CN110690577A

CN110690577A - Dual-polarization band-pass three-dimensional frequency selection surface with bilateral steep drop characteristic

Info

Publication number: CN110690577A
Application number: CN201910902076.6A
Authority: CN
Inventors: 于正永; 董进; 束美其; 华山; 徐彤
Original assignee: Huaian Vocational College of Information Technology
Current assignee: Huaian Vocational College of Information Technology
Priority date: 2019-09-17
Filing date: 2019-09-17
Publication date: 2020-01-14

Abstract

The invention discloses a dual-polarized band-pass three-dimensional frequency selection surface with bilateral steep drop characteristics. The frequency selective surface is composed of a plurality of identical unit structures which are arranged periodically, and each unit structure is composed of three layers. The outermost layer is a medium square cylinder; the middle layer is a metal square cylinder; the innermost layer is a medium square, a metal square ring is etched on the upper surface and the lower surface of the medium square, the two metal square rings are the same in size and are distributed in an up-down axial symmetry mode. The two metal square rings are electromagnetically coupled through the dielectric square, the single resonance mode is split into an odd mode resonance mode and an even mode resonance mode, two transmission poles are generated, and therefore a flat pass band is formed. Because the signal phases in the outermost medium square tube and the innermost medium square tube are reversed and electromagnetically coupled, three transmission zeros are generated, so that the frequency selection surface of the invention has the characteristic of bilateral steep drop, the frequency selection performance is improved, and meanwhile, the invention has good angle stability in a dual-polarization working mode.

Description

Dual-polarization band-pass three-dimensional frequency selection surface with bilateral steep drop characteristic

Technical Field

The invention belongs to the technical field of electromagnetic fields and microwaves, and particularly relates to a dual-polarized band-pass three-dimensional frequency selection surface with bilateral steep drop characteristics.

Background

Frequency Selective Surface (FSS) is generally a two-dimensional array structure composed of periodic units with specific shapes, and has the function of a spatial filter. Under the irradiation of electromagnetic waves, the FSS does not absorb the electromagnetic waves, but a resonance phenomenon occurs at a certain specific frequency, and at this time, the transmission field or the reflection field is maximized, so that the effect of transmitting or reflecting the electromagnetic waves can be effectively achieved, and therefore, the FSS can be roughly divided into two types, namely a band-pass type and a band-stop type. In recent decades, FSS has been widely used in the fields of space filtering, antenna covers, electromagnetic shielding, reflectors, and wave absorbers. In practical application, the research and application of the band-pass type FSS are particularly extensive, and the out-band inhibition degree of the FSS has great influence on the performance of the whole system.

The out-of-band rejection performance of FSS is typically improved by introducing transmission zeros out-of-band of the passband. The traditional two-dimensional FSS structure can realize band-pass FSS through various modes such as metal patches, metal rings, metal strip lines, grooves and the like, but a transmission zero point is often introduced into one side of a pass band, so that the bilateral steep drop performance of the pass band is difficult to realize; later researchers adopted a multilayer stacking mode, although transmission zero points are introduced to two sides of a passband, the bilateral steep drop performance of the passband is realized, and the frequency selectivity is well improved, the multilayer stacking mode causes the electrical size and the thickness of the whole FSS unit structure to be increased, so that the angle stability of the FSS is influenced, and the practical application in a communication system is difficult. Compared with a two-dimensional structure, the three-dimensional structure has one more design dimension, and more resonant cavities can be constructed by utilizing the advantage to generate more transmission zero points so as to improve out-of-band rejection performance. Therefore, it is significant to design a dual-polarized three-dimensional FSS with a steep two-edge drop characteristic and good angular stability.

Disclosure of Invention

The invention provides a dual-polarized band-pass three-dimensional frequency selection surface with bilateral steep drop characteristics, which realizes stable frequency response under different polarizations and different incident angles.

The invention provides a dual-polarized band-pass three-dimensional frequency selection surface with bilateral steep drop characteristics, which is formed by periodically arranging a plurality of same unit structures, wherein each unit structure consists of three layers. The outermost layer is a medium square cylinder; the middle layer is a metal square cylinder; the innermost layer is a dielectric square block, metal square rings are etched on the upper surface and the lower surface of the dielectric square block, the two metal square rings are identical in size and are distributed in an up-down axial symmetry mode.

