CN111555037A - Time domain switch regulation and control frequency selection surface with polarization selection characteristic - Google Patents

Abstract

The invention relates to the technical field of electromagnetic compatibility, and discloses a time-domain switching control frequency selection surface with polarization selection characteristics, comprising a three-layer structure cascaded together, the first layer is a passive grating structure, and the second layer is a frequency selection surface The surface structure is selected. The third layer is an active grating structure loaded with diodes. The second layer is located between the first layer and the third layer. The frequency selective surface structure includes a dielectric layer. The left and right sides of the dielectric layer are provided with cross covers. The copper layer, this time-domain switch-controlled frequency-selective surface with polarization-selective characteristics, can be polarization-selectable and time-domain adjustable. The diode-loaded active grating can realize the reflection and projection at the frequency point of electromagnetic waves, which can realize Transmission type polarization selection, the operating frequency band is in the low frequency range.

Description

A Time-Domain Switching Controlled Frequency Selective Surface with Polarization Selective Properties

technical field

The invention relates to the technical field of electromagnetic compatibility, in particular to a time-domain switching frequency selective surface with polarization selective characteristics.

Background technique

The frequency selective surface is a periodic array structure composed of a large number of resonant elements (metal patches or slots), which can effectively control the reflection and transmission of electromagnetic waves of a specific frequency, and is widely used in spatial filters and radomes. Compared with the traditional radome, the frequency selective surface radome can not only improve the wave transmittance within the working frequency band of the radar to ensure the normal operation of the radar, but also reduce the reflectivity of electromagnetic waves outside the working frequency band to obtain a good stealth effect. The active frequency selective surface is to add some kind of excitation to the traditional FSS, and then through the artificial control of the excitation, the electrical performance is variable. At present, there are three main ways to realize active FSS: adding active devices (PIN tube and varactor diode) to the passive FSS structure, using a dielectric substrate with variable electromagnetic properties, and controlling the coupling between different layers. The addition of active devices to the source FSS structure is the most widely studied. With the development of technology, there is an urgent need for active frequency selection surfaces with simple structure, strong frequency tunability, stable polarization, stable incidence angle, and simple feeding network. Radar technology plays an increasingly important role in the detection, reconnaissance and monitoring of military targets such as aircraft and ships. However, the working frequency band of the current active frequency selective surface has always been selected at high frequency. In addition, the cost is generally high, the feeding network is difficult to design, and the adjustment of reflection and transmission is rarely proposed.

Based on this new challenge, the present invention provides a time-domain switching control frequency selection surface with polarization selection characteristics, the feeding network is simple and adjustable, and the operating frequency band is in the low frequency range, and a time-domain controllable switch is realized. Adjust the reflection and transmission of electromagnetic waves.

SUMMARY OF THE INVENTION

The invention provides a time-domain switch control frequency selection surface with polarization selection characteristics, which can realize reflection and projection at the frequency point of electromagnetic waves, realize transmission-type polarization selection, and the working frequency band is in the low frequency range.

The present invention provides a time-domain switching control frequency selective surface with polarization selectivity, comprising: a three-layer structure cascaded together, the first layer is a passive grating structure, the second layer is a frequency selective surface structure, The third layer is an active grating structure loaded with diodes, and the second layer is located between the first layer and the third layer.

The first, second, and third layers all include dielectric plates.

In the passive grating structure, a plurality of mutually parallel and equidistant copper lines are arranged along the y direction on the left side of the dielectric plate in the first layer.

The frequency selective surface structure is that a first cross copper clad layer is arranged on the left side of the dielectric plate in the second layer, and a second cross copper clad layer is arranged on the right side of the dielectric plate. The lengths of the copper layer and the second cross copper clad layer are equal to the length of the dielectric board, and the widths of the first cross copper clad layer and the second cross copper clad layer are equal to the width of the dielectric board.

The active grating structure of the loading diode is two parallel multi-segment copper lines arranged along the x direction on the right side of the dielectric plate.

The dielectric plate is a square with a side length of 11 mm, the material of the dielectric plate is F4B, the dielectric constant is 2.65, and the loss angle is 0.001;

The left side of the dielectric plate in the first layer is provided with 5 copper wires parallel to each other and equally spaced along the y direction, the distance between two adjacent copper wires is 1.8mm, and the length of the copper wires is 11mm. The width b is 0.4mm, and the thickness is 0.017mm;

In the first cross copper clad layer, the length m of the copper wire outside the intersection point is 5.435mm, the length and width n of the copper wire is 0.13mm, the thickness of the copper wire is 0.017mm, and the second cross copper clad layer, its intersection point The length q of the outer copper layer is 2.75mm, the width p of the copper clad layer of the second cross is 5.3mm, and the thickness of the copper clad layer is 0.017mm.

