CN119627385B - A unit structure of a dual-passband FSR, a dual-passband FSR and a radome - Google Patents

Abstract

The application belongs to the technical field of microwaves, and particularly relates to a unit structure of a double-passband FSR, the double-passband FSR and an antenna housing, the unit structure comprises an impedance layer and an FSS layer, the impedance layer comprises a dielectric substrate I, a double-spiral resonance structure, an interdigital capacitor structure and connecting wires, the double-spiral resonance structure and the interdigital capacitor structure are arranged on two sides of the dielectric substrate I, the double-spiral resonance structure and the interdigital capacitor structure which are positioned on the same side are connected through the connecting wires, a resistor is arranged on the connecting wires, the two connecting wires on the two sides of the dielectric substrate I are in a crossed position relationship, and the FSS layer is provided with double-square-ring gaps to construct two transmission belts. The radar antenna can be unaffected in two working frequency bands, radar low detectability can be realized in out-of-band wave absorption, dual polarization is realized, and the section is as low as 0.085And the oblique incidence stability performance reaches 45 degrees, so that the requirements of low profile, dual polarization and large-angle performance stability are simultaneously met.

Description

Unit structure of double-passband FSR, double-passband FSR and radome

Technical Field

The application belongs to the technical field of microwaves, and particularly relates to a unit structure of a double-passband FSR, the double-passband FSR and an antenna housing.

Background

Conventional radomes are typically composed of a frequency selective surface (Frequency Selective Surface, FSS) structure that relies on the frequency selective characteristics of the FSS for the incident wave to perform the radome function. FSS (Frequency Selective Surface ) is a two-dimensional structure of periodically arranged conductive or dielectric elements capable of selectively reflecting or transmitting electromagnetic waves according to the frequency of the incident wave. The basic principle of FSS is to design the shape, size and arrangement of its elements so that they exhibit bandpass or bandstop filter characteristics in a specific frequency range.

Double pass band FSR (Frequency Selective Rasorber) refers to a frequency selective structure having two pass bands. Such a frequency selective structure is capable of allowing signals to pass through in two specific frequency ranges, while attenuating or blocking signals in other frequency ranges.

In one known technique, two transmission windows are implemented over a wide operating frequency range, cascading from top to bottom two similar lossy layers, a low-pass FSS, and a double-bandpass multilayer FSS. The low-pass FSS acts as a ground for the lossy layer, employing bent conductive lines to create a high frequency absorption band. The interaction between the double bandpass FSS and the two lossy layers results in low and medium frequency absorption bands. When the two transmission frequency bands of the lossy layer are overlapped with the transmission frequency bands of the low-pass and double-band-pass FSS, two transmission windows can be realized. The FSR has two-3 dB transmission bands, the fractional bandwidths are 45.98% and 23.31% respectively, and three absorption bands, the fractional bandwidths are 81.11%, 13.67% and 3.36% respectively, the wave absorption rate is more than 80%, but in the practical application process, the structural layer number is excessive, the thickness reaches 0.15,Representing the free space wavelength corresponding to the lowest frequency with a reflection coefficient less than-10 dB. The thickness processing of the structure is fixed and complex, and the requirement of low profile is not met in practical application.

In one known technique, stealth is used for broadband antennas. The design combines a spiral inductor and an interdigital capacitor parallel resonator to meet the requirement of wide passband at lower frequencies of the operating band. In practical testing, the design is capable of achieving two pass bands between 4.9-6 GHz (20.0%) and 8.6-9 GHz (6.3%). The device also achieves three absorption bands with fractional bandwidths of 48.4%, 25.7% and 22.0%, respectively. However, the model has the characteristic of single polarization, can not realize frequency selection under the condition of two incident waves of horizontal polarization and vertical polarization, has no angular stability, and can not be applied to practical engineering.

In one known technique, the absorber consists of a lossy layer and a lossless layer. The two layers are separated by an air gap. The upper loss layer is formed by four square rings with two branches, so that dual-band transmission response is realized. At 8 and 11.9 GHz, the insertion loss under TE polarization is 0.39 and 0.64 dB, respectively, and the insertion loss under TM polarization is 0.40 and 0.66 dB, respectively. The frequency band with reflection coefficient lower than-10 dB is 5-12.8 GHz. In practical tests, the angular stability of the design is only 30 degrees, and stable performance cannot be ensured under the condition of large-angle incidence.

In summary, the prior art frequency selective subsurface of dual passband is not capable of satisfying the characteristics of low profile, dual polarization and wide angle stability simultaneously.

Content of the application

The application aims to solve the technical problem of providing a unit structure of a dual-passband FSR, the dual-passband FSR and an antenna housing, and solves the problem that a passive frequency selection surface in the prior art cannot realize low profile, dual polarization and stable large-angle performance at the same time.

The application provides a unit structure of a dual passband FSR, which comprises:

The impedance layer comprises a dielectric substrate I, a double-spiral resonance structure, an interdigital capacitor structure and connecting wires, wherein the double-spiral resonance structure and the interdigital capacitor structure are arranged on two sides of the dielectric substrate I, the double-spiral resonance structure and the interdigital capacitor structure which are positioned on the same side are connected through the connecting wires, the connecting wires are provided with resistors, and the connecting wires on two sides of the dielectric substrate I are in a crossed position relationship;

an FSS layer having a double square ring gap to construct two transmission belts;

The resistive layer is spaced from the FSS layer.

