Wide-interval dual-band frequency selective surface structure and radar communication equipment

Abstract

The invention relates to a wide-interval dual-band frequency selective surface structure and radar communication equipment, the wide-interval dual-band frequency selective surface structure comprises a plurality of frequency selective surface structure units forming a periodic rectangular array, and each frequency selective surface structure unit comprises a dielectric substrate; the metal layer is arranged on one side of the dielectric substrate, the metal layer comprises a metal square patch and a plurality of bent dipole units etched on the metal square patch, the bent dipole units are arranged in a hollowed-out mode, and the bent dipole units are distributed around the center of the metal square patch in a central symmetry mode; the multiple frequency selective surface structure units are arranged in a central symmetry mode, it is guaranteed that the filtering characteristic insensitive to polarization is obtained, two wide-interval dual-frequency filtering passbands are generated in the X band and the K band, the two frequency bands have good polarization stability and filtering characteristic, and the structure is easy to machine.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, in particular to a wide-interval dual-band frequency selective surface structure and radar communication equipment. Background Art

[0002] Frequency Selective Surface (FSS) refers to a two-dimensional or three-dimensional periodic array structure composed of periodically arranged metal patch units or aperture units on a metal screen. It is a periodic structure that can selectively transmit or reflect electromagnetic waves of different frequencies. It has high research value and application prospects in the military and meteorological fields. It has been widely used in stealth technology of aircraft and warships, antenna sub-reflectors, radar communications, electromagnetic shielding and other fields.

[0003] With the rapid development of modern communication and radar technology, the demand for multi-band communication is becoming increasingly prominent. In practical applications, whether it is used for reflective surface antennas for frequency division multiplexing or for radomes, the key is to design a multi-band FSS with transmission and reflection characteristics, and the frequency response characteristics need to have good polarization stability. In engineering applications, the design and implementation of two large-interval filtering characteristics generally adopt multi-screen cascade technology, because the filtering characteristics of the frequency selective surface structure are related to the unit size. Due to the unit size limitation and coupling interference between units, it is generally difficult to achieve a larger frequency band interval through a single-layer structure. However, the introduction of a multi-layer structure may lead to an increase in the overall thickness and volume of the FSS, and the surface processing error and complexity are high, which also leads to an increase in manufacturing costs. In some application scenarios, especially for systems that are sensitive to space constraints, the increased thickness and volume may not be desirable. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problems in the prior art that it is difficult to achieve a larger frequency band interval in a multi-band frequency selective surface structure through a single-layer structure, and the introduction of a multi-layer structure will lead to an increase in the volume and weight of the frequency selective surface structure, and thus provide a wide-interval dual-band frequency selective surface structure and radar communication equipment, which achieves two wide-interval dual-frequency filtering passbands in the X-band and K-band through a single-layer structure, and has good polarization stability and filtering characteristics in both frequency bands, and the structure is also easy to process.

[0005] In order to solve the above technical problems, the present invention provides a wide-interval dual-band frequency selective surface structure and a radar communication device, comprising a plurality of frequency selective surface structure units forming a periodic rectangular array, wherein the frequency selective surface structure unit comprises:

[0006] dielectric substrate;

[0007] A metal layer is arranged on one side of the dielectric substrate, the metal layer includes a metal square patch and a plurality of bent dipole units etched on the metal square patch, the bent dipole units are hollowed out, and the plurality of bent dipole units are centrally symmetrically distributed around the center of the metal square patch.

[0008] In one embodiment of the present invention, four bent dipole units are included, and each bent dipole unit is formed by rotating the previous bent dipole unit counterclockwise by 90°.

[0009] In one embodiment of the present invention, the bent dipole unit is formed by bending a straight dipole unit 90 degrees multiple times, and an "S"-shaped section is provided at the end of the bent dipole unit.

[0010] In one embodiment of the present invention, the metal layer is connected to the dielectric substrate through a photolithography process or a printed circuit board process.

[0011] In one embodiment of the present invention, the metal layer is configured to be one of Au, Ag, Cu or Al.

[0012] In one embodiment of the present invention, the dielectric substrate is configured to be one of a fiber material and a resin material, or is configured to be a composite material of the fiber material and the resin material.

[0013] In one embodiment of the present invention, the dielectric substrate is made of F4B-2 polytetrafluoroethylene.

[0014] In one embodiment of the present invention, the thickness of the dielectric substrate may be 0.1-1 mm.

[0015] In one embodiment of the present invention, the bent dipole unit is located on a side of the metal square patch opposite to the side connected to the dielectric substrate.

[0016] To solve the above problems, the present invention also provides a radar communication device, which includes the wide-spaced dual-band frequency selective surface structure.

