CN107086374B - Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof - Google Patents
Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof Download PDFInfo
- Publication number
- CN107086374B CN107086374B CN201710222729.7A CN201710222729A CN107086374B CN 107086374 B CN107086374 B CN 107086374B CN 201710222729 A CN201710222729 A CN 201710222729A CN 107086374 B CN107086374 B CN 107086374B
- Authority
- CN
- China
- Prior art keywords
- frequency selective
- selective surface
- layer
- metal patch
- metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
-
- 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
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0053—Selective devices used as spatial filter or angular sidelobe filter
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Landscapes
- Aerials With Secondary Devices (AREA)
Abstract
The invention discloses a miniaturized low-profile ultra-wide passband frequency selective surface and a design method thereof, comprising the following steps: the first metal patch layer, the middle layer and the second metal patch layer are sequentially pressed together, the units of the first metal patch layer are rectangular with the same length and width, four corners of the rectangular are respectively provided with a quarter square ring with outward openings, the center of each unit is a complete rectangular ring, and after the plane period is prolonged, a staggered square ring array is formed; the second metal patch layer is rectangular, the size of the unit is the same as that of the first metal patch layer, the center of the second metal patch layer is a cross-shaped metal wire, and rectangular metal patches are connected with the cross-shaped metal wire at the midpoint of each side of the unit. The frequency selection structure has ultra-wide passband characteristics, and simultaneously, the overall thickness of the frequency selection is greatly reduced. The frequency selective structure provided by the invention has extremely low section, and can be freely combined with structures such as skins, shells, protective covers and the like with most thicknesses, so that the unique electrical performance of the frequency selective structure is exerted.
Description
Technical Field
The invention belongs to the technical field of electromagnetic fields and microwaves, and particularly relates to a miniaturized low-profile ultra-wide passband frequency selective surface and a design method thereof.
Background
Modern war is in the information age, and target information detected by radar determines the fate of targets. Radar antenna systems on board aircraft are important scattering sources, with very high Radar Cross Sections (RCSs) at certain frequencies and viewing angles, and reducing the RCS of the antenna system is an important issue for aircraft to achieve stealth. The traditional aircraft medium radome is transparent in the full frequency band, and has no stealth effect, so the design of the wave-transparent/stealth multifunctional integrated radome is extremely important, for example, how to reduce the backscattering of the radar antenna at the head of the aircraft has become one of the key factors affecting the stealth performance of the aircraft. The RCS cannot be reduced by a common dielectric radome, and the application of the wave absorbing material, while reducing backscatter, can affect normal communications of the aircraft. The application of the frequency selective surface structure, namely the frequency selective surface technology (Frequency Selective Surface, FSS) in the dielectric radome can overcome the defects, and the FSS has the spatial filtering characteristic, so that the reflection and transmission performance of electromagnetic waves can be effectively controlled.
The frequency selective surface structure is a two-dimensional structure composed of a plurality of periodically arranged metal patch units or gaps between metal planes with specific shapes, when the frequency of the incident electromagnetic wave is at the resonance frequency of the units, the FSS presents total reflection (patch type) or total transmission (aperture type), and electromagnetic waves with other frequencies can penetrate the FSS or be totally reflected (aperture type), so that the FSS is a special spatial filter in nature and can effectively control the transmission characteristics of the electromagnetic wave. The FSS technology is applied to the radome, so that the radome can obtain the function of frequency selection, and frequency selective wave transmission is performed. The radome keeps normal wave transmission in the designed frequency band; and outside the designed frequency band, the antenna housing is equivalent to a metal housing for shielding electromagnetic waves. The function of the method is to enable the aircraft antenna cabin to show different RCS characteristics in the designed frequency band and the appearance.
Journal "design of bandpass frequency selective surface with broadband characteristics" as proposed by telecommunication technologies 2012, 52 (3): 371-374, li Yoqing, pei Zhi, qu Shaobo et al; simulation in journal paper shows that the 3 poles of the frequency selective surface are 6.44GHz, 8.80GHz and 10.97GHz, respectively. The 3 poles are coupled to form a flat-top wide passband with small central insertion loss, the maximum central insertion loss is only 0.45dB, the 3dB working bandwidth is 5.40-11.47 GHz, the absolute bandwidth is 6.07GHz, and the relative bandwidth reaches 72%. And outside the passband, S2l can drop below-20 dB rapidly and remain all the time, and the frequency selective surface structure has good sideband selection and out-of-band rejection characteristics. However, the technical scheme has a problem objectively that the thickness of the frequency selection surface is large and the section is high due to the adoption of the multi-layer cascade structure. As a microwave passive material, the thickness of the structure directly determines its applicability. The frequency selective surface is mainly applied near the high RCS parts of the aircraft, in the form of a skin or an external cover, so that the high thickness of the frequency selective surface structure will present considerable difficulties for the design of the skin and the cover, which is often not practical.