Optionally, the two connecting wires on one surface and the other surface of the dielectric substrate are in a crisscross position relationship.

Optionally, the double-spiral resonance structure comprises two spiral conducting plates which are mutually surrounded, a spiral gap is formed between the two spiral conducting plates, the outer end of one spiral conducting plate is connected with a connecting wire, and the outer end of the other spiral conducting plate is connected with a T-shaped conducting plate I.

Optionally, the structure of the spiral conductive sheet is a rectangular spiral structure or a circular spiral structure.

Optionally, the width of the spiral gap between the two spiral conductive sheets is g, the width of the spiral conductive sheet is c, the widths of the transverse line part and the vertical line part of the T-shaped conductive sheet are w ₂, the length of the connecting wire is l ₃, the distance between the transverse line part of the T-shaped conductive sheet and the spiral conductive sheet which is not connected with the T-shaped conductive sheet is l ₄, the width of the interdigital capacitor structure is f_l, and the length is f_w;

and g: c: w ₂:l₃:l₄: f_l: f_w=0.1:0.15:0.25:5.2:1.15:2.5:2;

And/or the connecting wires are made of metal or conductive composite materials;

and/or the spiral conducting strip is made of metal or a conducting composite material;

And/or the first T-shaped conductive sheet is made of metal or conductive composite material.

Optionally, the spiral gap width of the two spiral conducting strips is 0.1+/-10% mm;

And/or the width of the spiral conducting strip is 0.15+/-10% mm;

And/or the widths of the transverse line part and the vertical line part of the T-shaped conducting strip I are 0.25+/-10% mm;

And/or the length of the connecting wire is 5.2+/-10% mm;

And/or the distance between the transverse line part of the T-shaped conducting strip I and the spiral conducting strip which is not connected with the T-shaped conducting strip I is 1.15+/-10% mm;

And/or, the width of the interdigital capacitor structure is 2.5+/-10% mm, and the length is 2+/-10% mm.

Optionally, the interdigital capacitor structure comprises a first multi-tooth structure and a second multi-tooth structure which are meshed with each other, the first multi-tooth structure is connected with the second multi-tooth structure, one side, deviating from the second multi-tooth structure, of the first multi-tooth structure is connected with the connecting wire, and one side, deviating from the first multi-tooth structure, of the second multi-tooth structure is connected with the second T-shaped conducting strip.

Optionally, the first multi-tooth structure comprises a plurality of first conductive strips and a first conductive connecting sheet, wherein the first conductive strips are distributed at intervals, the first conductive connecting sheet is connected with the first conductive strips, the second multi-tooth structure comprises a plurality of second conductive strips and a second conductive connecting sheet, the second conductive strips are connected with the second conductive strips, the first conductive strips and the second conductive strips are distributed alternately, and one of the first conductive strips is connected to the second conductive connecting sheet in an extending manner;

And/or the widths of the transverse line part and the vertical line part of the second T-shaped conductive sheet are w ₁, the length of the transverse line part of the second T-shaped conductive sheet is l ₅, and the distance between the transverse line part of the second T-shaped conductive sheet and the edge of the first medium substrate is l ₁;w₁:l₅:l₁ =0.2:4:0.75;

and/or the material of the first multi-tooth structure and the second multi-tooth structure is metal or conductive composite material;

And/or the material of the second T-shaped conducting strip is metal or a conducting composite material.

Optionally, the FSS layer includes a second dielectric substrate, a first square-ring conductive sheet disposed on the second dielectric substrate, a second square-ring conductive sheet disposed on the second dielectric substrate and located in the first square-ring conductive sheet, and a second square-ring conductive sheet disposed on the second dielectric substrate and located in the second square-ring conductive sheet, wherein a first square-ring gap is formed between the first square-ring conductive sheet and the second square-ring conductive sheet, and a second square-ring gap is formed between the second square-ring conductive sheet and the second square-ring conductive sheet;

and/or, the interval between the impedance layer and the FSS layer is 10+/-10% mm.

The present application provides a dual passband FSR comprising one or more of said cell structures.

The application provides a radome comprising one or more of said frequency selective surfaces.

The dual-passband FSR unit structure and the impedance layer structure design provided by the application have the beneficial effects that the coupling influence of a dual-helical resonance structure and an interdigital capacitor structure is avoided, the superposition of performances is realized, the wave absorption rate of a wave absorption band is improved, the stability of the structure is enhanced, and the dual-passband FSR unit structure has the performances of simultaneously realizing low profile, dual polarization and large-angle performance stability.

The double-passband FSR of the application can lead the radar antenna not to be affected in two working frequency bands, realize low detectability of radar in out-of-band wave absorption, has dual polarization and has a section as low as 0.085And the oblique incidence stability performance reaches 45 degrees, so that the requirements of low profile, dual polarization and large-angle performance stability are simultaneously met.

