A frequency selective surface with electromagnetic switching and polarization selection functions

Abstract

The present invention discloses a frequency selective surface with electromagnetic switch and polarization selection function, comprising: two layers of dielectric substrate, upper metal structure unit, lower metal structure unit and air cavity, the upper metal structure unit is a deformed Jerusalem cross metal structure, the lower metal structure unit is composed of a deformed "I" type metal structure and two rows of metal fine wire structures parallel thereto, the upper metal structure unit is arranged on both sides of the dielectric substrate and the metal structures on both sides are connected by metal vias, the lower metal structure unit is orthogonally arranged on both sides of the dielectric substrate, and there is an air cavity between the upper metal structure unit and the lower metal structure unit. The present invention can effectively solve the problems of complex feeder, single function, polarization sensitivity, etc. of the existing active frequency selective surface.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic metamaterials, in particular to a frequency selective surface with electromagnetic switching and polarization selection functions. Background Art

[0002] The frequency selective surface (FSS) is composed of a periodically arranged metal topological structure and has good spatial filtering characteristics. It is a kind of spatial filter that can realize different electromagnetic control functions such as absorption, transmission, and reflection.

[0003] Once the traditional FSS is manufactured, its performance parameters are basically fixed and it cannot adapt to the complex and changeable external electromagnetic environment. The active frequency selective surface (AFSS) can change the electromagnetic performance as the external excitation (current intensity, electromagnetic wave energy intensity, electromagnetic wave frequency, etc.) changes. By controlling the controllable semiconductor devices (such as varactor diodes, PIN diodes, etc.) loaded on the AFSS structure, the active switching of the AFSS function can be achieved. In order to control these semiconductor devices, it is usually necessary to add additional feeders to the AFSS structure. However, the additional feeders will have a negative impact on the electromagnetic performance of the AFSS (such as increased insertion loss, resonant frequency shift, etc.). Through the reasonable design of the AFSS topology structure, the feeder and the topology structure can be conformally designed, and the topology itself can be used as the feeder, which greatly reduces the negative impact of the introduction of additional feeders on the electromagnetic performance of the frequency selective surface.

[0004] As the modern electromagnetic environment becomes increasingly complex, single-function AFSS can no longer adapt to the changing application scenarios. Therefore, active frequency selective surfaces that integrate multiple electromagnetic control functions have important research value. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a frequency selective surface with electromagnetic switch and polarization selection function, which can effectively solve the problems of complex feeder, single function and polarization sensitivity of the existing active frequency selective surface.

[0006] In order to solve the above technical problems, the present invention provides a frequency selective surface with electromagnetic switch and polarization selection functions, comprising: two layers of dielectric substrates, an upper metal structure unit, a lower metal structure unit and an air cavity, the upper metal structure unit is a deformed Jerusalem cross metal structure, the lower metal structure unit is composed of a deformed "I"-shaped metal structure and two rows of metal fine wire structures parallel to it, the upper metal structure unit is arranged on both sides of the dielectric substrate and the metal structures on both sides are connected by metal vias, the lower metal structure unit is orthogonally arranged on both sides of the dielectric substrate, and there is an air cavity between the upper metal structure unit and the lower metal structure unit.

[0007] Preferably, the two layers of dielectric substrates are made of the same material, which may be polytetrafluoroethylene, epoxy glass fiber or epoxy resin, and the metal structural unit material may be made of a metal with good electrical conductivity and stable properties.

[0008] Preferably, every two adjacent cross metal unit structures in the upper layer are identical and orthogonal to each other and are connected by a PIN diode, and each of the four gaps in the middle of the cross metal unit structure is loaded with a resistor respectively; a PIN diode is integrated between the gaps of every two adjacent "I"-type metal unit structures in the lower layer, the PIN diodes arranged along the same polarization in the same metal layer are in the same direction, and the PIN diodes loaded in the same row of metal periodic structures are connected in series.

