A Construction Method of S-Band Electromagnetic Bandgap Structure Based on Dual Polarization

Abstract

The present invention discloses a method for constructing a dual-polarized S-band energy selective surface, belonging to the electromagnetic field. The method of the present invention includes: selecting the shape of the electromagnetic unit of the energy selective surface according to the requirements of dual polarization. The electromagnetic unit adopts a cross structure, including metal patches located around and a cross-shaped metal patch located in the middle; determining the model of the required diode through the principle of equivalent circuit; scaling the electromagnetic unit as a whole to determine the dimensions of each component of the electromagnetic unit that meet the insertion loss and shielding effectiveness; and implementing the energy selective surface using the final energy selective surface unit and the required diode. The energy selective surface designed by the present invention has the characteristics of excellent performance, simple structure, low cost, dual polarization realization, and wide bandwidth in the S-band, expands the functions of the energy selective surface, and further enriches the design methods and ideas of the energy selective surface.

Description

Technical Field

[0001] The present invention belongs to the electromagnetic field, relates to microwave radio frequency technology, and particularly relates to a method for constructing a dual-polarized S-band energy selection surface (ESS). Background Art

[0002] With the development of microwave technology, people are becoming more and more sensitive to electromagnetic radiation. Especially the high-power signals generated by high-power microwave (HPM) and electromagnetic pulse (EMP) weapons will couple with electronic and electrical systems, thereby generating destructive currents, posing a serious threat to the security of electronic systems, network systems and communication systems.

[0003] Traditional methods for protecting electronic devices, such as filter components, frequency selection surfaces (FSS), shielding, absorption and grounding, etc., can provide limited protection, but each has its own characteristic defects. For example, grounding can conduct the induced current on the device shell and cannot protect the main channel; the limiter works in the circuit after the antenna and cannot block strong electromagnetic pulses from entering the antenna port in space; while metal shielding, as one of the commonly used protection means for electromagnetic pulses, blocks the signal transceiver of the protected device while effectively shielding strong electromagnetic pulses. FSS can block signals from outside the band, but allows HPM to propagate within the working band. The problems existing in traditional detection technologies are that they cannot effectively distinguish high-power signals and cannot effectively detect weak signals required for wireless communication.

[0004] As a new concept proposed based on the research of frequency selection surfaces, the energy selection surface uses a periodic structure to achieve the required filtering characteristics: in addition to selecting the frequency of the incident electromagnetic wave, it can also screen the magnitude of the electromagnetic wave energy. Within the designed safety threshold, it allows the incident electromagnetic wave to pass through with low loss, while having a large attenuation effect on high-power microwaves with energy greater than the safety threshold. Simply put, it can play an adaptive role in the external electromagnetic environment effect, thereby ensuring that the internal electronic devices are not damaged by high-power microwaves on the basis of normal operation. The current S-band energy selection surface has not controlled the production cost while realizing the dual-polarization function, and the production cost is relatively high. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a method for constructing a dual-polarized S-band energy selection surface, which adopts a large size while realizing dual-polarization operation, reduces the number of required diodes and the number of energy selection surface units, and reduces the cost while realizing the large-angle stability of the energy selection surface.

[0006] A method for constructing a dual-polarized S-band energy selection surface of the present invention includes the following steps:

[0007] Step 1: Select the shape of the electromagnetic unit of the energy selection surface according to the requirements of dual polarization;

[0008] Use simulation software to simulate the equivalent circuit of the electromagnetic unit and perform frequency-domain simulation, obtain the insertion loss and shielding effectiveness when the diode in the electromagnetic unit is fully connected and disconnected, and verify whether the selected electromagnetic unit meets the requirements;

[0009] The electromagnetic unit adopts a cross structure, including metal patches located around and a cross-shaped metal patch located in the middle;

[0010] Step 2: Determine the model of the required diode through the principle of equivalent circuit;

[0011] It is required that for the required diode, when the electromagnetic energy wave of the incident S-band signal is less than the required value, the diode is in the off state, allowing the signal to pass through normally; otherwise, the diode is turned on, preventing the incident signal from passing through;

[0012] Step 3: Use simulation software to adjust the period length of the electromagnetic unit of the energy selection surface, the arrangement of the diodes, and the thickness of the dielectric plate to determine the final energy selection surface unit, so that the insertion loss of the electromagnetic unit is less than 10 dB and the shielding effectiveness is greater than 20 dB;

[0013] Step 4: Use the final energy selection surface unit and the required diode to implement the energy selection surface.

