CN207250729U - Double-side-frequency broadband wave absorber with controllable pass band - Google Patents

Abstract

To stealthy and the electromagnetic compatibility problem under the complicated electromagnetic environment, this practicality provides a controllable bilateral broadband wave absorber of passband. The wave absorber is composed of a plurality of periodic unit structures arranged in an array; the periodic unit structure comprises an electric control switch screen, a periodic impedance layer and a foam layer, wherein the periodic impedance layer and the electric control switch screen are respectively arranged on the upper side and the lower side of the foam layer, and the foam layer is supported between the electric control switch screen and the periodic impedance layer to separate the electric control switch screen from the periodic impedance layer. This practicality is through the operating condition of the feed network control diode at the automatically controlled switch screen back to change the structure of automatically controlled switch screen, realize the switching between band-pass and the total reflection. This practicality can realize surveying and interference signal absorption to the operating band both sides to transmission window in the operating band carries out automatically controlled, makes it open the window under normal environment and does not influence signal receiving and dispatching, and closes the window in complicated electromagnetic environment.

Description

Controllable pass-band double-band frequency broadband absorber

technical field

The utility model relates to the technical field of electromagnetic stealth and electromagnetic protection, in particular to a double-band frequency broadband wave absorber with controllable passband, which is mainly used for single/double-station radar scattering cross-section (RCS) reduction and communication in complex electromagnetic environments System front-end immunity and protection.

Background technique

With its advantages of all-weather, all-time, strong anti-interference ability and high detection accuracy, radar occupies an important position in the detection equipment of modern warfare. Effectively avoid enemy radar detection, reduce the accuracy and completeness of the enemy's information on our military targets, and improve the penetration capabilities of our important military targets such as bombers and fighter jets, which is to ensure that our military tasks can be successfully completed Stealth and strong electromagnetic protection are crucial to ensure the survivability of information equipment in complex electromagnetic environments. Advanced stealth technology can shorten the distance for the enemy to find our targets (such as fighter jets, bombers, etc.), reduce the enemy's The early warning time increases the probability of success of our military operations. However, the emergence of multi-base radar technology, high-frequency over-the-horizon radar technology and space-based radar technology has brought serious challenges to stealth technology.

With the diversification and generalization of electronic equipment, the electromagnetic environment is becoming more and more, how to deal with the interference signal and high-intensity radiation field in the working frequency band has become an important issue. High-intensity radiation fields cover a wide frequency band, respond quickly, and have both soft and hard lethal capabilities, posing a great threat to electronic communications.

The RCS reduction of the antenna has always been a difficult problem for target stealth. It is necessary to select reasonable materials and design special structures to achieve the purpose of absorbing or reflecting the detection signal outside the working frequency band of the antenna and reducing the RCS of the antenna without affecting the signal within the working frequency band of the antenna. Send and receive normally. With the increasing use of modern electronic equipment, the electromagnetic environment has become more and more complex. In this case, interference signals or strong electromagnetic radiation within the operating frequency band can interfere with electronic equipment and even cause irreversible damage.

There are two existing stealth and protection technologies, one is to design a space surface with a specific shape structure; the other is to absorb waves. Frequency selective surfaces can reflect out-of-band signals, but for bistatic radar, their shadowing effect is extremely limited. The structure of the absorber can effectively reduce the radar cross-sectional area of single/dual radar detection, but the broadband absorber absorbs waves on one side of the passband, and the absorbing bandwidth of the bilateral absorber is difficult to design, and the bandwidth is extremely limited.

In addition, the passbands designed by the above two methods are fixed, leaving a communication window for the target, but also leaving a coupling channel for strong electromagnetic attacks, which cannot cope with interference signals and high-intensity radiation fields in the working frequency band. Energy can enter the interior of the equipment along this channel and damage the information equipment.

Utility model content

Aiming at the problems of stealth and electromagnetic compatibility in complex electromagnetic environments, the utility model proposes a double-band frequency broadband absorber with controllable passband. It can realize detection and interference signal absorption on both sides of the working frequency band, and electronically control the transmission window in the working frequency band, so that opening the window in a normal environment does not affect signal sending and receiving, and closing the window in a complex electromagnetic environment.

