CN201994420U - Cross helical frequency selective surface (FSS) structure with dual-band characteristic - Google Patents

Abstract

The utility model discloses a cross helical frequency selective surface (FSS) structure with a dual-band characteristic. The structure consists of an upper dielectric layer, a lower dielectric layer and a middle cross helical FSS structural layer, wherein a structural unit of the cross helical FSS structural layer consists of a large-size cross helical structure and four small-size cross helical structures of which the size is relatively halved; the large and small cross helical structures consist of cross arms and S-shaped arms at the cross tail ends; the large-size cross helical structure is positioned in the center of the structural unit of the cross helical FSS structural layer; the four small-size cross helical structures are obtained by halving and turning the large-size cross helical structure and then translating the large-size cross helical structure upwards and leftwards, upwards and rightwards, downwards and leftwards, and downwards and rightwards respectively; and in the structure, two isomorphic cross helical structures with different sizes are used, so that a produced pass band has the dual-band characteristic, and the selectivity can be obviously improved. The structure has few parameters, is easy and convenient to manufacture and has practical value and broad application prospect in the technical field of microwave frequency band antenna engineering.

Description

A kind of cross spiral FSS structure with dual-band characteristic

(1) technical field

The utility model relates to a kind of cross spiral frequency-selective surfaces structure (hereinafter to be referred as cross spiral FSS structure) that is applied to radar system and communication system, relate in particular to a kind of cross spiral FSS structure and construction method thereof with dual-band characteristic, this cross spiral FSS structure can reduce the antenna radar scattering section, designs the multiplexing parabolic antenna of many feeds multifrequency.It belongs to microwave frequency band antenna works technical field.

(2) background technology

The electronic reconnaissance technology is largely depended in modern war, so the counterreconnaissance technology is extremely urgent.Reduction armament systems radar reflection cross sections (RCS) come into one's own as the important means of counterreconnaissance.And the RCS of antenna is very big to the whole RCS contribution of aircraft or guided missile, how to design a kind of radome, can effectively reduce the RCS of antenna, and this is one of research direction of stealth technology.Because the satellite distance earth is remote, electromagnetic wave space loss is big, so the normal parabolic antenna with high-gain that uses in the satellite communication.How to make same parabolic antenna realize many feeds, multiband is worked simultaneously, effectively improves the space availability ratio on the satellite, and this also is to be badly in need of one of difficult problem that solves in the antenna works.Therefore how reducing the antenna radar scattering section and designing the multiplexing parabolic antenna of many feeds multifrequency is two subject matters that run in the antenna works.

Frequency-selective surfaces structure (FSS structure) is used for the designing antenna cover reduces the RCS of antenna system, can realize the purpose of radar invisible.When plane wave incident, signal in the working frequency range sees through radome with minimum insertion loss and enters local antenna, guaranteed the operate as normal of local antenna, and the outer electromagnetic signal of band will be reflexed to fully away from coming wave line of propagation, outwards produce bigger scattering to such an extent as to stoped it to enter that radome produces induced current on antenna, realized the function of radar invisible, simultaneously also improved anti-jamming capacity because having masked the unwanted electromagnetic wave beyond the service band.With the subreflector of frequency-selective surfaces, improve the utilization ratio of antenna as parabolic antenna.FSS is used for the subreflector of parabolic antenna, subreflector can be made hyperboloid, and bi-curved virtual focus overlaps with parabolic focus, with the feed of the different frequency bi-curved actual situation focus that is placed in, realizes that double frequency is multiplexing.Effectively raise paraboloidal utilization ratio like this, thereby reduce weight, volume and the expense of antenna system.

The main performance of FSS structure is a frequency selective characteristic, for incident direction and the sensitivity of polarization and the stability of bandwidth of driving source.Traditional individual layer plane FSS structure choice characteristic is general, for plane wave different angles incident unstable properties.In order to improve selectivity characteristic, the multilayer planar cascade is the method for normal employing, but causes manufacturing cost high so again, and the structure more complicated can't design fast and effectively.Therefore the utility model has designed a kind of novel center and connects combination frequency to select new unit, surface be cross spiral FSS structure, and it has realized the angle stability of multiband characteristic and relative incident wave.