Drawings

FIG. 1 is a schematic diagram of a unit structure of a dual passband FSR provided by the present application;

FIG. 2 is a schematic diagram of a structure of an impedance layer according to the present application;

Fig. 3 is a schematic structural diagram of an interdigital capacitor structure provided by the present application;

FIG. 4 is a schematic diagram of the FSS layer structure according to the present application;

FIG. 5 is an equivalent circuit diagram of a cell structure provided by the present application;

FIG. 6 is a graph of full wave simulation and equivalent circuit simulation results for an impedance layer provided by the present application;

FIG. 7 is a graph of full-wave simulation and equivalent circuit simulation results of the FSS layer provided by the application;

FIG. 8 is a graph of full-wave simulation and equivalent circuit simulation results for a cell structure of a dual passband FSR provided by the present application;

FIG. 9 is a graph showing the distribution of electric field and current of the resistive layer according to the present application;

fig. 10 (a) is a graph of simulation results of oblique incidence performance under TE polarization conditions of a unit structure of a dual passband FSR provided by the present application, and (b) is a graph of simulation results of oblique incidence performance under TM polarization conditions;

Fig. 11 (a) and (b) are diagrams showing a comparison of the cell structure of the dual passband FSR provided by the present application with the dual station RCS of the conductive plate at f _A1, and (c) and (d) are diagrams showing a comparison of the dual station RCS at f _A2;

FIG. 12 is a diagram showing a comparison of a cell structure of a dual passband FSR provided by the present application with a single station RCS of a conductive plate;

FIG. 13 (a) is a diagram of a dual passband FSR measurement environment provided by the present application, and (b) is a sample diagram;

Fig. 14 (a) is a graph showing a comparison between an actual measurement result and a simulation result of S parameters of a sample provided by the present application, and (b) is a graph showing a comparison between an actual measurement result and a simulation result of a wave absorption rate;

Fig. 15 (a) is a graph showing a comparison between a measured result and a simulation result of 45 ° oblique incidence performance of a sample provided by the present application under a TE polarization condition, and (b) is a graph showing a comparison between a measured result and a simulation result of 45 ° oblique incidence performance of a sample provided by the present application under a TM polarization condition.

In the figure, 10, an impedance layer, 11, a dielectric substrate I, 12, a double-spiral resonance structure, 121, a spiral conducting sheet, 13, an interdigital capacitor structure, 131, a multi-tooth structure I, 1311, a conducting strip I, 1312, a conducting connecting sheet I, 132, a multi-tooth structure II, 1321, a conducting strip II, 1322, a conducting connecting sheet II, 14, a connecting wire, 15, a resistor, 16, a T-shaped conducting sheet I, 17, a T-shaped conducting sheet II, 20, an FSS layer, 21, a dielectric substrate II, 22, a square ring conducting sheet I, 23, a square ring conducting sheet II, 24, a square conducting sheet, 25, a square ring gap I, 26, a square ring gap II.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of the application only and is not intended to be limiting of the application.

Before describing embodiments of the present application in detail, some terms and expressions which are referred to in the embodiments of the present application will be described first, and the terms and expressions which are referred to in the embodiments of the present application are applicable to the following explanation:

in FSS, S parameters generally include S11, S21, etc., wherein:

S11 represents the reflection loss (return loss) at port 1, also referred to as the input reflection coefficient (Input Reflection Coefficient). It measures the proportion of energy that the signal is reflected back at the input port (port 1). The closer the value of S11 is to 0 (typically expressed in dB, such as-25 dB, -40dB, etc.), the smaller the reflection, i.e. the smaller the reflection loss in the transmission path.

S21 represents insertion loss (insertion loss) in the process of signal transfer from port 1 to port 2. It measures the loss of signal during transmission. The closer the value of S21 is to 1 (0 dB), the smaller the loss in the transfer process.

TE polarization is a polarization state in which an electric field vector E representing an electromagnetic wave is perpendicular to a propagation direction and an angle of 0 ° is formed between the electric field vector E and a specific direction (typically, a reference direction). In radio frequency and microwave technology, TE polarization is often used to describe the propagation characteristics of electromagnetic waves in waveguides, antennas, and the like.

TM polarization is a polarization state in which a magnetic field vector H of an electromagnetic wave is perpendicular to a propagation direction and an angle of 0 ° is formed between the magnetic field vector H and a specific direction (typically, a reference direction). In radio frequency and microwave technology, TM polarization is often used to describe the propagation characteristics of electromagnetic waves in waveguides, antennas, and the like.

Herein "±10%" refers to a range of 10% from the value minus the value by 10% to the value plus the value by 10% based on the value preceding ±10% ".

As shown in fig. 1-5, the unit structure of the dual-passband FSR provided by the application comprises an impedance layer 10 and an FSS layer 20, wherein the impedance layer 10 comprises a dielectric substrate 11, a dual-spiral resonance structure 12, an interdigital capacitor structure 13 and a connecting wire 14, the dual-spiral resonance structure 12 and the interdigital capacitor structure 13 are arranged on two sides of the dielectric substrate 11, the dual-spiral resonance structure 12 and the interdigital capacitor structure 13 which are positioned on the same side are connected through the connecting wire 14, a resistor 15 is arranged on the connecting wire 14, the connecting wire 14 on two sides of the dielectric substrate 11 are in a crossed position relationship, the FSS layer 20 is provided with a double-square ring gap to construct two transmission bands, and the impedance layer 10 and the FSS layer 20 are spaced.

