CN104051825A - A Bandpass Hopping Active Frequency Selective Surface - Google Patents

Abstract

The invention provides a band-pass hop active frequency selective surface which is of an appressed layered structure. A second protection layer is arranged at the front end, and a first layer frequency selective surface, a first protection layer, a second layer frequency selective surface and a third protection layer are arranged afterwards in sequence. The first layer frequency selective surface and the second layer frequency selective surface are parallel to each other, medium substrates are attached to the surface of the first layer frequency selective surface and the surface of the second layer frequency selective surface, six hollow channels are photo-etched on each frequency selective surface in the mode of symmetric with the central axis parallel to the short edges, the first channels, the third channels, the fourth channels and the sixth channels are parallel to the long edges of the frequency selective surfaces, the second channels and the fifth channels are parallel to the short edges of the frequency selective surfaces, the first channels, the second channels and the third channels are connected, the fourth channels, the fifth channels and the sixth channels are connected, and at least two sets of active switches symmetric with the central axis parallel to the short edges are arranged in the hollow channels. According to the band-pass hop active frequency selective surface, hop of wave-transparent frequency bands can be achieved through the on and off of the active switches, quite good damping effects on the frequency other than the wave-transparent frequency bands are achieved, and the suitable angle range is larger.

Description

A Bandpass Hopping Active Frequency Selective Surface

technical field

The present invention relates to the field of microwave filtering, in particular to a bandpass hopping active frequency selective surface.

Background technique

Frequency Selective Surface (FSS) is a two-dimensional periodic array structure with frequency selective characteristics for incident electromagnetic waves. The array structure is composed of a large number of passive resonant units periodically arranged. The frequency selective surface shows the frequency selection characteristics of total reflection or total transmission for the incident electromagnetic wave at the resonant frequency. In essence, the frequency selective surface is a special spatial filter.

Frequency selective surfaces have many important applications in many modern technologies, the representative one is the application of frequency selective surfaces in stealth technology. Among the three modern military technologies, stealth technology can be described as a major military technology that has attracted worldwide attention. Since the 1960s, frequency selective surfaces have shown excellent performance in radar stealth technology, making it highly valued by many countries. With the development of frequency selective surface technology, more and more cell structures have been researched by scholars, and various excellent stealth properties have been realized. However, the existing frequency selective surface is a passive frequency selective surface. The resonant frequency, operating bandwidth, and stability of this structure cannot be changed after processing, so it cannot quickly adapt to the external electromagnetic environment in a complex and changeable electromagnetic environment. changes that reduce its effectiveness.

Contents of the invention

In order to overcome the problems existing in the prior art, the object of the present invention is to provide an active frequency selective surface of pass-hopping type.

The technical solution for realizing the purpose of the present invention is: a band-pass hopping active frequency selective surface, which is a close-fitting layered structure, the front end is the second protection layer, and the back is the first layer of frequency selection surface, the first protection layer layer, the second layer of frequency selective surface and the third protective layer; the first layer of frequency selective surface and the second layer of frequency selective surface are parallel to each other, and the two sides are sequentially plated with metal dielectric layer and dielectric substrate; the first On the frequency selective surface of the layer, six hollow channels are symmetrically etched according to the central axis parallel to the shorter side, in which channel one and channel six are not connected and distributed symmetrically and parallel to the longer side, channel two and channel of the first layer of frequency selective surface Five symmetrically distributed and parallel to the shorter side of the first layer of frequency selective surface, channel three and channel four are not connected and symmetrically distributed and parallel to the longer side of the first layer of frequency selective surface, said channel one, channel two and The channels are connected in three phases, and the channel four, channel five and channel six are connected; the size and structure of the frequency selective surface of the second layer are the same as those of the frequency selective surface of the first layer; at least Two sets of cantilever wall MEMS switches, each set of cantilever wall MEMS switches include two cantilever wall MEMS switches symmetrically arranged about the central axis parallel to the shorter side, the feed network and the cantilever beam are arranged on the first layer of frequency selection surface Wall-type MEMS switch connection; at least two sets of cantilever-beam wall-type MEMS switches are set in the hollow channel on the second-layer frequency-selective surface, and the position of each group of cantilever-beam wall-type MEMS switches is the same as that of the cantilever-beam wall-type MEMS switch on the first-layer frequency-selective surface. corresponding to the position.

