CN111817011A

CN111817011A - Narrow-band-pass frequency selection surface

Info

Publication number: CN111817011A
Application number: CN202010708416.4A
Authority: CN
Inventors: 董进; 于正永
Original assignee: Jiangsu Vocational College of Electronics and Information
Current assignee: Jiangsu Vocational College of Electronics and Information
Priority date: 2020-07-15
Filing date: 2020-07-15
Publication date: 2020-10-23

Abstract

The invention discloses a narrow-band-pass frequency selection surface. The frequency selective surface is formed by periodically arranging a plurality of same unit structures, and each unit structure comprises a square metal cylinder and a square dielectric block. The upper and lower surfaces of the square dielectric block are carved with a pair of identical Yelu spreading cold metal crosses, and the middle layer is a square metal plate with four identical rectangular apertures. The upper surface and the lower surface of the unit structure are electromagnetically coupled through the rectangular aperture of the middle layer, so that two transmission poles are generated, and a flat pass band is formed. Meanwhile, two transmission zeros are introduced outside the right side of the passband, so that the invention has high frequency selectivity and wide out-of-band rejection. Meanwhile, the frequency selective surface has good angular stability in a dual-polarization mode.

Description

Narrow-band-pass frequency selection surface

Technical Field

The invention belongs to the technical field of electromagnetic fields and microwaves, and particularly relates to a narrow-band-pass frequency selection surface.

Background

Frequency Selective Surface (FSS) has recently attracted much attention by researchers as a type of spatial filter. Due to the unique spatial filtering characteristic, the composite material is often applied to a radome, a wave-absorbing material, an antenna sub-reflector and the like. In a narrow-band communication application scenario, it is necessary to design a band-pass FSS with narrow-band characteristics.

The conventional two-dimensional FSS is often limited in achieving high performance, for example, limited resonant modes cannot introduce more transmission zero points, the working bandwidth of a single-layer FSS is limited, and the thickness and electrical size increase caused by a multi-layer FSS are insufficient. Later researchers put forward the concept of three-dimensional FSS, compared with two-dimensional FSS, the three-dimensional FSS increases the design freedom of one dimension, the unit structure can realize the construction of a plurality of resonance modes more easily, and a thought is provided for the design of high-performance FSS. Three-dimensional FSS concepts were originally proposed by Shenzhou Xiang professor team of the southern Yangtze university of Singapore, and they designed a series of band-pass three-dimensional FSSs based on a shielding microstrip line structure, so that the above problems were effectively improved, but these structures can only work in a single polarization mode, and the practical application of the structures was limited. Later, researchers have proposed a dual-polarization bandpass three-dimensional FSS based on a square coaxial waveguide structure, and due to the symmetrical design of the unit structure, the dual-polarization performance is easy to realize, but the dual-polarization performance is heavy, complex to assemble and high in cost. Researchers load a dielectric resonator on a metal plate based on a through hole, and realize the band-pass three-dimensional FSS with the broadband characteristic by means of the electromagnetic coupling effect, but both sides of a pass band do not have any transmission zero point, and the frequency selection performance and the out-of-band rejection performance of the resonator are general. Therefore, in the context of narrow-band communication applications, it is significant to design an FSS having the advantages of narrow-band characteristics, high frequency selectivity, wide out-of-band rejection, good angular stability, dual polarization, and the like.

Disclosure of Invention

The invention provides a narrow-band-pass frequency selection surface, which realizes stable frequency response under two polarization modes of TE and TM and different incidence angles, and has the advantages of narrow-band characteristic, high frequency selectivity, wide out-of-band rejection and smaller electrical size.

The invention provides a narrow-band-pass frequency selection surface, which is formed by periodically arranging a plurality of same unit structures, wherein each unit structure comprises a square metal tube and a square dielectric block. The upper and lower surfaces of the square dielectric block are carved with a pair of identical Yelu spreading cold metal crosses, and the middle layer is a square metal plate with four identical rectangular apertures.

According to the narrow-band-pass frequency selection surface provided by the invention, the upper surface and the lower surface of the unit structure are electromagnetically coupled through the rectangular aperture of the middle layer, so that two transmission poles are generated, and a flat pass band is formed. Meanwhile, two transmission zeros are introduced outside the right side of the passband, so that the invention has high frequency selectivity and wide out-of-band rejection. The unit structure of the invention has symmetry, so that dual polarization is easy to realize; meanwhile, under the TE and TM dual-polarization modes, the high-power-factor antenna has good angle stability when the light is incident at angles of 0 degrees, 30 degrees and 60 degrees. Compared with the existing band-pass FSS, the FSS has the advantages of narrow-band characteristics, high frequency selectivity, wide out-of-band rejection, good angular stability, dual polarization, smaller electrical size and the like.

Drawings

Fig. 1 is a three-dimensional schematic diagram of a unit structure of a narrowband bandpass frequency selective surface according to the present invention.

FIG. 2 is a schematic view of the components that make up the cell structure of the present invention (a) a square metal can; (b) a square dielectric block.

