CN114498061A - Frequency selection surface unit, frequency selection surface and frequency selection method - Google Patents
Frequency selection surface unit, frequency selection surface and frequency selection method Download PDFInfo
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- CN114498061A CN114498061A CN202210391020.0A CN202210391020A CN114498061A CN 114498061 A CN114498061 A CN 114498061A CN 202210391020 A CN202210391020 A CN 202210391020A CN 114498061 A CN114498061 A CN 114498061A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
- H01Q15/002—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective said selective devices being reconfigurable or tunable, e.g. using switches or diodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
- H01Q15/0026—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective said selective devices having a stacked geometry or having multiple layers
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Abstract
The invention discloses a frequency selection surface unit, a frequency selection surface and a frequency selection method, comprising the following steps: a first electromagnetic dipole antenna and a second electromagnetic dipole antenna; the first electromagnetic dipole antenna is arranged above the second electromagnetic dipole antenna and connected in a back-to-back mode to form a tightly coupled antenna with small space and dual polarization; the first electromagnetic dipole antenna includes: a first filtering antenna and a first metal pillar; the first filtering antenna is fixedly connected with the first metal column; the second electromagnetic dipole antenna includes: the second filtering antenna is fixedly connected with the second metal column; according to the invention, the first electromagnetic dipole antenna and the second electromagnetic dipole antenna are set as the broadband antennas with filtering characteristics, and the filtering characteristics of the antennas are realized under the condition of not increasing the thickness of the antennas and an additional circuit structure, so that the frequency selection surface has the characteristics of low thickness, high selectivity and broadband.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a frequency selective surface unit, a frequency selective surface, and a frequency selection method.
Background
For a system with mutual interference, the frequency selection surface can be used for shielding out-of-band signals, can be used for decoupling in an antenna system only through the frequency which needs to be passed by the system per se, and can be used as a covering layer to improve the performances of antenna gain, isolation, selectivity, beam regulation and the like. The frequency selective surface is a structure which utilizes the uniform distribution of periodic units, and is used as a spatial filter for carrying out frequency selection on the spatial electromagnetic waves, and the frequency selective surface with high selectivity is required in practical application.
Currently, the solutions for increasing the selectivity of the frequency selective surface are:
the first is to realize multi-order filtering by a multilayer structure;
the second is by introducing different coupling paths;
the third is to adopt a 3D structure.
In the three solutions, the multilayer structure results in a large thickness of the design, whereas the 3D structure has a large thickness and requires a complicated assembly after processing.
Therefore, a frequency selective surface capable of realizing a low thickness, a high selectivity, and a high bandwidth is required to be adapted to various applications while improving the selective characteristics of the frequency selective surface.
Disclosure of Invention
The present invention provides a frequency selective surface unit, a frequency selective surface and a frequency selective method, aiming at the defects of the prior art, so as to solve the technical problems of high thickness, low selectivity and narrow bandwidth of the existing frequency selective surface.
The technical scheme adopted by the invention for solving the technical problem is as follows:
in a first aspect, the present invention provides a frequency selective surface unit comprising:
a first electromagnetic dipole antenna and a second electromagnetic dipole antenna; the first electromagnetic dipole antenna is arranged above the second electromagnetic dipole antenna and is connected in a back-to-back mode to form a tightly coupled antenna with small space and dual polarization;
the first electromagnetic dipole antenna comprises: a first filtering antenna and a first metal pillar; the first filtering antenna is fixedly connected with the first metal column;
the second electromagnetic dipole antenna comprises: the second filtering antenna is fixedly connected with the second metal column;
the first metal column penetrates through the floor structure and is fixedly connected with the second filter antenna, and the second metal column penetrates through the floor structure and is fixedly connected with the first filter antenna;
the second filtering antenna and the first filtering antenna are arranged back to back, and the second filtering antenna and the first filtering antenna form coupling connection through a coupling gap of the floor structure.
In one implementation, the first filtering antenna is a rectangular metal sheet;
the rectangular metal sheet is less than 0.1 wavelength away from the boundary of the frequency selective surface unit; the first filtering antenna is provided with a first area, a second area, a third area and a fourth area, and hollowed linear gaps are formed between every two areas in the first area, the second area, the third area and the fourth area.
In one implementation manner, the first region, the second region, the third region, and the fourth region are mirror-symmetric structures; the first region, the second region, the third region and the fourth region are all C-shaped bent structures or arc-shaped structures.
