CN106329040B

CN106329040B - Composite cross-shaped gap frequency selection surface

Info

Publication number: CN106329040B
Application number: CN201610803551.0A
Authority: CN
Inventors: 华光; 高梓晟
Original assignee: Southeast University; Jiangsu Hengxin Technology Co Ltd
Current assignee: Southeast University; Jiangsu Hengxin Technology Co Ltd
Priority date: 2016-09-05
Filing date: 2016-09-05
Publication date: 2020-08-04
Anticipated expiration: 2036-09-05
Also published as: CN106329040A

Abstract

The invention provides a composite cross-shaped gap frequency selective surface, which is a Frequency Selective Surface (FSS) structure with low insertion loss, wide frequency band and space and frequency band-pass filtering performance. The present invention encompasses single and dual layer frequency selective surface structures. Wherein, the single-layer frequency selective surface layered structure is as follows from top to bottom: the copper-clad layer is a periodic metal patch unit and is formed by combining a four-leg loading gap unit and a cross gap unit, and the unit structure is a square periodic structure; the double-layer frequency selective surface layered structure comprises the following components in sequence from top to bottom: the copper-clad layer, the substrate layer, the dielectric layer, the substrate layer and the copper-clad layer are the same as the single-layer frequency selective surface metal patch in terms of the copper-clad layer patch unit and the periodic structure. The frequency selective surface has the advantages of simple structure, convenient processing and realization.

Description

Composite cross-shaped gap frequency selection surface

Technical Field

The invention relates to the technical field of antennas and microwaves, in particular to a Frequency Selective Surface (FSS) structure with low insertion loss, wide frequency band and space and frequency band-pass filtering performance. The antenna can be applied to the antenna housing of mobile communication base stations, radars, electronic navigation and other equipment to achieve the purposes of resisting interference and reducing radar scattering cross sections (RCS).

Background

The Frequency Selective Surface (FSS) is a two-dimensional periodic structure with frequency selective characteristics, which is widely used as a spatial filter on antenna covers in wireless communication, radar, and electronic countermeasure systems. The radome loaded with the frequency selective surface has frequency selective characteristics of low insertion loss in the pass band and out-of-band rejection to reduce interference, in addition to the basic functions of a basic dustproof, waterproof, and wind-resistant protection antenna. With the rapid development of mobile communications and the increasingly stringent requirements for spectrum resources, base station antennas increasingly require better frequency selection characteristics to radiate efficiently and reduce mutual interference between wireless devices. In addition, electromagnetic compatibility is also required between wireless devices such as radar, communication and navigation devices through the spatial filtering characteristics of the frequency selective surface.

Disclosure of Invention

The technical problem is as follows: the technical problem to be solved by the invention is to provide a band-pass type composite cross-shaped slot frequency selection surface structure which can be used for antenna equipment (such as mobile communication base station antenna covers) with a frequency band around 2.6GHz, and has the characteristics of low insertion loss and wide frequency band.

The technical scheme is as follows: the composite cross-shaped gap frequency selection surface is formed by periodic units which periodically extend along the horizontal direction and the vertical direction, the periodic units are rectangular, the structure of each unit is formed by combining a four-leg loading gap unit and a cross gap, and the gaps of different units are mutually isolated.

When the gap frequency selective surface is a single-layer frequency selective surface, the single-layer frequency selective surface structure comprises 3 layers of media, which are sequentially from top to bottom: copper-clad layer, base plate layer, dielectric layer; wherein:

the copper-clad layer is attached to the surface of the substrate layer and is a frequency selective surface periodic structure printing layer;

the substrate layer is attached to the surface of the dielectric layer, is a conventional thin-layer substrate dielectric material layer and has the characteristic of easy commonality;

the dielectric layer is a radome commonly used for mobile communication.