[0014] In the above-mentioned Step 1, the structure of the designed energy selection surface includes: designing an electromagnetic unit array on the front of the dielectric plate. Each electromagnetic unit is formed by four metal patches on the upper, lower, left, and right of the periphery, a cross-shaped metal patch in the middle, and a diode connecting the peripheral metal patch and the middle cross-shaped metal patch; on the back of the dielectric plate, a cross-shaped metal patch is designed corresponding to each electromagnetic unit.

[0015] In the above-mentioned Step 3, the period length of each electromagnetic unit of the determined final energy selection surface is 15 mm, and the thickness of the dielectric plate is 0.5 mm. The length of each metal patch on the upper, lower, left, and right of the periphery of each electromagnetic unit is 8.4 mm, the width is 0.8 mm, and the gap from the edge of the electromagnetic unit is 0.05 mm; the middle cross-shaped metal patch is formed by four metal patches, and each patch is 10.3 mm long and 1 mm wide. A diode is set at each extension of each metal patch in the middle cross of each electromagnetic unit and is connected to the peripheral metal patch. The length of the diode is 1.5 mm. The cross-shaped metal patch of each electromagnetic unit on the back of the dielectric plate of each electromagnetic unit is formed by two metal patches, and each patch is 1.1 mm wide.

[0016] Compared with the prior art, the advantages and positive effects of the method of the present invention are as follows:

[0017] (1) The energy selective surface implemented by the method of the present invention realizes dual-polarization application. In the dual-polarization working mode, the number of antennas can be saved, and at the same time, electromagnetic pulses from the x-direction and y-direction on the energy selective surface can be protected.

[0018] (2) The method of the present invention is simple to manufacture and low in cost. When the frequency and the array size are fixed, the implemented energy selective surface can save 4 times the number of diodes compared with the conventional cross-shaped energy selective surface, greatly reducing the manufacturing cost and the cost of manual soldering.

[0019] (3) For the energy selective surface implemented by the method of the present invention, when a normal signal is incident, in the case where the insertion loss is lower than 5 dB, the frequency band with a shielding effectiveness greater than 17 dB is 2.12 - 4 GHz, and the bandwidth is 61.4%, featuring a wide bandwidth in the S band.

[0020] (4) When controlling the transmission coefficient of the energy selective surface unit by the method of the present invention, while keeping the overall structure of the unit unchanged, only by adjusting the unit scaling ratio can the transmission coefficient be adjusted. The overall design is relatively simple, and the required energy selective surface unit can be conveniently obtained.

[0021] (5) Considering the cost factor, the method of the present invention expands the period length as much as possible in the same frequency band, reduces the required number of diodes and the number of energy selective surface units, reduces the cost of manual soldering, and through experiments, it is proved that for the energy selective surface structure designed by the method of the present invention, by changing the incident angle of the incident wave, the large-angle stable characteristic of the energy selective surface can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the construction flow chart of the S-band energy selective surface based on dual polarization of the present invention;

[0023] Figure 2 is the schematic diagram of the model when the energy selective surface designed by using HFSS simulation software in this embodiment is completely on and off;

[0024] Figure 3 is Figure 2 the schematic diagram of the shielding effectiveness when the diodes of the energy selective surface in

[0025] Figure 4 is Figure 2 the schematic diagram of the insertion loss when the diodes of the energy selective surface in

[0026] Figure 5 is the structural diagram of the energy selective surface unit designed by the method of the present invention;

[0027] Figure 6Insertion loss diagram of the embodiment of the present invention when the incident wave is normally incident;

[0028] Figure 7 Shielding effectiveness diagram of the embodiment of the present invention when the incident wave is normally incident;

[0029] Figure 8 Insertion loss diagram of the embodiment of the present invention when the TM wave is incident at different angles;

[0030] Figure 9 Insertion loss diagram of the embodiment of the present invention when the TE wave is incident at different angles;

[0031] Figure 10 Shielding effectiveness diagram of the embodiment of the present invention when the TM wave is incident at different angles;

[0032] Figure 11 Shielding effectiveness diagram of the embodiment of the present invention when the TE wave is incident at different angles. Detailed implementation manners

[0033] The implementation of the technical solution of the present invention will be described below in conjunction with the drawings and embodiments.

