a solid, then, as shown in FIG. 12, the upper end and the lower end of the first medium unit 3, 4, 5, 6, 7, 8 and the background medium 16 are respectively
- the fourth solid partitions 34 are spaced apart, at this time, the structure of the electromagnetic wave stealth device of the present invention or the third solid between the first solid partition 22 and the second medium unit and the stealth region 9 shown in FIG.
- the first solid partition 22, the second solid partition 23, the third solid partition 24 between the second medium unit and the stealth region 9, and the adjacent first and fifth side walls are in direct contact . If the first medium unit is a fluid and the second medium unit is a fluid, then the upper end and the lower end of the first medium unit 3, 4, 5, 6, 7, 8 and the background medium 16 are as shown in FIGS. 12 and 14. Separated by a fourth solid partition 34, respectively, the upper end and the lower end of the second medium unit 27, 28, 29, 35, 36, 37 are separated from the background medium 16 by a fourth solid partition 34, respectively.
- the structure of the invention electromagnetic wave stealth device is shown in FIG.
- the electromagnetic beam 31 is sequentially arranged in a direction perpendicular to the third side wall 1 of the first dielectric unit 8 in order.
- adjacent second media unit 27, the first media unit 3, the second media unit 28, a first media unit 4, a second media unit 29 impinges background medium trajectory with trajectory 16 31 g of the incident direction 31a Same and on the same line, and without passing through the middle of the invisible area.
- the width of the shadow of the object generated in the invisible region is also the thickness and refractive index determined by a first solid and a second solid separator separator, since the refractive index of the background medium 3 ⁇ 4 ⁇ , the refractive index of the first 3 ⁇ 4 a media unit, the first The refractive index of the two dielectric units / 3 ⁇ 4 - and the first apex angle ⁇ of the first dielectric unit satisfy the following conditions: ⁇ / 3 ⁇ 4 ⁇ /1.8, w sin 30
- the electromagnetic wave stealth device of the present invention can effectively reduce the shadow of the stealth object, so that The width L of the shadow produced by the stealth area of the stealth device when the object of the same shape and size is placed in the stealth device is always smaller than the width H of the shadow generated when the object is not placed in the stealth device, and thus always has a certain stealth effect.
- the thinner the thickness of the first solid partition or the second solid partition i.e., the smaller the spacing between the first dielectric unit and the second dielectric unit
- the thinner the width of the shadow i.e., the smaller the spacing between the first dielectric unit and the second dielectric unit
- the width L of the shadow is 0, and complete stealth can be achieved at this time.
- the electromagnetic wave stealth device of the present invention is a hexagonal structure, it has six-fold symmetry, electromagnetic waves.
- the beam can be incident from the electromagnetic wave stealth device in a direction perpendicular to the third side wall of any one of the first dielectric units, and has the same stealth effect. Therefore, the electromagnetic wave stealth device of the present invention can achieve the effect of stealth in six directions.
- contact when referring to the sidewall of the first dielectric unit being in contact with the sidewall of the second dielectric unit, By “contact” is meant that there is no other medium between the sidewall of the first dielectric unit and the sidewall of the second dielectric unit; when referring to the first dielectric unit, the sidewall of the second dielectric unit and the corresponding solid When the separator is in contact, the so-called “contact” means that there is no other medium between the side walls of the first medium unit, the second medium unit and the corresponding solid partition.