A double-band frequency broadband absorber with controllable passband, characterized in that the absorber is composed of a plurality of periodic unit structures arranged in an array; the periodic unit structure includes an electronically controlled switch screen, a periodic impedance layer and a foam layer, the periodic impedance layer, and the electric control switch screen are respectively arranged on the upper and lower sides of the foam layer, and the foam layer is supported between the electric control switch screen and the periodic impedance layer to separate the two.

The electric control switch screen includes a dielectric substrate, the upper surface of the dielectric substrate is coated with a "Tian"-shaped metal grid network, and the dielectric substrate in each grid of the metal grid network is coated with There is a metal patch, the metal patch is arranged in the middle of each grid and there is a gap between the edge of the metal patch and the grid network, and the same connection is made between each metal patch and the grid network. The number of evenly arranged diodes, the number of diodes is an integer multiple of 4.

The lower surface of the dielectric substrate is provided with a "well"-shaped feed network that controls the working state of the diodes on the upper surface, and the center position of each metal patch and the dielectric substrate corresponding to the center position are provided with connections to the lower surface of the dielectric substrate. The conductive through hole of the feed network, the metal patch on the upper surface of the dielectric substrate and the feed network on the lower surface of the dielectric substrate are electrically connected through the conductive through hole. The feed network is connected to the positive pole, and the grid network is connected to the negative pole. The terminal forms a potential difference to control the on-off state of the diode.

The periodic resistance layer includes a dielectric substrate of the resistance layer, a metal patch of the resistance layer and a chip resistor are arranged on the dielectric substrate of the resistance layer, and a chip resistor is loaded on the metal patch of the resistance layer.

When the diode on the electronically controlled switch panel of the utility model is not conducting, the metal patch on the upper surface of the dielectric substrate, the grid network and the feed network on the lower surface of the dielectric substrate form a resonance, and the electronically controlled switch panel forms a circuit in the working frequency band. passband, and reflect out-of-band signals; after the diode on the electronically controlled switch screen is turned on, the metal patch on the upper surface of the dielectric substrate is electrically connected to the grid network, and the metal patch on the upper surface of the dielectric substrate and the grid network The resonant structure of the feed network and the lower surface of the dielectric substrate is destroyed, the resonant frequency point disappears, the passband is closed, and the full frequency band is reflected.

The distances between the metal patches on the electric control switch screen of the utility model and the grid network are all equal; the distances between adjacent metal patches are equal, and the size and shape of all the metal patches are exactly the same, and each metal patch The positions and numbers of the diodes connected to the screen are exactly the same; the electronically controlled switch screen and the metal patches, diodes, metal grids and feeder network arranged on the screen are bilaterally symmetrical and vertically symmetrical.

The resistance layer metal patch in the utility model includes a circle of ring-shaped metal patches with the same shape as the resistance layer dielectric substrate arranged near the edge of the resistance layer dielectric substrate, and is arranged in the middle of the resistance layer dielectric substrate and also inside the ring metal patch. The first-order Minkowski fractal ring metal patch, the ring metal patch and the first-order Minkowski fractal ring metal patch are loaded with chip resistors.

The electric control switch screen, the periodic impedance layer and the foam layer described in the utility model are all square; the metal patch on the electric control switch screen is a square or circular metal patch; the ring metal patch on the periodic impedance layer The patch is a square ring metal patch or a circular metal patch.

The annular metal patch and the first-order Minkowski fractal ring metal patch of the utility model are loaded with a plurality of chip resistors, and the plurality of chip resistors are respectively set in the current distribution when the absorber absorbs the resonant frequency maximum location. That is, the loading position of the chip resistor is the position where the maximum induced current is generated on the metal patch of the impedance layer of the periodic impedance layer 2 when the incoming wave of the resonant frequency is radiated.

In the utility model: the resistance models of the multiple chip resistors loaded on the first-order Minkowski fractal ring metal patch are completely the same; the resistance models of the multiple chip resistors loaded on the annular metal patch are completely the same . The resistance value of the chip resistor is determined by the real part of the input impedance of the double-band frequency broadband absorber, which realizes impedance matching with free space and achieves full absorption.