In one embodiment, in order to avoid the coupling influence of the double-spiral resonant structure 12 and the interdigital capacitor structure 13, the performance is superimposed, so that the wave absorption rate of the wave absorption band is improved, and meanwhile, the stability of the structure is enhanced, the double-spiral resonant structure 12 and the interdigital capacitor structure 13 are arranged on two sides of the diagonal line of the dielectric substrate 11 and the distance is expanded as much as possible, that is, two connecting wires 14 on two sides of the dielectric substrate 11 are in a crisscrossed position relationship. It will be appreciated that the two connection wires 14 may intersect perpendicularly in a projection perpendicular to the first dielectric substrate 11, or may intersect at a position not limited to 45 °, 60 °, 70 °. The double-spiral resonant structure 12 and the interdigital capacitor structure 13 need to be connected in the same polarization direction, namely, on the same surface of the first dielectric substrate 11 respectively, so that dual-polarized wave transmission of two passbands is realized. If the double-spiral resonant structure 12 and the interdigital capacitor structure 13 are respectively arranged on two surfaces of the first dielectric substrate 11, which is equivalent to two identical structures in one polarization direction, different polarization results respectively show a single passband effect, and the double passband effect cannot be achieved.

More double-helix resonant structures 12 and interdigital capacitor structures 13 are arranged on one side of the first dielectric substrate 11, electromagnetic effect coupling among the structures can be caused, and grating lobes and the like can be generated to influence wave transmission and wave absorption effects.

In one embodiment, resistor 15 is located in the middle of connecting wire 14. It can be understood that the two resistors 15 on the two sides of the first dielectric substrate 11 are coincident in the projection perpendicular to the first dielectric substrate 11 and are located in the middle between the double-spiral resonant structure 12 and the interdigital capacitor structure 13, so that the coupling influence of the double-spiral resonant structure 12 and the interdigital capacitor structure 13 is reduced, and the current and the electric field are mainly concentrated on the connecting wires 14 connecting the double-spiral resonant structure 12 and the interdigital capacitor structure 13, and loss wave absorption is generated when the current flows through the lumped resistor 15. In some embodiments, the resistor 15 is also located at any position of the connecting wire 14, and the two resistors 15 may also be offset.

In one embodiment, as shown in fig. 2, the double-spiral resonant structure 12 includes two spiral conductive sheets 121 surrounding each other with a spiral gap between the two spiral conductive sheets 121, wherein an outer end of one spiral conductive sheet 121 is connected to the connection wire 14, and an outer end of the other spiral conductive sheet 121 is connected to the T-shaped conductive sheet one 16. Specifically, one end of the two spiral conductive sheets 121 is wound in a spiral path in the same direction for a plurality of turns on the same plane at the diagonal position of the rectangle, and the other ends of the two spiral conductive sheets 121 are in opposite positions with the two remaining at a uniform interval. The number of turns of the spiral conductive sheet 121 is 3, 4 or more.

The double-helical resonant structure 12 has higher wave transmissivity and better passband selectivity than the single-helical structure. And the other end of the single spiral structure is generally arranged in the spiral, so that the two sides are not easy to connect.

In some embodiments, the structure of the double spiral conductive sheet 121 is a rectangular spiral structure or a circular spiral structure. It is noted that, in the research, it is found that the square spiral structure is easier to control individual parameters for optimization during simulation, and is easy to design, process and manufacture. The effect top square can reach the same effect with circular, and square is adjusted more easily.

In one embodiment, the width of the spiral gap between the two spiral conductive sheets 121 is g, the width of the spiral conductive sheet 121 is c, the widths of the transverse line portion and the vertical line portion of the T-shaped conductive sheet one 16 are w ₂, the length of the connecting wire 14 is l ₃, the distance between the transverse line portion of the T-shaped conductive sheet one 16 and the spiral conductive sheet 121 which is not connected with the T-shaped conductive sheet one 16 is l ₄, the width of the interdigital capacitor structure 13 is f_l, and the length is f_w;

g:c:w₂:l₃:l₄:f_l:f_w=0.1:0.15:0.25:5.2:1.15:2.5:2;

In one embodiment, the spiral gap width g of the two spiral conductive sheets 121 is 0.1±10% mm, the width c of the spiral conductive sheet 121 is 0.15±10% mm, the widths w ₂ of the transverse line portion and the vertical line portion of the T-shaped conductive sheet one 16 are 0.25±10% mm, the length l ₃ of the connecting wire 14 is 5.2±10% mm, the spacing l ₄ of the transverse line portion of the T-shaped conductive sheet one 16 from the spiral conductive sheet 121 not connected to the T-shaped conductive sheet one 16 is 1.15±10% mm, the width f_l of the interdigital capacitor structure 13 is 2.5±10% mm, and the length f_w is 2±10% mm.