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Abstract
一种柱状电磁波隐身器件,包括六个第一介质单元(3、4、5、6、7、8)和六个第二介质单元(10、11、12、13、14、15),第一介质单元(3、4、5、6、7、8)、第二介质单元(10、11、12、13、14、15)对入射的电磁波(17)是透明的,第一介质单元(3、4、5、6、7、8)的折射率大于第二介质单元(10、11、12、13、14、15)的折射率,第一介质单元(3、4、5、6、7、8)为横截面呈等腰三角形的柱体,第二介质单元(10、11、12、13、14、15)或为横截面呈等腰三角形的柱体、或为横截面呈等腰梯形的柱体;每两个相邻的第一介质单元(3、4、5、6、7、8)之间设有一个第二介质单元(10、11、12、13、14、15),第一介质单元(3、4、5、6、7、8)的横截面的腰所在的侧壁为第一侧壁,底边所在的侧壁为第三侧壁(1),第二介质单元(10、11、12、13、14、15)的横截面的腰所在的侧壁为第二侧壁,底边所在的侧壁为第四侧壁(2);相邻的第二侧壁和第一侧壁相对,各第三侧壁(1)面向隐身区域(9);当第二介质单元(10、11、12、13、14、15)的横截面呈等腰三角形时,各第四侧壁(2)向背景介质(16);当第二介质单元的横截面呈等腰梯形时,其底边所在的侧壁为第六侧壁,顶边所在的侧壁为第七侧壁,各第六侧壁面向背景介质(16)且各第七侧壁面向隐身区域(9)。所述的隐身器件有六个方向的隐身效果,对电磁波极化方向不敏感,适用整个电磁波段。
Description
一种柱状电磁波隐身器件
技术领域
本发明涉及一种柱状电磁波隐身器件, 属于电磁波隐身领域。
背景技术
电磁波隐身一直是人类长期以来的一种梦想, 但是一直没有得以实现。 电磁波是指由同 相振荡且互相垂直的电场与磁场在空间中以周期波动的形式进行能量和动量传递的一种波。 电磁波谱包括电磁辐射所有可能的频率, 电磁波谱频率从低到高分別列为无线电波、 微波、 红外线、 可见光、 紫外线、 X射线和伽马射线。 电磁波谱是无限的, 而且是连续的。 一般地, 电磁波照射到物体上时, 不能完全地传播到物体后面, 而会在物体上发生散射, 因此电磁波 照射在物体上时会在物体的后面产生阴影, 物体后面的处在阴影区域中的背景就被物体挡住 而不能被探测到。 理想的电磁波隐身技术, 可以使电磁波绕过被隐身的物体, 并在物体的另 一边按照原来的路径出射, 从而使物体的后面不产生任何阴影, 物体后面的背景或者其他物 体也不会被前面的物体挡住。 这种情况下, 电磁波没有照射到物体上, 相当于物体不存在, 也即物体得到了完美的隐身。
目前已有的隐身技术, 比如隐形飞机等采用的隐身技术, 并不是消除飞机在雷达波照射 下的阴影, 而是通过在物体表面涂抹能吸收雷达波的材料让反射回去的电磁波达到最小, 来 防止飞机被雷达发现, 从而实现隐形。 这种技术不是真正的隐身, 这种技术主要工作在微波 波段, 且只能对单基站雷达隐身, 而不能对双基站雷达隐身, 因此很容易就被双基站雷达发 现。 在光波段, 现有的隐身技术主要还是军事迷彩等, 然而, 随着背景环境的改变, 这种技 术将不再具有隐身效果, 因此这只是一种伪装技术, 而不是真正地从视线中消失。 另有一种 隐身装置, 它通过摄像头和显示屏, 将一侧的物体拍下后显示在另一侧, 但它的效果受图像 的质量的影响, 而且需要额外的能量, 并且外面的摄像头、 电源连线等装置都是可以看到的, 这种方法也不是真正的隐身。 还有一种方式, 通过光纤, 将光线从一侧引导到另一侧, 从而 绕过中间的物体, 但这样的装置对光纤的工艺要求较高, 并且需要数量庞大的光纤, 而且只 能实现一个方向上的隐身。 因此, 这些隐身方法都不是一般人所理解的理想的隐身方法, 所 谓的"理想的隐身方法", 是指可以使电磁波绕过被隐身的物体, 并在物体的另一边按照原来 的路径出射, 电磁波不会被物体挡住, 从而使物体后面不会呈现出阴影区域的隐身技术。
Pendry等在 2006年的 Science期刊 [Science 312, 1780 (2006)]上发表文章提出了一种理想
的隐身技术方法。 他们通过变换光学的方法, 设计出介电常数和磁导率参数随空间变化的隐 身器件,并在微波波段进行了实验验证。在实验验证中,他们采用一种异向介质(Metamaterial) 材料来实现: 采用金属图案阵列构造出等效介电常数和等效磁导率参数随空间变化的、 具有 各向异性特性的介质, 并使这些等效介质在柱坐标系中按照一定要求放置, 来实现圆柱形的 隐身器件。 但是这种采用金属图案阵列构造隐身器件的方法, 构造方法比较复杂, 并且由于 金属在光频段的损耗很大, 以及尺度变小后加工困难, 上述方法基本上只能用于微波或远红 外频段。 在 Pendry等人的实验验证中, 他们采用了很多近似, 因此实际中他们的隐身器件使 物体的散射截面只减少了 24%, 还没有达到完全隐身的效果。 虽然 Pendry等实现的隐身器件 没有完全消除物体在电磁波照射下的阴影, 但是由于这种隐身器件使物体后面的阴影得到了 一定程度的减少, 因此可以说是一种行之有效的隐身器件。 在实际工程中, 由于非理想情况 的存在, 隐身器件事实上很难完全地除掉物体的阴影。 当电磁波照射到有隐身器件的物体和 没有隐身器件的物体时, 在物体的后面垂直于入射方向的平面上, 存在隐身器件时物体产生 的阴影面积小于没有隐身器件时物体产生的阴影面积, 也即隐身器件可以使物体在电磁波照 射时在物体的后面所产生的阴影面积减少。 在这种情况下, 由于这种隐身器件也达到了一定 程度的隐身效果, 因此也被认为是一种行之有效的隐身器件。 一般的, 科学家通过计算物体 在电磁波照射下后面阴影的减少量来定量地评价这些隐身器件的隐身效果。
由于 Pendry等提出的隐身器件设计方法要求所用材料的电磁参数随空间变化, 并且要求 材料的电磁参数遍历 0到无穷大的区间内所有的值, 对材料的要求非常苛刻, 实现起来很困 难, 价格昂贵, 同时这种材料由于色散很剧烈, 只能工作在很窄的一个频率区间, 而且采用 这种方法实现的隐身器件只对特定极化的电磁波有效,不能实现对任意极化的电磁波的隐身, 因此在实际应用中有很大的局限性。
发明内容
本发明的目的在于提供一种柱状电磁波隐身器件,从而克服现有技术的全部或部分缺陷。 本发明所指的电磁波谱包括电磁辐射所有可能的频率, 电磁波谱频率从低到高分別列为 无线电波、 微波、 红外线、 可见光、 紫外线、 X射线和伽马射线, 电磁波谱是无限的, 而且 是连续的。 物体的折射率是指电磁波在空气中传播的速度与在该物体中传播的速度值之比。 电磁波经过两个不同折射率的介质时, 会在交界面发生折射, 从而使电磁波发生偏移。
为实现上述目的, 本发明所采取的技术方案是:
本发明柱状电磁波隐身器件包括六个第一介质单元和六个第二介质单元, 所述第一介质 单元和第二介质单元对入射的电磁波是透明的, 第一介质单元的折射率大于第二介质单元的 折射率, 第一介质单元为横截面呈等腰三角形的柱体, 第二介质单元或者为横截面呈等腰三
角形的柱体、 或者为横截面呈等腰梯形的柱体;
所述各第一介质单元的横截面的顶角为第一顶角, 各第一介质单元的横截面的两个腰为 第一腰, 各第一介质单元的横截面的底边为第一底边, 第一介质单元的所述第一腰所在的侧 壁为第一侧壁, 第一介质单元的所述第一底边所在的侧壁为第三侧壁;
若第二介质单元的横截面呈等腰三角形, 则第二介质单元的横截面的顶角为第二顶角、 两个腰为第二腰、 底边为第二底边, 第二介质单元的所述第二腰所在的侧壁为第二侧壁, 第 二介质单元的所述第二底边所在的侧壁为第四侧壁;
若第二介质单元的横截面呈等腰梯形, 则第二介质单元的横截面的两腰的延长线所构成 的夹角为第三角, 第二介质单元的横截面的两个腰为第三腰、 下底边为第三底边、 上底边为 第四底边, 第二介质单元的所述第三腰所在的侧壁为第五侧壁, 第二介质单元的所述第三底 边所在的侧壁为第六侧壁, 第二介质单元的所述第四底边所在的侧壁为第七侧壁;
当第二介质单元的横截面呈等腰三角形时, 每两个相邻的第一介质单元之间设有一个第 二介质单元, 相邻的第二侧壁和第一侧壁相对, 各第二介质单元的第四侧壁面向背景介质, 各第一介质单元的第三侧壁面向隐身区域;