The periodical resistance layer of the utility model includes the metal patch of the resistance layer and the chip resistor arranged on the dielectric substrate of the resistance layer, and the overall structure is symmetrical from left to right and symmetrical from top to bottom.

The foam layer described in the utility model is a polymethacrylimide foam layer.

The thickness of the foam layer in the utility model is an odd multiple of the quarter wavelength of the resonant frequency point of the absorber.

The beneficial technical effect of the utility model is:

1) The passband is switchable and controllable. The working state of the diode is controlled through the feed network on the back of the electronically controlled switch panel, thereby changing the structure of the electronically controlled switch panel and realizing the switch between bandpass and total reflection.

2) Bilateral wide band absorbing. The current research on absorbers is focused on single side frequency absorbing, and the absorbing band is relatively limited.

3) By designing the layer spacing h, that is, the thickness of the PMI foam layer, and selecting the patch impedance value, surface matching is achieved, the absorption bandwidth is wide, the absorption rate is high, and the passband insertion loss is small.

Description of drawings

Fig. 1 is the structural representation of the periodic cell structure of a specific embodiment provided by the utility model

Fig. 2 is a structural schematic diagram of an electric control switch panel of a specific embodiment provided by the utility model

Fig. 3 is a schematic structural diagram of a periodic impedance layer unit of a specific embodiment provided by the present invention

Fig. 4 is the simulation result figure of the specific embodiment provided by the utility model

In the figure: 1. Electric control switch screen; 101. Square dielectric substrate; 102. Metal grid network; 103. Square metal patch; 104. Diode; 105. Feed network; 106. Conductive through hole;

2. Periodic impedance layer; 201. Anti-layer dielectric substrate; 202. Chip resistor; 203. Square ring metal patch; 204. First-order Minkowski fractal ring metal patch;

3. Foam layer.

Detailed ways

In order to make the technical solutions and advantages of the utility model more clear, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, not to limit the utility model.

The embodiment of the utility model proposes a double-band frequency broadband absorber with controllable passband. The absorber is composed of a plurality of periodic unit structures arranged in an array. Referring to FIG. 1 , it is a schematic structural diagram of a periodic unit structure according to a specific embodiment of the present invention, where k is the incoming wave incident direction. The periodic unit structure includes an electric control switch screen 1 , a periodic resistance layer 2 and a polymethacrylimide (PMI) foam layer 3 . The periodic impedance layer 2 and the electric control switch screen 1 are arranged on the upper and lower sides of the foam layer 3 respectively, and the foam layer 3 is supported between the electric control switch screen 1 and the periodic impedance layer 2 to separate them. The thickness of the periodic resistance layer 2 is h ₁ , the thickness of the electric control switch screen 1 is h ₂ , and the thickness of the foam layer 3 is h.

The utility model electric control switch screen 1 its various parameters, diode position and quantity are designed according to the system working frequency band. Referring to Fig. 2, Fig. 2 is a schematic structural diagram of an electric control switch panel according to a specific embodiment of the present invention. In this embodiment, taking the working frequency of 8.2 GHz as an example, the electronically controlled switch screen 1 includes a square dielectric substrate 101, and the square dielectric substrate 101 is Rogers 4350. Referring to FIG. 2( a ), the upper surface of a square dielectric substrate 101 is covered with a "Tian"-shaped metal grid network 102 . The "Tian"-shaped metal grid network 102 has an axisymmetric structure (up-down symmetry and left-right symmetry). The "Tian"-shaped metal grid network 102 includes four square grids with the same size and shape, and the length of each side of the square grid is l ₆ . A square metal patch 103 of the same size is pasted on the dielectric substrate in each square grid. The square metal stickers 103 are all arranged in the middle of the square grid, and the center points of the square metal stickers 103 coincide with the center points of the square grid. The distance from each side of the square metal patch 103 to the inner side of the opposite square grid is equal, and the distance is equal to (l ₆ -l ₇ )/2. The side length of the square metal patch 103 is l ₇ , and the distance between adjacent square grids is equal to w ₂ .