In one implementation, in the first region, the second region, the third region and the fourth region, each region is provided with a hollowed residual corner rectangle; the residual angle rectangle is arranged at the center of each area, and a branch is formed from the tail end of the residual angle rectangle to one corner of the first filtering antenna.
In one implementation, the sum of the total length of the sides of the residual angle rectangle and the length of the branch is greater than 0.2 wavelength of the high-frequency zero point.
In one implementation, the structure of the second filtering antenna has the same structural characteristics as the first filtering antenna.
In one implementation, the floor structure is provided with a cross-shaped gap structure, the cross-shaped gap structure is a gap structure subjected to angle rounding, and the total side length of the cross-shaped gap structure is greater than or equal to 0.1 wavelength.
In one implementation, the cross-shaped gap structure is a larger-than-two-step structure formed along the orthogonal direction, or the cross-shaped gap structure is a linear and wavy structure formed along the orthogonal direction.
In one implementation, the intersection of the cross-shaped gap structure is a right-angle or arc-angle structure, and the end of the cross-shaped gap structure is any one of a right-angle structure, an obtuse-angle structure, an acute-angle structure, a 0-degree-angle structure and an arc-shaped structure.
In a second aspect, the present invention provides a frequency selective surface comprising: a plurality of frequency selective surface units as described in the first aspect.
In a third aspect, the present invention provides a frequency selection method applied to the frequency selection surface according to the second aspect, the frequency selection method comprising:
generating a low-frequency transmission zero point through an electric dipole and a magnetic dipole of the electromagnetic dipole antenna;
generating a high-frequency transmission zero point through an open resonant ring formed by the first filtering antenna and the second filtering antenna;
and disconnecting and transmitting the corresponding frequency signal through the low-frequency transmission zero point and/or the high-frequency transmission zero point, or rejecting and receiving the corresponding frequency signal through the low-frequency transmission zero point and/or the high-frequency transmission zero point.
In one implementation, the generating a low-frequency transmission zero by an electric dipole and a magnetic dipole of an electromagnetic dipole antenna includes:
determining the input impedance of the electromagnetic dipole antenna according to the characteristic impedances of the electric dipole and the magnetic dipole;
adjusting an input impedance of the electromagnetic dipole antenna to 0 or infinity to create a low frequency transmission zero of the frequency selective surface.
In one implementation, the generating a high-frequency transmission zero by the split resonant loops of the first filtering antenna and the second filtering antenna includes:
determining the length of the split resonant ring required for generating a first high-frequency according to the split resonant ring of the first filtering antenna;
determining the length of the split resonant ring required for generating a second high-frequency according to the split resonant ring of the second filtering antenna;
adjusting the split resonant ring of the first filter antenna to be in a resonant state according to a first current, and adjusting the split resonant ring of the second filter antenna to be in an off-state according to a default current so as to generate a high-frequency transmission zero point based on the first filter antenna;
adjusting the open resonant ring of the second filter antenna to be in a resonant state according to a second current, and adjusting the open resonant ring of the first filter antenna to be in an off-working state according to a default current so as to generate a high-frequency transmission zero point based on the second filter antenna;
and exchanging the zero position corresponding to the first high-frequency with the zero position corresponding to the second high-frequency, and generating two high-frequency transmission zeros again through the length difference between the open resonant ring of the first filtering antenna and the open resonant ring of the second filtering antenna so as to realize the out-of-band rejection characteristic.
The invention adopts the technical scheme and has the following effects:
the invention sets the frequency selection surface into a small antenna transceiving system based on the reciprocity theorem, thereby changing the selectivity problem of the frequency selection surface into a filter characteristic problem of a designed antenna, and realizes the filter characteristic of the antenna by using the radiation zero point of the antenna under the condition of not increasing the thickness of the antenna and an additional circuit mechanism, thereby realizing the characteristics of low thickness, high selectivity and broadband of the frequency selection surface. The miniaturization of the cell structure is achieved by the tightly coupled design, so that a good angular stability of the frequency selective surface is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic diagram of a frequency selective surface unit in one implementation of the invention.
Fig. 2 is a schematic structural diagram of a first filtering antenna in an implementation manner of the present invention.
Fig. 3 is a schematic view of the structure of the floor panel in one implementation of the invention.
Fig. 4 is a schematic diagram of a branch structure of each region in the first filtering antenna in another implementation manner of the present invention.
Fig. 5 is a schematic structural diagram of a cross-shaped slit in another implementation of the invention.
Fig. 6 is a schematic diagram of a filtering antenna in one implementation of the invention.