[0034] When describing the embodiments of the present invention, the orientation or positional relationships expressed by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" are based on the orientation or positional relationships shown in the relevant drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0035] The construction method of the dual-polarized S-band energy selective surface of the present invention adopts the equivalent circuit theory of the energy selective surface, determines the shape of the energy selective surface by simulating the frequency selective surface to achieve the dual-polarization effect, determines the dimensions of each position unit, determines the type of diode through the equivalent circuit principle, connects the frequency selective surface and the diode to determine the final energy selective surface, and fine-tunes the unit dimensions to achieve the effect of shielding high pulses and transmitting low pulses. The energy selective surface constructed by the method of the present invention has the advantages of dual-polarization, low cost, simple manufacturing, etc., has good energy selection characteristics, and is of great significance for the further popularization and application of microwave wireless power transmission.

[0036] The embodiments of the present invention are mainly implemented based on the ANSYS Electronics simulation software or the high-frequency structure simulation HFSS software. As Figure 1 shown, the construction method of the dual-polarized S-band energy selective surface of this embodiment includes the following 4 steps, and each step will be described separately below.

[0037] Step 1: Determine the shape of the energy selection surface through the simulation frequency selection surface to achieve the effect of dual polarization.

[0038] The energy selection surface is composed of metal patches, diodes, a metal backplane, and a dielectric board. An electromagnetic unit array is designed on the front side of the dielectric board. As Figure 2 shown, for the energy selection surface designed in the embodiment of the present invention, an electromagnetic unit array is designed on the front side of the dielectric board. Each electromagnetic unit is formed by four metal patches located in the upper, lower, left, and right directions at the periphery, a cross-shaped metal patch in the middle, and diodes connecting the peripheral metal patches and the cross-shaped metal patch in the middle.

[0039] Since the energy selection surface of the present invention wants to achieve the function of dual polarization, a cross-shaped structure is selected for the electromagnetic unit. According to the desired shape, an equivalent model for normal signal passing and strong electromagnetic pulse passing is designed using HFSS simulation software, as Figure 2 shown. Figure 2 The left side is the unit pattern when the metal patches are completely connected, that is, corresponding to the case where the diodes of the energy selection surface are fully conducting, which is the equivalent model when a strong electromagnetic pulse passes. Figure 2 The right side is the unit pattern when the metal patches are completely disconnected, that is, corresponding to the case where the diodes of the energy selection surface are completely disconnected, which is the equivalent model when a normal signal passes. By using the simulation software to perform frequency-domain simulation on the equivalent models in different cases, their shielding effectiveness and insertion loss can be seen.

[0040] As Figure 3 shown, perform frequency-domain simulation on the equivalent model when the diodes of the energy selection surface are fully conducting. It can be seen from the figure that in the S-band, the frequency band with a shielding effectiveness greater than 30 dB when the signal is incident is 2 - 3.4 GHz, and the bandwidth is 51.8%. As Figure 4 shown, perform frequency-domain simulation on the equivalent model when the diodes of the energy selection surface are completely disconnected. It can be seen from the figure that the insertion loss S21 in the S-band is within 7 dB, indicating that low-pulse signals can pass normally. In the figure, TE mode represents the input of a transverse electric wave, TM mode represents the input of a transverse magnetic wave, the abscissa represents the frequency of the incident S-band signal, and the ordinate represents the parameter S21, which respectively represent the insertion loss and shielding effectiveness in the figure.

[0041] From Figure 3 and Figure 4 it can be seen that the surface unit with a cross-shaped structure selected in the present invention can protect high-power pulse signals and allow low-power signals to pass normally, meeting the basic requirements of the energy selection surface, and the next step of work can be carried out.

[0042] As Figure 5As shown, for the energy selective surface designed in the embodiment of the present invention, the metal backplane refers to the cross-shaped metal patches designed on the back of the dielectric plate corresponding to each electromagnetic unit.

[0043] Step 2: Determine the sizes of the unit positions on the energy selective surface, and determine the diode model through the equivalent circuit principle. Determine the selected diode model. The present invention requires that when the electromagnetic energy wave of the incident S-band signal is small, the diode is in the off state and the energy can pass through; when the electromagnetic energy wave of the incident S-band signal is large, the diode is turned on at this time and the incident electromagnetic energy wave cannot pass through.

[0044] To achieve the above purpose, the selected diode should have the characteristics of low capacitance and low loss. The diode model selected in the embodiment of the present invention is BAP70-03.

[0045] The size of the electromagnetic unit designed in the present invention is larger than that of the unit of the energy selective surface in the prior art. The size of the existing unit is generally designed as 4mm * 4mm, while the present invention is designed as 15mm * 15mm, as Figure 5 shown in Table 1.