当第二介质单元的横截面呈等腰三角形时,如果第一介质单元和第二介质单元均为固体, 那么, 或者相邻的第一侧壁和第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固 体分隔物相隔且第一侧壁和第二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为固体, 第二介质单元为 流体, 那么, 第二介质单元的第四侧壁与背景介质之间由第一固体分隔物相隔, 第二介质单 元的上端、 下端与背景介质之间分别由第四固体分隔物相隔; 并且, 或者相邻的第一侧壁和 第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第 二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为流体, 第二介质单元为 固体, 那么, 第一介质单元的上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第一 介质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔; 并且, 或者相邻的第一侧壁和 第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第 二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为流体, 第二介质单元为 流体, 那么, 相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第二侧壁 均与对应的第二固体分隔物接触, 第二介质单元的第四侧壁与背景介质之间由第一固体分隔 物相隔, 第一介质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的
上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第二介质单元的上端、 下端与背景 介质之间分别由第四固体分隔物相隔;
当第二介质单元的横截面呈等腰梯形时, 每两个相邻的第一介质单元之间设有一个第二 介质单元, 相邻的第五侧壁和第一侧壁相对, 各第二介质单元的第六侧壁面向背景介质, 各 第二介质单元的第七侧壁面向隐身区域, 各第一介质单元的第三侧壁面向隐身区域;
当第二介质单元的横截面为等腰梯形时, 如果第一介质单元和第二介质单元均为固体, 那么, 或者相邻的第一侧壁和第五侧壁接触, 或者相邻的第一侧壁和第五侧壁之间由第二固 体分隔物相隔且第一侧壁和第五侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为固体, 第二介质单元为流 体, 那么, 第二介质单元的第六侧壁与背景介质之间由第一固体分隔物相隔, 第二介质单元 的第七侧壁与隐身区域之间由第三固体分隔物相隔, 第二介质单元的上端、 下端与背景介质 之间分别由第四固体分隔物相隔; 并且, 或者相邻的第一侧壁和第五侧壁接触, 或者相邻的 第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五侧壁均与相应的第二固体 分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为流体, 第二介质单元为固 体, 那么, 第一介质单元的上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第一介 质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔; 并且, 或者相邻的第一侧壁和第 五侧壁接触, 或者相邻的第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五 侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为流体, 第二介质单元为流 体, 那么, 相邻的第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五侧壁均 与对应的第二固体分隔物接触, 第二介质单元的第六侧壁与背景介质之间由第一固体分隔物 相隔, 第二介质单元的第七侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的第 三侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的上端、 下端与背景介质之间 分别由第四固体分隔物相隔; 第二介质单元的上端、 下端与背景介质之间分别由第四固体分 隔物相隔;
所述第一固体分隔物、 第二固体分隔物和第四固体分隔物对入射的电磁波是透明的, 第 一固体分隔物的折射率大于等于第二介质单元的折射率, 第二固体分隔物的折射率大于等于 第二介质单元的折射率, 并且第一固体分隔物的厚度、 第二固体分隔物的厚度和第一介质单 元的第一底边的长度之间满足如下式 (1 ) 所示的关系:
w1+7.04xw2 <2A (1) 式 (1) 中, ^表示第一固体分隔物的厚度, ^表示第二固体分隔物的厚度, A表示第 一介质单元的第一底边的长度。
进一步地, 本发明所述隐身器件置于背景介质中, 第二介质单元的折射率与背景介质的 折射率之间满足如下式 (2) 所示的的关系:
: 11 (2) 式 (2) 中, ¾ 表示背景介质的折射率, ¾二表示第二介质单元的折射率。 进一步地, 以垂直于本发明的其中一个第一介质单元的第三侧壁的方向由背景介质向所 述隐身器件入射的同一电磁波波束, 能够按先后顺序经过依次相邻的第二介质单元、 第一介 质单元、 第二介质单元、 第一介质单元、 第二介质单元出射到所述背景介质中, 且同一电磁 波波束在出射时与入射时在同一直线上。
进一步地, 若本发明的第二介质单元的横截面呈等腰三角形, 则第一介质单元的折射率、 第二介质单元的折射率、 背景介质的折射率、 第一介质单元的第一顶角、 第二介质单元的第 二顶角、 第一介质单元的第一底边的长度和第二介质单元的第二底边的长度相互之间满足如 下式 (3) 至式 (8) 所示的关系:
sin 30
sm 60° - arcsin -all
/½一 sm arcsm n^- sm (3) 第一
sin 30°
0° <a < 2 arcsin -60c (4)
β = 60° + α (5)
sin(30° + «/2) B
<UxV (6) sin al A 其中,
sm 30。 + arcsin + αΙ2
第二
V (8)
sin30c
2sin( /2)sin 90° -arcsin
第二 若第二介质单元的横截面呈等腰梯形, 则第一介质单元的折射率、 第二介质单元的折射 率、 背景介质的折射率、 第一介质单元的第一顶角、 第二介质单元的第三角、 第一介质单元 的第一底边的长度和第二介质单元的第三底边的长度相互之间满足如上式(3)、 (4)、 (7)和 (8) 及如下式 (9)、 (10) 所示的关系:
=60。 + (9) sm ° + /2) C
~~—L<— <U V (10) sin( /2) A 在式 (3) 至 (10) 中, ¾一表示第一介质单元的折射率, ¾二表示第二介质单元的折射 率, /¾ 表示背景介质的折射率, 表示第一顶角, ^表示第一介质单元的第一底边的长度, ^表示第二介质单元的第二底边的长度, ^表示第二顶角, C表示第二介质单元的第三底边的 长度, 表示第三角 <
与现有技术相比, 本发明的有益效果是:
本发明以第一介质单元和第二介质单元作为构造电磁波隐身器件的材料, 同一电磁波束 通过该隐身器件时, 通过不同折射率的介质控制波束的轨迹, 由背景介质以垂直于隐身器件 的其中任意一个第一介质单元的第三侧壁的方向入射, 并顺次经过构成本发明隐身器件的依 次相邻的第二介质单元、 第一介质单元、 第二介质单元、 第一介质单元、 第二介质单元, 绕 过中间的隐身区域, 出射到背景介质中, 且出射波束在入射波束的延长线上 (即同一束电磁 波束在出射时与入射时在同一直线上), 由此, 电磁波束没有入射到隐身区域内, 从而使隐身 区域内的物体达到隐身的效果。 本发明通过第一介质单元和第二介质单元围成整个电磁波隐 身器件, 不需要利用金属图案, 而只需利用自然界中容易获得的材料, 不需要较高的工艺, 易于实现; 在隐身器件工作时, 通过第一介质单元和第二介质单元来控制电磁波的轨迹, 不 需要外加电源等设备, 性能稳定; 相对于现有的只能实现对一个极化方向的电磁波隐身的技 术, 由于构成本发明电磁波隐身器件的第一介质单元和第二介质单元是各向同性的, 因此对 电磁波的极化方向不敏感, 尤其在可见光频段, 自然光都是非相干、 全极化的, 本发明在可 见光频段具有非常好的隐身效果; 本发明电磁波隐身器件具有六个方向隐身效果, 可适用于 整个电磁波段。
附图说明
图 1是本发明电磁波隐身器件的第一介质单元的示意图;
图 2是本发明电磁波隐身器件的横截面为等腰三角形的第二介质单元的示意图;
图 3是本发明电磁波隐身器件的第一种实施方式的整体结构示意图, 其中, 第二介质单元的 横截面为等腰三角形, 且不存在固体分隔物;
图 4是电磁波束通过图 3所示的电磁波隐身器件时的隐身效果示意图;
图 5是电磁波束在图 3所示的电磁波隐身器件中传播的轨迹图;
图 6是电磁波通过平行板介质时的折射示意图;
图 7是电磁波束在本发明电磁波隐身器件的第二种实施方式的轨迹图, 其中, 第二介质单元 的横截面为等腰三角形, 并且存在固体分隔物;
图 8是本发明电磁波隐身器件的横截面为等腰梯形的第二介质单元的示意图;
图 9是电磁波束通过本发明电磁波隐身器件的第三种实施方式的隐身效果示意图, 其中, 第 二介质单元的横截面为等腰梯形, 并且不存在固体分隔物;
图 10是电磁波束在本发明电磁波隐身器件的第四种实施方式中传播的轨迹图, 其中, 第二介 质单元的横截面为等腰梯形, 并且存在固体分隔物;