Journal literature: liang B Y, xue Z H, li W M, et al ultra-wideband frequency selective surface at K and Ka band [ C ]. IEEE International Conference on Microwave Technology & computer electric magnetic ics.IEEE,2013:55-57, the purpose of which is to design a novel ultra-wide passband frequency selective surface structure, and provide a structural scheme for the wave-transparent filtering requirement of ultra-wideband electromagnetic fields. The unit size is 2.898mm by 4.733mm, the thickness of the structural single layer is 2mm, the thickness of the adhesive layer between the dielectric plates is about 0.05mm, and the total thickness is about 6.1mm. The 3dB bandwidth is from 17.83GHz to 45.66GHz, the relative bandwidth reaches 88%, and the ultra-wide passband frequency selective surface is provided. However, the technical scheme still has the problems of high profile and large thickness, and the total thickness still reaches 6.1mm although the number of layers is only three, so that the application range is greatly influenced.
Disclosure of Invention
In view of the foregoing, it is an object of the present invention to provide a miniaturized low-profile ultra-wideband frequency selective surface and a design method thereof, which solve the above-mentioned drawbacks of the prior art. The invention ensures that the frequency selective surface structure has ultra-wide passband characteristics and simultaneously greatly reduces the overall thickness of the frequency selective surface; can be freely combined with structures such as skins, shells, protective covers and the like with most thickness, thereby exerting the unique electrical performance.
In order to achieve the above object, a miniaturized low-profile ultra-wideband frequency selective surface of the present invention is composed of three layers, respectively: the first metal patch layer, the middle layer and the second metal patch layer are sequentially pressed together, the units of the first metal patch layer are rectangular with the same length and width, four corners of the rectangular are respectively provided with a quarter square ring with outward openings, the center of each unit is a complete rectangular ring, and after the plane period is prolonged, a staggered square ring array is formed; the second metal patch layer is rectangular, the size of the unit is the same as that of the unit of the first metal patch layer, the center of the second metal patch layer is a cross-shaped metal wire, the middle points of all sides of the unit are respectively provided with a rectangular metal patch which is connected with the cross-shaped metal wire, and the second metal patch layer presents a grid-like array in which the cross-shaped metal wire and the rectangular metal patch alternately appear after the plane period extends.
Preferably, the intermediate layer is a high-frequency microwave circuit board.
The invention relates to a design method of a miniaturized low-profile ultra-wide passband frequency selective surface, which comprises the following steps:
1) Selecting a proper microwave filter according to the bandwidth and profile requirements of the required frequency selection surface, and giving an equivalent circuit;
2) The equivalent circuit of the microwave filter is approximately transformed to a form of matching the design of the frequency selective surface according to the impedance matching principle, and the basic structure of the frequency selective surface is obtained;
3) Deducing the parameter range in the basic structure of the design frequency selection surface through a conversion formula of the distributed parameter electric elements and the integrated parameter electric elements and a parallel circuit resonance frequency formula;
4) The metal patch and the dielectric layer structure in the frequency selective surface are utilized to realize the electrical properties of the capacitor, the inductor and the transmission line in the equivalent circuit in the step 2), and the specific frequency selective surface structure is defined;
5) Selecting processing materials, and producing the designed frequency selective surface finished product by adopting a copper clad laminate technology.
Preferably, the operating bandwidth of the microwave filter in step 1) above and the operating bandwidth of the corresponding frequency selective surface structure should be of an order of magnitude, e.g. an ultra wideband frequency selective surface structure should select an ultra wideband filter as reference. The frequency response curve order of the microwave filter determines the structural thickness, i.e. the profile, of the frequency selective surface, the higher the order of the microwave filter the higher the profile of the frequency selective surface.
Preferably, the equivalent circuit of the microwave filter in the step 1) is a first-order parallel capacitor-inductor combined resonant circuit, and the resistor Z1 and the resistor Z2 are respectively input impedance and output impedance of a two-port network in the equivalent circuit; in the two groups of inductance-capacitance series resonant circuits of the inductance L1 and the capacitance C1, the inductance L3 and the capacitance C3, the values of the inductance L1 and the inductance L3 are high, and the values of the capacitance C1 and the capacitance C3 are low; in the group of the capacitor-inductor parallel resonant circuit of the capacitor C2 and the inductor L2, the value of the capacitor C2 is high and the value of the inductor L2 is low.
Preferably, in the step 2), first, the input of the two-port networkAnd a free impedance Z of a free space for output impedance 0 =377Ω substitution, and secondly, ignoring the low value capacitor C 1 、C 3 And inductance L 2 According to the transmission line theory, the original inductance-capacitance-inductance T-shaped network L 1 -C 2 -L 3 A pi-network C ' -L ' -C ' transformed into capacitance-inductance-capacitance; the equivalent circuit of the short transmission line is regarded as a loop formed by connecting a specific resistor in parallel with a capacitor-inductor series, and one capacitor C' in the pi-type network is used for the short transmission line Z 12 Instead, the component values of the remaining capacitor C ' and inductor L ' in the network are corrected to C and L to match the overall impedance of the pi-network C ' -L ' -C ' circuit; corresponding equivalent circuits to the frequency-selective surface, Z 0 The free impedance of free space is used for replacing, the capacitor C uses a layer of metal patch to realize the capacitance characteristic, and the transmission line Z 12 The impedance characteristic is realized by using a dielectric layer, and the inductance L is realized by using a metal patch; the first and the third layers are thin metal patch layers, and the second layer is a dielectric layer with a certain thickness.