The dual-polarized band-pass three-dimensional frequency selection surface with the bilateral steep drop characteristic can be manufactured by combining two processing technologies of three-dimensional printing and a common Printed Circuit Board (PCB), and is simple to manufacture. The two metal square rings are electromagnetically coupled through the dielectric square block, a single resonance mode is split into two resonance modes, namely an odd mode and an even mode, two transmission poles are generated correspondingly, and therefore a flat pass band is formed. Because the signal phases in the outermost medium square tube and the innermost medium square tube are reversed and electromagnetically coupled, three transmission zeros are generated, so that the frequency selection surface of the invention has the characteristic of bilateral steep drop, and the frequency selection performance is improved. The dual polarization is realized due to the symmetry of the unit structure; and has stable frequency response under the incidence of 0-60 degrees.

Drawings

Fig. 1 is a three-dimensional schematic diagram of a dual-polarized bandpass three-dimensional frequency selective surface with a bilateral steep drop characteristic according to the present invention, which is exemplified by 4 × 4 units.

FIG. 2 is a schematic diagram of the cell structure of the present invention.

FIG. 3 is a schematic view of the three-layer structure constituting the unit structure of the present invention (a) the outermost layer; (b) an intermediate layer; (c) the innermost layer.

FIG. 4 is a top view of the cell structure of the present invention.

FIG. 5 is a simulation curve of transmission coefficient and reflection coefficient when electromagnetic waves are vertically incident.

FIG. 6 is a simulated TE polarization curve of transmission coefficient at different incident angles according to the present invention; (b) the TM is polarized.

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.

The specific embodiment discloses a dual-polarized bandpass three-dimensional frequency selection surface with bilateral steep-drop characteristics, which takes 4 × 4 units as an example, and is composed of 16 same unit structures 1 which are periodically arranged as shown in fig. 1.

Fig. 2 shows a schematic diagram of the cell structure of the present invention, which includes three layers of the dielectric square tube 11 at the outermost layer, the metal square tube 12 at the middle layer, and the dielectric square block 13 at the innermost layer, and simultaneously, the metal square ring 131 and the metal square ring 132 are etched on the upper surface and the lower surface of the dielectric square block 13, respectively. The two metal square rings have the same size and are distributed in an up-and-down axial symmetry mode.

Fig. 3 shows a schematic diagram of a three-layer structure constituting the unit structure of the present invention. Fig. 3(a) is the outermost layer, namely, the medium square tube 11; FIG. 3(b) shows the intermediate layer, i.e., the metal square tube 12; fig. 3(c) shows the dielectric block 13 with the innermost layer, i.e., the upper surface and the lower surface, etched with the metal square ring 131 and the metal square ring 132, respectively.

FIG. 4 is a top view of the cell structure of the present invention. The design parameters p is 12.4mm, a is 10mm, b is 7.6mm, w is 0.6mm, and t is 0.8mm, and the height of the frequency selective surface in the z-axis direction is 6 mm. The dielectric relative dielectric constant of the outermost dielectric square tube 11 is 2.2, and the dielectric relative dielectric constant of the innermost dielectric square tube 13 is 4.4.

FIG. 5 is a simulation curve of transmission coefficient and reflection coefficient when electromagnetic waves are vertically incident. As can be seen from the figure, the two transmission poles are respectively positioned at 5.17GHz and 5.31GHz, a flat passband is formed, the center frequency is 5.2GHz, and the 3dB relative bandwidth of the passband is 7.9%. In addition, three transmission zero points generated outside the band are respectively positioned at 4.14GHz, 5.62GHz and 7.46GHz, so that better bilateral steep drop performance is realized, and the frequency selectivity is improved; the suppression depth reaches below-20 dB in the frequency range of 5.54GHz-8.16GHz, and the relative bandwidth of 20dB of the stop band is 38.2%, so that the frequency selection surface has better out-of-band suppression performance.

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. It can be seen from the figure that, in both the TE and TM polarization modes, the electromagnetic wave has better angle stability when incident at angles of 0 °, 30 ° and 60 °, which fully proves that the present invention has better practicability.

Claims

1. A dual-polarized band-pass three-dimensional frequency selective surface with bilateral steep drop characteristics is composed of a plurality of same unit structures which are periodically arranged, and is characterized in that the unit structures are composed of three layers; the outermost layer is a medium square cylinder; the middle layer is a metal square cylinder; the innermost layer is a dielectric block.

2. The dual-polarized bandpass three-dimensional frequency selective surface with bilateral steep drop characteristics according to claim 1, wherein the dielectric square block is etched on both the upper surface and the lower surface thereof with a metal square ring.

3. The dual-polarized bandpass three-dimensional frequency selective surface with bilateral steep dip characteristics according to claim 2, wherein the etched two metal square rings have the same size and are distributed in an up-down axial symmetry.