图 11是电磁波束照射到未处于隐身器件内的物体时, 在物体后面产生阴影区域的示意图;
图 12是本发明电磁波隐身器件中, 第一介质单元的上端、下端与第四固体分隔物的位置关系 示意图;
图 13是本发明电磁波隐身器件中, 横截面为等腰三角形的第二介质单元的上端、下端与第四 固体分隔物的位置关系示意图;
图 14是本发明电磁波隐身器件中, 横截面为等腰梯形的第二介质单元的上端、下端与第四固 体分隔物的位置关系示意图。
图中, 1.第一介质单元的第三侧壁; α.第一介质单元的第一顶角; 2.第二介质单元的 第四侧壁; β.第二介质单元横截面为等腰三角形时的第二顶角; γ .第二介质单元的横截面 为等腰梯形时的第三角; 3.电磁波隐身器件的第一介质单元; 4.电磁波隐身器件的第一介 质单元; 5.电磁波隐身器件的第一介质单元; 6.电磁波隐身器件的第一介质单元; 7.电磁 波隐身器件的第一介质单元; 8.电磁波隐身器件的第一介质单元; 9.电磁波隐身器件的隐 身区域; 10.电磁波隐身器件的第二介质单元; 11.电磁波隐身器件的第二介质单元; 12. 电磁波隐身器件的第二介质单元; 13.电磁波隐身器件的第二介质单元; 14.电磁波隐身器 件的第二介质单元; 15.电磁波隐身器件的第二介质单元; 16.背景介质所在区域; 17a. 电磁波束入射前在背景介质中的轨迹; 17b.电磁波束在第二介质单元内的轨迹; 17c.电磁 波束在第一介质单元内的轨迹; 17d.电磁波束在第二介质单元内的轨迹; 17e.电磁波束在 第一介质单元内的轨迹; 17f.电磁波束在第二介质单元内的轨迹; 17g.电磁波束出射到背 景介质后的轨迹; 18. 折射率为 /¾的介质; 19. 厚度为 w、 折射率为 的介质平行板; 20. 折射率为 的介质; 21a.电磁波束入射到本发明电磁波隐身器件前在背景介质中的轨迹;
21b.电磁波束在第二介质单元内的轨迹; 21c.电磁波束在第一介质单元内的轨迹; 21d.电 磁波束在第二介质单元内的轨迹; 21e.电磁波束在第一介质单元内的轨迹; 21f.电磁波束 在第二介质单元内的轨迹; 21g.电磁波束出射到背景介质后的轨迹; 22.电磁波隐身器件的 第一固体分隔物; 23.电磁波隐身器件的第二固体分隔物; 24.电磁波隐身器件的第三固体分 隔物; 25.第二介质单元的第六侧壁; 26.第二介质单元的第七侧壁; 27.电磁波隐身器件的 第二介质单元; 28.电磁波隐身器件的第二介质单元; 29.电磁波隐身器件的第二介质单元; 30a.电磁波束入射到本发明电磁波隐身器件前在背景介质中的轨迹; 30b.电磁波束在第二介 质单元内的轨迹; 30c.电磁波束在第一介质单元内的轨迹; 30d.电磁波束在第二介质单元 内的轨迹; 30e.电磁波束在第一介质单元内的轨迹; 30f.电磁波束在第二介质单元内的轨 迹; 30g.电磁波束出射到背景介质后的轨迹; 31a.电磁波束入射到本发明电磁波隐身器件 前在背景介质中的轨迹; 31b.电磁波束在第二介质单元内的轨迹; 31c.电磁波束在第一介
质单元内的轨迹; 31d.电磁波束在第二介质单元内的轨迹; 31e.电磁波束在第一介质单元 内的轨迹; 31f.电磁波束在第二介质单元内的轨迹; 31g.电磁波束出射到背景介质后的轨 迹; 32.未置于隐身器件中而直接被电磁波束照射的物体; 33.在电磁波束照射下, 未置于隐 身器件内的物体在垂直于电磁波束的出射方向的平面上所产生的矩形阴影的宽度; 34.电磁 波隐身器件的第四固体分隔物; 35.电磁波隐身器件的第二介质单元; 36.电磁波隐身器件 的第二介质单元; 37.电磁波隐身器件的第二介质单元; ^入是电磁波束从背景介质 16入 射到第一个第二介质单元 10发生折射时的入射角 (即入射波束与界面法线的夹角); ^出是 电磁波束从背景介质 16入射到第一个第二介质单元 10发生折射时的折射角 (即折射波束与 界面法线的夹角); ^入是电磁波束从第一个第二介质单元 10入射到第一个第一介质单元 3 发生折射时的入射角; 2 是电磁波束从第一个第二介质单元 10入射到第一个第一介质单元 3发生折射时的折射角; ^入是电磁波束从第一个第一介质单元入射到第二个第二介质单元发 生折射时的入射角; 是电磁波束从第一个第一介质单元 3入射到第二个第二介质单元 11 发生折射时的折射角; 是电磁波从折射率为 的介质 18入射到折射率为 的介质 19发生 折射时的入射角; 为电磁波从折射率为/ ¾的介质 18入射到折射率为 的介质 19发生折射 时的折射角; 2为电磁波从折射率为 的介质 19入射到折射率为/ ¾的介质 20发生折射时的 入射角; 为电磁波从折射率为 的介质 19入射到折射率为/ ¾的介质 20发生折射时的折射 角; 为没有平行板介质 19时, 电磁波直接从折射率为/¾的介质 18入射到折射率为/ ¾的介 质 20发生折射时的折射角; w为平行板介质的厚度; 为电磁波通过折射率为 的平行板介 质 19与不通过平行板介质 19所产生的位移差。
具体实施方式
电磁波是指由同相振荡且互相垂直的电场与磁场在空间中以周期波动的形式进行能量和 动量传递的一种波。 按照频率分类, 从低频到高频, 电磁波包括无线电波、 微波、 红外线、 可见光、 紫外光、 X射线和伽马射线等等, 其中人眼可以接受的电磁波, 波长大约在 380至 780 纳米之间, 称为可见光。 在不同的介质中, 电磁波的传播速度各不相同。 两种介质相比 时, 电磁波传播速度大的介质折射率较小, 电磁波传播速度小的介质折射率较大。 本发明所 指的流体是液体和气体的总称。
图 1所示为构成本发明电磁波隐身器件的第一介质单元, 该第一介质单元为横截面呈等 腰三角形的柱体。如图 1所示, 各第一介质单元的横截面的顶角为第一顶角 α、两个腰为第一
腰、 底边为第一底边, 第一介质单元的第一腰所在的侧壁为第一侧壁, 第一介质单元的第一 底边所在的侧壁为第三侧壁 1。
图 2所示为构成本发明电磁波隐身器件的第二介质单元的一种结构。 在图 2中, 第二介 质单元为横截面呈等腰三角形的柱体。 如图 2所示, 第二介质单元的横截面的顶角为第二顶 角3、 两个腰为第二腰、 底边为第二底边, 第二介质单元的第二腰所在的侧壁为第二侧壁, 第 二介质单元的第二底边所在的侧壁为第四侧壁 2。
图 3示出的是本发明电磁波隐身器件的第一种实施方式的整体结构示意图, 在图 3中, 电磁波隐身器件是由六个对入射电磁波是透明的第一介质单元和六个对入射电磁波是透明的 第二介质单元构成, 其中, 第一介质单元和第二介质单元均为固体。 在图 3中, 六个第一介 质单元 3、 4、 5、 6、 7和 8的横截面均为等腰三角形。 第一介质单元 3、 4、 5、 6、 7和 8依 次沿顺时针方向排列并共同围成一个隐身区域 9, 且这六个第一介质单元的第三侧壁 1均面 向隐身区域 9。 六个第二介质单元 10、 11、 12、 13、 14和 15的横截面均为等腰三角形。 每 个第二介质单元分别位于相邻的两个第一介质单元之间, 即每两个相邻的第一介质单元之间 有一个第二介质单元, 且每个第二介质单元的第二侧壁分别与同其相邻的第一介质单元的第 一侧壁相对并接触。 六个第二介质单元的第四侧壁 2均面向背景介质 16。 其中, 第二介质单 元 10位于第一介质单元 3与第一介质单元 8之间, 相应地, 第二介质单元 11、 12、 13、 14 和 15依次沿顺时针方向位于相应的两个相邻的第一介质单元之间。
具体地说, 如图 3所示, 六个第一介质单元围成一个隐身区域 9, 第二介质单元 10位于 第一介质单元 3和第一介质单元 8之间,第二介质单元 11位于第一介质单元 4和第一介质单 元 3之间, 同理类推, 第二介质单元 12、 13、 14、 15依次沿顺时针方向分别位于相应的两个 相邻的第一介质单元之间。 由此, 第一介质单元 3、 第二介质单元 11、 第一介质单元 4、 第 二介质单元 12、 第一介质单元 5、 第二介质单元 13、 第一介质单元 6、 第二介质单元 14、 第 一介质单元 7、 第二介质单元 15、 第一介质单元 8、 第二介质单元 10按顺时针方向依次相邻 排列而构成本发明电磁波隐身器件的一种实施方式。 其中, 六个第二介质单元的第四侧壁 2 面向背景介质 16, 六个第一介质单元的第三侧壁 1面向隐身区域 9, 而隐身区域 9则用来放 置被隐身的物体。
众所周知, 当电磁波束入射到两种不同介质的交界面时, 会发生折射, 折射的方向跟电 磁波入射的角度和两种介质的折射率有关, 即遵循斯奈尔定律 8111 = 8111 ,其中, /¾和 n2分别为入射电磁波和折射电磁波所在介质的折射率, 和 θ2分别为电磁波的入射角和折射 角。 相对而言, 交界面两边介质的折射率相差越大, 电磁波在这一交界面出射时相对于入射
时发生的偏移越大。 电磁波在各向异性介质交界面处的折射情况与入射电磁波的极化方向有 关。 与各向异性介质的情况不同, 本发明电磁波隐身器件所用的第一介质单元和第二介质单 元都是各向同性的, 在这些介质的交界面处的折射与电磁波的极化方向无关, 所以本发明电 磁波隐身器件的隐身效果与电磁波的极化方向无关, 可以对全极化电磁波实现隐身。