One leg of a diode 104 is welded at the midpoint of each side of the square metal patch 103 , and the other legs of the diodes 1-4 are welded on the metal grid network 102 . In this way, four diodes 104 are connected between each square metal patch 103 and the grid network. In this embodiment, the diode is selected as BAP5102, which has fast response speed and small package capacitance.

Referring to FIG. 2( b ), the lower surface of the square dielectric substrate 101 is provided with a "well"-shaped feed network 105 for controlling the working state of the diode 104 on the upper surface. The feed network 105 of "well" shape is an axisymmetric structure (symmetrical up and down and symmetrical to left and right), which includes two horizontally distributed feeding metal sheets and two vertically distributed feeding metal sheets, and two horizontally distributed feeding metal sheets. The electric metal sheet and the two vertically distributed feeding metal sheets are distributed in a "well" shape. The distance between two horizontally distributed feeding metal sheets is ₈ , and the distance between two vertically distributed feeding metal sheets is also, _8. The horizontally distributed feeding metal sheets and the vertically distributed feeding metal sheets The same length means that the side length of the square dielectric substrate 101 is x. The widths of the horizontally distributed feed metal sheets and the vertically distributed feed metal sheets are the same, that is, w ₃ . The center position of each square metal patch 103 and the square dielectric substrate 101 corresponding to the center position are provided with conductive vias 106 connected to the feed network 105 on the lower surface of the square dielectric substrate. The distribution of the four conductive vias 106 corresponds to the positions of the intersections of the four horizontally distributed feed metal sheets and the vertically distributed feed metal sheets in the feed network 105 on the lower surface of the square dielectric substrate.

The square metal patch 103 on the upper surface of the square dielectric substrate 101 is electrically connected to the feed network 105 on the lower surface of the square dielectric substrate through the conductive through hole 106. The feed network 105 is connected to the positive pole, and the metal grid network 102 is connected to the negative pole. A potential difference is formed across the diode 104 to control the on-off state of the diode 104 .

When the diode 104 on the electronic control switch screen 1 is not conducting, the square metal patch 103 on the upper surface of the square dielectric substrate 101, the metal grid network 102 and the feed network 105 on the lower surface of the square dielectric substrate 101 form a resonant structure, The electronic control switch screen 1 forms a passband in the working frequency band, and reflects out-of-band signals; after the diode 104 on the electronic control switch screen 1 is turned on, the square metal patch 103 on the upper surface of the square dielectric substrate 101 and the metal grid The network 102 is electrically connected, the resonant structure of the square metal patch 103 on the upper surface of the square dielectric substrate 101 and the metal grid network 102 and the feed network 105 on the lower surface of the square dielectric substrate 101 is destroyed, the resonance frequency point disappears, and the passband is closed , full-band reflection.

Referring to FIG. 3 , FIG. 3 is a schematic structural diagram of a periodic impedance layer unit according to a specific embodiment of the present invention. In this embodiment, the periodic resistance layer 2 includes a square resistance layer dielectric substrate 201 , and a resistance layer metal patch and a chip resistor 202 are disposed on the resistance layer dielectric substrate 201 . In this embodiment, the resistive layer metal patch includes a circle of square ring-shaped metal patches 203 that are set near the edge of the resistive layer dielectric substrate 201 and have the same shape as the resistive layer dielectric substrate 201, and a square annular metal patch 203 that is arranged in the middle of the resistive layer dielectric substrate 201 and is also square. The first-order Minkowski fractal ring metal patch 204 inside the annular metal patch 203 is loaded with chip resistors 202 . By designing the annular metal patch structure (in this embodiment, a square annular metal patch) that produces multi-frequency resonance, the absorption resonance is generated on both sides of the passband, and a lossless resonance is formed at the passband of the electronically controlled switch screen, and then The purpose of impedance matching and incoming wave energy dissipation is achieved by loading chip resistors. All chip resistors in the utility model are respectively arranged at the position where the current distribution is the largest when the absorber absorbs the resonant frequency. That is, the loading position of the chip resistor is the position where the maximum induced current is generated on the metal patch of the impedance layer of the periodic impedance layer 2 when the incoming wave of the resonant frequency is radiated.

