Ultra-wideband and high-protection-efficiency filtering energy selective surface

Abstract

The present invention relates to the field of electronic devices of wireless communication systems. Disclosed is an ultra-wideband and high-protection-efficiency filtering energy selective surface, comprising one or more layers of reflecting surfaces; each reflecting surface is mainly composed of a plurality of metal sheets which are located on the same plane, have the same shape and are arranged in central symmetry; a gap for electrical isolation is formed between every two adjacent metal sheets; each gap is provided with a PIN diode; the anodes and cathodes of all the PIN diodes are arranged in a clockwise or counterclockwise direction; and all the gaps form an interconnected gap structure on the plane where the reflecting surface is located. The ultra-wideband and high-protection-efficiency filtering energy selective surface can be achieved by a first-order filtering energy selective surface unit or a second-order filtering energy selective surface unit. The filtering energy selective surface of the present invention has a small surface thickness and a simple structure, can achieve fast roll-off filtering for low-power signals, achieve an ultra-wide suppression stopband, and achieve ultra-wideband and high-efficiency protection for high-power electromagnetic waves.

Description

An ultra-wideband, high-protection-efficiency filtering energy-selective surface Technical Field

[0001] The present invention belongs to the field of electronic devices of wireless communication systems, and in particular relates to an ultra-wideband, high-protection-efficiency filtering energy selective surface. Background Art

[0002] Strong electromagnetic pulses can interfere with, degrade, or even damage critical electronic equipment, such as communications systems, through antenna arrays and sensors in the "front door," as well as apertures and cables in the "back door." Front door devices are the primary route through which strong electromagnetic pulses threaten communications equipment, making it crucial to establish front door protection for electronic equipment. To date, proposed front door protection devices include frequency selective surfaces and absorbers. These electromagnetic surfaces can effectively suppress interference signals outside the passband, but they cannot shield high-power electromagnetic waves within the passband, leaving strong electromagnetic pulses still a threat to communications equipment.

[0003] In recent years, a new type of electromagnetic surface, the energy-selective surface, has been proposed. It can adaptively shield high-power electromagnetic waves while transmitting low-power communication signals. The energy-selective surface is designed by loading diodes onto electromagnetic periodic units. When a low-power communication signal is incident, the diodes on the surface are disconnected, and the energy-selective surface behaves as a transmissive surface, enabling signal transmission. However, when a high-power electromagnetic wave is incident, the diodes are turned on by the strong induced current on the surface, and the energy-selective surface behaves as a reflective surface, shielding the high-power electromagnetic wave. Compared to electromagnetic surfaces such as frequency-selective surfaces that only filter passband signals, energy-selective surfaces can more effectively achieve "front door" protection.

[0004] In the literature, energy selective surfaces designed for "front door" protection are divided into two categories. The first category is based on a single functional layer. By designing a multi-resonant circuit that can achieve bandpass and bandstop responses when the diode is in the off and on states, a single-function electromagnetic multi-resonant unit is realized. This type of energy selective surface can achieve very low transmission loss for low-power in-band signals, but the filtering performance is poor. At the same time, there are disadvantages such as narrow shielding bandwidth and low efficiency for high-power electromagnetic waves. The second category is based on a multifunctional layer. By adding multiple functional electromagnetic surfaces such as frequency selective surfaces and absorbers to the energy selective surface of the first type of single functional layer, it can achieve low-power signal filtering and broadband out-of-band suppression. However, this type of energy selective surface introduces electromagnetic surfaces with different functions, resulting in a complex overall structure. The simultaneous addition of multiple functional layers increases the transmission loss of low-power in-band signals. Summary of the Invention

[0005] Technical purpose: In response to the above technical problems, the present invention proposes a simple filtering energy selective surface with small surface thickness and simple structure. It can achieve fast roll-off filtering and ultra-wide out-of-band suppression for low-power signals, and can achieve ultra-wideband and high protection efficiency for high-power electromagnetic waves.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] An ultra-wideband, high-protection-efficiency filtering energy selective surface comprises one or more layers of reflective surfaces, the reflective surfaces primarily consisting of a plurality of metal sheets located on the same layer, having the same shape and arranged in a centrally symmetrical manner. Adjacent metal sheets are provided with electrically isolated gaps, and PIN tubes are provided between each gap. The positive and negative poles of all PIN tubes are arranged in a clockwise or counterclockwise direction, forming a gap structure in which all gaps are connected on the plane of the reflective surface.