Fig. 7 is a schematic diagram of a specific structure of a frequency selective surface unit in an implementation of the present invention.
Fig. 8 is a diagram illustrating the frequency selection results of a frequency selective surface in one implementation of the invention.
Fig. 9 is an equivalent schematic of an electromagnetic dipole in one implementation of the invention.
Fig. 10 is a schematic diagram of the variation of the frequency selective surface with the height of the metal pillar in one implementation of the invention.
Fig. 11 is a schematic representation of the variation of the frequency selective surface with center-to-center spacing of metal posts in one implementation of the invention.
Fig. 12 is a schematic representation of the variation of the frequency selective surface with the diameter of the metal pillar in one implementation of the invention.
Fig. 13 is a schematic diagram of the variation of the high frequency transmission zero with the split resonant ring in one implementation of the invention.
Fig. 14 is a schematic diagram of the current distribution of the high frequency transmission zero in one implementation of the invention.
FIG. 15 is a schematic diagram of the current distribution of the transmission pole in one implementation of the invention.
Fig. 16 is a flow chart of a method of frequency selection in one implementation of the invention.
In the figure:
100. a first filtering antenna; 200. a floor structure; 300. a second filtering antenna; 400. a magnetic dipole; 1. a first region; 2. a second region; 3. a third region; 4. and a fourth region.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Exemplary devices
As shown in fig. 1 to 8, the present embodiment provides a frequency selective surface, which includes a plurality of frequency selective surface units.
As shown in fig. 1, in one implementation of the present embodiment, the frequency selective surface unit includes:
a first electromagnetic dipole antenna and a second electromagnetic dipole antenna; the first electromagnetic dipole antenna is arranged above the second electromagnetic dipole antenna and is connected in a back-to-back mode to form a tightly coupled antenna with small space and dual polarization;
the first electromagnetic dipole antenna comprises: a first filter antenna 100 and a first metal pillar; the first filtering antenna 100 is fixedly connected with the first metal column;
the second electromagnetic dipole antenna comprises: a second filtering antenna 300, a second metal pillar, and a floor structure 200, wherein the second filtering antenna 300 is fixedly connected to the second metal pillar;
the first metal pillar passes through the floor structure 200 and is fixedly connected with the second filtering antenna 300, and the second metal pillar passes through the floor structure 200 and is fixedly connected with the first filtering antenna 100;
the second filtering antenna 300 and the first filtering antenna 100 are disposed back to back, and the second filtering antenna 300 and the first filtering antenna 100 form a coupling connection through a coupling gap of the floor structure 200.
The first metal pillar and the second metal pillar form a magnetic dipole 400.
The embodiment is based on the reciprocity theorem, the frequency selective surface is understood to be a small-sized antenna transceiving system, so that the selectivity problem of the frequency selective surface is changed into the filtering characteristic problem of designing an antenna, the radiation zero point of the antenna is utilized, the design has good high selectivity, the angle stability is good, the broadband design frequency selective surface is adopted, and the difficulty of the selective design of the frequency selective surface is greatly reduced.
In this embodiment, the first filtering antenna 100 and the second filtering antenna 300 are connected back to form a small-sized "transceiving system" for receiving electromagnetic waves, filtering the electromagnetic waves, and transmitting the filtered electromagnetic waves, and the structural design principle is shown in fig. 1.
According to the reciprocity theorem, the radiation null of the antenna can generate a transmission null corresponding to the frequency selective surface. Therefore, the selective transmission zero of the frequency selection surface is converted into the design of the radiation zero of the filter antenna, and the design of the radiation zero greatly reduces the design difficulty of the frequency selection surface. The design considerations for a filtering antenna are generally of two types: one is to realize the radiation zero point of the antenna through the filter circuit of the feed structure; another category is the realization of the radiating null by the structure of the antenna itself. According to the design idea of this embodiment, a broadband antenna with a filtering characteristic (i.e., an electromagnetic dipole antenna composed of the first filtering antenna 100, the second filtering antenna 300, and the magnetic dipole 400) is selected, and the filtering characteristic of the antenna is realized without increasing the thickness of the antenna and an additional circuit mechanism, so that the low thickness, high selectivity, broadband characteristic, and good angular stability of the frequency selective surface are realized.
Specifically, as shown in fig. 2, in an implementation manner of the present embodiment, when the antenna transceiver system is disposed, the first filtering antenna 100 is a rectangular metal sheet; the first filter antenna 100 is provided with four structures, namely, a first region 1, a second region 2, a third region 3 and a fourth region 4, and in the first region 1, the second region 2, the third region 3 and the fourth region 4, a hollowed linear gap is formed between every two regions.