Preferably, the values of the electrical components in the circuit of step 3) above are mapped to specific parameter ranges of the patches and dielectric layers in the frequency selective surface structure by the following formula:
wherein C is the capacitance value of the final equivalent circuit, L is the inductance value of the final equivalent circuit, ε 0 ≈8.85*10^(-12)、μ 0 Approximately equal to 1.26 x 10 (-6) and pi approximately equal to 3.14 are constant, ε r For the dielectric constant of the selected specific dielectric layer, p is the unit period size of the frequency selective surface, s is the interval width of the first layer metal patch, and w is the width of the second layer metal grid line; s and w represent the overall dimensions of the cell structure after periodic extension, and are not independently present in the parameters of the cell; as can be seen from the formulas (1) and (2), increasing the cell period size p, decreasing the metal patch interval width s or the metal grid line width w, and increasing the values of C and L; according to the resonant frequency of parallel circuits
The resonant frequency is proportional to the cell period size p, inversely proportional to the metal patch spacing width s and the metal grid line width w.
Preferably, the step 4) uses the electrical performance with excellent conductivity to match the metal patches of the capacitor and the inductance element in the circuit in the step 2), and realizes the performance of the lumped capacitor C' in the circuit by the distributed capacitor structure; similarly, the characteristics of the inductor L' are realized by utilizing metals with the same materials and in a grid structure; a frequency selective surface structure of a capacitive metal patch layer-impedance matching dielectric slab-inductive metal patch layer is obtained by means of a high frequency microwave circuit board with a suitable dielectric constant and loss tangent instead of a short transmission line.
Preferably, the processing sample piece on the frequency selective surface in the step 5) at least comprises 3*3 unit arrays, the first layer and the second layer of metal patches are made of metal with excellent conductivity, the thickness of the patches is controlled within 35um-70um, the dielectric plate of the middle layer needs to meet the relative dielectric constant requirement deduced during design, meanwhile, the loss tangent is ensured to be low, the dielectric plate and the metal patches need to be tightly connected during processing, and the copper-clad laminate technology is adopted for lamination.
Preferably, the metal with excellent conductivity is silver or copper in the step 5).
The invention has the beneficial effects that:
the invention greatly reduces the overall thickness of the frequency selective surface while ensuring that the frequency selective surface structure has ultra-wide passband characteristics. The frequency selective surface structure provided by the invention has extremely low profile, and can be freely combined with structures such as skins, shells, protective covers and the like with most thicknesses, so that the unique electrical performance of the frequency selective surface structure is exerted. Has high practical value in the fields of stealth, electromagnetic compatibility, radiation shielding and the like of aircrafts.
Drawings
Fig. 1 is a top view of a frequency selective surface finish.
Fig. 2 is a side view of a frequency selective surface finish.
Fig. 3 is a top view of a first layer unit structure of the frequency selective surface.
Fig. 4 is a plan view of the frequency selective surface after planar periodic extension of the first layer unit structure.
Fig. 5 is a top view of a third layer unit structure of the frequency selective surface.
Fig. 6 is a plan view of a planar periodic extension of a third layer of cell structure of the frequency selective surface.
Fig. 7 is an equivalent circuit diagram of a microwave filter in the embodiment.
Fig. 8 is an equivalent circuit diagram of an approximate transformed suitable frequency selective surface design in an embodiment.
Fig. 9 is a reflection curve and transmission curve of the frequency selective surface under normal incidence conditions.
Fig. 10 is a graph of reflection and transmission curves of a frequency selective surface under an angle of incidence.
Fig. 11 is a graph showing the surface electric field intensity distribution of a first layer of metal patch on a frequency selective surface at a resonant frequency.
Fig. 12 shows the surface electric field intensity distribution at the resonance frequency of the second metal patch layer of the frequency selective surface.
Detailed Description
The invention will be further described with reference to examples and drawings, to which reference is made, but which are not intended to limit the scope of the invention.
Referring to fig. 1 to 6, a miniaturized low-profile ultra-wideband frequency selective surface of the present invention is composed of three layers, respectively: the first metal patch layer 1, the middle dielectric layer 2 and the second metal patch layer 3 are sequentially pressed together, the units of the first metal patch layer 1 are rectangular with the same length and width, four corners of the rectangular are respectively provided with a quarter square ring with outward openings, the center of each unit is provided with a complete rectangular ring, and after the plane period is prolonged, a staggered square ring array is formed; the second metal patch layer 3 has a rectangular unit with the same size as the unit of the first metal patch layer, a cross-shaped metal wire is arranged at the center, rectangular metal patches are connected with the cross-shaped metal wire at the midpoint of each side of the unit, and a grid-like array with the cross-shaped metal wires and the rectangular metal patches alternately appears after the plane period is prolonged.