[0009] Preferably, the metal unit structure itself is connected to the PIN diode as a part of the feeder line, so that no additional feeder line is required, thereby effectively reducing the negative impact of the additional feeder line on the electromagnetic performance.

[0010] Preferably, the situation of applying a DC bias voltage to the upper and lower metal structure units is encoded, and the working states of the PIN diodes in different polarization directions of the upper and lower layers are independently controlled to change the encoding state, so that the three functions of stealth, bandpass and shielding can be realized, including independent selection of TE polarized wave stealth, bandpass and shielding and independent selection of TM polarized wave stealth, bandpass and shielding, a total of nine different combination states.

[0011] The beneficial effects of the present invention are as follows: (1) a conformal topological structure is adopted, and the topology itself is connected to the PIN diode as part of the feeder, which greatly reduces the influence of introducing an additional feeder on the electromagnetic performance of the frequency selective surface; (2) by independently controlling the working state of the PIN diodes in different polarization directions of the upper and lower layers and changing the coding state, the three functions of stealth, bandpass and shielding can be realized, including independent selection of TE polarized wave stealth, bandpass and shielding and independent selection of TM polarized wave stealth, bandpass and shielding, a total of nine different combination states, integrating multiple electromagnetic functions in one, with a simple feeder line design and a wider working frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a side view of the unit structure of the frequency selective surface of the present invention.

[0013] FIG. 2( a ) is a schematic diagram of the upper surface of the upper unit structure of the frequency selective surface of the present invention.

[0014] FIG. 2( b ) is a schematic diagram of the lower surface of the upper unit structure of the frequency selective surface of the present invention.

[0015] FIG. 3( a ) is a schematic diagram of the upper surface of the lower unit structure of the frequency selective surface of the present invention.

[0016] FIG. 3( b ) is a schematic diagram of the lower surface of the lower unit structure of the frequency selective surface of the present invention.

[0017] FIG. 4( a ) is a schematic diagram of the upper array structure of the frequency selective surface of the present invention.

[0018] FIG. 4( b ) is a schematic diagram of the lower array structure of the frequency selective surface of the present invention.

[0019] Figure 5 This is a relationship diagram between the scattering parameters and the frequency of the frequency selective surface of the present invention in different encoding states.

[0020] Among them, 1. two layers of dielectric substrate; 2. upper metal structure unit; 3. lower metal structure unit; 4. air cavity; 5. deformed Jerusalem cross metal unit structure; 6. metal patch on the lower side of the upper metal structure unit; 7. deformed "I" type metal unit structure; 8. excitation port of the feeder. DETAILED DESCRIPTION

[0021] like Figure 1-Figure 3(b) As shown, a frequency selective surface with electromagnetic switch and polarization selection function includes: two layers of dielectric substrate 1, upper metal structure unit 2 and lower metal structure unit 3 arranged on both sides of the two layers of dielectric substrate 1, and an air cavity 4 in the middle. The upper metal structure unit 2 is a deformed Jerusalem cross metal unit structure 5, in which two PIN diodes (A1, A2) and four resistors (B1, B2, B3, B4) are loaded and connected to the metal patch 6 on the lower side by metal vias (C1, C2); the lower metal structure unit 3 includes a deformed "I" type metal unit structure 7 and a metal fine wire structure (D1, D2, D3, D4) parallel thereto, wherein every two adjacent deformed "I" type metal unit structures 7 are connected by PIN diodes (A3, A4).

[0022] As shown in FIG4 , the frequency selective surface with electromagnetic switch and polarization selection function of the present invention comprises two layers of periodically distributed metal structural units and an external DC bias voltage. The external DC bias voltage comprises an external DC bias voltage V in the TE polarization direction of the upper layer. TTE+ ; External DC bias voltage V in TM polarization direction TTM+ and the external DC bias voltage V in the TE polarization direction of the lower layer BTE+ ; External DC bias voltage V in TM polarization direction BTM+ The external DC bias voltage of the frequency selective surface having electromagnetic switching and polarization selection functions is introduced from the excitation port 8 of the feed line.