Furthermore, the first region 1, the second region 2, the third region 3 and the fourth region 4 are mirror-symmetrical structures with each other; the first region 1, the second region 2, the third region 3 and the fourth region 4 are all in a C-shaped bent structure or an arc-shaped structure. In the first region 1, the second region 2, the third region 3 and the fourth region 4, each region is provided with a hollowed residual corner rectangle; the corner stub rectangle is disposed at the center of each region, and a branch is formed from the end of the corner stub rectangle to a corner of the first filtering antenna 100. And the sum of the total length of the side lengths of the residual angle rectangles and the length of the branches is more than 0.2 wavelength of the high-frequency zero point.
It is worth mentioning that the structure of the second filtering antenna 300 is the same as the structure of the first filtering antenna 100.
In the actual setting process, the frequency selection surface is completely formed by the integrated process of a PCB (printed circuit board) without assembly, but is not limited to the PCB process, and the same performance can be realized by only realizing the same structural characteristics, such as a chip process, a CMOS (complementary metal oxide semiconductor) process and the like; as shown in fig. 2, the first filtering antenna 100 is a residual rectangle hollowed in a rectangular metal sheet, the residual rectangle is hollowed along a line connected to one corner of the rectangular metal sheet along the center of the original rectangle, and a branch is grown at the end, and the total length of the side length of the residual rectangle and the length of the branch are 0.2 wavelength longer than the high-frequency zero point. And a trapped wave structure is realized, and out-of-band transmission zero is realized. The first filtering antenna 100 is composed of four structures, i.e., a first region 1, a second region 2, a third region 3, and a fourth region 4.
As shown in fig. 2, in order to realize electromagnetic wave regulation in two polarization directions and operate in the same frequency range, in this embodiment, four structures, i.e., a first region 1, a second region 2, a third region 3, and a fourth region 4, are adopted to be mirror-symmetric.
In another implementation manner of this embodiment, if the operating frequency bands are not required to be consistent only for single-polarization operation or in different polarization directions, the four structures of the first region 1, the second region 2, the third region 3, and the fourth region 4 may not be consistent; the four structures of the first region 1, the second region 2, the third region 3 and the fourth region 4 may adopt a bending form similar to a C-shaped bending, and may be a plurality of times of bending or an arc. The bent branch structure may be outward or inward, and some examples are shown in fig. 4. The distances of the four structures of the first region 1, the second region 2, the third region 3, and the fourth region 4 from the boundary (i.e., the boundary of the first filter antenna 100) are small (W7- (2 × L1+ W1) <0.1 wavelength), which results in a characteristic of a tightly coupled antenna, so that the bandwidth of the antenna is widened.
As shown in fig. 3, in one implementation manner of the present embodiment, the floor structure 200 is provided with a cross-shaped gap structure, the cross-shaped gap structure is a gap structure subjected to angle rounding, and the total side length of the cross-shaped gap structure is greater than or equal to the total side length of the floor structure. The cross-shaped gap structure is a stepped structure formed along the orthogonal direction and larger than two sections, or the cross-shaped gap structure is a linear and wavy structure formed along the orthogonal direction.
Furthermore, the intersection of the cross-shaped gap structure is a right-angle or arc-angle structure, and the end of the cross-shaped gap structure is any one of the right-angle structure, the obtuse-angle structure, the acute-angle structure, the 0-degree angle structure and the arc-shaped structure.
In the actual setup, the floor structure 200 is a Yellows cold cross-shaped gap, which serves to transmit two polarized electromagnetic waves between the different layers. The cross slit structure is a polygon with more than or equal to four sides and a change shape with smooth processing of the angle. Viewed from a plane structure, the electromagnetic wave transmission structure is in a step shape or a straight line shape along 2 sections in two orthogonal directions, and is in a wavy line shape, the total length of gaps in the two orthogonal directions is more than 0.1 wavelength, the width of the gaps is more than 0.001 wavelength, and the length and the width influence the transmission efficiency of electromagnetic waves of different layers. When the two polarized electromagnetic waves do not work in the same frequency band, the two orthogonal slots may be different. The slits 9 and 10 are divided into three parts and distributed with different slit widths, and can also be divided into a plurality of sections and have different slit widths. The angle 5 in the gap can be a right angle or a circular arc, the angles 6-9 can be right angles, obtuse angles, acute angles or 0 degree or arc, and an example of partial change is shown in fig. 5.