The intermediate layer adopts a high-frequency microwave circuit board, the selection of the intermediate layer is matched with the impedance of a short transmission line in the equivalent circuit in the step 2), and the Rogers series high-frequency microwave circuit board can be selected. It should be noted that when actually processing the frequency selective surface, n (n is a positive integer and is greater than or equal to 3) units are generally selected to form a complete structure to reflect the periodic characteristic, and the size of the high-frequency circuit board of the middle layer is always matched with the size of the upper and lower layers, that is, n is equal to (n is p) mm, where p is the period of the frequency selective surface unit.
The invention relates to a design method of a miniaturized low-profile ultra-wide passband frequency selective surface, which comprises the following steps:
1) Selecting a proper microwave filter according to the bandwidth and profile requirements of the required frequency selection surface, and giving an equivalent circuit;
the working bandwidth of the microwave filter in the step 1) should be similar to the corresponding frequency selective surface structure, and the order of the frequency response curve of the microwave filter determines the structure thickness of the frequency selective surface, i.e. the profile, and the higher the order of the microwave filter, the higher the profile of the frequency selective surface. In order to meet the requirements of ultra-wideband and low profile, a first-order wideband band-pass microwave filter is selected as a design prototype, and an equivalent circuit of the filter can be obtained according to a circuit analysis basic theory. The circuit is only used for illustrating the working principle of the microwave filter, so the numerical values of the electric elements are not required to be quantitative, and only qualitative description is required.
The equivalent circuit of the filter in this embodiment is shown in fig. 7, and it can be seen that the equivalent circuit of the microwave filter is a first-order parallel capacitor-inductor combined resonant circuit; resistance Z 1 And resistance Z 2 Input impedance and output impedance of two-port network in the equivalent circuit respectively; inductance L 1 And capacitor C 1 Inductance L 3 And capacitor C 3 In the two groups of inductance-capacitance series resonant circuits, the inductance value L 1 、L 3 High capacitance C 1 、C 3 Low; and capacitor C 2 And inductance L 2 In the group of capacitance-inductance parallel resonant circuits, the capacitance value C 2 High inductance value L 2 Low.
2) The equivalent circuit of the microwave filter is approximately transformed to a form suitable for the design of the frequency selective surface according to the impedance matching principle, and the basic structure of the frequency selective surface is obtained;
first, since the frequency selective surface is a spatial structure, the input and output impedance of the two-port network is free-space free impedance Z 0 =377Ω substitution, and secondly, ignoring the low value capacitor C 1 、C 3 And inductance L 2 According to the transmission line theory, the original inductance-capacitance-inductance T-shaped network L 1 -C 2 -L 3 A pi-network C ' -L ' -C ' transformed into capacitance-inductance-capacitance; the equivalent circuit of the short transmission line is regarded as a loop formed by connecting a specific resistor in parallel with a capacitor-inductor series, and one capacitor C' in the pi-type network is used for the short transmission line Z 12 Instead, the component values of the remaining capacitor C ' and inductor L ' in the network are corrected to C and L to match the overall impedance of the pi-network C ' -L ' -C ' circuit; thus, the pi-type capacitance-resistance-inductance network C-Z in FIG. 8 can be obtained 12 L, it can be seen that this circuit is a first order resonant structure. Corresponding equivalent circuits to the frequency-selective surface, Z 0 The free impedance of free space is used for replacing, the capacitor C uses a layer of metal patch to realize the capacitance characteristic, and the transmission line Z 12 The impedance characteristic is realized by using a dielectric layer, and the inductance L is realized by using a metal patch; it can be seen that the frequency selective surface corresponding to the equivalent circuit of fig. 8 has a three-layer structure, and the first and third layers are thin metal patch layers, and the second layer is a dielectric layer with a certain thickness.
3) Deducing the parameter range in the basic structure of the design frequency selection surface through a conversion formula of the distributed parameter electric elements and the integrated parameter electric elements and a parallel circuit resonance frequency formula;
the values of the electrical components in the circuit of step 3) are mapped to the specific parameter ranges of the patch and the dielectric layer in the frequency selective surface structure by the following formula:
wherein C is the capacitance value of the final equivalent circuit, L is the inductance value of the final equivalent circuit, ε 0 ≈8.85*10^(-12)、μ 0 Approximately equal to 1.26 x 10 (-6) and pi approximately equal to 3.14 are constant, ε r For the dielectric constant of the selected specific dielectric layer, p is the unit period size of the frequency selective surface, s is the interval width of the first layer metal patch, and w is the width of the second layer metal grid line; s and w represent the overall dimensions of the cell structure after periodic extension, and are not independently present in the parameters of the cell; as can be seen from the formulas (1) and (2), increasing the cell period size p, decreasing the metal patch interval width s or the metal grid line width w, and increasing the values of C and L; according to the resonant frequency of parallel circuits
The resonant frequency is proportional to the cell period size p, inversely proportional to the metal patch spacing width s and the metal grid line width w.