When the gap frequency selective surface is a double-layer frequency selective surface structure, the double-layer frequency selective surface structure comprises 5 layers of media, the middle layer is a dielectric layer, two surfaces of the dielectric layer are respectively provided with a substrate layer, and the outer sides of the two substrate layers are respectively provided with a copper-clad layer; wherein:

the copper-clad layer is attached to the surface of the substrate layer and is a frequency selective surface periodic structure printing layer, and the frequency selective surface periodic structures of the upper and lower metal layers are the same;

the dielectric layer is a radome commonly used for mobile communication.

Has the advantages that: by adopting the antenna housing with the spatial filtering characteristic, the antenna housing with the spatial filtering characteristic can be realized, the wave-transmitting performance in a pass band is good, the signal loss is small, the obvious suppression effect is achieved in a stop band, and the anti-interference capability is strong.

TABLE 1 Combined Unit Performance

Index (I)	Single layer FSS	Double layer FSS
			Passband frequency (-0.5 dB, GHz)	2.46～2.78	1.72～2.71
Relative bandwidth	12.2％	44.7％
			2.555GHz insertion loss (dB)	～0.34	～0.18
12GHz insertion loss (dB)	～0.30	～0.31
			Stopband frequency (-10 dB, GHz)	～～1.27	～～1.02
0.96GHz insertion loss (dB)	～13.31	～11.10
			0.89GHz insertion loss (dB)	～14.12	～12.39

Drawings

FIG. 1 is a schematic view of a layered structure of a frequency selective surface according to the present invention, wherein (a) is a single layer structure; (b) has a double-layer structure.

FIG. 2 is a schematic diagram of a frequency selective surface period distribution structure according to the present invention.

Fig. 3 is a schematic diagram of a combined structure of a frequency selective surface four-leg loading slot unit and a cross slot according to the present invention.

FIG. 4 is a graph of the transmission coefficient of electromagnetic waves for a frequency selective surface according to the present invention. Wherein (a) is a single-layer structure transmission coefficient; (b) the transmission coefficient of the double-layer structure.

The figure shows that: the device comprises a dielectric layer 1, a substrate layer 2, a copper-clad layer 3, a cross gap 4 and a four-leg loading annular gap 5.

Detailed Description

The single-layer frequency selective surface structure of the invention comprises: a substrate layer, a periodic metal plane structure (copper clad layer), and a dielectric. The periodic planar metal structure is attached to the substrate, and the medium is located below the substrate layer. The thickness of the substrate is about 0.1mm, and the dielectric constant is between 4 and 5. The dielectric thickness is about 2-3 mm, and the dielectric constant is between 3-6.

The double-layer frequency selective surface structure of the invention comprises: a substrate layer, a periodic metal plane structure (copper clad layer), and a dielectric. Wherein, two layers of periodic planar metal structures are attached to respective substrates and respectively attached to two sides of the medium. The thickness of the substrate is about 0.1mm, and the dielectric constant is between 4 and 5. The dielectric thickness is about a quarter of the guide wavelength corresponding to the center frequency of the passband, and the dielectric constant is about 1.1.

The metal periodic structure unit is square (rectangular) and has the side length of about 24mm, and comprises a combined structure of four-leg loading gaps and cross gaps, wherein: the perimeter of the central line of the peripheral four-leg loading gap is about the wavelength corresponding to the low frequency of the passband frequency; the length of the center line of the internal cross-shaped slot is about the wavelength corresponding to the high frequency of the passband.

In order to make the frequency selective surface structure easy to manufacture, the periodic metal elements are usually printed on a very thin medium substrate material. For a single-layer frequency selective surface, the support is the antenna housing material, and no additional support medium is needed. For a two-layer frequency selective surface, the support is a low dielectric constant medium with a thickness of about a quarter of the guide wavelength.

The units are periodically expanded along the horizontal direction and the vertical direction and are regularly arranged to form a plane pattern, the periphery of one unit is connected with four units, and the size of the formed frequency selection surface is the same as that of the target antenna housing.

Fig. 2 is a frequency selective surface layered structure of the present invention, which is divided into a single layer FSS layer and a double layer FSS layer. The outer side is a substrate medium printed with periodic metal units, the inner side is a medium, and the metal is completely the same as the periodic structure. In order to facilitate conformability with the antenna cover and reduce loss of the frequency selective surface, the substrate may be a thin medium, such as a medium with a thickness of 0.1mm as a substrate of the substrate.