Specifically, in one implementation manner of this embodiment, the magnetic dipole 400 is a metal pillar antenna, the middle of the magnetic dipole 400 penetrates through the floor structure, and two ends of the magnetic dipole 400 are respectively connected to the first filtering antenna 100 and the second filtering antenna 300.
In the actual setting process, the metal columns are used to form magnetic dipoles 400, and the positions of the metal columns are located on the four structures, namely the first region 1, the second region 2, the third region 3 and the fourth region 4, and are respectively connected with the four structures.
In a specific design example, in order to realize broadband characteristics, an electromagnetic dipole antenna having broadband and dual-polarization characteristics is selected as shown in fig. 6. Two electromagnetic dipole antennas are placed back-to-back and connected through a coupling slot in the floor to implement a frequency selective surface, the structure of which is schematically shown in fig. 7. The dielectric slab used was Rogers RO4350, the frequency selective surface overall thickness was 0.12 wavelength (center frequency), and the unit period was 0.19 wavelength.
The specific dimensions are (in mm): l1 = 2.1, L2 = 1.96, L3+ = 1.3, L3- = 1.0, L4 = 0.4, L5 = 0.6, L6 = 3.1, L7 = 0.65, W1 = 0.3, W2 = 0.35, W3 = 0.6, W4 = 0.4, W5 = 0.2, W6 = 0.2, W7 = 0.2, 2a = 0.4D = 1.5, H = 1.524.
Wherein, L1+ L2+ L3>0.4 wavelength, H < =0.5 wavelength, W1, W2, W3, W4, W5, W6, W7 are all less than 0.5 wavelength, D < W7, L6+ 2L 4< = W7, L5< = W7, a >0.1mm, W7- (2L 1+ W1) <0.1 wavelength) of the frequency selective surface implemented in this embodiment) has a frequency response as shown in fig. 8, and a relative 3dB passband bandwidth is 38.6%, an out-of-band rejection bandwidth of-20 dB is 6.7% for the high band and 13.8% for the low band, respectively. The bandwidth is defined as follows:
because of the symmetry of the design, the frequency response of the frequency to the incident waves of the two polarization directions is consistent, and the dual polarization characteristic is provided.
The embodiment adopting the technical scheme has the following effects:
the embodiment is based on the reciprocity theorem and sets the frequency selective surface to be a small antenna transceiving system, so that the problem of selectivity of the frequency selective surface is changed into the problem of filter characteristic of a designed antenna, and the filter characteristic of the antenna is realized by using the radiation zero point of the antenna under the condition of not increasing the thickness of the antenna and an additional circuit mechanism, so that the characteristics of low thickness, high selectivity and broadband of the frequency selective surface are realized.
Exemplary method
As shown in fig. 9 to 16, based on the above embodiments, the present embodiment provides a frequency selection method applied to the frequency selection surface of the above embodiments.
As shown in fig. 16, in one implementation manner of the present embodiment, the method includes the following steps:
step S100, generating a low-frequency transmission zero point through an electric dipole and a magnetic dipole of an electromagnetic dipole antenna;
step S200, generating a high-frequency transmission zero point through an open resonant ring formed by a first filtering antenna and a second filtering antenna;
step S300, the corresponding frequency signals are cut off and transmitted through the low-frequency transmission zero point and/or the high-frequency transmission zero point, or the corresponding frequency signals are refused to be received through the low-frequency transmission zero point and/or the high-frequency transmission zero point.
In one implementation, step S100 specifically includes:
step S101, determining the input impedance of the electromagnetic dipole antenna according to the characteristic impedance of the electric dipole and the magnetic dipole;
step S102, the input impedance of the electromagnetic dipole antenna is adjusted to 0 or infinity to generate a low-frequency transmission zero of the frequency selective surface.
In this embodiment, the implementation and control of each transmission zero on the frequency selective surface:
the implementation of the low-frequency transmission zero is as follows:
the electromagnetic dipole antenna can be equivalent to a circuit diagram as shown in fig. 9, and the electromagnetic dipole can be divided into two of an electric dipole and a magnetic dipoleA plurality of sections. The magnetic dipole may be equivalent to a transmission line having a characteristic impedance of
Electrical length of
Electric dipole equivalent to magnetic dipole load
Thus, an electromagnetic dipole can be equivalent to a transmission line model:
loaded electric dipole
：
Wherein the content of the first and second substances,
characteristic impedance of electric dipole
，
And
is the length and equivalent width of the electric dipole,
and
loss constant and phase constant.