[0008] Preferably, the ultra-wideband, high-protection-efficiency filtering energy selective surface is a first-order filtering energy selective surface unit, comprising a first-order unit PIN tube layer, a first-order unit first metal layer, a first-order unit substrate layer and a first-order unit second metal layer arranged from top to bottom; wherein the first-order unit first metal layer is a square patch etched with a "cross"-shaped gap; the first-order unit PIN tube layer is composed of four PIN tubes, which are surface-mounted on the gap of the first metal layer; the first-order unit second metal layer is a "cross"-shaped metal strip; in the first-order unit PIN tube layer, the square patch is isolated into four areas by corresponding "cross"-shaped gaps, and adjacent areas are electrically connected through a PIN tube.

[0009] Preferably, the period of the ultra-wideband, high-protection-efficiency filtering energy selection surface is set to 10 mm, the width of each cross-shaped gap is set to 0.4 mm, and the width of the cross-shaped metal strip of the second metal layer of the first-order unit is set to 1.1 mm.

[0010] Preferably, the ultra-wideband, high-protection-efficiency filter energy selective surface is a second-order filter energy selective surface unit, comprising, from top to bottom, a second-order unit first PIN tube layer, a second-order unit first metal layer, a second-order unit first substrate layer, a second-order unit second metal layer, a second-order unit bonding layer, a second-order unit second substrate layer, a second-order unit third metal layer, and a second PIN tube layer; wherein the second-order unit first metal layer and the second-order unit third metal layer are square patches etched with "cross"-shaped gaps; the second-order unit first PIN tube layer and the second-order unit second PIN tube layer are each composed of four PIN tubes, the second-order unit first PIN tube layer being attached to the gaps in the second-order unit first metal layer, and the second-order unit second PIN tube layer being attached to the gaps in the second-order unit third metal layer; the second-order unit second metal layer is a "cross"-shaped metal strip; and in the second-order unit first PIN tube layer and the second-order unit second PIN tube layer, the square patches are separated into four regions by corresponding "cross"-shaped gaps, and adjacent regions are electrically connected via a PIN tube.

[0011] Preferably, the period of the ultra-wideband, high-protection-efficiency filtering energy selection surface is set to 10 mm, the width of each cross-shaped gap is set to 0.4 mm, and the width of the cross-shaped metal strip of the second metal layer of the second-order unit is set to 6 mm.

[0012] Preferably, the period of the ultra-wideband, high-protection-efficiency filtering energy selective surface is less than λ / 4.

[0013] Beneficial effects: Compared with the prior art, due to the adoption of the above technical solution, the present invention provides an ultra-wideband, high-protection-efficiency filter energy selective surface, which can be implemented by a first-order filter energy selective surface unit or a second-order filter energy selective surface unit. Its advantages are:

[0014] (1) The first-order filter energy selective surface unit and the second-order filter energy selective surface unit adopt the coupled resonator architecture, which can achieve a high Q value in a very small thickness. The first-order filter energy selective surface unit can achieve a thickness of less than 0.0002λ, and the second-order filter energy selective surface unit can achieve a thickness of less than 0.003λ;

[0015] (2) The first-order filter energy selection surface unit adopts a square patch with a cross-shaped gap etched on it. By changing the width of the gap, a PIN layer can be easily attached to the cross-shaped gap of the square patch without the need for additional pads. When the four PIN tubes are disconnected, the gap capacitance of the square patch is connected in parallel with the equivalent capacitance of the PIN tube, which can obtain a very high capacitance value. The first-order filter energy selection surface unit becomes a high-Q transmission unit, which can achieve fast roll-off filtering for low-power electromagnetic waves. At the same time, the unit period is less than λ / 4, which can achieve an ultra-wide suppression stopband. By reducing the unit period, the suppression stopband can be further widened.

[0016] (3) The first-order filter energy selective surface unit has a layer of square patches and a layer of PIN layer. When the four PIN tubes in the PIN layer are turned on, the square patches are electrically connected through the PIN tubes and become a reflective surface, which can achieve high protection efficiency against high-power electromagnetic waves. At the same time, the unit period is less than λ / 4, and the first-order filter energy selective surface unit achieves an ultra-wide protection band of more than 200%. By reducing the unit period, the electrical connection between the square patches when the PIN tubes are turned on can be enhanced, further widening the protection band against high-power electromagnetic waves.

[0017] (4) The second-order filter energy selective surface unit has two layers of square patch layers with "cross" shaped gaps etched on them. By simply changing the width of the gaps, the two layers of PIN layers can be easily surface-mounted on the "cross" shaped gaps of the two layers of square patches, without the need for additional pads. When the four PIN transistors of the two layers of PIN layers are disconnected, the gap capacitance of the square patch is connected in parallel with the equivalent capacitance of the PIN transistor, which can obtain a very high capacitance value. The second-order filter energy selective surface unit becomes a high-Q transmission unit, which can achieve fast roll-off filtering for low-power electromagnetic waves. At the same time, the unit period is less than λ / 4, which can achieve an ultra-wide suppression stopband. By reducing the unit period, the suppression stopband can be further widened.