Fig. 2 shows a frequency selective surface periodic distribution structure of the present invention, that is, the frequency selective structure units are arranged in a square shape and arranged regularly to form a plane, and four units are connected to one unit, and the size of the unit is the same as that of the target radome.

Fig. 3 is a combined structure of a frequency selective surface four-leg loading slot unit and a cross slot, wherein a periodic unit is square, a black part is a metal patch, and the pattern of the metal patch comprises: the outermost metal filling part and the filling part in the middle of the gap. In the figure 5 a four-legged loaded ring slot with a centre line with a circumference around the wavelength corresponding to the low frequency of the passband, in the figure 4 a cross slot with a circumference around the wavelength corresponding to the high frequency of the passband, and in the figure 3 a metal patch part.

FIG. 3 is a graph of the transmission coefficients of electromagnetic waves for a frequency selective surface structure according to the present invention, as shown in Table 1, for the transmission coefficients of the frequency selective surface structure described herein when electromagnetic waves are incident. For a single-layer FSS, the insertion loss of the frequency selective surface is less than 0.5dB in a frequency band range of 2.46-2.78 GHz, the relative frequency bandwidth is 12.2%, and the insertion loss at the frequency of less than 1.27GHz is more than 10 dB. Therefore, the single-layer FSS has good suppression characteristic on signals with the frequency below 1.27GHz, and has small signal loss in the frequency band of 2.46-2.78 GHz. For the double-layer FSS, the insertion loss of the frequency selective surface is less than 0.5dB in the frequency band range of 1.72-2.71 GHz, the relative frequency bandwidth is 44.7%, and the insertion loss at the frequency less than 1.02GHz is more than 10 dB. Therefore, the double-layer FSS has good inhibition on signals with the frequency below 1.02GHz, and has small signal loss in the frequency band of 1.72-2.71 GHz.

The above are technical embodiments and technical features of the present invention, which are merely used to illustrate the technical solutions of the present invention and are not limited thereto. Modifications and equivalents of the disclosed embodiments may occur to persons skilled in the art based on the teachings and teachings of the present disclosure. Accordingly, the scope of the present invention should not be limited to the embodiments disclosed, but should include various alternatives and modifications without departing from the invention and encompassed by the appended claims.

Claims

1. A composite cross-shaped slot frequency selective surface, comprising: the gap frequency selection surface is composed of composite cross-shaped gap periodic units which are periodically arranged along the horizontal direction and the vertical direction, the composite cross-shaped gap periodic units are rectangular, each unit comprises a first hollow cross-shaped gap and a second cross-shaped gap, the second cross-shaped gap is superposed with the horizontal symmetry axis and the vertical symmetry axis of the first hollow cross-shaped gap, four end points of the second cross-shaped gap are connected with the middle points of the upper side, the lower side, the left side and the right side of the first hollow cross-shaped gap, and the gap structures of the adjacent composite cross-shaped gap periodic units are isolated from each other;

when the gap frequency selective surface is a single-layer frequency selective surface, the single-layer frequency selective surface structure comprises 3 layers of media, which are sequentially from top to bottom: copper-clad layer, base plate layer, dielectric layer;

wherein:

the copper-clad layer is attached to the surface of the substrate layer and is a periodic unit printing layer of the frequency selection surface;

the substrate layer is attached to the surface of the medium layer;

when the gap frequency selective surface is a double-layer frequency selective surface structure, the double-layer frequency selective surface structure comprises 5 layers of media, the middle layer is a dielectric layer, two surfaces of the dielectric layer are respectively provided with a substrate layer, and the outer sides of the two substrate layers are respectively provided with a copper-clad layer;

wherein:

the copper-clad layer is attached to the surface of the substrate layer and is a periodic unit printing layer of a frequency selective surface, and the periodic structures of the frequency selective surfaces of the upper and lower metal layers are the same;

the substrate layer is attached to the surface of the dielectric layer.