The magnetic dipole consists of four short-circuited metal posts,
characteristic impedance equivalent to parallel double line
Half of that.
Here, the first and second liquid crystal display panels are,
the equivalent dielectric constant D is the center distance of the adjacent metal posts,
is the diameter of the metal post.
Thus, the equivalent input impedance of an electromagnetic dipole antenna is:
when in use
Or
The electromagnetic dipole is a transmission zero point, and can generate a transmission zero point of a corresponding frequency selection surface, specifically:
equations (6) and (7) represent two zeros at low frequencies, and H,
d may affect the frequency of both transmission zeroes.
As shown in FIGS. 10-12, it can be seen that as H increases, there are two transmission zeros: (
And
) Will increase because H does not affect
And
but will not affect
. When D and
when increased, two transmission zeros: (
And
) Will also increase. Therefore, two transmission zeros of low frequency can be independently controlled by the thickness of the dielectric plate and the short-circuited metal post.
In one implementation, step S200 specifically includes:
step S201, determining the length of the split ring resonator required for generating the first high-frequency according to the split ring resonator of the first filtering antenna;
step S202, determining the length of the split ring resonator required for generating the second high-frequency according to the split ring resonator of the second filter antenna;
step S203, adjusting the split resonant ring of the first filter antenna to be in a resonant state according to the first current, and adjusting the split resonant ring of the second filter antenna to be in an inoperative state according to a default current so as to generate a high-frequency transmission zero point based on the first filter antenna;
step S204, adjusting the split resonant ring of the second filtering antenna to be in a resonant state according to the second current, and adjusting the split resonant ring of the first filtering antenna to be in an inoperative state according to the default current so as to generate a high-frequency transmission zero point based on the second filtering antenna;
step S205, the zero position corresponding to the first high frequency and the zero position corresponding to the second high frequency are exchanged, and two high frequency transmission zeros are generated again by the difference between the lengths of the open resonant loop of the first filtering antenna and the open resonant loop of the second filtering antenna, so as to implement the out-of-band rejection characteristic.
The implementation of the high-frequency transmission zero point is as follows:
in order to realize the out-of-band rejection characteristic of the designed frequency selective surface, a high-frequency transmission zero point is introduced in a mode of an open resonant ring, and the resonant frequency of the open resonant ring is as follows:
in order to further improve the out-of-band rejection characteristics of the frequency selective surface of the design, an asymmetric design is adopted,
the two high-frequency transmission zeros are realized through different sizes of the split resonant rings, namely, the length of the split resonant ring required for generating a first high-frequency is determined according to the split resonant ring of the first filtering antenna, and the length of the split resonant ring required for generating a second high-frequency is determined according to the split resonant ring of the second filtering antenna, wherein the lengths of the split resonant rings required for the first high-frequency and the second high-frequency are not equal. As shown in fig. 13, for comparison between the symmetric design and the asymmetric design, it can be found that the asymmetry can effectively improve the out-of-band rejection characteristic of high frequency, and the out-of-band-20 dB reaches the bandwidth of 1.2 GHz.
To further illustrate the effect of the split ring resonator, the frequency selective surface is designed to be at the high frequency null
, 
The current of (2) is shown in fig. 14.
From the current distribution, it can be found that when the frequency is
At the time, the open-loop resonator of the upper layer (i.e., the first filter antenna) resonates, and the current used at this time is the first current (as shown in fig. 14, the first current is 500 to 600A/m); the open loop current of the lower layer (i.e., the second filter antenna) is very weak, and the current used at this time is a default current (as shown in fig. 14, the default current is 0 to 100A/m) and is in an inoperative state.
When the frequency is
Meanwhile, the open loop current of the upper layer (i.e., the first filtering antenna) is weak and does not work, and the current adopted at this time is a default current (as shown in fig. 14, the default current is 0 to 100A/m); the open loop current of the lower layer (i.e., the second filter antenna) is strongly in a strong resonance state, and the current used at this time is the second current (as shown in fig. 14, the second current is 500 to 600A/m). It can be seen that the introduction of the split resonant ring, the strong resonance state of the split resonant ring, results in the current not being transmitted between the two electromagnetic dipoles, thereby forming a transmission zero point (as shown in fig. 15). When the frequency is in the band pass, the two electromagnetic dipoles work, and electromagnetic waves can be transmitted between the two layers of electromagnetic dipoles, so that the transmission characteristic is realized.