[0017] The above technical solution of the present invention has the following advantages compared with the prior art:

[0018] The wide-interval dual-band frequency selective surface structure described in the present invention has a centrally symmetrical structure and a single-layer structure, which ensures that filtering characteristics that are insensitive to polarization are obtained; the stability of the center frequency can be maintained in both TE and TM polarization modes, and no matter the electromagnetic wave is incident in TE or TM polarization mode, it has stable filtering characteristics, the center frequency is almost not offset, and the maximum center frequency offset rate is only 1.2%, which can achieve reliable transmission, enhance its applicability and versatility, and is easier to integrate into various communication, radar and other systems; it only includes a dielectric substrate layer and a metal layer, has a simple structure, reduces the complexity of the manufacturing process, reduces the manufacturing cost, and is more feasible in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of the wide-interval dual-band frequency selective surface structure of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram of the structure of the metal layer of the wide-spaced dual-band frequency selective surface structure shown;

[0022] Figure 3 The transmission characteristics of the wide-spaced dual-band frequency selective surface structure of the present invention when the electromagnetic wave is vertically incident in TE polarization mode;

[0023] Figure 4 The transmission characteristics of the wide-spaced dual-band frequency selective surface structure of the present invention when the electromagnetic wave is vertically incident in TM polarization mode;

[0024] Figure 5 for Figure 1 The surface current density distribution diagram of the wide-spaced dual-band frequency selective surface structure at 9.6 GHz under vertical incidence of electromagnetic waves;

[0025] Figure 6 for Figure 1 The surface current density distribution diagram of the wide-spaced dual-band frequency selective surface structure at 19 GHz under vertical incidence of electromagnetic waves;

[0026] Figure 7 for Figure 2 Schematic diagram of the structure of the metal square patch and the bent dipole unit of the metal layer shown.

[0027] Description of the accompanying drawings in the specification: 1. Metal layer; 11. Bent dipole unit; 111. "S"-shaped section; 2. Dielectric substrate. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0029] Example

[0030] Reference Figure 1 As shown, in one embodiment of the present invention, a wide-spaced dual-band frequency selective surface structure is disclosed, which is an array structure based on an improved dipole unit structure compactly arranged and designed, and is a single-layer structure, including a plurality of frequency selective surface structure units forming a periodic rectangular array, the frequency selective surface structure units are arranged in a square arrangement, the array period Dx = Dy = 6.4 mm, and the frequency selective surface structure units include,

[0031] Dielectric substrate 2;

[0032] A metal layer 1 is arranged on one side of the dielectric substrate 2, the metal layer 1 specifically comprises a metal square patch and a plurality of bent dipole units 11 etched on the metal square patch, the bent dipole unit 11 comprises two parallel metal bars, the bent dipole unit 11 is bent to form a hollow unit, and the plurality of bent dipole units 11 are centrally symmetrically distributed around the center of the metal square patch and the plurality of bent dipole units 11 do not have any intersection, and the entire structure is designed to be a centrally symmetrical structure, thereby ensuring that a filtering characteristic that is insensitive to polarization is obtained;

[0033] Furthermore, detailed geometric parameters of the metal layer 1 are shown in Table 1 below:

[0034] Table 1 FSS unit structure parameters

[0035]

[0036] In one embodiment of the present invention, referring to Figure 1 As shown, it includes four bent dipole units 11, each of which is formed by rotating the previous bent dipole unit 11 counterclockwise by 90°. When an electromagnetic wave is incident on the frequency selective surface structure, the metal strips parallel to the electric field direction can be equivalent to inductance, and the gaps between the metal strips perpendicular to the electric field direction are equivalent to capacitance. The bent dipole unit 11 can be equivalent to an inductor and capacitor parallel resonant circuit. The overall inductance is increased by the zigzag design, and the compact design reduces the unit spacing. The reduced spacing increases the equivalent capacitance, thereby reducing the resonant frequency.

[0037] In one embodiment of the present invention, referring to Figure 1As shown, the bent dipole unit 11 is formed by a linear dipole unit being bent 90° seven times, and an "S"-shaped section 111 formed by bending 90° four times is provided at the end of the bent dipole unit 11. The bent dipole unit 11 generates a transmission pole in the first frequency band, and the transmission pole in the second frequency band is generated by the resonance of the "S"-shaped section 111 at the end of the bent dipole unit 11.

[0038] Furthermore, the bent dipole unit 11 resonates when the unit length is approximately equal to half the effective wavelength, so the length of the bent dipole unit 11 can be obtained according to the resonance frequency.

[0039] When the medium is loaded on one side, the resonant wavelength λ of the frequency selective surface structure can be calculated by the following formula:

[0040]

[0041] Where λ0 is the resonant wavelength of the frequency selective surface structure without dielectric loading, ε r is the relative dielectric constant of the dielectric plate.

[0042] The relationship between λ0 and the resonant frequency f is as follows,

[0043] λ0=c / f (2)

[0044] Among them, c is the speed of light in vacuum and f is the resonant frequency.

[0045] According to equations (1) and (2), the effective wavelength of the X-band when the dielectric substrate 2 of F4B-2 polytetrafluoroethylene with a dielectric constant of 2.65 is loaded can be calculated. The length of the bent dipole unit 11 can be roughly estimated to be about 11.6 mm. By adjusting the number of bends, length and width of the bent dipole unit 11, the filtering characteristics of the frequency selective surface can be fine-tuned.