FIG. 3 is a perspective view of a unit structure dimension labeling schematic diagram (a) and parameter labeling of a narrowband bandpass frequency selection surface according to the present invention; (b) upper and lower surfaces and parametric markings (c) intermediate layer and parametric markings.

Fig. 4 is a three-dimensional schematic diagram of a narrowband bandpass frequency selective surface (4 × 4 unit structure) proposed by the present invention.

Fig. 5 is a diagram showing simulation results of transmission coefficients and reflection coefficients of the narrowband bandpass frequency selective surface provided by the invention when electromagnetic waves are vertically incident.

Fig. 6 is a transmission coefficient simulation result graph (a) of the narrowband bandpass frequency selective surface proposed by the present invention under different incident angles; (b) the TM mode.

Detailed Description

For the purpose of explaining the technical solution disclosed in the present invention in detail, the following description is further made with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a three-dimensional schematic diagram of a unit structure of a narrowband bandpass frequency selective surface according to the present invention. Each unit structure is formed by combining a square metal cylinder 1 and a square medium block 2.

Figure 2 shows a schematic of the components making up the cell structure of the present invention. Fig. 2(a) shows a square metal can 1; fig. 2(b) shows a square dielectric block 2. The upper and lower surfaces of the square dielectric block 2 are carved with a pair of identical Yelu cold metal crosses 21, and the middle layer is a square metal plate 22 with four identical rectangular apertures.

Fig. 3 is a schematic diagram illustrating the dimension of the unit structure of the narrowband bandpass frequency selective surface according to the present invention. Fig. 3(a) is a perspective view of a unit structure, fig. 3(b) is a schematic view of upper and lower surfaces of the unit structure, and fig. 3(c) is a schematic view of an intermediate layer of the unit structure. The design parameter is p ═ 9.5mm, l₀＝3mm，l＝7mm，w₀0.5mm, 1.5mm, and a square dielectric block having a relative dielectric constant of 4.4.

Fig. 4 is a three-dimensional schematic diagram of a narrowband bandpass frequency selective surface (4 × 4 unit structures) proposed by the present invention, which is formed by the unit structures shown in fig. 1 being periodically arranged in a two-dimensional plane direction.

FIG. 5 is a simulation curve of transmission coefficient and reflection coefficient when electromagnetic waves are vertically incident. It can be seen from the figure that the two transmission poles are generated at 6.36GHz and 6.42GHz, respectively, thereby forming a flat pass band with a center frequency of 6.39GHz and a 3dB relative bandwidth of the pass band of only 2.8%. And meanwhile, two transmission zeros (respectively positioned at 7GHz and 8.2 GHz) are generated outside the right side band, so that the frequency selection performance is improved. The 20dB bandwidth of the right side stop band is 6.4GHz (6.6-13 GHz), and the corresponding relative bandwidth is 65.3%. The electrical size (p × p × h) of the unit structure is 0.2 λ₀×0.2λ₀×0.03λ₀Wherein λ is₀Is the free space wavelength. It can be seen that the FSS has narrow band characteristics, high frequency selectivity, wide out-of-band rejection, and small electrical size.

Fig. 6(a) and fig. 6(b) are transmission coefficient simulation curves corresponding to different incident angles in two polarization modes of TE and TM, respectively. As can be seen from the figure, in both the TE polarization mode and the TM polarization mode, the electromagnetic wave has better angle stability when being incident at angles of 0 degrees, 30 degrees and 60 degrees.

The invention discloses a narrow-band-pass frequency selection surface, which is formed by periodically arranging a plurality of same unit structures, wherein each unit structure comprises a square metal cylinder and a square dielectric block. The upper and lower surfaces of the square dielectric block are carved with a pair of identical Yelu spreading cold metal crosses, and the middle layer is a square metal plate with four identical rectangular apertures. According to the narrow-band-pass frequency selection surface provided by the invention, the upper surface and the lower surface of the unit structure are subjected to electromagnetic coupling through the aperture of the middle layer, so that two transmission poles are generated, and a flat pass band is formed. Meanwhile, two transmission zeros are introduced outside the right side of the passband, so that the invention has high frequency selectivity and wide out-of-band rejection. The unit structure of the invention has symmetry, so that dual polarization is easy to realize; meanwhile, under the TE and TM dual-polarization modes, the high-power-factor antenna has good angle stability when the light is incident at angles of 0 degrees, 30 degrees and 60 degrees. Compared with the existing band-pass FSS, the FSS has the advantages of narrow-band characteristics, high frequency selectivity, wide out-of-band rejection, good angular stability, dual polarization, smaller electrical size and the like.

Claims

1. A narrow-band-pass frequency selection surface is composed of a plurality of identical unit structures which are periodically arranged, and is characterized in that each unit structure is composed of a square metal cylinder and a square medium block.

2. The narrowband bandpass frequency-selective surface of claim 1, wherein the upper and lower surfaces of the square dielectric block are engraved with a pair of identical yered metal crosses.

3. The narrowband bandpass frequency-selective surface of claim 1, wherein the middle layer of the square dielectric block is a square metal plate with four identical rectangular apertures.