In a specific implementation, the frequency selective surface element is provided with a size of 0.19 wavelength and a thickness of 0.12 wavelength, and consists of 45 × 45 elements, and the overall size is 8.56 wavelength × 0.12 wavelength. Tests show that the designed frequency selection surface still keeps good selection characteristics and out-of-band rejection characteristics under 40-degree incident waves, and has the characteristics of wide band, low thickness, high selectivity and good angle stability; in addition, by exchanging the zero position corresponding to the first high-frequency with the zero position corresponding to the second high-frequency, and by the difference in length between the open resonant loop of the first filter antenna and the open resonant loop of the second filter antenna, two high-frequency transmission zeros can be generated again to realize the out-of-band rejection characteristic.
The embodiment adopting the technical scheme has the following effects:
the embodiment is based on the reciprocity theorem and sets the frequency selective surface to be a small antenna transceiving system, so that the problem of selectivity of the frequency selective surface is changed into the problem of filter characteristic of a designed antenna, and the filter characteristic of the antenna is realized by using the radiation zero point of the antenna under the condition of not increasing the thickness of the antenna and an additional circuit mechanism, so that the low thickness, high selectivity, broadband characteristic and good angle stability of the frequency selective surface are realized.
It will be understood by those skilled in the art that all or part of the processes of the methods of the above embodiments may be implemented by hardware related to instructions of a computer program, which may be stored in a non-volatile storage medium, and when executed, may include the processes of the embodiments of the methods described above. Any reference to memory, storage, databases, or other media used in embodiments provided herein may include non-volatile and/or volatile memory.
In summary, the present invention provides a frequency selective surface unit, a frequency selective surface and a frequency selection method, including: a first electromagnetic dipole antenna and a second electromagnetic dipole antenna; the first electromagnetic dipole antenna is arranged above the second electromagnetic dipole antenna and connected in a back-to-back mode to form a tightly coupled antenna with small space and dual polarization; the first electromagnetic dipole antenna includes: a first filtering antenna and a first metal pillar; the first filtering antenna is fixedly connected with the first metal column; the second electromagnetic dipole antenna includes: the second filtering antenna is fixedly connected with the second metal column; according to the invention, the first electromagnetic dipole antenna and the second electromagnetic dipole antenna are set as the broadband antennas with filtering characteristics, and the filtering characteristics of the antennas are realized under the condition of not increasing the thickness of the antennas and an additional circuit structure, so that the frequency selection surface has the characteristics of low thickness, high selectivity and broadband.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (13)
1. A frequency selective surface element, characterized in that it comprises:
a first electromagnetic dipole antenna and a second electromagnetic dipole antenna; the first electromagnetic dipole antenna is arranged above the second electromagnetic dipole antenna and is connected in a back-to-back mode to form a tightly coupled antenna with small space and dual polarization;
the first electromagnetic dipole antenna comprises: a first filtering antenna and a first metal pillar; the first filtering antenna is fixedly connected with the first metal column;
the second electromagnetic dipole antenna comprises: the second filtering antenna is fixedly connected with the second metal column;
the first metal column penetrates through the floor structure and is fixedly connected with the second filter antenna, and the second metal column penetrates through the floor structure and is fixedly connected with the first filter antenna;
the second filtering antenna and the first filtering antenna are arranged back to back, and the second filtering antenna and the first filtering antenna form coupling connection through a coupling gap of the floor structure.
2. The frequency selective surface unit of claim 1, wherein the first filtering antenna is a rectangular metal sheet;
the rectangular metal sheet is less than 0.1 wavelength away from the boundary of the frequency selective surface unit; the first filtering antenna is provided with a first area, a second area, a third area and a fourth area, and hollowed linear gaps are formed between every two areas in the first area, the second area, the third area and the fourth area.
3. The frequency selective surface unit of claim 2, wherein the first region, the second region, the third region, and the fourth region are mirror symmetric structures; the first region, the second region, the third region and the fourth region are all C-shaped bent structures or arc-shaped structures.
4. The frequency selective surface unit of claim 3, wherein in the first region, the second region, the third region, and the fourth region, each region is provided with a hollowed-out stub rectangle; the residual angle rectangle is arranged at the center of each area, and a branch is formed from the tail end of the residual angle rectangle to one corner of the first filtering antenna.
5. The frequency selective surface unit of claim 4, wherein the sum of the total length of the sides of the stub rectangle and the length of the stub is greater than 0.2 wavelength of the high frequency zero.
6. The frequency selective surface unit of claim 1, wherein the second filtering antenna has a structure with the same structural characteristics as the first filtering antenna.