[0023] In the present invention, a design method of conformal feeding line and topological structure is adopted. Through reasonable design, the gap size of the deformed Jerusalem cross and the deformed "I" type metal structure is suitable for PIN diode loading, and the metal structure itself is connected to the PIN diode as part of the feeder. The external DC bias voltage conditions in the TE and TM polarization directions of the upper and lower structures are encoded by the symbol "IJ / LK" (I = 0,1; J = 0,1; L = 0,1 and K = 0,1), where "I" and "J" respectively represent the bias voltage conditions in the TE and TM polarization directions of the upper layer, and "L" and "K" respectively represent the bias voltage conditions in the TE and TM polarization directions of the lower layer. The working state of the PIN diode is different under different bias voltage conditions. When the bias voltage is applied, it indicates that the PIN diode is turned on, marked as a number "1"; when the bias voltage is zero, it indicates that the PIN diode is disconnected, marked as a number "0". By independently controlling the working states of the PIN diodes in different polarization directions of the upper and lower layers and changing the coding state, nine effective external bias voltage combinations ("00 / 00", "11 / 11", "11 / 00", "01 / 01", "01 / 00", "10 / 10", "10 / 00", "11 / 10" and "11 / 01") can be obtained. In different coding states, the equivalent impedance of the frequency selective surface is different, and the regulation function of the electromagnetic waves is also different.

[0024] According to the specific working frequency band of the frequency selective surface with electromagnetic switch and polarization selection functions, the material of the two layers of dielectric substrate 1 is the same, and polytetrafluoroethylene, epoxy glass fiber and epoxy resin can be selected. The metal structure material can select metals with good conductivity and stable properties, such as copper, gold and silver, and the semiconductor element can select different types of PIN diodes that meet the requirements.

[0025] Figure 5 The relationship between the scattering parameters and the frequency of the frequency selective surface with electromagnetic switch and polarization selection function of the present invention is given when the external DC bias voltage is in different encoding states, where:

[0026] (a) Scattering parameters of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “00 / 00” state;

[0027] (b) Scattering parameters of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “11 / 11” state;

[0028] (c) is the scattering parameter of the frequency selective surface with electromagnetic switch and polarization selection function in the coded “11 / 00” state;

[0029] (d) is the scattering parameter of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “01 / 01” state;

[0030] (e) is the scattering parameter of the frequency selective surface with electromagnetic switch and polarization selection function in the coded “01 / 00” state;

[0031] (f) is the scattering parameter of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “10 / 10” state;

[0032] (g) is the scattering parameter of the frequency selective surface with electromagnetic switch and polarization selection function in the coded “10 / 00” state;

[0033] (h) is the scattering parameter of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “11 / 10” state;

[0034] (i) Scattering parameters of the frequency selective surface with electromagnetic switching and polarization selection functions in the coded “11 / 01” state;