In one embodiment, the first dielectric substrate 11 is square in shape and has a side length p of 16±10% mm;

In some embodiments, the connecting wire 14 is made of metal or conductive composite material, wherein the metal includes but is not limited to copper, silver, and gold, and the conductive composite material includes composite material of carbon fiber and resin, composite material of graphite and resin, or composite material of graphene and resin.

In some embodiments, the spiral conductive sheet 121 is made of metal or conductive composite material, and the spiral conductive sheet 121 is made of the same or different material as the T-shaped conductive sheet 16. The metal comprises copper, silver and gold, but is not limited to copper, silver and gold, and the conductive composite material comprises a composite material formed by mixing carbon fibers with resin, a composite material formed by mixing graphite with resin or a composite material formed by mixing graphene with resin.

In one embodiment, as shown in fig. 2, the interdigital capacitor structure 13 includes a first multi-tooth structure 131 and a second multi-tooth structure 132 that are meshed with each other, the first multi-tooth structure 131 is connected to the second multi-tooth structure 132, a side of the first multi-tooth structure 131 facing away from the second multi-tooth structure 132 is connected to the connecting wire 14, and a side of the second multi-tooth structure 132 facing away from the first multi-tooth structure 131 is connected to the second T-shaped conductive sheet 17. Specifically, the first multi-tooth structure 131 and the second multi-tooth structure 132 are connected at a point, and the rest is provided with a gap, and preferably, the first multi-tooth structure 131 is connected with the second multi-tooth structure 132 at an intermediate position. The material of the interdigital capacitor structure 13 is the same as that of the spiral conductive sheet 121, and of course, the material of the interdigital capacitor structure 13 and the spiral conductive sheet 121 may be different.

In one embodiment, as shown in fig. 3, the first multi-tooth structure 131 includes 5 first conductive strips 1311 and first conductive connecting strips 1312 connecting the 5 first conductive strips 1311, the second multi-tooth structure 132 includes 4 second conductive strips 1321 and second conductive connecting strips 1322,5 connecting the 4 second conductive strips 1321 alternately distributed, and one of the first conductive strips 1311 is connected to the second conductive connecting strips 1322 in an extending manner. Specifically, the first conductive strip 1311 and the second conductive strip 1321 have a long strip shape, a triangle shape, or a trapezoid shape.

In some embodiments, the first multi-tooth structure 131 may also be a three-finger structure, a four-finger structure, or a six-finger structure, and the second multi-tooth structure 132 may be a two-finger structure, a three-finger structure, or a five-finger structure.

In some embodiments, the first and second multi-tooth structures 131 and 132 are made of metal or conductive composite materials, wherein the metal includes but is not limited to copper, silver, and gold, and the conductive composite materials include composite materials formed by mixing carbon fiber with resin, composite materials formed by mixing graphite with resin, or composite materials formed by mixing graphene with resin.

In some embodiments, the material of the second T-shaped conductive sheet 17 is metal or a conductive composite material, wherein the metal includes copper, silver, gold, but is not limited to copper, silver, gold, and the conductive composite material includes a composite material formed by mixing carbon fiber with resin, a composite material formed by mixing graphite with resin, or a composite material formed by mixing graphene with resin.

The widths of the transverse line part and the vertical line part of the second T-shaped conductive sheet 17 are w ₁, the length of the transverse line part of the second T-shaped conductive sheet 17 is l ₅, and the distance between the transverse line part of the second T-shaped conductive sheet 17 and the edge of the first medium substrate 11 is l ₁;w₁:l₅:l₁ =0.2:4:0.75.

In one embodiment, the width w ₁ of the transverse line portion and the vertical line portion of the second T-shaped conductive sheet 17 is 0.2±10% mm, the length l ₅ of the transverse line portion of the second T-shaped conductive sheet 17 is 4±10% mm, and the distance l ₁ between the transverse line portion of the second T-shaped conductive sheet 17 and the edge of the first dielectric substrate 11 is 0.75±10% mm.

In one embodiment, as shown in fig. 4, the FSS layer 20 includes a second dielectric substrate 21, a first square-ring conductive sheet 22 disposed on the second dielectric substrate 21, a second square-ring conductive sheet 23 disposed on the second dielectric substrate 21 and disposed in the first square-ring conductive sheet 22, and a second square-ring conductive sheet 24 disposed on the second dielectric substrate 21 and disposed in the second square-ring conductive sheet 23, wherein a square-ring gap 25 is formed between the first square-ring conductive sheet 22 and the second square-ring conductive sheet 23, and a square-ring gap 26 is formed between the second square-ring conductive sheet 23 and the second square-ring conductive sheet 24.

In one embodiment, the resistive layer 10 is spaced from the FSS layer 20 by a distance h, preferably the resistive layer 10 is spaced from the FSS layer 20 by a distance of 10.+ -. 10% mm.

In one embodiment, the second dielectric substrate 21 is square in shape and has a side length p, the outer side edge of the first square ring conductive sheet 22 coincides with the edge of the second dielectric substrate 21, the inner side edge of the first square ring conductive sheet 22 is a ₄, the outer side edge of the second square ring conductive sheet 23 is a ₃, the inner side edge is a ₂, the side edge of the second square ring conductive sheet 24 is a ₁, and h: p: a ₄:a₃:a₂:a₁ =10:16:10.08:9.27:6.72:6.05.