以下结合图 4和图 5详细说明电磁波束从背景介质入射到如图 3所示的电磁波隐身器件 所经历的轨迹。 以图 4作为示例, 假设电磁波束在背景介质 16中沿水平方向从左至右入射到 本发明电磁波隐身器件, 此时电磁波束垂直于第一介质单元 8的第三侧壁 1。 电磁波束的传 播可以形象地用很多平行的射线来表示。 这些射线表示所在位置处的电磁波束的传播特性, 射线的方向表示在射线所在位置处的电磁波束的能量的传播方向, 也即坡印廷矢量的方向, 射线也可以表示为在射线位置处的电磁波束的传播轨迹, 所有这些平行的射线的传播也形象 地构成了总的电磁波束的传播特性。 电磁波束入射前在背景介质 16中的传播方向(或称之为 "轨迹", 也即图 4所示的背景介质 16中的平行射线)与第一介质单元 8的第三侧壁 1垂直。 由于第二介质单元 10与第二介质单元 15之间的 "结合点"形成一个奇点, 入射到本发明电 磁波隐身器件中的电磁波束将分为三部分: (1 ) 在 "结合点"处以上部分的波束 (归类为电 磁波束 I ); ( 2 ) 在 "结合点"处以下部分的波束 (归类为电磁波束 I I ); ( 3 ) 入射到 "结合 点"处的波束(归类为电磁波束 111)。 电磁波束在本发明电磁波隐身器件中的传播也可以由 很多平行射线表示。 这些平行射线在本发明电磁波隐身器件的各个区域的传播轨迹也形象地 构成了整个电磁波束在本发明电磁波隐身器件的相应区域的传播轨迹。 以电磁波束 17 (包括 轨迹 17a、 17b、 17c、 17d、 17e、 17f和 17g) 为例, 其他平行电磁波束在本发明电磁波隐身 器件的各个区域的传播轨迹分别与电磁波束 17 在本发明电磁波隐身器件的各个区域的传播 轨迹平行, 因此可以作类似分析。 在电磁波束 17中, 17a表示的是电磁波束入射到本发明电 磁波隐身器件前在背景介质中的轨迹, 轨迹 17a与第一介质单元 8的第三侧壁 1垂直。 当电 磁波束 17从背景介质 16入射到该电磁波隐身器件的外壁时,电磁波在背景介质 16与第二介 质单元 10的交界面处发生折射,电磁波束 17在第二介质单元 10内偏移到如轨迹 17b所在位 置。 当电磁波束 17经过第二介质单元 10与第一介质单元 3的交界面时发生第二次折射, 电 磁波束 17在第一介质单元 3内再度发生偏移至轨迹 17c所在的位置。 偏移后的电磁波束 17 继续经过第一介质单元 3与第二介质单元 11的交界面时发生第三次折射, 电磁波束 17在第 二介质单元 11内偏移至轨迹 17d所在位置, 此时电磁波束 17所在的轨迹 17d的方向恰好能 与入射到本发明电磁波隐身器件前的轨迹 17a的方向平行但有一个纵向的位移。 当电磁波束 17继续经过第二介质单元 11与第一介质单元 4的交界面时发生第四次折射, 电磁波束 17在 第一介质单元 4内向下发生偏移至轨迹 17e所在的位置。当电磁波束 17向前经过第一介质单
元 4与第二介质单元 12的交界面时发生第五次折射,电磁波束 17在第二介质单元 12内偏移 至轨迹 17f所在位置。当电磁波束 17向前经过第二介质单元 12与背景介质 16的交界面时发 生第六次折射, 电磁波束 17出射回到背景介质 16中的轨迹 17g的方向与入射时的轨迹 17a 的方向相同, 即电磁波束 17在入射到本发明电磁波隐身器件前的轨迹 17a与出射时的轨迹 17g 在同一直线上。 由于其他电磁波束在本发明电磁波隐身器件的各个区域的传播轨迹分别 与电磁波束 17在本发明电磁波隐身器件的各个区域的传播轨迹平行,它们在入射到本发明电 磁波隐身器件前的轨迹与出射时各自的轨迹都在相应的同一直线上, 没有发生任何改变。 因 此电磁波束 I入射到本发明电磁波隐身器件前的轨迹与出射时的轨迹相比也没有发生任何改 变。
以上通过图 4分析了电磁波在 "结合点"处以上部分的波束 (电磁波束 I ) 由背景介质 16以垂直于第一介质单元 8的第三侧壁 1的方向向本发明电磁波隐身器件入射, 然后依次沿 着依次相邻的第二介质单元 10、 第一介质单元 3、 第二介质单元 11、 第一介质单元 4、 第二 介质单元 12后出射到背景介质 16的轨迹。 由于对称性, 显然可以确定, 电磁波的下半部分 波束 (即电磁波束 Π ) 由背景介质 16 向本发明电磁波隐身器件入射后, 则是依次经由依次 相邻的第二介质单元 15、 第一介质单元 7、 第二介质单元 14、 第一介质单元 6、 第二介质单 元 13, 最后出射到背景介质 16。 因此, 电磁波束入射到本发明电磁波隐身器件时, 上半部分 的波束将向上偏转, 下半部分的波束将向下偏转, 从而绕过中间部分的隐身区域 9, 并在出 射时回到原来的路径上, 使隐身区域 9内的物体达到隐身。
对于电磁波恰好从背景介质入射到 "结合点"处的电磁波束 (即电磁波束 111 ), 由于第 二介质单元 10与第二介质单元 15的 "结合点" 只是一个奇点, 面积无限小, 也即表示照射 在 "结合点"上总的的电磁波功率 (单位面积的坡印廷功率与结合点处面积的乘积) 为 0, 所以该 "结合点"本身不会破坏器件的整体隐身效果。 可见, 所有电磁波进入本发明电磁波 隐身器件后均经过多次的折射而绕过中间的隐身区域 9, 从而使隐身区域 9内的物体不可见, 并且同一波束在出射时的轨迹与入射时的轨迹在同一直线上, 如同没有受到任何阻碍一般, 因此起到了很好的隐身效果。
以下结合图 5举例说明本发明电磁波隐身器件的结构参数及各介质单元的折射率之间的 关系。 假定第一介质单元的折射率为 ¾一, 第二介质单元的折射率为 ¾二, 背景介质的折射 率为 ¾ , 第一介质单元的第一顶角为《, 第二介质单元的第二顶角为 ,第一介质单元的第 一底边的长度为 A第二介质单元的第二底边的长度 ?。当电磁波束以图 5所示的水平方向(即 以垂直于第一介质单元 8和第一介质单元 5的第三侧壁的方向)从背景介质 16入射到第二介
质单元 10时在交界面处发生折射, 在背景介质 16中电磁波束的入射方向与第一介质单元 8 的第三侧壁 1垂直。 电磁波束在背景介质 16与第二介质单元 10的交界面处发生折射时的入 射角为 人 =30°, 折射角为 出 , 根据斯奈尔定律, ¾景 sin 30° = ¾: sin 出 。 当折射后的电 磁波束继续入射到第二介质单元 10与第一介质单元 3 的交界面时再次发生折射, 入射角为 入 =60。 - 出 -α/2,折射角为 出 ,根据斯奈尔定律, "第二 sin(60°— -a/2) = ¾—sin r 当折射后的电磁波束继续入射到第一介质单元 3与第二介质单元 11的交界面时发生第三次折 射, 入射角为 Θ认 =θ^+α , 折射角为 3出 =30° + «/2 , 根据斯奈尔定律, w第一 sin ( 出 = "第二 sin(30。 + a/2) 。 综 合 以 上 公 式 , 可 得 到 : sin
w sin arcsin + a w第二 sin (30。 + a/2)。 此夕卜:
第一
第二介质单元的等腰三角形横截面的底角为 90°-^,根据几何结构,「90°-^^χ2 + « = 120°
2 ^ 2) 可得到 = 60° + 。 同时, 为保证在第二介质单元 10 处的电磁波束能入射到第二介质单元 nMaL sin 30
10与第一介质单元 3的交界面, 可得到: 《<2arcsin -60°。 为保证在第一介质
1第二
单元 3 的电磁波束能入射到第一介质单元 3 与第二介质单元 11 的交界面, 可得到:
假设背景介质的折射率为 ½ = 1. 33, 第二介质单元的折射率采用/ ¾第二- =1, 第一介质单元 的第一顶角采用《=13 ° , 根据以上公式可以得到: β :Ί?>。 以及第一介质单元的折射率 ¾一 = 1. 78。 在实际应用中, 可以根据背景介质的折射率/ ¾¾的情况, 设定第一介质单元的第 一顶角《、 第一介质单元的折射率¾ 第二介质单元的折射率¾二这三个变量中的任意两 个变量得出其他的变量的值。
图 6所示为电磁波从折射率为 的介质 18入射到厚度为 w、 折射率为 的平行板介质
19,并在平行板介质的第二个交界面出射到折射率为/ ¾的介质 20中的电磁波折射情况。根据 斯奈尔定律, 可以得到: sin θχ = nx sin θχ1 , ηχ sin θχ2 = sin < 2。 其中, 是电磁波从折射 率为/ ¾的介质 18入射到折射率为 的介质 19发生折射时的入射角; 为电磁波从折射率为 的介质 18入射到折射率为 的介质 19发生折射时的折射角; 2为电磁波从折射率为 的 介质 19入射到折射率为/ ¾的介质 20发生折射时的入射角; 为电磁波从折射率为 的介质
19 入射到折射率为/ ¾的介质 20 发生折射时的折射角。 因为 = 2, 所以可以得到
A sin ^ sin 。 另外, 为没有平行板介质 19时, 电磁波直接从折射率为/¾的介质 18入 射到折射率为/ ¾的介质 20 发生折射时的折射角, 由于同样满足如下斯奈尔定律: nx sin θ1 = n2 sin θ2', 可以得到: = , 即电磁波从折射率为 的介质 18直接传播到折射率 为/ ¾的介质 20,与电磁波从折射率为 的介质 18先入射到折射率为 的平板介质 19再传播 到折射率为/ ¾的介质 20, 两者出射到介质 20的电磁波的方向保持不变, 只会产生一个较小 的 位 移 , 如 图 6 所 示 , 通 过 分 析 计 算 得 到 的 位 移 的 距 离 为 :