[0018] (5) The second-order filter energy selective surface unit has two layers of square patches and two layers of PIN layers. When the four PIN tubes of the two PIN layers are turned on, the two layers of square patches are electrically connected through the PIN tubes and become two layers of reflective surfaces, which can achieve a protection efficiency twice as high as that of the first-order filter energy selective surface unit. At the same time, the unit period is less than λ / 4, and the second-order filter energy selective surface unit achieves an ultra-wide protection band of more than 300%. By reducing the unit period, the electrical connection between the square patches when the PIN tube is turned on can be enhanced, further widening the protection band for high-power electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a three-dimensional schematic diagram of an ultra-wideband, high-protection-efficiency filter energy selective surface, namely, a first-order filter energy selective surface unit, proposed in Example 1;

[0020] FIG2 is a schematic diagram of the decomposition structure of a first-order filter energy selection surface unit;

[0021] FIG3 is a schematic diagram of a stack of first-order filter energy selection surface units;

[0022] FIG4 is a three-dimensional schematic diagram of an ultra-wideband, high-protection-efficiency filter energy selective surface, namely, a second-order filter energy selective surface unit, proposed in Example 2;

[0023] FIG5 is a schematic diagram of the decomposition structure of a second-order filter energy selection surface unit;

[0024] FIG6 is a schematic diagram of a stack of second-order filter energy selective surface units;

[0025] FIG7 shows the transmission coefficient of the first-order filter energy selective surface unit in the transmission state and the reflection state;

[0026] FIG8 shows the transmission coefficient of the second-order filtered energy selective surface unit in the transmission state and the reflection state;

[0027] Wherein, 1-first-order filter energy selective surface unit, 2-second-order filter energy selective surface unit;

[0028] 1a-first-order unit PIN tube layer, 1b-first-order unit first metal layer, 1c-first-order unit substrate layer, 1d-first-order unit second metal layer;

[0029] 2a-second-order unit first PIN tube layer, 2b-second-order unit first metal layer, 2c-second-order unit first substrate layer, 2d-second-order unit second metal layer, 2e-second-order unit bonding layer, 2f-second-order unit second substrate layer, 2g-second-order unit third metal layer, 2h-second-order unit second PIN tube layer. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] As shown in FIG1 , this embodiment proposes an ultra-wideband, high-protection-efficiency filtering energy selective surface, namely, a first-order filtering energy selective surface unit 1, the unit period of which is less than λ / 4, where λ is the vacuum wavelength corresponding to the center frequency, which is set to 10 mm here.

[0033] As shown in Figures 2 and 3, the first-order filter energy selective surface unit 1 consists of a PIN layer, two metal layers and a substrate layer; from top to bottom are the first-order unit PIN tube layer 1a, the first-order unit first metal layer 1b, the first-order unit substrate layer 1c and the first-order unit second metal layer 1d.

[0034] Among them, the first-order unit PIN tube layer 1a is composed of four PIN tubes. The first-order unit first metal layer 1b is a square patch with a "cross" slit etched on it. The four PIN tubes of the first-order unit PIN tube layer 1a are surface-mounted on the slit of the first-order unit first metal layer 1b, without the need for additional pads. The positive and negative poles of the four PIN tubes are arranged in a clockwise or counterclockwise direction. The first-order unit second metal layer 1d is a "cross" shaped metal strip. When the four PIN transistors are disconnected, the first-order filter energy selective surface unit 1 becomes a first-order bandpass resonant transmission unit. The capacitance is achieved by the parallel connection of the square patch's gap capacitance and the PIN transistor's equivalent capacitance. The gap capacitance decreases with the width of the square patch. To facilitate soldering of the PIN transistor, the gap width is set to 0.4mm. The inductance is achieved by a cross-shaped metal strip. The inductance decreases with the width of the strip, which is set to 1.1mm here. Because the square patch and the cross-shaped metal strip are centrosymmetrical, the first-order filter energy selective surface unit 1 can transmit low-power electromagnetic waves of any polarization. When the four PIN transistors are connected, the square patch is electrically connected through the PIN transistors, becoming a reflective surface, achieving high protection against high-power electromagnetic waves. In addition, the square patch with etched "cross" slits and the "cross" shaped metal strips have only one degree of freedom in size. The first-order filtering energy selective surface unit 1 can achieve any operating frequency band by adjusting the width of the "cross" slits and the "cross" shaped metal strips. Here it is set to work in the S band. By reducing the unit period, an ultra-wide suppression stop band in the transmission state and an ultra-wide protection band for high-power electromagnetic waves in the reflection state can also be achieved.