Compared with the prior art, the present invention has significant advantages in that: (1) through the conduction and disconnection of the cantilever wall MEMS switch, the hopping of the wave-transparent frequency band is realized; (2) the two-layer frequency selection surface and the Small unit spacing has a very good attenuation effect for frequencies other than the wave-transmitting frequency band; (3) Good flatness of passband, wide range of applicable angles, small loss, and high stability; (4) Relatively simple processing and widely applicable in the radar system.

Description of drawings

Fig. 1 is a schematic diagram of a bandpass hopping active frequency selective surface.

Fig. 2 is a schematic diagram of a loading method of a cantilever beam MEMS switch with a bandpass hopping active frequency selective surface.

Fig. 3 is a wave transmission performance curve of a bandpass hopping active frequency selective surface when three groups of switches are turned off.

Fig. 4 is a wave transmission performance curve of a band-pass hopping active frequency selective surface when only the first group of switches is turned on.

Fig. 5 is a wave transmission performance curve of a band-pass hopping active frequency selective surface when only the second group of switches is turned on.

Fig. 6 is a wave transmission performance curve of a band-pass hopping active frequency selective surface when only the third group of switches is turned on.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

A bandpass hopping active frequency selective surface, in a close-fitting layered structure, the front end is the second protective layer 2, followed by the first layer of frequency selective surface 4, the first protective layer 1, and the second layer of frequency The selection surface 5 and the third protective layer 3; the first frequency selection surface 4 and the second frequency selection surface 5 are parallel to each other, and a dielectric substrate is attached on both sides; the first frequency selection surface 4 The size and structure of the second-layer frequency selective surface 5 are exactly the same. Furthermore, the dimensions and positions of the hollow channels on the first-layer frequency selective surface 4 and the second-layer frequency selective surface 5 are exactly the same. In actual operation, two layers of frequency selective surfaces play a more obvious role in filtering than one layer. If more than two layers of frequency selective surfaces are installed, the filtering characteristics will be significantly reduced.

The first layer of frequency selective surface 4 has six hollowed-out channels etched by light, and every two hollowed-out channels are symmetrical according to the central axis parallel to the shorter side, wherein channel 1, channel 2 and channel 3 are connected, and channel 4, channel 5 and channel The six phases are connected, channel one and channel six are not connected and distributed symmetrically and parallel to the longer side of the first layer of frequency selective surface 4, channel two and channel five are symmetrically distributed and parallel to the shorter side of the first layer of frequency selective surface 4 , channel three and channel four are not connected and distributed symmetrically and parallel to the longer side of the frequency selective surface 4 of the first layer;

On the frequency selective surface 5 of the second layer, six hollowed-out channels are also etched by light, wherein every two hollowed-out channels are symmetrical according to the central axis parallel to the shorter side, wherein the seven channels and the twelve channels are not connected and symmetrically distributed and parallel to the second layer The longer side of the frequency selective surface 5, channel eight and channel eleven are symmetrically distributed and parallel to the shorter side of the second layer of frequency selective surface 5, channel nine and channel ten are not connected and symmetrically distributed and parallel to the second layer of frequency selective surface On the longer side of 5, said passage seven, passage eight and passage nine are connected, and said passage ten, passage eleven and passage twelve are connected;

In order to realize the function of pass band jumping, at least two groups of cantilever wall MEMS switches are arranged in the hollow channel of the first layer of frequency selection surface 4. When one group of switches is turned on, a frequency band selection is completed; when the other switches are turned on, The passband jump can be realized instantaneously, and then the wave-transmissive frequency band will change. Each group of cantilever wall MEMS switches includes two cantilever wall MEMS switches that are symmetrically arranged about the central axis parallel to the shorter side, and the number of feeders that is the same as the number of cantilever wall MEMS switch groups is set on the frequency selection surface 4 of the first layer. The electrical network is respectively connected to the cantilever wall MEMS switch for power feeding; at least two groups of cantilever wall MEMS switches are set in the hollow channel of the frequency selection surface 5 of the second layer, and the position of each group of cantilever wall MEMS switches is the same as that of the first layer of frequency selection. The positions of the cantilever wall MEMS switches on the surface 4 are corresponding, that is, the positions of the cantilever wall MEMS switches on the first frequency selective surface 4 and the second frequency selective surface 5 are exactly the same on the frequency selective surfaces. The first protective layer 1, the second protective layer 2 and the third protective layer 3 are all filled with foam.