In one embodiment, the distance h between the impedance layer 10 and the FSS layer 20 is 10±10% mm, the shape of the second dielectric substrate 21 is square, the side length p is 16±10% mm, the outer side of the first square ring conductive sheet 22 coincides with the edge of the second dielectric substrate 21, the inner side length a ₄ of the first square ring conductive sheet 22 is 10.08±10% mm, the outer side length a ₃ of the second square ring conductive sheet 23 is 9.27±10% mm, the inner side length a ₂ is 6.72±10% mm, and the side length a ₁ of the second square ring conductive sheet 24 is 6.05±10% mm.

In one embodiment, the first dielectric substrate 11 and the second dielectric substrate 21 are made of polytetrafluoroethylene.

In one embodiment, the square ring conductive sheet one 22, the square ring conductive sheet two 23 and the square conductive sheet 24 are made of metal or conductive composite materials, wherein the metal comprises copper, silver and gold, but is not limited to copper, silver and gold, and the conductive composite materials comprise composite materials formed by mixing carbon fibers with resin, composite materials formed by mixing graphite with resin or composite materials formed by mixing graphene with resin.

Example 1

The dimensional parameters of the unit structure of the double passband FSR are shown in table 1, and an equivalent circuit of the impedance layer 10 and the FSS layer 20 with a double parallel LC structure is established in the circuit simulation software ADS, and the equivalent circuit is shown in fig. 5.

TABLE 1

In the physical structure model (fig. 1), the impedance layer double-spiral structure and the interdigital capacitor structure are equivalent to two parallel capacitor-inductor structures at the lower left side in the equivalent circuit model (fig. 5), and are transparent at a specific frequency. The longitudinal conductive wires connected with the capacitive structure are of an inductive structure, and the transverse conductive wires form a capacitive structure to form a series capacitive-inductive-resistive structure for absorbing waves. Each square annular gap of the FSS layer is equivalent to two parallel capacitor-inductor structures on the right side, and wave transmission is carried out at a specific frequency.

In order to facilitate understanding, full-wave simulation and equivalent circuit simulation are performed on the unit structures of the impedance layer 10, the FSS layer 20 and the dual-passband FSR provided in this embodiment, and simulation results are shown in fig. 6, 7 and 8, it can be seen that the wave absorption frequency point is obtained by the combined design of the impedance layer 10=4.7 GHz and=8.3 GHz and transmission frequency points=6.3 GHz and=9.8 GHz. Wherein the double helical resonant structure 12 creates a low frequency transmission poleAnd double-side wave-absorbing frequency band, and the interdigital capacitor structure 13 generates a high-frequency transmission poleA double sided absorbent belt. The two structures avoid coupling influence in the design process, the performances are overlapped, the wave absorption rate of the wave absorption frequency band is improved, and meanwhile, the stability of the structure is enhanced.

When the FSS layer 20 is designed, a double-side annular gap type band-pass FSS with proper size is selected, and two transmission bands of the FSS layer 20 and two pass bands of the impedance layer 10 are respectively matched, so that the A-T-A-T type double-pass FSR design is realized.

Fig. 9 shows the surface current distribution of the dual passband FSR impedance layer 10 at the absorption and transmission bands for TE polarization. Can be seen in the double side absorption bandAndHere, the current and the electric field are mainly concentrated on the conductive wires connecting the double spiral resonant structure 12 and the interdigital capacitor structure 13, and loss wave absorption is generated when the current flows through the lumped resistor 15. Transmission frequency bandThe current is mainly concentrated on the double-spiral structure, the incident electromagnetic wave generates parallel resonance to induce current, so that free electron oscillation in the conductive wire radiates electromagnetic wave to free space to generate transmission band, and the transmission band is formed in the transmission bandThe current is mainly concentrated on the interdigital capacitor structure 13 to generate parallel resonance, and a transmission pole is generated to transmit electromagnetic waves. The distribution of the surface currents demonstrates the performance implementation of the proposed structure in the actual design process described above.

The cell structure of the dual passband FSR is shown in fig. 10 for oblique incidence performance and polarization stability within 45 °. Fig. 10 (a) and fig. 10 (b) are oblique incidence performance curves of the cell structure under TE polarization and TM polarization conditions, respectively, and it can be seen that the cell structure has substantially identical performance under TE polarization and TM polarization conditions, and in simulation results of TM polarization, a high-frequency part is affected by a grating lobe, but is not limited by structural dimension design, and exhibits good polarization stability. From the perspective of oblique incidence performance, it can be seen that under the TE polarization condition, the unit structure performance is hardly affected by the oblique incidence angle, under the TM polarization, as the oblique incidence angle is increased, the bandwidth of the low-frequency and high-frequency absorption bands gradually decrease, the high-frequency transmission band is shifted to the high-frequency offset, and the insertion loss is increased.