[0035] It should be noted that the gap structure in the present invention is not limited to the cross shape, and can also be a gap structure of other shapes that can achieve connectivity in the x and y directions.

[0036] Example 2

[0037] As shown in Figures 4 to 6, this embodiment proposes an ultra-wideband, high-protection efficiency filtering energy selective surface, namely a second-order filtering energy selective surface unit 2, with a unit period less than λ / 4, where λ is the vacuum wavelength corresponding to the center frequency, which is set to 10 mm here.

[0038] The second-order filter energy selection surface unit 2 consists of two PIN tube layers, three metal layers, two substrate layers and one bonding layer; from top to bottom are the second-order unit first PIN tube layer 2a, the second-order unit first metal layer 2b, the second-order unit first substrate layer 2c, the second-order unit second metal layer 2d, the second-order unit bonding layer 2e, the second-order unit second substrate layer 2f, the second-order unit third metal layer 2g and the second PIN tube layer 2h.

[0039] Among them, the second-order unit first PIN tube layer 2a and the second-order unit second PIN tube layer 2h are both composed of four PIN tubes. The second-order unit first metal layer 2b and the second-order unit third metal layer 2g are both square patches with "cross" etched gaps. The second-order unit first PIN tube layer 2a is attached to the gap of the second-order unit first metal layer 2b, and the second-order unit second PIN tube layer 2h is attached to the gap of the second-order unit third metal layer 2g. No additional pads are required. The positive and negative poles of the four PIN tubes in the two PIN layers are arranged in a clockwise or counterclockwise direction. The second metal layer 2d of the second-order unit is a "cross" shaped metal strip. When all four PIN transistors in both PIN layers are disconnected, the second-order filter energy selective surface unit 2 becomes a second-order bandpass resonant transmission unit. The capacitance is realized by the parallel connection of the gap capacitance of the square patch and the equivalent capacitance of the PIN transistor. The gap capacitance decreases with increasing square patch size. To facilitate soldering of the PIN transistor, the gap width is set to 0.4mm. The second-order bandpass resonant inductance of the second-order unit in the transmission state is realized by a cross-shaped metal strip. The inductance decreases with increasing strip width, which is set to 6mm here. Because the square patch and the cross-shaped metal strip are centrosymmetrical, the second-order filter energy selective surface unit 2 can transmit low-power electromagnetic waves of any polarization. When the four PIN transistors in both PIN layers are connected, the two square patches are electrically connected through the PIN transistors, forming two reflective surfaces, achieving twice the protection efficiency of the first-order filter energy selective surface unit 1. In addition, the square patch with etched "cross" slits and the "cross" shaped metal strip have only one degree of freedom in size. The second-order filtering energy selective surface unit 2 can achieve any operating frequency band by adjusting the width of the "cross" slits on the two layers of square patches and the middle "cross" shaped metal strip. Here it is set to work in the S band. By reducing the unit period, an ultra-wide suppression stop band in the transmission state and an ultra-wide protection band for high-power electromagnetic waves in the reflection state can also be achieved.

[0040] FIG7 shows the transmission coefficients of the first-order energy selective surface unit 1 in the transmission state and the reflection state. It can be seen that the first-order energy selective surface unit 1 has filtering characteristics in the transmission state, with a bilateral roll-off bandwidth of less than 13%, a 3-dB insertion loss bandwidth of 10.5%, and can achieve a suppression stopband of less than -15 dB in the ultra-wide band of 5-14 GHz; in the reflection state, the center frequency of the transmission coefficient of the first-order energy selective surface unit 1 is -31.5 dB, and is less than -20 dB in the frequency band of DC-8.5 GHz. The protection effectiveness is the absolute value of the transmission coefficient in the reflection state, that is, the protection effectiveness of the first-order energy selective surface unit 1 in this frequency band is greater than 20 dB;

[0041] Figure 8 shows the transmission coefficients of the second-order filtering energy selective surface unit 2 in the transmission state and the reflection state. It can be seen that the transmission state of the second-order filtering energy selective surface unit 2 has filtering characteristics, the bilateral roll-off bandwidth is less than 5%, the 3-dB insertion loss bandwidth is 13.1%, and it can achieve a suppression stopband of less than -30dB in the ultra-wide band of 5-13GHz; in the reflection state, the transmission coefficient of the second-order filtering energy selective surface unit 2 is -60.1dB at the center frequency and is less than -30dB in the frequency band of DC-10GHz, that is, the protection effectiveness of the second-order filtering energy selective surface unit 2 in this frequency band is greater than 30dB.