7. The frequency selective surface unit according to claim 1, wherein the floor structure is provided with a cross-shaped gap structure, the cross-shaped gap structure being angle-rounded, and the cross-shaped gap structure having a total side length greater than or equal to 0.1 wavelength.
8. The frequency selective surface unit of claim 7, wherein the cross-shaped slot structure is a more than two-step structure formed along orthogonal directions, or the cross-shaped slot structure is a linear, wavy structure formed along orthogonal directions.
9. The frequency selective surface unit of claim 7, wherein the intersection of the cross-shaped slot structures is a right-angle or arc-angle structure, and the end of the cross-shaped slot structure is any one of a right-angle structure, an obtuse-angle structure, an acute-angle structure, a 0-angle structure and an arc-shaped structure.
10. A frequency selective surface, comprising: a plurality of frequency selective surface units as claimed in any one of claims 1 to 9.
11. A frequency selection method applied to the frequency selection surface of claim 10, the frequency selection method comprising:
generating a low-frequency transmission zero point through an electric dipole and a magnetic dipole of the electromagnetic dipole antenna;
generating a high-frequency transmission zero point through an open resonant ring formed by the first filtering antenna and the second filtering antenna;
and disconnecting and transmitting the corresponding frequency signal through the low-frequency transmission zero point and/or the high-frequency transmission zero point, or rejecting and receiving the corresponding frequency signal through the low-frequency transmission zero point and/or the high-frequency transmission zero point.
12. The frequency selection method of claim 11, wherein the generating a low frequency transmission zero by an electric dipole and a magnetic dipole of an electromagnetic dipole antenna comprises:
determining the input impedance of the electromagnetic dipole antenna according to the characteristic impedances of the electric dipole and the magnetic dipole;
adjusting an input impedance of the electromagnetic dipole antenna to 0 or infinity to create a low frequency transmission zero of the frequency selective surface.
13. The frequency selection method of claim 11, wherein the generating a high frequency transmission zero by the split resonant loops of the first and second filter antennas comprises:
determining the length of the split resonant ring required for generating a first high-frequency according to the split resonant ring of the first filtering antenna;
determining the length of the split resonant ring required for generating a second high-frequency according to the split resonant ring of the second filtering antenna;
adjusting the split resonant ring of the first filter antenna to be in a resonant state according to a first current, and adjusting the split resonant ring of the second filter antenna to be in a non-operating state according to a default current so as to generate a high-frequency transmission zero point based on the first filter antenna;
adjusting the split resonant ring of the second filter antenna to be in a resonant state according to a second current, and adjusting the split resonant ring of the first filter antenna to be in a non-operating state according to a default current so as to generate a high-frequency transmission zero point based on the second filter antenna;
and exchanging the zero position corresponding to the first high-frequency with the zero position corresponding to the second high-frequency, and generating two high-frequency transmission zeros again through the length difference between the open resonant ring of the first filtering antenna and the open resonant ring of the second filtering antenna so as to realize the out-of-band rejection characteristic.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115275634A (en) * | 2022-07-26 | 2022-11-01 | 鹏城实验室 | Polarization selector |
| WO2024017164A1 (en) * | 2022-07-21 | 2024-01-25 | 华为技术有限公司 | Antenna and communication device |
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| CN108717992A (en) * | 2018-04-09 | 2018-10-30 | 杭州电子科技大学 | The Dual-polarized electricity magnetic-dipole antenna of millimeter wave differential feed |
| CN110011048A (en) * | 2019-04-26 | 2019-07-12 | 华南理工大学 | A kind of wideband dual polarized filtering dipole antenna of no additional circuit |
| US20200028231A1 (en) * | 2018-07-18 | 2020-01-23 | City University Of Hong Kong | Filtering dielectric resonator antennas implementing radiation cancellation |
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| CN108717992A (en) * | 2018-04-09 | 2018-10-30 | 杭州电子科技大学 | The Dual-polarized electricity magnetic-dipole antenna of millimeter wave differential feed |
| US20200028231A1 (en) * | 2018-07-18 | 2020-01-23 | City University Of Hong Kong | Filtering dielectric resonator antennas implementing radiation cancellation |
| CN110011048A (en) * | 2019-04-26 | 2019-07-12 | 华南理工大学 | A kind of wideband dual polarized filtering dipole antenna of no additional circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024017164A1 (en) * | 2022-07-21 | 2024-01-25 | 华为技术有限公司 | Antenna and communication device |
| CN115275634A (en) * | 2022-07-26 | 2022-11-01 | 鹏城实验室 | Polarization selector |
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