For the two parallel multi-section copper wires, the distance between the upper and lower copper wires is 3.8mm, and the left and right adjacent copper wires are connected by diodes. The length k of the copper wires is 4.1mm, and the width l is 1.7mm. , the thickness is 0.017mm, and the length of the two copper wires at the left and right ends is half of the length k of the middle copper wire.

Compared with the prior art, the beneficial effects of the present invention are:

The invention is cascaded together through a three-layer structure, the first layer and the third layer are both provided with gratings, the middle layer is a frequency-selective surface structure, which can be selected by polarization and can be adjusted in time domain, and the third layer is loaded with diodes. The active grating can realize the reflection and projection at the frequency point of electromagnetic wave, and can realize the polarization selection of transmission type, and the working frequency band is in the low frequency range.

Description of drawings

FIG. 1 is a schematic structural diagram of a time-domain switching frequency selective surface with polarization selective characteristics according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a time-domain switch with polarization-selective characteristics provided by the present invention to regulate frequency-selective surface electromagnetic wave projection and reflection.

FIG. 3 is a simulation graph of the present invention.

Detailed ways

A specific embodiment of the present invention will be described in detail below with reference to the accompanying drawings 1-3, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

The invention is mainly applied in the field of electromagnetic compatibility, and in addition, a specific frequency point is selected in the broadband in the process of radar communication to realize the time domain adjustment of communication, which means that electromagnetic waves can transmit information to the radar through the structure, and can also be used at any time. Electromagnetic waves are all reflected in a wide frequency band, closing this communication window. In addition, this technology adopts an active way to design, which greatly increases the tunability and controllability.

This design reasonably proposes a three-layer structure, pioneering the combination of grating and frequency selective surface to achieve the purpose of electromagnetic compatibility. And for the grating, the combination of two layers of the active grating and the passive grating is proposed for the first time, and the stable and efficient structure of the cross is also proposed in the frequency selective surface part. The invention adopts a frequency selection structure formed by two cross-shaped metal structures in the middle layer, and the frequency selection structure can realize the characteristics of low frequency electromagnetic wave transmission and high frequency reflection. The equivalent circuit mechanism of the cross-shaped structure can be equivalent to the series connection of the inductor and the capacitor. The cross structure on the left affects the formation of the low-frequency resonance point and is composed of the series connection of the inductor and the resistor. The cross structure on the right mainly affects the absorption in the band, also formed by the series circuit of inductance and resistance. By adjusting the size of the structural unit and the resistance value of the resistor, the transmission coefficient and reflection coefficient in the working frequency band can be greatly improved. In the three-layer structure, the front and rear gratings and a frequency selective surface structure are proposed for the first time, and a novel design concept is given, so that this concept can well solve the polarization selective characteristics at the working frequency and time-domain tunability. The three-layer structure of this design has good stability, and is suitable for various scenarios, and the effect is also very good at large angles. In addition, the structure is very cheap, and the price of the diode is also very low, about 0.7 yuan a piece. The design of the feeding network is also very stable and easy to operate, and the voltage can be adjusted within a range of 40v±5v, and the characteristics of the diode have also been fully utilized.

The invention aims to solve the problem of aircraft or some equipments requiring stealth performance, but also to ensure a certain communication function. For example, when the equipment does not need the antenna to work, the electromagnetic wave will not enter the antenna. After passing through the structure, the 0.1GHz-15GHz and even higher frequency cross-polarized electromagnetic waves will be reflected. When it needs to work, the diode is disconnected, and the electromagnetic wave only enters the antenna at the frequency of 3.1GHz, and the rest will also be reflected. This greatly protects the stealth characteristics of the antenna in the equipment, and also flexibly realizes time-domain secure communication.

As shown in Figure 1, the medium is F4B, the dielectric constant is 2.65, the loss tangent is 0.001, a=2mm, b=0.4mm, m=5.435mm, n=0.13mm, p=5.3mm, q=2.75mm , k=4.1mm, l=1.7mm, the thickness of copper is 0.017mm.

As shown in Figure 2, it can be seen that when the y-polarized electromagnetic wave is incident on the structure, the first layer is a grating in the y-direction, and then the y-polarized electromagnetic wave will be completely reflected. When the x-polarized electromagnetic wave is incident on the structure, the grating in the y-direction of the first layer has no effect, and the x-polarization continues to transmit forward. After the second layer of frequency selection structure, the x-polarized electromagnetic wave of 1GHz-15GHz is only about 3GHz. The electromagnetic waves can pass through the structure. The last layer is the electromagnetic wave along the x direction. When the diode is disconnected and the grating is not connected, it is equivalent to a short metal wire. At this time, the electromagnetic wave after frequency selection will be transmitted forward. When the diode is turned on, a grating will be formed, at which point the x-polarized electromagnetic waves will be fully reflected. Controlling the switch of the diode will achieve time-domain controllability of the electromagnetic wave.