[0042] In summary, the present invention proposes a simple energy-selective filtering surface that can be implemented by configuring only unit 1 or only unit 2. This surface has the advantages of small thickness and simple structure. Both configurations can achieve fast roll-off filtering and ultra-wide out-of-band suppression for low-power signals, and ultra-wideband and high protection efficiency for high-power electromagnetic waves. Compared with unit 1, unit 2 achieves faster roll-off filtering performance in the transmission state and nearly doubles the protection efficiency in the reflection state. This invention has important application prospects in the field of "front-door" protection against strong electromagnetic pulses.

[0043] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. An ultra-wideband, high protection efficiency filtering energy selective surface, characterized by: The invention comprises more than one reflecting surface, wherein the reflecting surface is mainly composed of a plurality of metal sheets located at the same level, having the same shape and being arranged in a central symmetrical manner, and electrically isolated gaps are arranged between adjacent metal sheets, and PIN tubes are arranged between each gap, and the positive and negative poles of all PIN tubes are arranged in a clockwise or counterclockwise direction, and all gaps form a gap structure connected on the plane where the reflecting surface is located.

2. The ultra-wideband, high protection efficiency filtering energy selective surface according to claim 1, characterized in that: The ultra-wideband, high-protection-efficiency filtering energy selective surface is a first-order filtering energy selective surface unit (1), comprising a first-order unit PIN tube layer (1a), a first-order unit first metal layer (1b), a first-order unit substrate layer (1c) and a first-order unit second metal layer (1d) arranged from top to bottom; wherein the first-order unit first metal layer (1b) is a square patch with a "cross"-shaped gap etched; the first-order unit PIN tube layer (1a) is composed of four PIN tubes, which are surface-mounted on the gap of the first metal layer (1b); the first-order unit second metal layer (1d) is a "cross"-shaped metal strip; in the first-order unit PIN tube layer (1a), the square patch is isolated into four areas by corresponding "cross"-shaped gaps, and adjacent areas are electrically connected through a PIN tube.

3. The ultra-wideband, high protection efficiency filtering energy selective surface according to claim 2, characterized in that: The period of the ultra-wideband, high-protection-efficiency filtering energy selection surface is set to 10 mm, the width of each cross-shaped gap is set to 0.4 mm, and the width of the cross-shaped metal strip of the second metal layer (1d) of the first-order unit is set to 1.1 mm.

4. The ultra-wideband, high protection efficiency filtering energy selective surface according to claim 1, characterized in that: The ultra-wideband, high-protection-efficiency filtering energy selective surface is a second-order filtering energy selective surface unit (2), comprising, from top to bottom, a second-order unit first PIN tube layer (2a), a second-order unit first metal layer (2b), a second-order unit first substrate layer (2c), a second-order unit second metal layer (2d), a second-order unit bonding layer (2e), a second-order unit second substrate layer (2f), a second-order unit third metal layer (2g) and a second PIN tube layer (2h); wherein the second-order unit first metal layer (2b) and the second-order unit third metal layer (2g) are both square patches with "cross"-shaped gaps etched; the second-order unit first PIN tube layer (2a) and the second-order unit first substrate layer (2c) are respectively provided. The IN tube layer (2a) and the second PIN tube layer (2h) of the second-order unit are both composed of four PIN tubes. The first PIN tube layer (2a) of the second-order unit is attached to the gap of the first metal layer (2b) of the second-order unit, and the second PIN tube layer (2h) of the second-order unit is attached to the gap of the third metal layer (2g) of the second-order unit. The second metal layer (2d) of the second-order unit is a "cross" shaped metal strip. In the first PIN tube layer (2a) of the second-order unit and the second PIN tube layer (2h) of the second-order unit, the square patch is isolated into four areas by the corresponding "cross" shaped gaps, and the adjacent areas are electrically connected through a PIN tube.

5. The ultra-wideband, high protection efficiency filtering energy selective surface according to claim 4, characterized in that: The period of the ultra-wideband, high-protection-efficiency filtering energy selection surface is set to 10 mm, the width of each "cross" shaped gap is set to 0.4 mm, and the width of the "cross" shaped metal strip of the second metal layer (2d) of the second-order unit is set to 6 mm.

6. The ultra-wideband, high protection efficiency filtering energy selective surface according to claim 1, characterized in that: The period of the ultra-wideband, high-protection-efficiency filtering energy selective surface is less than λ / 4.

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