[0035] When the code is in the "00 / 00" state, the external DC bias voltage of the upper and lower layers is 0V, all the PIN diodes work in the disconnected state, and the frequency selective surface with electromagnetic switch and polarization selection functions presents dual-polarization stealth characteristics at 6.0-11.9GHz (that is, both TE and TM polarized electromagnetic waves are absorbed), and the -10dB bandwidth is 5.9GHz; when the code is in the "11 / 11" state, the DC bias voltage of the upper and lower layers is 31.5V, all the PIN diodes work in the on state, and the frequency selective surface with electromagnetic switch and polarization selection functions presents dual-polarization bandpass characteristics at 9.2-10.4GHz (that is, both TE and TM polarized electromagnetic waves can be absorbed). The insertion loss of the signal transmitted through the receiver is less than 1dB; when the code is in the "11 / 00" state, the DC bias voltages of the upper and lower layers are 31.5V and 0V respectively, the PIN diodes of the upper and lower layers operate in the on and off states respectively, and the frequency selective surface with electromagnetic switch and polarization selection functions exhibits dual-polarization shielding characteristics in this frequency band (that is, both TE and TM polarized electromagnetic waves are reflected back); the six states of "01 / 01", "01 / 00", "10 / 10", "10 / 00", "11 / 10" and "11 / 01" represent other combination states of the frequency selective surface with electromagnetic switch and polarization selection functions when the TE polarization and TM polarization direction functions are different. For example, when the code is in the "10 / 00" state, the DC bias voltage in the upper TE polarization direction is 31.5V, and the DC bias voltage in the upper TM polarization direction and the lower TE and TM polarization directions is 0V. The PIN diode in the upper TE polarization direction works in the on state, and all other PIN diodes work in the off state. The frequency selective surface with electromagnetic switching and polarization selection functions shows obvious polarization selection characteristics in this frequency band. TE polarized electromagnetic waves are reflected back, and TM polarized electromagnetic waves are absorbed. The other five states all have corresponding polarization selection functions: when encoded as the "01 / 01" state, TE polarized electromagnetic waves are absorbed and TM polarized electromagnetic waves are transmitted; when encoded as the "01 / 00" state, TE polarized electromagnetic waves are absorbed and TM polarized electromagnetic waves are reflected back; when encoded as the "10 / 10" state, TE polarized electromagnetic waves are transmitted and TM polarized electromagnetic waves are absorbed; when encoded as the "11 / 10" state, TE polarized electromagnetic waves are transmitted and TM polarized electromagnetic waves are reflected back; when encoded as the "11 / 01" state, TE polarized electromagnetic waves are reflected back and TM polarized electromagnetic waves are transmitted.

[0036] The frequency selective surface with electromagnetic switch and polarization selection functions of the present invention realizes active adjustment of three electromagnetic functions of stealth, bandpass and shielding and nine different working states in one design by independently controlling the DC bias state. It also has the advantages of polarization stability and wide working frequency band, and has broad application prospects in the complex and changeable electromagnetic environment in the future.

Claims

1. A frequency selective surface with electromagnetic switching and polarization selection functions, characterized in that: include: The invention discloses a two-layer dielectric substrate, an upper metal structure unit, a lower metal structure unit and an air cavity. The upper metal structure unit is a deformed Jerusalem cross metal structure. The lower metal structure unit is composed of a deformed "I"-shaped metal structure and two rows of metal fine wire structures parallel thereto. The upper metal structure unit is arranged on both sides of the dielectric substrate and the metal structures on both sides are connected by metal vias. The lower metal structure unit is orthogonally arranged on both sides of the dielectric substrate. There is an air cavity between the upper metal structure unit and the lower metal structure unit. Every two adjacent cross metal unit structures in the upper layer are identical and orthogonal to each other and are connected by a PIN diode. A resistor is loaded in each of the four gaps in the middle of the cross metal unit structure. A PIN diode is integrated between the gaps of every two adjacent "I"-shaped metal unit structures in the lower layer. The PIN diodes arranged along the same polarization in the same metal layer have the same direction, and the PIN diodes loaded in the same row of metal periodic structures are connected in series.

2. The frequency selective surface with electromagnetic switch and polarization selection function as claimed in claim 1, characterized in that: The materials of the two dielectric substrates are the same, and polytetrafluoroethylene, epoxy glass fiber or epoxy resin is selected; the metal structural unit material is a metal with good conductivity and stable properties.

3. The frequency selective surface with electromagnetic switch and polarization selection function as claimed in claim 1, characterized in that: The metal cell structure itself is connected to the PIN diode as part of the feed line.

4. The frequency selective surface with electromagnetic switch and polarization selection function as claimed in claim 1, characterized in that: The situation of the DC bias voltage applied to the upper and lower metal structure units is encoded. By independently controlling the working states of the PIN diodes in different polarization directions of the upper and lower layers and changing the encoding state, the three functions of stealth, bandpass and shielding can be achieved, including independent selection of TE polarized wave stealth, bandpass and shielding and independent selection of TM polarized wave stealth, bandpass and shielding, a total of nine different combination states.

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