The first-order Minkowski fractal ring metal patch 204 is disposed at the center of the resistive layer dielectric substrate 201 (that is, at the center of the square ring metal patch 203 ). The square ring metal patch 203 is a square ring with a side length of 11. Two chip resistors 202 are loaded at the same position on each metal edge of the square ring metal patch 203 , and the distance between the two chip resistors 202 on each metal edge is equal to 15. In this embodiment, the two chip resistors 202 on each metal side of the annular metal patch 203 are arranged in the middle of the metal side. The model parameters of the eight chip resistors 202 on the square annular metal patch 203 are exactly the same, and their resistance values are all Rin. The first-order Minkowski fractal ring metal patch 204 is also loaded with 8 chip resistors 202 with identical model parameters, and their resistance value is Rout.

In this embodiment, taking the passband at 8.1 GHz as an example, the dielectric substrate 201 of the periodic impedance layer is FR4, the inner side is a first-order Minkowski fractal ring metal patch, and the outer side is a square ring formed by etching copper. The metal patch 203 realizes dual-band wave absorption on both sides of 8.2GHz. By loading the resistor at the position where the current distribution is the largest when absorbing the resonant frequency, a good absorbing effect is achieved.

In this embodiment, the periodic impedance layer includes the metal patch of the impedance layer and the chip resistor disposed on the dielectric substrate of the impedance layer, which are both left-right and vertically symmetrical, as shown in FIG. 3 .

At the absorbing frequency band, the switch electric control panel acts as a ground reflection surface, which can be considered as a short circuit from the perspective of the transmission line. The relative permittivity of PMI foam is close to the magnetic permeability and air, so its thickness can be preferably an odd multiple of the quarter wavelength of the wave-absorbing resonance frequency point. If the thickness of the foam is not selected properly, it will greatly reduce the absorbing effect and increase the insertion loss of the passband, so that the short circuit point will be converted into an open circuit point at the position of the impedance surface. Select the chip resistor resistance that can make the surface equivalent impedance match the air layer impedance, so that the transmission and reflection of the entire structure are close to zero, and perfect wave absorption is achieved.

In this embodiment: P=20mm; l ₁ =17.5mm, l ₂ =9.6mm, l ₃ =4.55mm, l ₄ =3.3mm, l ₅ =3.8mm, l ₆ =7.5mm, l ₇ =5.9mm , l ₈ =9.15mm, w ₁ =0.5mm, w ₂ =2.5mm, w ₃ =0.85mm, h=18.5mm, h ₁ =0.5mm, h ₂ =0.5mm, Rin=75Ω, Rout=120Ω. The meaning of each parameter has been marked in Figure 1, Figure 2 and Figure 3, and the selection of different parameters will lead to changes in the operating frequency of the absorber.

A controllable passband double-band frequency broadband absorber provided in the above embodiment is simulated by computer simulation software CST, and the simulation results are shown in 4. Figure 4(a) is the simulation result graph when the diode is off, and Figure 4(b) is the simulation result graph when the diode is on.

As shown in Figure 4, when the diode is turned off, a passband with an insertion loss of less than 1dB is produced at 8.2GHz. There is a wave absorbing band on both sides of the pass band. In the range of 1.3-6GHz and 10-12.5GHz, both S11 and S21 are less than -10dB, and the absorbing rate at this time exceeds 90%. After the diode is turned on, the pass band disappears and becomes a reflection band, while the absorbing band remains basically unchanged at 1.3-6GHz and 9.8-12.4GHz. Due to the symmetry of the designed structure, the simulation results obtained for incoming waves with TE polarization and TM polarization are consistent.

To sum up, although the present utility model has been disclosed as above with preferred embodiments, it is not intended to limit the present utility model, any person of ordinary skill in the art, without departing from the spirit and scope of the present utility model, should be able to use it as Various changes and modifications, so the scope of protection of the utility model should be determined by the scope defined in the claims.