[0046] In the actual engineering application of frequency selective surface structures, the polarization mode of the incident wave source is often unknown. Therefore, it is necessary to study the polarization stability of frequency selective surface structures. The research results are as follows: Figure 3 and Figure 4 They are the transmission characteristic curves of TE and TM polarized electromagnetic waves when they are vertically incident, Figure 3 It can be seen that the frequency selective surface structure has dual-bandpass selection characteristics, the passband center resonant frequencies are 9.6 GHz and 19 GHz respectively, the -3dB bandwidths of the first resonant frequency band and the second resonant frequency band are 1.41 GHz and 3.43 GHz respectively, and the corresponding passband insertion losses are only -0.09 dB and -0.1 dB.

[0047] Depend on Figure 4It can be seen that under different polarization modes, the center resonant frequencies of the two frequency bands remain almost unchanged, the offset is less than 1.2%, the insertion loss is less than -0.1dB, the bandwidth remains stable, and stable X-band and K-band dual-frequency filtering characteristics are achieved. The frequency selective surface structure is basically not affected by the polarization mode of the electromagnetic wave, and can give a stable center frequency for different polarization modes. It can be used in many situations where the polarization mode of the incident wave is unknown, such as radio communications and stealth radar covers, to achieve better transmission characteristics.

[0048] Figure 5 and Figure 6 They are the surface current density distribution diagram of the frequency selective surface structure under vertical incidence of TE electromagnetic wave, Figure 5 It can be seen that when the frequency selective surface structure operates at 9.6 GHz, the current is mainly distributed in the bent dipole unit 11, and when the frequency selective surface structure operates at 19 GHz, the current is mainly distributed in the "S"-shaped section 111 at the end of the bent dipole unit 11; the bent dipole unit 11 determines the size of the first resonant frequency, and the "S"-shaped section 111 at the end of the bent dipole unit 11 determines the size of the second resonant frequency.

[0049] In one embodiment of the present invention, referring to Figure 1 As shown, the metal layer 1 is disposed on the dielectric substrate 2 by a photolithography process or a printed circuit board process.

[0050] In one embodiment of the present invention, referring to Figure 1 As shown, the metal layer 1 is set to be made of Cu material. Cu material has low resistivity, easy preparation, low price and other advantages. In other embodiments, one of Au, Ag, Cu or Al materials can be set.

[0051] In one embodiment of the present invention, referring to Figure 1 As shown, the dielectric substrate 2 is configured to be one of a fiber material and a resin material, or is configured to be a composite material of the fiber material and the resin material.

[0052] In one embodiment of the present invention, referring to Figure 1 As shown, the dielectric substrate 2 is made of F4B-2 polytetrafluoroethylene, with a relative dielectric constant εr=2.65. The substrate has the advantages of high temperature resistance, low temperature resistance, corrosion resistance, high lubricity, non-adhesion, and non-toxicity.

[0053] In one embodiment of the present invention, referring to Figure 1 As shown, the thickness of the dielectric substrate 2 may be 0.1-1 mm, and preferably the thickness h=0.5 mm.

[0054] In one embodiment of the present invention, referring to Figure 1As shown, the bent dipole unit 11 is located on a side of the metal square patch opposite to the dielectric substrate 2 .

[0055] To solve the above problems, the present invention also provides a radar communication device, which includes the wide-spaced dual-band frequency selective surface structure.

[0056] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A widely spaced dual-band frequency selective surface structure, characterized in that: The invention comprises a plurality of frequency selective surface structural units forming a periodic rectangular array, wherein the frequency selective surface structural unit comprises: dielectric substrate; A metal layer is arranged on one side of the dielectric substrate, the metal layer includes a metal square patch and a plurality of bent dipole units etched on the metal square patch, the bent dipole units are hollowed out, and the plurality of bent dipole units are centrally symmetrically distributed around the center of the metal square patch.

2. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: It comprises four bent dipole units, each of which is formed by rotating the previous bent dipole unit counterclockwise by 90°.

3. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The bent dipole unit is formed by bending a straight dipole unit 90 degrees multiple times, and an "S"-shaped section is arranged at the end of the bent dipole unit.

4. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The metal layer is connected to the dielectric substrate through a photolithography process or a printed circuit board process.

5. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The metal layer is configured to be one of Au, Ag, Cu or Al.

6. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The dielectric substrate is configured to be one of a fiber material and a resin material, or is configured to be a composite material of the fiber material and the resin material.

7. A wide-spaced dual-band frequency selective surface structure according to claim 6, characterized in that: The dielectric substrate is made of F4B-2 polytetrafluoroethylene.

8. The wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The thickness of the dielectric substrate may be 0.1-1 mm.

9. A wide-spaced dual-band frequency selective surface structure according to claim 1, characterized in that: The bent dipole unit is located on a side of the metal square patch opposite to the dielectric substrate.

10. A radar communication device, characterized in that: It comprises a widely spaced dual-band frequency selective surface structure as claimed in any one of claims 1 to 9.

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