The unit structure is designed by superposition of an interdigital capacitor structure 13 and a double-spiral resonance structure 12, and the absorption wave bands of the interdigital capacitor structure and the double-spiral resonance structure are superposed to generate FSR (frequency shift register)The wave absorption rate is increased, the oblique incidence stability is improved, and the stable performance can be maintained within the range of 45 degrees.

As shown in fig. 11, the double station RCS reduction effect of the double passband FSR and the conductive reflector is compared at two wave absorption frequencies f _A1 and f _A2. As can be seen from FIG. 11 (a), inFSR can be realized in comparison with a conductive reflecting plateThe main lobe RCS within 140 degrees is reduced, and the RCS reduction effect is best at 0 degrees and can reach 9.8 dB. In FIG. 11 (b), inFSR can be realized in comparison with a conductive reflecting plateThe main lobe RCS within 100 degrees is reduced, and the RCS reduction effect can reach 11.9 dB at 0 degrees.

Fig. 12 shows a comparison of FSR and conductive plate single-station RCS, and it can be seen that the dual-passband FSR has a significant RCS reduction effect over the range of the simulated frequency bands. With the increase of frequency, the RCS of FSR and the conductive plate are increased, the RCS at 6 GHz and 9 GHz near the two wave-absorbing frequency bands has obvious reducing effect, and the RCS is in the transmission frequency bandRCS reduction effect around=6.3 GHz was relatively weak, atDecrease trend was slowed at=9.8 GHz.

Example 2

The present application provides a dual passband FSR comprising one or more cell structures.

To verify the performance of the dual-passband FSR proposed in this section, a sample was fabricated and a schematic diagram of the test environment and dual-passband FSR process sample is shown in fig. 13. The sample is an array of 20 x 20 units, 320mm x 320mm in size. The impedance layer 10 is printed on the F4B220 material, the conductive structure is etched on the two sides of the dielectric substrate by adopting a gold deposition process, and the lumped resistance 15 is 300 of 0201 packageResistor 15, fss layer 20 is printed on one side of the F4B350 material. The air layers between the two layers are replaced and separated by a 10mm foam plate.

The measuring method of the processing sample piece in this section is consistent with the measuring method, and the reflection coefficient and the transmission coefficient are respectively measured. And obtaining an angle stability measurement result by changing the oblique incidence angle, and obtaining a polarization stability measurement result by changing the angle of the horn antenna and changing the incident polarization angle.

Fig. 14 shows graphs of measurement results and simulation results, respectively, and it can be seen that the measurement results and simulation results substantially remain consistent within the error allowable range, and the small deviation can be attributed to the machining error, the measurement accuracy, and the like. As shown in fig. 14 (a), the reflection coefficient bandwidth of the measurement result is 4.85-11.28 GHz, the relative bandwidth is 80%, there are two transmission bands at 6.25 GHz and 9.8GHz, and the insertion loss is 1.2 dB and 1.1 dB, respectively. It can be seen from fig. 14 (b) that the range of the wave absorption ratio of more than 90% is 3.6-5.8 GHz and 6.6-9.1 GHz, and the wave absorption ratio is close to 100%.

Fig. 15 is a graph showing a comparison between the measurement result and the simulation result of the processing sample in the 45 ° oblique incidence range, fig. 15 (a) is a TE polarized incident electromagnetic wave measurement result, and fig. 15 (b) is a TM polarized incident electromagnetic wave measurement result. It can be seen that under 45-degree oblique incidence condition, the processing sample piece can still keep stable absorption and transmission performance and has excellent angle stability. The TE and TM polarization results are basically identical, and the dual polarization characteristics of the dual polarization antenna are verified, and the high frequency is greatly influenced by higher harmonic waves under the TM polarization condition, but the performance of the working frequency band is not influenced.

In sum, based on simulation results, the dual passband FSR of the present invention has two transmission passbands and two absorption bands, and has a thickness of 0.085,Representing the free space wavelength corresponding to the lowest frequency with a reflection coefficient less than-10 dB. The reflectance is in the range of 4.4-11.1 GHz with a relative bandwidth of 86.5% with a reflectance of less than-10 dB. The transmission band ranges above-3 dB are 6.03-6.64 GHz and 9.39-10.25 GHz, respectively, with an insertion loss of 0.5 dB at transmission pole f _T1 =6.3 GHz and 0.8 dB at transmission pole f _T2 =9.8 GHz. The practical test shows stable dual polarization characteristic and large angle stability.

The present application provides a radome comprising one or more frequency selective surfaces.

It will be appreciated by persons skilled in the art that the above discussion of any embodiment is merely exemplary and is not intended to imply that the scope of the application is limited to these examples, that combinations of technical features in the above embodiments or in different embodiments may also be implemented in any order, and that many other variations of the different aspects of one or more embodiments of the application as described above exist within the spirit of the application, which are not provided in detail for the sake of brevity.

One or more embodiments of the present application are intended to embrace all such alternatives, modifications and variations as fall within the broad scope of the present application. Accordingly, any omissions, modifications, equivalents, improvements and others which are within the spirit and principles of the one or more embodiments of the application are intended to be included within the scope of the application.