† sin θ1
d w tan θ - tan arcsm
n
图 7所示为本发明电磁波隐身器件的第二种实施方式的示意图。 在图 7所示的电磁波隐 身器件中, 六个第一介质单元 3、 4、 5、 6、 7、 8的横截面为等腰三角形, 且六个第一介质单 元的第三侧壁 1面向隐身区域 9; 六个第二介质单元 10、 11、 12、 13、 14、 15的横截面为等 腰三角形, 且分别位于相邻的两个第一介质单元之间, 六个第二介质单元的第四侧壁 2面向 背景介质 16 ; 相邻的第一侧壁和第二侧壁之间由第二固体分隔物 23相隔且第一侧壁和第二 侧壁均与对应的第二固体分隔物 23接触, 第二介质单元的第四侧壁 2与背景介质 16之间由 第一固体分隔物 22相隔, 第一介质单元的第三侧壁 1与隐身区域 9之间由第三固体分隔物 24相隔。 如果第一介质单元和第二介质单元均为固体, 那么, 此时本发明电磁波隐身器件的 结构或者如图 3、 4和 5所示, 或者相当于图 7所示但没有其中的第一固体分隔物 22和第三 固体分隔物 24的情形。 如果第一介质单元为固体, 第二介质单元为流体, 那么, 如图 13所 示, 第二介质单元 10、 11、 12、 13、 14、 15的上、 下端与背景介质 16之间分别由第四固体 分隔物 34相隔, 此时, 本发明电磁波隐身器件的结构或者相当于图 7所示但没有其中的第三 固体分隔物 24的情形, 或者相当于图 7所示但没有其中的第三固体分隔物 24和第二固体分 隔物 23且相邻的第一侧壁和第二侧壁直接接触的情形。如果第一介质单元为流体, 第二介质 单元为固体, 那么, 如图 12所示, 第一介质单元 3、 4、 5、 6、 7、 8的上端、 下端与背景介 质 16之间分别由第四固体分隔物 34相隔, 此时, 本发明电磁波隐身器件的结构或者相当于 图 7所示但没有其中的第一固体分隔物 22的情形,或者相当于图 7所示但没有其中的第一固 体分隔物 22和第二固体分隔物 23且相邻的第一侧壁和第二侧壁直接接触的情形。 如果第一 介质单元为流体, 第二介质单元为流体, 那么, 如图 12和图 13所示, 第一介质单元 3、 4、 5、 6、 7、 8的上端、 下端与背景介质 16之间分别由第四固体分隔物 34相隔, 第二介质单元 10、 11、 12、 13、 14、 15的上、 下端与背景介质 16之间分别由第四固体分隔物 34相隔, 此 时, 本发明电磁波隐身器件的结构如图 7所示。
以下通过对比入射到有固体分隔物的本发明电磁波隐身器件的电磁波束 21 (包括轨迹 21a, 21b, 21c , 21d, 21e, 21f和 21g )和入射到没有固体分隔物的本发明电磁波隐身器件的电 磁波束 17 (包括轨迹 17a, 17b, 17c , 17d, lie, 17f和 17g ) 的轨迹, 来分析各固体分隔物对 本发明电磁波隐身器件隐身效果的影响。 如图 7所示, 选取固体分隔物对电磁波束的影响最 大的情况来分析, 即在隐身器件中同时存在第一固体分隔物 22、 第二固体分隔物 23和第三 固体分隔物 24的情形。 当电磁波束 21从背景介质 16以垂直于第一介质单元 8的第三侧壁 1 的方向沿着轨迹 21a (电磁波束 21在背景介质 16中的轨迹 21a与电磁波束 17在背景介质 16 中的轨迹 17a的位置相同) 经过第一固体分隔物 22并入射到第二介质单元 10时, 电磁波束 的轨迹 21b的方向与没有经过第一固体分隔物而直接入射到第二介质单元 10的电磁波束的轨
迹相比不变, 而位移则偏移了 οί, 即: 电磁波束的轨迹 21b与轨迹 17b的方向相同, 但是有 一个 οί的位移,其中 οί的位移是由第二介质单元 10和背景介质 16之间的第一固体分隔物 22 所引起的。 当电磁波束 21进入到第二介质单元 10并继续传播, 进而通过第二介质单元 10和 第一介质单元 3之间的第二固体分隔物 23而入射到第一介质单元 3时,在第一介质单元 3的 轨迹 21c与轨迹 17c相比, 其方向保持不变, 但在位移方面, 轨迹 21c与轨迹 17c相比, 由 于第二介质单元 10和第一介质单元 3之间的第二固体分隔物 23的存在, 额外增加了 的位 移。 当电磁波束 21进入到第一介质单元 3并继续传播, 进而通过第一介质单元 3和第二介质 单元 11之间的第二固体分隔物 23而入射到第二介质单元 11时, 在第二介质单元 11的轨迹 21d与轨迹 17d相比,其方向保持不变,但在位移方面,轨迹 21d相对于轨迹 17d又增加了 ck 的偏移, 其中 4的位移是由第一介质单元 3和第二介质单元 11之间的第二固体分隔物 23所 引起的。 根据对称性和费马路径可逆原理, 电磁波束 21由第二介质单元 11通过第二介质单 元 11和第一介质单元 4之间的第二固体分隔物 23并入射到第一介质单元 4时, 第二介质单 元 11和第一介质单元 4之间的第二固体分隔物 23所引起的位移为 - k, 即与没有第二固体 分隔物 23时相比,第一介质单元 4的轨迹 21e与轨迹 17e之间的间距减少了 4的偏移,但方 向保持不变; 电磁波束 21由第一介质单元 4通过第一介质单元 4和第二介质单元 12之间的 第二固体分隔物 23并入射到第二介质单元 12时,第一介质单元 4和第二介质单元 12之间的 第二固体分隔物 23将引起 -^的位移, 即与没有第二固体分隔物 23时相比, 第二介质单元 1 的轨迹 21f 与轨迹 17f之间的间距又减少了 4的偏移, 但方向保持不变; 电磁波束 21由 第二介质单元 12通过第二介质单元 12和背景介质 16之间的第一固体分隔物 22入射到背景 介质 16时, 第二介质单元 12和背景介质 16之间的第一固体分隔物 22将引起 -οί的位移, 从而使最终出射到背景介质 16中的电磁波束的轨迹 21g的方向与轨迹 17g的方向相同,且两 者的轨迹重合。 因此, 电磁波束 21按先后顺序沿着依次相邻的第二介质单元 10、 第一介质 单元 3、 第二介质单元 11、 第一介质单元 4、 第二介质单元 12出射到背景介质 16中的轨迹 21g与入射时的轨迹 21a的方向仍然相同, 并且在同一直线上。
图 11所示是物体 32未置于隐身器件内而直接在电磁波束照射下产生阴影的示意图。 当 物体 32为横截面呈正六边形的柱体时,在电磁波束照射下,会在物体的后面呈现出阴影区域。 在垂直于电磁波波束传播方向的平面上, 该阴影的形状为矩形, 因此阴影面积的大小可以用 在垂直电磁波波束传播方向的平面上该阴影的宽度 33来量化表示。而将物体置于电磁波隐身 器件的隐身区域内时, 阴影的宽度则会减小, 由此使阴影的面积也减小。 阴影的面积越小, 则表明隐身的效果越好。
如图 7所示, 由于第二介质单元 10与第二介质单元 15不再直接接触形成一个面积无限
小的 "结合点", 而是在两者之间由有一定厚度的第二固体分隔物 23隔开, 因此, 从背景介 质 16入射到第二介质单元 10与第二介质单元 15之间的第二固体分隔物 23上的电磁波束并 不会按照电磁波束 21 的轨迹入射到第二介质单元 10, 从而不能实现正确的折射, 这部分电 磁波束因为没有能够在本发明电磁波隐身器件的另一边出射, 因此隐身器件的后面出现阴影 区域, 在垂直于电磁波束入射方向的平面上, 该阴影的形状为矩形。 下面以隐身效果最差的 情况 (对应为在垂直于电磁波束的入射方向的平面上的阴影的面积最大的情况) 为例, 分析 第一固体分隔物的厚度和第二固体分隔物的厚度需要满足何种条件, 隐身器件才能具有隐身 效果。 由于第一固体分隔物的折射率大于等于第二介质单元的折射率, 第二固体分隔物的折 射率大于等于第二介质单元的折射率, 因此在垂直于电磁波束出射的方向的平面上产生的阴 影的最大宽度 L与背景介质的折射率; ¾Λ、 第一介质单元的折射率/ ¾一、 第二介质单元的折 射率 ¾二、 第一介质单元的第一顶角《、 第一固体分隔物的厚度^以及第二固体分隔物的厚 度 ^2之间满足如下式所示的关系:
入 < 0
入 =30c
sin 30°
出 = arcsin
n第二
入 =60ο _ 出 一 / 2;
第二 sin (60° _ 出 _ « / 2)
6*2 =arcsin
1第一 出 =30。 + α / 2; 根据以上公式, 当第一固体分隔物的厚度 ^与第二固体分隔物的厚度 ^2确定时, 产生 的阴影的最大宽度 L与背景介质的折射率; ¾¾、 第一介质单元的折射率/ ¾一、 第二介质单元 的折射率 ¾—以及第一介质单元的第一顶角《有关。 由于背景介质的折射率 ½ 、 第一介质
单元的折射率 ¾一、 第二介质单元的折射率 ¾—以及第一介质单元的第一顶角《满足以下条 n,a . sin 30
nm . > — > nm . / 1.8、 > 禾口 0° < « < 2 arcsin - 60°。 根据计算可以
"第二
得到, 在上述条件下, 产生的阴影的最大宽度为 = + 7.04>^2。 而当与本发明隐身器件的 隐身区域的形状和大小相同的物体未置于隐身器件内时, 该物体在电磁波照射下, 在垂直于 电磁波束出射方向的平面上所产生的矩形阴影的宽度为 H。 可以计算得到 H≥2A,其中 A为 第一介质单元的第一底边的长度。 因此, 只要满足^ < 1, 即在 + 7.04 >< ^2 < 2^这种情况