(3) summary of the invention

1, goal of the invention

The purpose of this utility model provides a kind of cross spiral FSS structure with dual-band characteristic, and it has realized the multiband characteristic.This cross spiral FSS structure is compared with traditional individual layer plane FSS structure, overcome the shortcoming of its plane wave different angles incident unstable properties and can realize the broad passband characteristic of double frequency, it both can also can be with a wide range of applications in antenna communication system and radar system as transmission as reflection.The angle stability of cross spiral FSS structure in the utility model, also the design for double frequency-band FSS provides useful reference.

2, technical scheme

See Fig. 1, a kind of cross spiral FSS structure of the utility model with dual-band characteristic, it is made of upper and lower two layer medium layer and middle cross spiral FSS structure sheaf, position annexation between them is seen Fig. 2: wherein 1 and 2 are dielectric layer, at the upper and lower faces layer, intermediate layer 3 is cross spiral FSS structure sheafs.Wherein, this 1 and 2 dielectric layer is that to be 0.5 millimeter dielectric constant be 3.0 dielectric material to two thickness.Cross spiral FSS structure sheaf is the metal surface.Cross spiral FSS structural metal layer is a periodic structure, the construction unit of forming cross spiral FSS structure sheaf is obtained one 6 * 6 complete cross spiral FSS structure sheaf behind X, Y direction periodic extension, as shown in Figure 3.The construction unit of cross spiral FSS structure sheaf is made up of with four relative small size cross helical structures that dwindle half of size a large-sized cross helical structure, and large and small cross helical structure is made up of the S shape arm of cross-arms and cross end; Large-sized cross helical structure is positioned at the construction unit center of cross spiral FSS structure sheaf, four undersized cross helical structures by large-sized cross helical structure dwindle one times rotate 45 ° again after respectively upwards left, upwards to the right, after right translation, obtain left and downwards downwards, as shown in Figure 4.With the cross helical structure Terminal Design of the large and small size of cross spiral FSS structure sheaf construction unit is S shape, can make the structure coupling closely, use two kinds of isomorphisms in the cross spiral FSS structure sheaf but the different cross helical structure of size makes the passband of generation have dual-band characteristic, as shown in Figure 5.

A kind of construction method with cross spiral FSS structure of dual-band characteristic, these method concrete steps are as follows:

Step 1: use the CST of simulation software to set up the construction unit of the cross spiral FSS structure sheaf of a zero thickness, the construction unit of this cross spiral FSS structure sheaf is formed (see figure 4) by a large-sized cross helical structure and four with its small size cross helical structure with the shape structure.This large and small cross helical structure is made up of the S shape arm of cross-arms and cross end; Large-sized cross helical structure is positioned at the construction unit center of cross spiral FSS structure sheaf, four undersized cross helical structures by large-sized cross helical structure dwindle one times rotate 45 ° again after respectively upwards left, upwards to the right, after right translation, obtain left and downwards downwards;

Step 2: the construction unit of the cross spiral FSS structure sheaf that step 1 is obtained, use the modeling tool of the CST of simulation software to set up the cross spiral FSS structure sheaf (see figure 3) of a zero thickness.Concrete operation method is that the construction unit of cross spiral FSS structure sheaf that step 1 is obtained obtains one 6 * 6 complete cross spiral FSS structure sheaf (see figure 6) behind X, Y direction periodic extension.

Step 3: utilize the CST of simulation software to set up the dielectric layer of cross spiral FSS structure, cross spiral FSS structure sheaf is embedded in the substrate of medium.At first draw a cuboid model as dielectric layer with the software drawing tool, the upper surface of dielectric layer lower surface and cross spiral FSS structure sheaf overlaps, and the dielectric layer material is selected DIELECTRIC CONSTANT _r=3.0 medium.The cuboid model that remakes a same size makes the upper surface of dielectric layer overlap with the lower surface of cross spiral FSS structure sheaf as dielectric layer.The dielectric layer material is selected DIELECTRIC CONSTANT equally _r=3.0 medium (see figure 2).

Step 4: a unit of intercepting cross spiral FSS structure carries out the analysis of incident wave transmissivity in the CST of simulation software software, according in the application of practical project to the requirement of smooth pass band width scope, the parameter of adjusting cross spiral FSS construction unit changes the resonance frequency of stopband, and the cross spiral FSS structure of adjusting is substituted this original structure.