Combined with Figure 2, the feed network is set on the frequency selection surface to connect with the cantilever wall MEMS switch to play the role of feed. The feeder network consists of a feeder 7, a gold wire jumper 8 connecting the feeder and the cantilever wall MEMS switch, and a ground wire 9 connected to the cantilever wall MEMS switch. The feeder 7 is made of conductive metals such as gold and silver. , the feed network feeds the cantilever wall MEMS switch.

The working principle of the present invention is: after the cantilever wall MEMS switch is set on the frequency selection surface, the specific pattern of the frequency selection surface is changed, so that the electromagnetic wave shows different filtering characteristics, and the position of the cantilever wall MEMS switch can meet the frequency requirements. The selection surface selects different frequency bands, and the number of switches can realize that when each group of switches is turned on, the jump phenomenon of the wave-transmissive frequency band will occur. Specifically, several groups of cantilever wall MEMS switches are set on the frequency selective surface, and the on-off of the first group of switches can realize two groups of states; when the second group of switches is turned on, the pattern of the frequency selective surface changes, and its passband characteristics Make the first group of switches invalid, that is, no matter what state the first group of switches is in, it will no longer affect the frequency selection characteristics; similarly, after the third group of switches is turned on, the first group and the second group of switches will also fail; After each group of switches is turned on, the switches turned on before it no longer affect the frequency selection characteristics.

Specifically, the present invention selects the active frequency selective surface of the X-band as an example for description. It should be understood that for other wave bands, the working principle of the active frequency selective surface is the same, only the frequency selective surface size, channel width, cantilever wall MEMS switch The position and number of can be changed according to the frequency band requirements.

Referring to Figure 1, the thickness of the entire device is 24.834mm, in which the length and width of the first layer of frequency selective surface 4 and the second layer of frequency selective surface 5 are 5.1mm and 4.5mm respectively, the thickness is 0.29mm, and the width of the hollow channel is 0.5mm. The distance from the edge of the selection surface is 0.35mm, and three groups of cantilever wall MEMS switches are respectively set on the hollow channels of the first frequency selection surface 4 and the second frequency selection surface 5; the first group of cantilever wall MEMS switches 6-1 are set In channel one and channel six, close to the central axis parallel to the shorter side of the frequency selective surface 4 of the first layer, specifically, each switch in the first group of cantilever wall MEMS switches is 0.9mm away from the axis; the second The group of cantilever wall type MEMS switches 6-2 is arranged in channel one and channel six away from the central axis parallel to the shorter side of the frequency selective surface 4 of the first layer, specifically each of the second group of cantilever wall type MEMS switches The switches are all 1.4mm away from the axis; the third group of cantilever wall MEMS switches 6-3 are arranged in channel three and channel four, specifically, each switch in the third group of cantilever wall MEMS switches is 0.4mm away from the axis; Four groups of switches are arranged in the hollow channel of the second layer of frequency selective surface 5 and correspond to the positions of the first group of cantilever wall MEMS switches, and the fifth group of switches are arranged in the hollow channel of the second layer of frequency selective surface 5 and correspond to the positions of the first group of cantilever wall MEMS switches. The position of the second group of cantilever wall MEMS switches corresponds to that of the third group of cantilever wall MEMS switches.

The thickness of the dielectric substrate is made to be 0.127mm; the thickness of the first protective layer 1 is 2-12mm, and the dielectric constant is 1.5; the thickness of the second protective layer 2 and the third protective layer 3 is 8-20mm, and the dielectric constant The electric constant is 1.25.

As shown in Figure 3, when the three groups of cantilever wall MEMS switches on the first layer of frequency selective surface 4 and the three groups of cantilever wall MEMS switches on the second layer of frequency selective surface 5 are all disconnected, the band-pass jump has The wave-transmitting frequency band of the source frequency selection surface is 8-9GHz, where the abscissa indicates the frequency, and the ordinate indicates the unit decibel (dB), S11 is the standing wave curve, S22 is the attenuation curve, and the attenuation of frequencies other than 8-9GHz is very Fast; as shown in Figure 4, when the first group of cantilever wall MEMS switches on the first layer of frequency selective surface 4 and the fourth group of cantilever wall MEMS switches on the second layer of frequency selective surface 5 are turned on, the other cantilever wall When the type MEMS switch is disconnected, the wave-transparent frequency band jumps to 9-10GHz; The fifth group of cantilever wall MEMS switches is turned on, and the wave-transparent frequency band jumps to 10-11GHz; as shown in Figure 6, when the third group of cantilever wall MEMS switches on the first layer frequency selection surface 4 and the second layer The sixth group of cantilever wall MEMS switches on the frequency selection surface 5 are turned on, and the wave-transmitting frequency band jumps to 11-12GHz. Therefore, by controlling the turn-on or turn-off of the cantilever wall MEMS switch, the band-pass hopping active frequency selective surface can realize the function of filtering.

Claims (4)

1. the logical active frequency-selective surfaces of saltus step of band, be the layer structure of being close to, front end is the second protective layer (2), is ground floor frequency-selective surfaces (4), the first protective layer (1), second layer frequency-selective surfaces (5) and the 3rd protective layer (3) successively backward, described ground floor frequency-selective surfaces (4) and second layer frequency-selective surfaces (5) are parallel to each other, and surface is with dielectric substrate, upper six the hollow out passages that width is identical of axis symmetrical beam corrosion according to being parallel to compared with minor face of ground floor frequency-selective surfaces (4), wherein passage one, passage two and passage three are connected, described passage four, passage five and passage six are connected, described passage one is not connected with passage six and is symmetrical and be parallel to the longer sides of ground floor frequency-selective surfaces (4), passage two and passage five symmetrical and be parallel to ground floor frequency-selective surfaces (4) compared with minor face, passage three is not connected with passage four and is symmetrical and be parallel to the longer sides of ground floor frequency-selective surfaces (4), described passage one and passage three are about the axis symmetry that is parallel to longer sides, passage six and passage four are about the axis symmetry that is parallel to longer sides, the size of second layer frequency-selective surfaces (5) and structure are identical with ground floor frequency-selective surfaces (4), it is characterized in that:

Two groups of overarm wall type mems switches are at least set in the hollow out passage of ground floor frequency-selective surfaces (4), each group overarm wall type mems switch comprises two about being parallel to compared with the axis of minor face symmetrically arranged overarm wall type mems switch, feeding network is set on ground floor frequency-selective surfaces (4) and is connected with overarm wall type mems switch; The hollow out passage of second layer frequency-selective surfaces (5) at least arranges two groups of overarm wall type mems switches, and the position of each group overarm wall type mems switch is corresponding with the position of the overarm wall type mems switch on ground floor frequency-selective surfaces (4); Ground floor frequency-selective surfaces (4) with on second layer frequency-selective surfaces (5), be provided with feeding network and be connected with overarm wall type mems switch.

2. the logical active frequency-selective surfaces of saltus step of band according to claim 1, is characterized in that: three groups of overarm wall type mems switches are set respectively on the hollow out passage of ground floor frequency-selective surfaces (4) and second layer frequency-selective surfaces (5);

First group of overarm wall type mems switch is arranged at passage one and passage six is interior near being parallel to ground floor frequency-selective surfaces (4) compared with the position of the axis of minor face, second group of overarm wall type mems switch is arranged in passage one and passage six away from being parallel to ground floor frequency-selective surfaces (4) compared with the position of the axis of minor face, and the 3rd group of overarm wall type mems switch is arranged in passage three and passage four; The 4th group of switch is arranged in the hollow out passage of second layer frequency-selective surfaces (5) and is corresponding with the position of first group of overarm wall type mems switch, the 5th group of switch is arranged in the hollow out passage of second layer frequency-selective surfaces (5) and is corresponding with the position of second group of overarm wall type mems switch, and the 6th group of switch is arranged in the hollow out passage of second layer frequency-selective surfaces (5) and is corresponding with the position of the 3rd group of overarm wall type mems switch.

3. the logical active frequency-selective surfaces of saltus step of band according to claim 1, is characterized in that: dielectric substrate is glue, and its thickness is 0.127mm.

4. the logical active frequency-selective surfaces of saltus step of band according to claim 1; it is characterized in that: the first protective layer (1) second protective layer (2) and the 3rd protective layer (3) are by foam-filled; the thickness of the first protective layer (1) is 2 ~ 12mm; and dielectric constant is 1.5; the thickness of the second protective layer (2) and the 3rd protective layer (3) is 8 ~ 20mm, and dielectric constant is 1.25.