Claims (10)

1. the controllable bilateral bandwidth band wave-absorber of a kind of passband, it is characterised in that wave-absorber is by multiple cycles being arranged in array Property cellular construction composition；Periodic cells structure includes electric-controlled switch screen, cycle impedance layer and froth bed, electric-controlled switch screen, Cycle impedance layer is separately positioned on the upper and lower sides of froth bed, and the froth bed is supported between electric-controlled switch screen and cycle impedance layer Both are separated.

2. the controllable bilateral bandwidth band wave-absorber of passband according to claim 1, it is characterised in that：The electric-controlled switch screen Including medium substrate, the metal grate network of sphere of movements for the elephants type, the metal grate are covered with the upper surface of the medium substrate Metal patch is covered with medium substrate in each grid of network, the metal patch is arranged on the centre of each grid And spacing is remained between the edge and grid network of metal patch, it is respectively connected between each metal patch and grid network Multiple evenly arranged diodes of identical quantity, the integral multiple that the quantity of diode is 4 are a；

The lower surface of the medium substrate is provided with the feeding network of " well " font of control upper surface diode operation state, respectively The feedback of connection medium substrate lower surface is offered on the medium substrate of the center of metal patch and its center position correspondence The conductive through hole of electric network, the metal patch of medium substrate upper surface are logical by conduction with the feeding network of medium substrate lower surface Hole, which is realized, to be electrically connected, and feeding network connects cathode, and grid network connects anode, electrical potential difference will be formed at diode both ends, so as to control The on off operating mode of diode processed.

3. the controllable bilateral bandwidth band wave-absorber of passband according to claim 1, it is characterised in that：The cycle impedance layer Including impedance layer medium substrate, impedance layer metal patch and Chip-R, the impedance layer are provided with impedance layer medium substrate Chip-R is loaded with metal patch.

4. the controllable bilateral bandwidth band wave-absorber of passband according to claim 1,2 or 3, it is characterised in that：Electric-controlled switch The spacing between metal patch and grid network on screen is equal；Spacing between adjacent metal patch is equal, all metals The size shape of patch is identical, and the position of the diode connected on each metal patch and quantity are identical；The electricity Metal patch, diode, metal grate and the feeding network for controlling switchboard and upper setting are symmetrical and symmetrical above and below Structure.

5. the controllable bilateral bandwidth band wave-absorber of passband according to claim 4, it is characterised in that：The impedance layer metal Patch encloses the endless metal identical with impedance layer medium substrate shape including being positioned close to the one of impedance layer medium substrate edge Patch and it is arranged among impedance layer medium substrate while the also single order Minkowski point shape on the inside of endless metal patch Ring metal patch, endless metal patch and single order the Minkowski fractal ring metal patch are loaded with Chip-R.

6. the controllable bilateral bandwidth band wave-absorber of passband according to claim 5, it is characterised in that：The electric-controlled switch Screen, cycle impedance layer and froth bed are square；Metal patch on the electric-controlled switch screen is square or circular gold Belong to patch；Endless metal patch on the cycle impedance layer is square endless metal patch or circular ring metal patch.

7. the controllable bilateral bandwidth band wave-absorber of passband according to claim 5, it is characterised in that：The endless metal patch Piece and single order Minkowski fractal ring metal patch load promising multiple Chip-Rs, and the multiple Chip-R is divided equally It is located at the position of CURRENT DISTRIBUTION maximum when wave-absorber absorbs resonant frequency.

8. the controllable bilateral bandwidth band wave-absorber of passband according to claim 7, it is characterised in that：Loading can in single order Min The resistance value model of multiple Chip-Rs on Paderewski fractal ring metal patch is identical；Loading is on endless metal patch The resistance value model of multiple Chip-Rs is identical.

9. the controllable bilateral bandwidth band wave-absorber of passband according to claim 8, it is characterised in that：The cycle impedance layer It is overall all symmetrical and symmetrical above and below including the impedance layer metal patch set on impedance layer medium substrate and Chip-R Structure.

10. the controllable bilateral bandwidth band wave-absorber of passband according to claim 1, it is characterised in that：The froth bed Thickness is the quarter-wave odd-multiple of wave-absorber resonance frequency point.