Claims (10)

1. A cell structure of a dual passband FSR, comprising:

The impedance layer (10) comprises a first dielectric substrate (11), a double-spiral resonance structure (12), an interdigital capacitor structure (13) and a connecting wire (14), wherein the double-spiral resonance structure (12) and the interdigital capacitor structure (13) are arranged on two sides of the first dielectric substrate (11), the double-spiral resonance structure (12) and the interdigital capacitor structure (13) which are positioned on the same side are connected through the connecting wire (14), the double-spiral resonance structure (12) and the interdigital capacitor structure (13) are required to be connected in the same polarization direction, a resistor (15) is arranged on the connecting wire (14), and the connecting wires (14) on two sides of the first dielectric substrate (11) are in a cross position relationship;

An FSS layer (20) having a double square ring gap to construct two transmission belts;

the impedance layer (10) is spaced from the FSS layer (20);

the interdigital capacitor structure (13) comprises a first multi-tooth structure (131) and a second multi-tooth structure (132) which are meshed with each other, wherein the first multi-tooth structure (131) is connected with the second multi-tooth structure (132), and the first multi-tooth structure (131) and the second multi-tooth structure (132) are connected at one point position, and the rest parts are provided with gaps.

2. The unit structure according to claim 1, wherein two connecting wires (14) on both sides of the dielectric substrate one (11) are in a crisscross positional relationship.

3. The unit structure according to claim 1, characterized in that the double-spiral resonance structure (12) comprises two spiral conductive sheets (121) surrounding each other with a spiral gap between the two spiral conductive sheets (121), wherein the outer end of one spiral conductive sheet (121) is connected with a connecting wire (14), and the outer end of the other spiral conductive sheet (121) is connected with a T-shaped conductive sheet one (16).

4. A unit structure according to claim 3, characterized in that the structure of the spiral conductive sheet (121) is a rectangular spiral structure or a circular spiral structure.

5. A cell structure according to claim 3, wherein the spiral gap width of two spiral conductive sheets (121) is g, the width of the spiral conductive sheet (121) is c, the widths of the transverse line portion and the vertical line portion of the T-shaped conductive sheet (16) are both w ₂, the length of the connecting wire (14) is l ₃, the distance between the transverse line portion of the T-shaped conductive sheet (16) and the spiral conductive sheet (121) not connected to the T-shaped conductive sheet (16) is l ₄, the width of the interdigital capacitor structure (13) is f_l, the length is f_w, and g: c: w ₂:l₃:l₄: f_l: f_w = 0.1:0.15:0.25:5.2:1.15:2:2:15:2.5.5:2:2:2:2;

And/or the connecting wire (14) is made of metal or conductive composite material;

and/or the spiral conductive sheet (121) is made of metal or conductive composite material;

and/or the T-shaped conducting strip I (16) is made of metal or a conducting composite material.

6. The unit structure according to claim 1, wherein a side of the first multi-tooth structure (131) facing away from the second multi-tooth structure (132) is connected to the connecting wire (14), and a side of the second multi-tooth structure (132) facing away from the first multi-tooth structure (131) is connected to the second T-shaped conductive sheet (17).

7. The cell structure of claim 6, wherein the first multi-tooth structure (131) comprises a plurality of first conductive strips (1311) distributed at intervals, a first conductive connecting sheet (1312) connected to the plurality of first conductive strips (1311), the second multi-tooth structure (132) comprises a plurality of second conductive strips (1321) distributed at intervals, a second conductive connecting sheet (1322) connected to the plurality of second conductive strips (1321), the plurality of first conductive strips (1311) and the plurality of second conductive strips (1321) are distributed alternately, and one of the first conductive strips (1311) is connected to the second conductive connecting sheet (1322) in an extending manner;

And/or the widths of the transverse line part and the vertical line part of the T-shaped conducting strip II (17) are w ₁, the length of the transverse line part of the T-shaped conducting strip II (17) is l ₅, and the distance between the transverse line part of the T-shaped conducting strip II (17) and the edge of the dielectric substrate I (11) is l ₁;w₁:l₅:l₁ =0.2:4:0.75;

and/or the first multi-tooth structure (131) and the second multi-tooth structure (132) are made of metal or conductive composite materials;

And/or the T-shaped conducting strip II (17) is made of metal or a conducting composite material.

8. The unit structure according to claim 1, wherein the FSS layer (20) includes a dielectric substrate two (21), a square ring conductive sheet one (22) disposed on the dielectric substrate two (21), a square ring conductive sheet two (23) disposed on the dielectric substrate two (21) and located in the square ring conductive sheet one (22), and a square conductive sheet (24) disposed on the dielectric substrate two (21) and located in the square ring conductive sheet two (23), wherein a square ring gap one (25) is formed between the square ring conductive sheet two (22) and the square ring conductive sheet two (23), and a square ring gap two (26) is formed between the square ring conductive sheet two (23) and the square conductive sheet (24);

And/or the distance between the impedance layer (10) and the FSS layer (20) is 10+/-10% mm.

9. A dual passband FSR comprising one or more cell structures of any of claims 1 to 8.

10. A radome comprising one or more dual passband FSRs of claim 9.