It should be noted that although the parameter h representing the thickness of the frequency selective surface structure is not shown in the formula derivation, the value of h determines the spatial coupling strength between the first layer and the third layer of the frequency selective surface, and since the design in this embodiment is a first order resonant structure, the range of h is controlled between 0.5-1.5mm, with a relatively low profile thickness.
The parameters of the electric elements in the equivalent circuit after the filter conversion are C=6.34×10 (-13) F, and L=1.43×10 (-8) H. First, consider the requirement of designing the lowest frequency point (6 GHz) of the expected passband, denoted by f l ＝c/λ l The wavelength at this frequency point is 50mm, and p in the example is shown as lambda 0 5 (controlled between 9.95mm and 10.05 mm) and a half wavelength structure of a conventional frequency selective surfaceCompared with the prior art, the device has the characteristic of miniaturization. Then substituting the value of p into the formula (1) (2) to obtain the value of the parameter s between 2.15mm and 2.25mm and the value of the parameter w between 0.25 and 0.35mm, wherein the two parameters do not directly appear when the structure is designed, but the value of the specific parameter is determined. For example, in the present embodiment, the value of the parameter s is equal to (p-2 a 2 -a 4 ) The value of parameter w is equal to (a) 3 *(a 4 -a 1 )/a 4 +2a 1 *a 2 /a 4 ). Finally, according to the coupling condition of the upper and lower metal patches of the surface structure of the actual frequency selection, the value of the optimization parameter h is adjusted to be between 0.95mm and 1.05 mm.
4) The metal patch and the dielectric layer structure in the frequency selective surface are utilized to realize the electrical properties of the capacitor, the inductor and the transmission line in the equivalent circuit in the step 2), and the specific frequency selective surface structure is defined;
the step 4) utilizes the excellent electrical performance of conductivity to match the metal patches of the capacitor and the inductance element in the circuit in the step 2), and realizes the performance of the lumped capacitor C' in the circuit by a distributed capacitor structure; similarly, the characteristics of the inductor L' are realized by utilizing metals with the same materials and in a grid structure; a frequency selective surface structure of capacitive metal patch layer-impedance matching dielectric slab-inductive metal patch layer was obtained by means of Rogers RT5880 high frequency microwave circuit board with suitable dielectric constant and loss tangent instead of short transmission lines. The shape and arrangement mode of the distributed capacitor inductor directly influence the effect and stability of the frequency selection surface in free space operation, and the design with good performance can be obtained after pattern selection and parameter optimization.
The specific parameters of the miniaturized low-profile ultra-wideband frequency selective surface proposed in this embodiment are shown in Table 1, the specific parameter ε r The values of p and h are referred to the deductions in step 3), ε r Determining material selection of a dielectric layer, wherein p determines the size of a frequency selective surface unit, and h determines the overall thickness of the frequency selective surface; and the value ranges of s and w guide all specific parameters (a 1 -a 4 ，b 1 -b 4 ) Is a value of (a). The design shape is not unique, the practice is thatThe structure of the embodiment is the result of the completion of parameter optimization. Fig. 1 is a schematic top view of a complete structure obtained after the period of a frequency selective surface unit is prolonged, which intuitively shows the periodic characteristics of the structure, wherein an array structure consisting of 9 units is selected, and the number of specific units can be determined according to the visual field requirement. Table 1 is as follows:
TABLE 1
| Parameter name | a1 | a2 | a3 | a4 | p |
| Parameter value | 0.4mm | 1.4mm | 0.4mm | 2.8mm | 10.0mm |
| Parameter name | b1 | b2 | b3 | b4 | h |
| Parameter value | 2.8mm | 1.4mm | 0.3mm | 10.0mm | 1.0mm |
5) Selecting proper processing materials, and producing the designed frequency selective surface finished product by adopting the copper clad laminate technology.
The processing sample piece on the frequency selective surface in the step 5) at least comprises 3*3 unit arrays, the first layer and the second layer of metal patches are made of metal with excellent electric conduction performance, the best material is silver (the resistivity is 15.86 rho/nΩ & m), copper (the resistivity is 16.78 rho/nΩ & m) is generally selected, the processing sample piece has a better effect, the thickness of the patches is controlled within 35um-70um, the structural electric performance is not obviously influenced, and the pattern shape of the patches is manufactured by etching by using a national standard technology of printed circuit board (QJ 3103-99). The dielectric plate of the middle layer needs to meet the relative dielectric constant requirement deduced during design, meanwhile, the loss tangent is ensured to be as low as possible, a Rogers high-frequency microwave circuit board is generally selected, the structure provided by the invention adopts a Rogers-RT5880 material (the relative dielectric constant is 2.2, the relative magnetic conductivity is 1.0, and the loss tangent is 0.0009), and the effect is good. During processing, the dielectric plate and the metal patch layer need to be tightly connected, and are pressed by adopting the standard technology of the copper-clad laminate in the national standard of printed circuit boards (GB 4722-84).