[0046] Step 3: Scale the electromagnetic unit as a whole, measure the insertion loss and shielding effectiveness of the electromagnetic unit at different scaling sizes through simulation software, and determine the final energy selective surface unit that meets the requirements.

[0047] In order for the energy selective surface to adaptively adjust between the on and off states, the position of the diode is selected at a place where the switch can be controlled, connecting the cross-shaped metal patch (i.e., double cross-shaped metal patch) to the surrounding four metal patches, but the bandwidth in the S-band is too narrow. By adjusting the length of the unit patch, the width of the metal plate, the thickness of the dielectric plate, etc., the frequency point of the transmittance is shifted to the left and the bandwidth becomes larger, achieving the purpose of practical application - the insertion loss is less than 10 dB and the shielding effectiveness is greater than 20 dB.

[0048] The energy selective surface unit designed in the present invention is as Figure 2 shown. By changing the scaling size of the unit of the energy selective surface, the shielding effectiveness and insertion loss of the energy selective surface unit under different adjustment schemes can be obtained through simulation, that is, the purpose of adjusting the transmission coefficient of the input signal by adjusting the length of the unit periodic metal patch is achieved, so as to achieve the functions of low loss passing of low energy signals and suppression of strong electromagnetic pulses required by the present invention. The requirements set in the embodiment of the present invention are that the transmission coefficient is lower than -10 dB when the diode is off and lower than -2 dB when the diode is working.

[0049] The present invention finally determines the structural dimensions of the energy selective surface unit as shown in Table 1.

[0050] Structural Dimensions of the Determined Energy Selective Surface Unit in Table 1

[0051] Parameter Parameter Value / mm Parameter Parameter Value / mm P 15 H 0.5 A 8.4 d 0.8 w 1 L 10.3 wp 1.5 wx 1.1 ds 0.05

[0052] From Figure 5 It can be seen that on the front side of the dielectric plate, the double-cross metal patches are vertically distributed. The gap between the four surrounding metal patches and the dielectric plate is 0.05 mm. The four metal patches and the double-cross metal patches are connected by eight diodes. There is a cross metal patch on the back of the dielectric plate to improve the transmission rate of the low-pass signal.

[0053] More specifically, as Figure 5 shown in and Table 1, a dual-polarized S-band energy selective surface designed by the method of the present invention has an electromagnetic unit array designed on the front side of the dielectric plate. Each electromagnetic unit is formed by four metal patches located at the upper, lower, left, and right of the periphery, a cross-shaped metal patch located in the middle, and diodes connecting the peripheral metal patches and the middle cross-shaped metal patch; the size of each electromagnetic unit is 15 mm * 15 mm, that is, the period length P of the unit is 15 mm; the length A of each metal patch on the upper, lower, left, and right is 8.4 mm, the width d is 0.8 mm, and the gap ds from the edge of the electromagnetic unit is 0.05 mm; the middle cross-shaped metal patch is a double-cross metal patch formed by four metal patches, the length L of each metal patch is 10.3 mm, and the width w is 1 mm; the length wp of the diode connecting the cross-shaped metal patch and the surrounding metal patches is 1.5 mm; the thickness H of the dielectric plate is designed to be 0.5 mm; on the back of the dielectric plate, a cross-shaped metal patch is designed corresponding to each electromagnetic unit, and the length of each metal patch is 15 mm, and the width wx is designed to be 1.1 mm.

[0054] Step 4: To verify the stability of the energy selective surface at large incident angles, change different incident angles in the HFSS software. Since the energy selective surface designed by the present invention is dual-polarized, it is necessary to simultaneously consider the influence on the energy selective surface when the X-polarization and Y-polarization angles change. Change the incident angle from 0° to 40°, and observe whether there are obvious changes in the insertion loss and shielding effectiveness of the TE wave and TM wave.

[0055] From Figure 6 it can be seen that when the normal incidence occurs, the insertion loss in the range of 2 - 4 GHz is lower than 7.5 dB, the bandwidth lower than 5 dB is 2.37 - 4 GHz, and the bandwidth is 51.1%.

[0056] From Figure 7 it can be seen that when the normal incidence occurs, the frequency band with a shielding effectiveness greater than 17 dB is 2.12 - 4 GHz, and the bandwidth is 61.4%. Therefore, the energy selective surface realized by the present invention is a broadband energy selective surface.

[0057] From Figure 8It can be seen that the insertion loss of the TM wave decreases with the increase of the incident angle theta (θ), the bandwidth increases with the increase of the incident angle, and Figure 9 the variation trend of the TE wave in is opposite. The insertion loss increases with the increase of the incident angle, and the bandwidth decreases with the increase of the incident angle. Generally speaking, the change is relatively stable, and it still has a low insertion loss.