2A
下, 本发明电磁波隐身器件都能有效地减少物体产生的阴影面积, 使得与该隐身器件的隐身 区域的形状和大小相同的物体放在隐身器件中时产生的阴影的宽度 L始终小于物体未置于隐 身器件内时所产生的阴影的宽度 H, 因此始终具有一定的隐身效果。
以上给出了产生的阴影的最大宽度 L的公式, 其中, 第一固体分隔物或者第二固体分隔 物厚度越薄, 阴影的宽度就越小。 当第一介质单元和第二介质单元中的其中一种不为流体而 为固体时, 可以不需要相应的第一固体分隔物或者第二固体分隔物。 特别地, 当第一介质单 元与第二介质单元均为固体且没有固体分隔物时, 阴影的宽度 L=0, 此时能实现完全隐身。
图 8所示为构成本发明电磁波隐身器件的另一种第二介质单元, 该第二介质单元为横截 面呈等腰梯形的柱体。 图 9所示为本发明电磁波隐身器件的第三种实施方式的示意图。 在图 9中, 六个第一介质单元 3、 4、 5、 6、 7、 8的横截面均为等腰三角形, 且依次沿顺时针方向 排列并共同围成一个隐身区域 9, 这六个第一介质单元 3、 4、 5、 6、 7、 8的第三侧壁 1面向 隐身区域 9; 六个第二介质单元 27、 28、 29、 35、 36、 37的横截面均为等腰梯形, 且分别位 于相邻的两个第一介质单元之间, 即每两个相邻的第一介质单元之间有一个第二介质单元, 且每个第二介质单元的第五侧壁分别与同其相邻的第一介质单元的第一侧壁接触, 六个第二 介质单元 27、 28、 29、 35、 36、 37的第六侧壁 25面向背景介质 16, 六个第二介质单元 27、 28、 29、 35、 36、 37的第七侧壁 26则面向隐身区域 9。
参见图 9, 以电磁波束 30为例进一步说明如下:
电磁波束 30以垂直于第一介质单元 8的第三侧壁 1的方向入射,按先后顺序经过依次相 邻的第二介质单元 27、 第一介质单元 3、 第二介质单元 28、 第一介质单元 4、 第二介质单元 29后出射到背景介质 16中的轨迹 30g与入射时的轨迹 30a的方向相同且在同一直线上, 并 且不经过中间的隐身区域。 由于其他平行入射的电磁波束在本发明电磁波隐身器件的各个区 域的传播轨迹分别与电磁波束 30在本发明电磁波隐身器件的各个区域的传播轨迹平行,它们 在入射到本发明电磁波隐身器件前的轨迹与出射时各自的轨迹都在相应的同一直线上, 没有
发生任何改变, 并且由背景介质向隐身器件入射的同一电磁波波束, 都是按先后顺序经过依 次相邻的第二介质单元、 第一介质单元、 第二介质单元、 第一介质单元、 第二介质单元后出 射到所述背景介质中, 根据斯奈尔定律以及参照图 5的分析, 可以得出, 第一介质单元的折 射率 ¾一,第二介质单元的折射率¾二, 背景介质的折射率 ¾ ,第一介质单元的第一顶角《 满足如下式所示的关系:
此外, 第二介质单元的等腰梯形横截面的底角为 90° - , 根据几何结构,
7
90 :2 + « = 120° , 可得到 j = 60° + a。 同时, 为保证在第二介质单元 27处的电磁波束 能入射到第二介质单元 27与第一介质单元 3的交界面并进一步传播到第一介质单元 3与第二 介质单元 28的交界面处, 需要同时满足以下公式:
w sin 30 sin ° + /2) C
a < 2 arcsin - 60。和 ~ - ~~ <— < U x V
"第二 sin (a/2) A 其中,
上述公式中, A表示第一介质单元的第一底边的长度, C表示第二介质单元的第三底边 的长度。 另外, 第二介质单元的第四底边的长度 D 相应地可以根据 A 和 C 得到: ) = c _ sin (30° + a/2) A o 可以看到, 在满足^ ^:- + ^^时, 第二介质单元的第 sin («/2 sin («/2 四底边的长度 )都是大于等于 0, 而在 )等于 0时, 就是第二介质单元的横截面为等腰三角 形的情况。
图 10所示为本发明电磁波隐身器件的第四种实施方式的示意图。 在图 10中, 六个第一 介质单元 3、 4、 5、 6、 7、 8的横截面为等腰三角形, 且六个第一介质单元 3、 4、 5、 6、 7、 8的第三侧壁 1面向隐身区域 9; 六个第二介质单元 27、 28、 29、 35、 36、 37的横截面为等 腰梯形, 且分别位于相应的相邻的两个第一介质单元之间; 六个第二介质单元 27、 28、 29、 35、 36、 37的第六侧壁 25面向背景介质 16, 六个第二介质单元 27、 28、 29、 35、 36、 37的 第七侧壁 26面向隐身区域 9, 相邻的第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一 侧壁和第五侧壁均与对应的第二固体分隔物 23接触, 第二介质单元的第六侧壁 25与背景介 质 16之间由第一固体分隔物 22相隔,第二介质单元的第七侧壁 26与隐身区域 9之间由第三 固体分隔物 24相隔,第一介质单元第三侧壁 1与隐身区域 9之间由第三固体分隔物 24相隔。 如果第一介质单元和第二介质单元均为固体, 那么, 此时本发明电磁波隐身器件结构或者如 图 9所示, 或者相当于图 10中没有第一固体分隔物 22和第三固体分隔物 24的情形。如果第 一介质单元为固体, 第二介质单元为流体, 那么, 如图 14所示, 第二介质单元 27、 28、 29、 35、 36、 37的上端、 下端与背景介质 16之间分别由第四固体分隔物 34相隔, 此时, 本发明 电磁波隐身器件的结构或者相当于图 10所示但没有其中的第一介质单元与隐身区域 9之间的 第三固体分隔物 24的情形,或者相当于图 10所示但没有其中的第二固体分隔物 23和第一介 质单元与隐身区域 9之间的第三固体分隔物 24、 并且相邻的第一侧壁和第五侧壁直接接触的 情形。 如果第一介质单元为流体, 第二介质单元为固体, 那么, 如图 12所示, 第一介质单元 3、 4、 5、 6、 7、 8的上端、 下端与背景介质 16之间分别由第四固体分隔物 34相隔, 此时, 本发明电磁波隐身器件的结构或者相当于图 10所示但没有其中的第一固体分隔物 22和第二 介质单元与隐身区域 9之间的第三固体分隔物 24的情形, 或者相当于图 10所示但没有其中
的第一固体分隔物 22、第二固体分隔物 23、第二介质单元与隐身区域 9之间的第三固体分隔 物 24、 并且相邻的第一侧壁和第五侧壁直接接触的情形。 如果第一介质单元为流体, 第二介 质单元为流体, 那么, 如图 12和图 14所示, 第一介质单元 3、 4、 5、 6、 7、 8的上端、 下端 与背景介质 16之间分别由第四固体分隔物 34相隔, 第二介质单元 27、 28、 29、 35、 36、 37 的上端、 下端与背景介质 16之间分别由第四固体分隔物 34相隔, 此时, 本发明电磁波隐身 器件的结构如图 10所示。
如图 10所示, 通过分析入射到有固体分隔物的本发明电磁波隐身器件的电磁波束 31, 电磁波束 31以垂直于第一介质单元 8的第三侧壁 1的方向,按先后顺序经过依次相邻的第二 介质单元 27、 第一介质单元 3、 第二介质单元 28、 第一介质单元 4、 第二介质单元 29出射到 背景介质 16中的轨迹 31g与入射时的轨迹 31a的方向相同且在同一直线上,并且不经过中间 的隐身区域。 隐身区域内的物体产生的阴影的宽度也由第一固体分隔物和第二固体分隔物的 厚度和折射率所决定, 由于背景介质的折射率 ¾Λ、 第一介质单元的折射率¾一、 第二介质 单元的折射率/ ¾—以及第一介质单元的第一顶角 α满足如下条件: ≥/¾^ /1.8、 w sin 30
¾;— > ¾;-禾口 0° < α < 2arcsin - 60°。通过分析计算可以得到, 在上述条件下, 隐
"第二
身区域内的物体所产生的阴影的最大宽度为 = + 7.04 >< ^2。 当第一固体分隔物的厚度 和 第二固体分隔物的厚度^满足条件^1 + 7.04 >< ^2 < 2^时, 本发明电磁波隐身器件都能有效地 减少隐身物体的阴影, 使得与该隐身器件的隐身区域的形状和大小相同的物体放在隐身器件 中时产生的阴影的宽度 L始终小于物体未置于隐身器件内时所产生的阴影的宽度 H, 因此始 终具有一定的隐身效果。 同样地, 第一固体分隔物或者第二固体分隔物的厚度越薄 (即第一 介质单元和第二介质单元之间的间距越小), 阴影的宽度就越小。 当第一介质单元和第二介质 单元中有一种不为流体时, 可以不需要相应的第一固体分隔物或者第二固体分隔物。特别地, 当第一介质单元与第二介质单元均为固体且没有固体分隔物时, 阴影的宽度 L=0, 此时能实 现完全隐身。
虽然图 4、 图 5、 图 7、 图 9和图 10中只画出了电磁波束从左边水平入射时的情况, 但 是由于本发明电磁波隐身器件是六边形结构, 具有六重对称性, 电磁波束可以从垂直于任意 一个第一介质单元的第三侧壁的方向向电磁波隐身器件入射, 且具有同样的隐身效果, 因此, 本发明电磁波隐身器件能实现在六个方向上隐身的效果。
需要说明的是, 在本发明中, 当提及第一介质单元的侧壁与第二介质单元的侧壁接触时,
所谓的 "接触"是指在第一介质单元的侧壁与第二介质单元的侧壁之间不存在任何其他介质; 当提及第一介质单元、 第二介质单元的侧壁与相应的固体分隔物接触时, 所谓的 "接触"是 指在第一介质单元、 第二介质单元的侧壁与相应的固体分隔物之间不存在任何其他介质。
Claims
1.一种柱状电磁波隐身器件, 其特征是: 它包括六个第一介质单元和六个第二介质单元, 所述第一介质单元和第二介质单元对入射的电磁波是透明的, 第一介质单元的折射率大于第 二介质单元的折射率, 第一介质单元为横截面呈等腰三角形的柱体, 第二介质单元或者为横 截面呈等腰三角形的柱体、 或者为横截面呈等腰梯形的柱体;
所述各第一介质单元的横截面的顶角为第一顶角, 各第一介质单元的横截面的两个腰为 第一腰, 各第一介质单元的横截面的底边为第一底边, 第一介质单元的所述第一腰所在的侧 壁为第一侧壁, 第一介质单元的所述第一底边所在的侧壁为第三侧壁;
若第二介质单元的横截面呈等腰三角形, 则第二介质单元的横截面的顶角为第二顶角、 两个腰为第二腰、 底边为第二底边, 第二介质单元的所述第二腰所在的侧壁为第二侧壁, 第 二介质单元的所述第二底边所在的侧壁为第四侧壁;
若第二介质单元的横截面呈等腰梯形, 则第二介质单元的横截面的两腰的延长线所构成 的夹角为第三角, 第二介质单元的横截面的两个腰为第三腰、 下底边为第三底边、 上底边为 第四底边, 第二介质单元的所述第三腰所在的侧壁为第五侧壁, 第二介质单元的所述第三底 边所在的侧壁为第六侧壁, 第二介质单元的所述第四底边所在的侧壁为第七侧壁;
当第二介质单元的横截面呈等腰三角形时, 每两个相邻的第一介质单元之间设有一个第 二介质单元, 相邻的第二侧壁和第一侧壁相对, 各第二介质单元的第四侧壁面向背景介质, 各第一介质单元的第三侧壁面向隐身区域;
当第二介质单元的横截面呈等腰三角形时,如果第一介质单元和第二介质单元均为固体, 那么, 或者相邻的第一侧壁和第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固 体分隔物相隔且第一侧壁和第二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为固体, 第二介质单元为 流体, 那么, 第二介质单元的第四侧壁与背景介质之间由第一固体分隔物相隔, 第二介质单 元的上端、 下端与背景介质之间分别由第四固体分隔物相隔; 并且, 或者相邻的第一侧壁和 第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第 二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为流体, 第二介质单元为 固体, 那么, 第一介质单元的上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第一 介质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔; 并且, 或者相邻的第一侧壁和
第二侧壁接触, 或者相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第 二侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰三角形时, 如果第一介质单元为流体, 第二介质单元为 流体, 那么, 相邻的第一侧壁和第二侧壁之间由第二固体分隔物相隔且第一侧壁和第二侧壁 均与对应的第二固体分隔物接触, 第二介质单元的第四侧壁与背景介质之间由第一固体分隔 物相隔, 第一介质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的 上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第二介质单元的上端、 下端与背景 介质之间分别由第四固体分隔物相隔;
当第二介质单元的横截面呈等腰梯形时, 每两个相邻的第一介质单元之间设有一个第二 介质单元, 相邻的第五侧壁和第一侧壁相对, 各第二介质单元的第六侧壁面向背景介质, 各 第二介质单元的第七侧壁面向隐身区域, 各第一介质单元的第三侧壁面向隐身区域;
当第二介质单元的横截面为等腰梯形时, 如果第一介质单元和第二介质单元均为固体, 那么, 或者相邻的第一侧壁和第五侧壁接触, 或者相邻的第一侧壁和第五侧壁之间由第二固 体分隔物相隔且第一侧壁和第五侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为固体, 第二介质单元为流 体, 那么, 第二介质单元的第六侧壁与背景介质之间由第一固体分隔物相隔, 第二介质单元 的第七侧壁与隐身区域之间由第三固体分隔物相隔, 第二介质单元的上端、 下端与背景介质 之间分别由第四固体分隔物相隔; 并且, 或者相邻的第一侧壁和第五侧壁接触, 或者相邻的 第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五侧壁均与相应的第二固体 分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为流体, 第二介质单元为固 体, 那么, 第一介质单元的上端、 下端与背景介质之间分别由第四固体分隔物相隔, 第一介 质单元的第三侧壁与隐身区域之间由第三固体分隔物相隔; 并且, 或者相邻的第一侧壁和第 五侧壁接触, 或者相邻的第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五 侧壁均与对应的第二固体分隔物接触;
当第二介质单元的横截面呈等腰梯形时, 如果第一介质单元为流体, 第二介质单元为流 体, 那么, 相邻的第一侧壁和第五侧壁之间由第二固体分隔物相隔且第一侧壁和第五侧壁均 与对应的第二固体分隔物接触, 第二介质单元的第六侧壁与背景介质之间由第一固体分隔物 相隔, 第二介质单元的第七侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的第 三侧壁与隐身区域之间由第三固体分隔物相隔, 第一介质单元的上端、 下端与背景介质之间
分别由第四固体分隔物相隔; 第二介质单元的上端、 下端与背景介质之间分别由第四固体分 隔物相隔;
所述第一固体分隔物、 第二固体分隔物和第四固体分隔物对入射的电磁波是透明的, 第 一固体分隔物的折射率大于等于第二介质单元的折射率, 第二固体分隔物的折射率大于等于 第二介质单元的折射率, 并且第一固体分隔物的厚度、 第二固体分隔物的厚度和第一介质单 元的第一底边的长度之间满足如下式 (1 ) 所示的关系:
+ 7.04 x w, < 2A ( 1 ) 式 (1 ) 中, ^表示第一固体分隔物的厚度, ^表示第二固体分隔物的厚度, A表示第 一介质单元的第一底边的长度。
3.根据权利要求 1或 2所述的一种柱状电磁波隐身器件, 其特征是: 以垂直于其中一个 第一介质单元的第三侧壁的方向由背景介质向所述隐身器件入射的同一电磁波波束, 能够按 先后顺序经过依次相邻的第二介质单元、 第一介质单元、 第二介质单元、 第一介质单元、 第 二介质单元出射到所述背景介质中, 且同一电磁波波束在出射时与入射时在同一直线上。
4.根据权利要求 3所述的一种柱状电磁波隐身器件, 其特征是:
若第二介质单元的横截面呈等腰三角形, 则第一介质单元的折射率、 第二介质单元的折 射率、 背景介质的折射率、 第一介质单元的第一顶角、 第二介质单元的第二顶角、 第一介质 单元的第一底边的长度和第二介质单元的第二底边的长度相互之间满足如下式(3 )至式(8 ) 所示的关系:
n^^ sin 30c
n^- sm 60° - arcsin - a ll
第二
/½一 sm arcsm w第二 sm I (3) 第一
nMaL sin 30
0° < « < 2arcsin -60c (4)
1第二
^ = 60° + a (5) sin )° + all) _ B
<UxV (6) sinf«/2 A 其中,
sin 30°
sm 30。 + arcsin + a/2
V (8)
sin 30
2 sin (a/2) sin 90° -arcsin
若第二介质单元的横截面呈等腰梯形, 则第一介质单元的折射率、 第二介质单元的折射 率、 背景介质的折射率、 第一介质单元的第一顶角、 第二介质单元的第三角、 第一介质单元 的第一底边的长度和第二介质单元的第三底边的长度相互之间满足如上式(3)、 (4)、 (7)和 (8) 以及如下式 (9)、 (10) 所示的关系: =60。 + (9)
sin (30。 + (2/2) C 、
~ ~~ <— < U x V (10)
sin (or/2) A 在式 (3 ) 至 (10) 中, ¾一表示第一介质单元的折射率, ¾二表示第二介质单元的折射 率, /¾¾表示背景介质的折射率, 《表示第一顶角, ^表示第一介质单元的第一底边的长度, ?表示第二介质单元的第二底边的长度, 表示第二顶角, C表示第二介质单元的第三底边的 长度, ^表示第三角。
Priority Applications (2)
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