As can be seen from fig. 1, the frequency selective surface as a whole has a completely rotationally symmetrical characteristic, which gives it a certain polarization stability. Meanwhile, as the first layer of metal patch of the frequency selective surface adopts a plurality of miniaturized resonant units to be staggered, the second layer of metal patch adopts a non-resonant structure to be matched with the first layer of metal patch, the unit size is far smaller than half wavelength required by a common frequency selective surface unit, and the angle stability is improved compared with the traditional frequency selective surface. Meanwhile, the device has the characteristic of miniaturization, and 3*3 units are taken as an example, the whole structure is only 3cm by 3cm, and the minimum working size is enough to meet the demands of most occasions.
By means of simulation of CST STUDIO SUITE 2016 software, the frequency selection surface structure is a first-order resonance structure, reflection curves near resonance frequency points are smooth, Q values in corresponding equivalent circuits are low, namely 3dB pass bands are covered from 5.27GHz to 22.62GHz, the bandwidth is 17.35GHz, the relative bandwidth of 13.95GHz for a central frequency point reaches 124.4%, the common frequency band of the whole 6-18GHz aviation antenna is covered, and the relative bandwidth of the ultra-wideband frequency selection surface in the prior art is far exceeded. At the same time, the frequency selective surface also has a certain angular stability. As shown in fig. 10, at 15 degree oblique incidence, the 3dB passband covered from 5.40GHz to 21.42GHz, with a bandwidth of 16.02GHz, and a relative bandwidth of 119.5%. Under the condition of oblique incidence at an angle of 30 degrees, the 3dB passband is covered from 5.83GHz to 18.89GHz, the bandwidth is 13.06GHz, the relative bandwidth is 105.7 percent, and therefore, under the condition of oblique incidence, the frequency selection surface can still ensure the relative bandwidth of more than 100 percent, and the frequency selection surface has quite high angular stability.
Fig. 11 and fig. 12 show that the surface electric field distribution of the two-layer metal patch with the frequency selective surface structure is relatively uniform in the surface electric field distribution at the resonance frequency point (12.8 GHz) under the condition of normal incidence of electromagnetic waves, and each part of the patch is excited to generate a strong electric field (the field intensity of a black area is higher), so that the band-pass frequency selective surface has low loss in the aspect of energy transmission, high transmission efficiency and reasonable design.
The present invention has been described in terms of the preferred embodiments thereof, and it should be understood by those skilled in the art that various modifications can be made without departing from the principles of the invention, and such modifications should also be considered as being within the scope of the invention.
Claims (9)
1. A miniaturized low-profile ultra-wideband frequency selective surface, which is composed of three layers, characterized in that: the first metal patch layer, the middle layer and the second metal patch layer are sequentially pressed together, the units of the first metal patch layer are rectangular with the same length and width, four corners of the rectangular are respectively provided with a quarter square ring with outward openings, the center of each unit is a complete rectangular ring, and after the plane period is prolonged, a staggered square ring array is formed; the second metal patch layer is rectangular, the size of the unit is the same as that of the unit of the first metal patch layer, the center of the second metal patch layer is a cross-shaped metal wire, the middle points of all sides of the unit are respectively provided with a rectangular metal patch which is connected with the cross-shaped metal wire, and the second metal patch layer presents a grid-like array in which the cross-shaped metal wire and the rectangular metal patch alternately appear after the plane period extends.
2. The miniaturized low profile ultra-wideband frequency selective surface of claim 1, wherein said intermediate layer is a high frequency microwave circuit board.
3. A method of designing a miniaturized low-profile ultra-wideband frequency selective surface based on the miniaturized low-profile ultra-wideband frequency selective surface of claim 1, comprising the steps of:
1) Selecting a proper microwave filter according to the bandwidth and profile requirements of the required frequency selection surface, and giving an equivalent circuit;
2) The equivalent circuit of the microwave filter is approximately transformed to a form of matching the design of the frequency selective surface according to the impedance matching principle, and the basic structure of the frequency selective surface is obtained;
3) Deducing the parameter range in the basic structure of the design frequency selection surface through a conversion formula of the distributed parameter electric elements and the integrated parameter electric elements and a parallel circuit resonance frequency formula;
4) The metal patch and the dielectric layer structure in the frequency selective surface are utilized to realize the electrical properties of the capacitor, the inductor and the transmission line in the equivalent circuit in the step 2), and the specific frequency selective surface structure is defined;
5) The process materials are selected and laminate technology is used to produce the designed frequency selective surface finish.
4. A method of designing a miniaturized low profile ultra-wideband frequency selective surface as claimed in claim 3, wherein the operating bandwidth of the microwave filter in step 1) is an order of magnitude equal to the corresponding frequency selective surface structure, and the order of the frequency response curve of the microwave filter determines the structure thickness of the frequency selective surface, i.e. the profile, and the higher the order of the microwave filter, the higher the profile of the frequency selective surface.