[0058] From Figure 10 it can be seen that the shielding effectiveness of the TM wave decreases with the increase of the incident angle, the bandwidth decreases with the increase of the incident angle, and the frequency point has a tendency to shift to the right, and Figure 11 the variation trend of the TE wave in is opposite. The shielding effectiveness increases with the increase of the incident angle, the bandwidth increases with the increase of the incident angle, and the frequency point has a tendency to shift to the left. Generally speaking, the change is relatively stable, and it still has a strong shielding ability.

[0059] It can be seen from the above experiments that the method of the present invention can be used to more conveniently and simply design the required energy selection surface unit, solve the problem of high production cost when the energy selection surface in the current S band realizes the dual-polarization function. The designed energy selection surface has the characteristics of excellent performance, simple structure, low cost, realization of dual polarization, and wide bandwidth in the S band, expands the function of the energy selection surface, and further enriches the design idea of the energy selection surface.

[0060] Except for the technical features described in the specification, they are all well-known technologies to those skilled in the art. The present invention omits the description of well-known components and well-known technologies to avoid redundancy and unnecessary limitation of the present invention. The embodiments described in the above embodiments do not represent all embodiments consistent with the present application. Based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A method for constructing a dual-polarized S-band electromagnetic bandgap structure, characterized in that It includes the following steps: Step 1: Select the shape of the electromagnetic unit of the energy selection surface according to the dual-polarization requirement. Use simulation software to simulate the equivalent circuit of the electromagnetic unit and perform frequency-domain simulation to obtain the insertion loss and shielding effectiveness when the diodes in the electromagnetic unit are fully connected and disconnected, and verify whether the selected electromagnetic unit meets the requirements; The electromagnetic unit adopts a tic-tac-toe structure, including metal patches located around and a tic-tac-toe metal patch located in the middle. Diodes are arranged at the connection between the tic-tac-toe metal patch and the surrounding metal patches; Step 2: Determine the required diode model through the principle of equivalent circuit; When the electromagnetic energy wave of the incident S-band signal is less than the required value, the diode is in the off state, allowing the signal to pass through normally. Otherwise, the diode is turned on, preventing the incident signal from passing through; Step 3: Use simulation software to adjust the period length of the electromagnetic unit of the energy selection surface, the arrangement of the diodes, and the thickness of the dielectric plate to determine the final energy selection surface unit, so that the insertion loss of the electromagnetic unit is less than 10 dB and the shielding effectiveness is greater than 20 dB; Step 4: Use the final energy selection surface unit and the required diodes to implement the energy selection surface.

2. The method according to claim 1, wherein In the above-mentioned Step 1, the structure of the energy selection surface is designed as follows: An electromagnetic unit array is designed on the front of the dielectric plate. Each electromagnetic unit is formed by four metal patches located at the upper, lower, left, and right of the periphery, a tic-tac-toe metal patch located in the middle, and diodes connecting the peripheral metal patches and the middle tic-tac-toe metal patch; On the back of the dielectric plate, a cross-shaped metal patch is designed corresponding to each electromagnetic unit.

3. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 2, the selected diode model is BAP70-03.

4. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 3, in the determined final energy selection surface, the period length of each electromagnetic unit is 15 mm, and the thickness of the dielectric plate is 0.5 mm.

5. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 3, in the determined final energy selection surface, the length of each metal patch at the upper, lower, left, and right of the periphery of each electromagnetic unit is 8.4 mm, the width is 0.8 mm, and the gap from the edge of the electromagnetic unit is 0.05 mm; The middle tic-tac-toe metal patch is formed by four metal patches, and each patch is 10.3 mm long and 1 mm wide.

6. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 3, in the determined final energy selection surface, a diode is arranged at each extension of each metal patch in the middle tic-tac-toe of each electromagnetic unit, connecting to the peripheral metal patch, and the length of the diode is 1.5 mm.

7. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 3, in the determined final energy selection surface, the cross-shaped metal patch of each electromagnetic unit on the back of the dielectric plate of each electromagnetic unit is formed by two metal patches, and each patch is 1.1 mm wide.

8. The method according to claim 1 or 2, characterized in that, In the above-mentioned Step 3, for the electromagnetic unit designed in Step 1 perform overall scaling, and measure the insertion loss and shielding effectiveness of the electromagnetic unit at different scaling sizes through simulation software, to determine the final energy selection surface unit that meets the requirements.

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