Suppose that a plane wave is incident on that (in the middle of the model is the desired metallic layer, is positioned at the xz plane, and period profile the chip unit structure on the metal level, and the unit interval of x direction and z direction is expressed as D respectively on as shown in Figure 2 the cross spiral FSS structure _xAnd D _zBoth sides are dielectric layers.), this incident direction of wave travel can be expressed as s=xs _x+ ys _y+ zs _z

Ripple is distributed as by the electromagnetic field of cross spiral FSS structure transmissive side:

$E=\frac{Z}{2D_x{D}_z}\underset{k=-\∞}{\overset{\∞}{\mathrm{\Σ}}}\underset{n=-\∞}{\overset{\∞}{\mathrm{\Σ}}}\frac{e^{-\mathrm{j\β}(R-R^{\left(1\right)})\·r_{\±}}}{r_y}{e}_{\±}P---\left(1\right)$

In the formula $P=\∫I\left(l\right)e^{\mathrm{j\βlp}\·r_{\±}}\mathrm{dl}.$

If CURRENT DISTRIBUTION I (l) the unknown, then can adopt moment method, is the unknown function in the linear equation (1) linear combination that induced current I (l) is expressed as one group of basic function, select for use suitable test function to get inner product on the linear equation both sides then and generate a system of linear equations, find the solution this system of linear equations and just can try to achieve unknown function, thereby can obtain the transmission electromagnetic field of electromagnetic wave after easily through cross spiral FSS array of structures.

Step 5: when adding the incident wave incident from different perspectives of lump port calculated level polarization, the frequency response characteristic under each incident angle.According to the cross spiral FSS structure of having built up, the border of this structure is set, the angle of frequency sweep frequency and incident wave, the bandwidth stability and the frequency selectivity of test cross spiral FSS structure.

Step 6: according to the optimal size that step 4 is determined, processing and fabricating cross spiral FSS structure.The material of cross spiral FSS structure adopts double face copper.

3, advantage and effect

1) in design process, because cross spiral FSS structure comprises the structure of two kinds of sizes, by the filtering that has realized dual-band characteristic in its passband that is coupling in of two kinds of different modes of resonance.Select performance significantly to improve.And by the wherein cellular construction control of a class size, the size of every like this class unit can make an amendment respectively the performance of each passband, the process that can accelerate to design fully.

2) this cross spiral FSS structural behaviour with dual-band characteristic is stable, and its high selectivity and bandwidth stability do not change with the variation of the incident angle of incident wave.

3) this cross spiral FSS with dual-band characteristic is simple in structure, and this structure is covered with in common upper and lower surface on the dielectric substrate of metal and just can realizes.The construction unit shape and size and the size in cycle that only need to regulate cross spiral FSS structure sheaf in design process just can obtain needed performance.These structural parameters are few, save the time of design optimization greatly.

4) this cross spiral FSS structure with dual-band characteristic is made simple and conveniently, adopts existing conventional printed circuit board manufacturing process just can realize that cost is lower.

(4) description of drawings

Fig. 1 is the concrete composition schematic diagram of cross spiral FSS structure in the utility model

Fig. 2 is a cross spiral FSS structural representation in the utility model

Cross spiral FSS structure sheaf end view in Fig. 3 the utility model

Fig. 4 is the construction unit vertical view of cross spiral FSS structure sheaf in the utility model

Fig. 5 is a large scale cross helical structure vertical view in the utility model

Fig. 6 is a cross spiral FSS structure sheaf vertical view in the utility model

The transmission coefficient curve chart of cross spiral FSS structure when Fig. 7 is incident wave incident from different perspectives.

Fig. 8 is that the incident wave incident angle uses HFSS and CST emulation cross spiral FSS structure transmission coefficient curve comparison diagram when being 0 °

Fig. 9 is that the incident wave incident angle uses HFSS and CST emulation cross spiral FSS structure transmission coefficient curve comparison diagram when being 30 °

Emulation principle model figure when Figure 10 is to use software emulation.

Symbol description is as follows among the figure:

A slit arm; B slit terminal orthodrome; The little circular arc of C slit terminal;

The exradius of R1 slit terminal orthodrome; The interior radius of circle of R2 slit terminal orthodrome; The exradius of the little circular arc of R3 slit terminal; The interior radius of circle of the little circular arc of R4 slit terminal;

1 dielectric layer; 2 dielectric layers; The 3FSS layer; The CST simulation software; The HFSS simulation software.

(5) embodiment

Below in conjunction with accompanying drawing the utility model is described in further detail.

The utility model at radar system and Communication System Design a kind of cross spiral FSS structure with dual-band characteristic, it has realized the multiband characteristic.This structure is a S shape with the Terminal Design of the cross helical structure of the large and small size of cross spiral FSS structure sheaf construction unit, can make the structure coupling closely, use two kinds of isomorphisms in the cross spiral FSS structure sheaf but the different cross helical structure of size makes the passband of generation have dual-band characteristic, this cross spiral FSS structure by a cross spiral FSS construction unit in one plane periodic extension constitute.

As shown in Figure 2, cross spiral FSS Structure Calculation model in the utility model is made of upper and lower two layer medium layer 1,2 and middle cross spiral FSS structure sheaf 3, position annexation between them: wherein 1 and 2 is dielectric layer, at the upper and lower faces layer, intermediate layer 3 is cross spiral FSS structure sheafs.Wherein, this upper and lower dielectric layer 1 and 2 is that to be 0.5 millimeter dielectric constant be 3.0 dielectric material to two thickness.Cross spiral FSS structure sheaf 3 is the metal surface.

Described cross spiral FSS structure sheaf as shown in Figure 6.This structure is a periodic structure, and the periodic unit shape is that a large-sized cross helical structure is formed with four relative small size cross helical structures that dwindle half of size, and the cross helical structure is made up of the cross-arms at center and the S shape arm of cross end.Large-sized cross helical structure is positioned at the center, makes progress left respectively after four undersized cross helical structures rotate 45 ° by large-sized cross helical structure; Upwards to the right; Downwards left; After right translation, obtain downwards, as shown in Figure 4.The horizontal longitudinal translation of construction unit of the cross spiral FSS structure sheaf that obtains is obtained one 6 * 6 cross spiral FSS layer (see figure 6).According to different engineering application needs, the size that Simulation Calculation is concrete has determined the quantity of the new unit of respective cycle.Just can provide good frequency band selection as long as the quantity of this new unit of cycle is horizontal and vertical to surpass three.In order to strengthen the frequency selective characteristic of cross spiral FSS structure, at the upper and lower surface adding dielectric layer of cross spiral FSS structure sheaf.As shown in Figure 2.

Referring to shown in Figure 2, the utility model is a kind of to have dual-band characteristic cross spiral FSS structure, need use a computer that can move CST software and HFSS and carry out modeling and simulation and calculate.A kind of construction method with dual-band characteristic cross spiral FSS structure, these method concrete steps are as follows:

Step 1: the construction unit of setting up the cross spiral FSS structure sheaf of a zero thickness.At first use the drawing tool in the CST simulation software to set up a large-sized cross helical structure, wherein brachium A in slit is 2.0mm, wide 0.187mm, the arm terminal is two sections circular arcs, the outer radius of orthodrome B is 1.5mm, and inside radius is that 1.3mm orthodrome B and slit arm A intersect vertically at slit arm A right-hand member; The outer radius of little circular arc C is 0.737mm, and inside radius is 0.55mm, and the orthodrome B center of circle 1.7mm that moves right moves down the center of circle that 1.1mm is little circular arc C.Three slit arms of other of cross helical structure be followed successively by slit arm A be rotated counterclockwise 90 the degree, 180 the degree and 270 the degree obtain.The large scale cross helical structure that obtains is turned clockwise 6 °, obtain large-sized cross helical structure as shown in Figure 5.Utilize the modeling function of CST software that structure shown in Figure 5 is dwindled one times then, use the translation functions in the CST software modeling function to do translation after rotating 45 ° to X, Y direction, X, the translation distance of Y direction is 4.5mm.Obtain X at last, four undersized cross helical structures of Y both direction, large-sized cross helical structure is at the center of four small size cross helical structures, as shown in Figure 4.

Step 2: the construction unit of the cross spiral FSS structure sheaf that step 1 is obtained is along X, and the Y direction is done periodic extension and obtained cross spiral FSS structure sheaf.Use the figure translation functions in the modeling of CST simulation software, with the construction unit of the cross spiral FSS structure sheaf that obtains in the step 1 along X, the Y direction is done periodic extension, the translation distance of X and Y direction figure is 9mm, cross spiral FSS structure sheaf after the translation is 6 * 6 structural plan, as shown in Figure 6.

Step 3: the dielectric layer of setting up cross spiral FSS structure.Cross spiral FSS structure sheaf is embedded in the substrate of medium.At first make the cuboid of a 61mm * 61mm * 0.5mm with the drawing tool in the CST simulation software, the upper surface of cuboid bottom surface and cross spiral FSS structure sheaf overlaps.It is 3.0 that the cuboid material is set to dielectric constant, and magnetic permeability is 1, and loss angle tangent is 0.025.And then make the cuboid of a 61mm * 61mm * 0.5mm with the drawing tool in the CST software, the lower surface of cuboid end face and cross spiral FSS structure sheaf overlaps.It is 3.0 that the cuboid material is set to dielectric constant, and magnetic permeability is 1, and loss angle tangent is 0.025.So just obtain a cross spiral FSS structure of adding dielectric layer, as shown in Figure 2.

Step 4: unit of intercepting cross spiral FSS structure carries out the analysis of incident wave transmissivity in the CST simulation software.Because to be radiated at the structural angular range of cross spiral FSS big for incident wave in actual applications, the incident wave incident angle θ of horizontal polarization gets 0 °, 30 °, 45 ° and 60 ° of (see figure 10)s respectively, utilize the port excitation of the emulation boundary condition and the incident wave of HFSS software setting cross spiral FSS structure, cross spiral FSS array of structures is calculated and analyzes, obtain under each incident angle frequency response characteristic as shown in Figure 7.The cross spiral FSS structural table of two kinds of cross helical structure combinations has revealed a kind of characteristic that has high pass and stopband concurrently.Incident electromagnetic wave for the TE polarization, the CFS center frequency stabilization of first stopband of this cross spiral FSS structure is at 5GHz, the CFS center frequency stabilization of passband is at 10GHz, even the drift value of the centre frequency of second stopband when 0 ° and 60 ° of wide-angle incidents is still very little, only be 0.3GHz, so this cross spiral FSS structure have good angle stability.The different incidence angles degree sees the following form to the influence of the stopband center frequency of cross spiral FSS structure:

In application of practical project, to the requirement difference of smooth pass band width scope.Because the resonance frequency of stopband mainly is subjected to the influence of patch array, therefore can changes the resonance frequency of stopband, thereby adjust the bandwidth of the saturating wave system number curve of cross spiral FSS structure by the parameter of adjusting paster.For the incident electromagnetic wave of TE polarization, the incident angle bandwidth of grand cross spiral FSS structure more is narrow more.The distance of these two passbands and bandwidth can be regulated by the ratio and the relative position that change big or small cross spiral FSS structure chip unit size.Incidence angle θ sees the following form to the influence of the pass band width characteristic of cross spiral FSS structure:

Step 5: further checking is to cross spiral FSS structure simulation result's accuracy.Use the CST simulation software to do the analysis of ripple transmissivity cross spiral FSS structure.When the ripple incident angle is 0 °, HFSS that obtains and CST ripple transmission coefficient correlation curve as shown in Figure 8, when the ripple incident angle was 45 °, HFSS that obtains and CST ripple transmission coefficient correlation curve were as shown in Figure 9.

Step 6: according to above definite cross spiral FSS structure optimal size, processing and fabricating cross spiral FSS structure.Use the processes cross spiral of the present utility model FSS structure of laser ablation.Here selecting dielectric constant for use is 3.0, and the thickness of two layer medium is 0.5mm up and down, and middle cross spiral FSS structure sheaf gets final product with the sheet metal that upper and lower surface is covered with the metal copper film.

Claims (1)

1. cross spiral FSS structure with dual-band characteristic, it is characterized in that: it is made of upper and lower two layer medium layer and middle cross spiral FSS structure sheaf, upper and lower two layer medium layer be thickness to be 0.5 millimeter, dielectric constant be 3.0 dielectric material, middle cross spiral FSS structure sheaf is the metal surface; The construction unit of cross spiral FSS structure sheaf is made up of with four relative small size cross helical structures that dwindle half of size a large-sized cross helical structure, and large and small cross helical structure is made up of the S shape arm of cross-arms and cross end; Large-sized cross helical structure is positioned at the construction unit center of cross spiral FSS structure sheaf, four undersized cross helical structures by large-sized cross helical structure dwindle one times rotate 45 ° again after respectively upwards left, upwards to the right, after right translation, obtain left and downwards downwards; This cross spiral FSS structural metal layer is a periodic structure, and the construction unit of forming cross spiral FSS structure sheaf is obtained one 6 * 6 complete cross spiral FSS structure sheaf behind X, Y direction periodic extension; The Terminal Design of the cross helical structure of the large and small size of cross spiral FSS structure sheaf construction unit is a S shape, can make structure coupling closely, use two kinds of isomorphisms in the cross spiral FSS structure sheaf but the different cross helical structure of size makes the passband of generation have dual-band characteristic.

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