5. The method for designing a miniaturized low-profile ultra-wideband frequency selective surface as recited in claim 3, wherein in said step 2), first, the free impedance Z of the free space for the input and output impedance of the two-port network 0 =377Ω substitution, and secondly, ignoring the low value capacitor C 1 、C 3 And inductance L 2 According to the transmission line theory, the original inductance-capacitance-inductance T-shaped network L 1 -C 2 -L 3 A pi-network C ' -L ' -C ' transformed into capacitance-inductance-capacitance; the equivalent circuit of the short transmission line is regarded as a loop formed by connecting a specific resistor in parallel with a capacitor-inductor series, and one capacitor C' in the pi-type network is used for the short transmission line Z 12 Instead, the component values of the remaining capacitor C ' and inductor L ' in the network are corrected to C and L to match the overall impedance of the pi-network C ' -L ' -C ' circuit; the equivalent circuit is corresponding to the frequency selective surface, the capacitor C realizes the capacitance characteristic by using a layer of metal patch, and the transmission line Z 12 The impedance characteristic is realized by using a dielectric layer, and the inductance L is realized by using a metal patch; the first and the third layers are thin metal patch layers, and the second layer is a dielectric layer with a certain thickness.
6. The method of claim 3, wherein the values of the electrical components in the circuit in step 3) are mapped to specific parameter ranges of the patch and dielectric layer in the frequency selective surface structure by the following formula:
wherein C is the capacitance value of the final equivalent circuit, L is the inductance value of the final equivalent circuit, ε 0 ≈8.85*10^(-12)、μ 0 Approximately equal to 1.26 x 10 (-6) and pi approximately equal to 3.14 are constant, ε r For the dielectric constant of the selected dielectric layer, p is the unit period size of the frequency selective surface, s is the interval width of the first layer metal patch, and w is the width of the second layer metal grid line; s and w represent the overall dimensions of the cell structure after periodic extension, and are not independently present in the parameters of the cell; as can be seen from the formulas (1) and (2), increasing the cell period size p, decreasing the metal patch interval width s or the metal grid line width w, and increasing the values of C and L; according to the resonant frequency of parallel circuits
The resonant frequency is proportional to the cell period size p, inversely proportional to the metal patch spacing width s and the metal grid line width w.
7. The method of claim 5, wherein the step 4) uses the electrical performance with excellent conductivity to match the metal patches of the capacitor and the inductance element in the circuit in the step 2), and the lumped capacitor C' is implemented in the circuit with a distributed capacitor structure; similarly, the characteristics of the inductor L' are realized by utilizing metals with the same materials and in a grid structure; a frequency selective surface structure of a capacitive metal patch layer-impedance matching dielectric slab-inductive metal patch layer is obtained by means of a high frequency microwave circuit board having a dielectric constant and a loss tangent instead of a short transmission line.
8. The method for designing a miniaturized low-profile ultra-wideband frequency selective surface according to claim 3, wherein the frequency selective surface processing sample in step 5) at least comprises 3*3 unit arrays, the first layer and the second layer of metal patches are made of metal with excellent conductivity, the thickness of the patches is controlled within 35um-70um, the dielectric plate of the middle layer needs to meet the relative dielectric constant requirement deduced during design, meanwhile, the loss tangent is ensured to be low, the dielectric plate and the metal patches need to be tightly connected during processing, and the copper-clad laminate technology is adopted for lamination.