As shown in Figure 3, in a, when the diode is disconnected, the y-polarization jumps and reflects efficiently. In the figure b, when the diode is turned on, the y-polarization is still reflected efficiently. In the figure c, when the diode is disconnected, the x-polarization efficiency has a very high projection frequency point at 3.1GHz, and the rest of the frequency bands are all reflected. In d, when the diode is turned on, the x-polarization is efficiently reflected. The results meet the design requirements.

The front and rear gratings and the middle layer are frequency-selective surface structures, which can be polarization-selectable and time-domain adjustable.

The other gratings are active gratings loaded with diodes. Active grating can realize reflection and projection at the frequency point of electromagnetic wave, and realize the polarization selection of transmission type.

The aircraft's warhead radar can be considered loaded with this mechanism, which can realize polarization selection and time domain control. In addition, the radar surface of many military equipment can achieve this function in the appropriate frequency band.

The ability of a device or system to operate satisfactorily in its electromagnetic environment without causing intolerable electromagnetic interference to any device in its environment. This structure is very suitable for use in many electromagnetic compatibility fields.

The invention is cascaded together through a three-layer structure, the first layer and the third layer are both provided with gratings, the middle layer is a frequency-selective surface structure, which can be selected by polarization and can be adjusted in time domain, and the third layer is loaded with diodes. The active grating can realize the reflection and projection at the frequency point of electromagnetic wave, and can realize the polarization selection of transmission type, and the working frequency band is in the low frequency range.

The above disclosures are only a few specific embodiments of the present invention, however, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims (8)

1. A time domain switch regulation frequency selective surface with polarization selective characteristics is characterized by comprising three layers of structures which are cascaded together, wherein the first layer is a passive optical grating structure, the second layer is a frequency selective surface structure, the third layer is an active optical grating structure of a loading diode, and the second layer is positioned between the first layer and the third layer.

2. The time domain switching regulation frequency selective surface of claim 1, wherein the first layer, the second layer, and the third layer each comprise a dielectric slab.

3. The time-domain switching-regulated frequency-selective surface with polarization-selective properties according to claim 2, wherein said passive grating structure is formed by disposing a plurality of copper lines parallel to each other and equally spaced along the y-direction on the left side of the first layer of dielectric plate.

4. The time domain switching control frequency selective surface having polarization selective properties of claim 3, wherein the frequency selective surface structure is formed by providing a first cross copper-clad layer on a left side of the dielectric plate in the second layer, and providing a second cross copper-clad layer on a right side of the dielectric plate, the first cross copper-clad layer and the second cross copper-clad layer having a length equal to the length of the dielectric plate, the first cross copper-clad layer and the second cross copper-clad layer having a width equal to the width of the dielectric plate.

5. The time domain switching control frequency selective surface with polarization selective properties of claim 4, wherein the active grating structure of said loading diode is two parallel multi-segment copper lines arranged along x-direction on the right side of the dielectric slab.

6. The time domain switching control frequency selective surface having a polarization selective characteristic according to claim 5, wherein the dielectric plate is a square with a side length of 11mm, the dielectric plate is made of F4B, the dielectric constant is 2.65, and the loss angle is 0.001;

the left side face of the first layer of interposer board is provided with 5 copper wires which are parallel to each other and are at equal intervals along the y direction, the interval between two adjacent copper wires is 1.8mm, the length of each copper wire is 11mm, the width b of each copper wire is 0.4mm, and the thickness of each copper wire is 0.017 mm.

7. The time domain switching control frequency selective surface having polarization selective properties of claim 6, wherein said first cross copper-clad layer has a length m of copper line outside the cross point of 5.435mm, a length width n of copper line of 0.13mm, a thickness of copper line of 0.017mm, a second cross copper-clad layer has a length q of copper layer outside the cross point of 2.75mm, a width p of second cross copper-clad layer of 5.3mm, a thickness of copper-clad layer of 0.017 mm.

8. The time domain switch controlled frequency selective surface having polarization selective properties according to claim 7, wherein said two parallel copper lines have a spacing of 3.8mm between the upper and lower copper lines, the two adjacent copper lines are connected by a diode, the length k of the copper line is 4.1mm, the width l is 1.7mm, the thickness is 0.017mm, and the length of the two copper lines at the left and right ends is one half of the length k of the intermediate copper line.

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