9. The method of claim 8, wherein the metal with excellent conductivity is silver or copper in the step 5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710222729.7A CN107086374B (en) | 2017-04-07 | 2017-04-07 | Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710222729.7A CN107086374B (en) | 2017-04-07 | 2017-04-07 | Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107086374A CN107086374A (en) | 2017-08-22 |
| CN107086374B true CN107086374B (en) | 2023-06-23 |
Family
ID=59614305
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710222729.7A Active CN107086374B (en) | 2017-04-07 | 2017-04-07 | Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107086374B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947392A (en) * | 2017-12-14 | 2018-04-20 | 中国科学院长春光学精密机械与物理研究所 | A kind of low section small microwave delivery of energy rectifier |
| CN108565557A (en) * | 2018-04-20 | 2018-09-21 | 西安天和防务技术股份有限公司 | A kind of frequency-selective surfaces and ultra-thin frequency select antenna house |
| CN109873250B (en) * | 2019-03-27 | 2020-07-07 | 北京理工大学 | Overload protection antenna housing and preparation method thereof |
| CN112803171B (en) * | 2019-11-14 | 2022-08-12 | 南京理工大学 | Electromagnetic lens with miniaturized frequency selective surface |
| CN111029724B (en) * | 2019-12-24 | 2021-03-05 | Oppo广东移动通信有限公司 | Mobile terminal |
| CN111613892B (en) * | 2020-06-29 | 2022-02-18 | 中国舰船研究设计中心 | Double-side steep out-of-band rejection frequency selection radome composite material interlayer structure |
| CN112784464B (en) * | 2021-01-30 | 2023-02-21 | 中国人民解放军空军工程大学 | Wave absorber with arbitrary absorption frequency spectrum based on intelligent algorithm and design method thereof |
| CN114976660B (en) * | 2021-02-23 | 2024-06-21 | 西安电子科技大学 | Band-pass type frequency selection surface with ultra-wideband suppression characteristic |
| CN114614266B (en) * | 2022-05-11 | 2022-08-12 | 成都飞机工业（集团）有限责任公司 | X-band-pass absorption and penetration integrated frequency selective surface structure |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102637932A (en) * | 2012-05-04 | 2012-08-15 | 中国科学院长春光学精密机械与物理研究所 | Concentrated configuration type cross-shaped annulus passband frequency selection surface with high angle stability |
| KR20130004736A (en) * | 2011-07-04 | 2013-01-14 | 단국대학교 산학협력단 | Frequency selective surface for multiband |
| CN106295038A (en) * | 2016-08-17 | 2017-01-04 | 大连理工大学 | A kind of active frequencies selects surface method for designing |
| CN206789705U (en) * | 2017-04-07 | 2017-12-22 | 南京航空航天大学 | One kind miniaturization low section ultra-wide band connection frequency selection surface |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9362615B2 (en) * | 2012-10-25 | 2016-06-07 | Raytheon Company | Multi-bandpass, dual-polarization radome with embedded gridded structures |
-
2017
- 2017-04-07 CN CN201710222729.7A patent/CN107086374B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20130004736A (en) * | 2011-07-04 | 2013-01-14 | 단국대학교 산학협력단 | Frequency selective surface for multiband |
| CN102637932A (en) * | 2012-05-04 | 2012-08-15 | 中国科学院长春光学精密机械与物理研究所 | Concentrated configuration type cross-shaped annulus passband frequency selection surface with high angle stability |
| CN106295038A (en) * | 2016-08-17 | 2017-01-04 | 大连理工大学 | A kind of active frequencies selects surface method for designing |
| CN206789705U (en) * | 2017-04-07 | 2017-12-22 | 南京航空航天大学 | One kind miniaturization low section ultra-wide band connection frequency selection surface |
Non-Patent Citations (1)
| Title |
|---|
| Study on the transmission characteristics of a double layered complementary frequency selective surface;ZHAO Hui等;《2016 11th International Symposium on Antennas Propagation and EM Theory(ISAPE)》;20161221;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107086374A (en) | 2017-08-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107086374B (en) | Miniaturized low-profile ultra-wide passband frequency selective surface and design method thereof | |
| CN108270085B (en) | Suction-through integrated frequency selective surface structure | |
| CN107394410B (en) | 2.5-dimensional closed loop type frequency selective surface structure and design method thereof | |
| CN107171043B (en) | Ultra-wide passband frequency selective surface with improved angular stability | |
| CN110048240B (en) | High-impedance band suppression low-radar scattering sectional area transmission array antenna | |
| CN114421152B (en) | Miniaturized reconfigurable frequency selective surface with high selective characteristics and application | |
| Liu et al. | A miniaturized FSS based on tortuous structure design | |
| Rahim et al. | Design of X-band frequency selective surface (FSS) with band pass characteristics based on miniaturized unit cell | |
| Zhu et al. | A compact tapered EBG structure with sharp selectivity and wide stopband by using CSRR | |
| CN206789705U (en) | One kind miniaturization low section ultra-wide band connection frequency selection surface | |
| Ebrahimi et al. | Narrowband bandpass frequency selective surface with miniaturized elements | |
| CN207052731U (en) | Improve the ultra-wide band connection frequency selection surface of angle stability | |
| Shome et al. | A novel filtenna design for ultra-wideband applications | |
| CN113346250B (en) | Millimeter wave three-frequency selection surface based on multilayer coupling structure | |
| He et al. | A tri-band highly selective passband frequency selective surface based on multi-layer coupling | |
| Zhao et al. | Design of dual-band frequency selective surface with large band ratio for 5G communication | |
| Xu et al. | An ultra wideband FSS operating at Ka band | |
| Rahim et al. | X-band Band-pass Frequency Selective Surface for Radome Applications | |
| Jin et al. | A novel wideband frequency selective surface design based on cascaded patch resonators with a slotted ground | |
| CN111682292A (en) | Four-way band-pass power division filter based on four-mode resonator | |
| Qiang | Simple structure high selectivity dual-band filtering antenna | |
| Ahmad et al. | Reconfigurable UWB filtennas with sharp WLAN dual bandnotch | |
| Yu et al. | Frequency Selective Surface based on fractal structure with wide angular stability | |
| Liu et al. | Design of FSS-based UWB absorber using multi-layer modified circular ring | |
| Al-Ani et al. | Design a crlh antenna for mimo applications with single and dual band |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |