CN106654567B - Capacitive and Inductive Surface Coupling Mechanism Miniaturized High Performance High Band Communication Radome - Google Patents

Abstract

The invention discloses a capacitive and inductive surface coupling mechanism miniaturized high-performance high-frequency band communication radome. The frequency selective surface is mainly composed of periodic unit arrays. Each periodic unit is divided into a dielectric layer and a metal layer. The dielectric layer includes the upper and lower dielectric layers and the middle dielectric layer. The metal layer includes the upper and lower dielectric layers. A complete metal patch and a metal gap patch between adjacent dielectric layers; electromagnetic waves in free space are selectively filtered by the radome to output electromagnetic waves in the required working frequency band. The invention is suitable for the design of ultra-wideband communication radome with high angle and polarization stability, the insertion loss in the passband is small and stable, after the passband has a wide stopband with high suppression, and the conversion speed from bandpass to bandstop working state is fast, Excellent angular and polarization stability. It has great application value in the fields of modern communication, radar and military defense.

Description

Capacitive and Inductive Surface Coupling Mechanism Miniaturized High Performance High Band Communication Radome

technical field

The invention relates to the field of antenna technology, in particular to a capacitive and inductive surface coupling mechanism miniaturized high-performance high-frequency communication radome, which can be applied to high-frequency 5G communication and radar.

Background technique

With the mature launch of 4G communication technology, ultra-high-speed 5G communication technology is a new generation of communication technology that meets higher mobile communication performance requirements, and has become a research hotspot in the mobile communication industry today. The launch target of 5G mobile communication in 2020 has also greatly promoted Research on 5G communication technology.

5G communication will pay more attention to user experience, improve the transmission rate of the communication network, reduce energy consumption, make full use of high-band spectrum resources, and realize the widespread application of 5G. Therefore, 5G communication is required to have higher transmission rate and wider bandwidth. According to the transmission rate requirements of 10Gbit/s, a passband bandwidth of 2GHz is actually required, and in order to ensure communication quality, the insertion loss in such a wide passband must be less than 0.8dB. In addition, electromagnetic wave signals come from all directions in actual communication, requiring equipment Only good angular stability can ensure the communication quality, which puts forward higher requirements for the design of the radome.

Nowadays, the design of radome is usually realized by frequency selective surface technology, which has been studied for several years at home and abroad. The traditional frequency selective surface structure can achieve a narrower passband or stopband, and now some people have designed many new frequency selective surfaces, which can achieve a wider passband, but most of them are still limited to the low frequency band of 10GHz or even lower , In addition, today's structural selection performance needs to be improved, mainly in the passband insertion loss is too large, resulting in a decline in communication quality, on the other hand, the main reason is that the edge of the passband drops slowly, and the conversion speed from the passband to the stopband is not fast enough , leading to poor selectivity. A more important issue is that angular stability is a major problem today. When the incident angle of electromagnetic waves changes, it will cause a large offset and greatly affect the transmission performance.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a capacitive and inductive surface coupling mechanism miniaturized high-performance high-frequency communication radome, through the ingenious coupling design of 4 layers of metal layers, for electromagnetic waves incident in multiple directions in space It has stable and efficient selective permeability.

The technical solution adopted by the present invention to solve the problems of the technologies described above is:

1. A capacitive and inductive surface coupling mechanism miniaturized high-performance high-frequency communication radome:

The radome is a frequency selective surface mainly composed of periodic unit arrays. Each periodic unit is divided into a dielectric layer and a metal layer. The dielectric layer includes two upper and lower dielectric layers and a middle dielectric layer. The complete metal patch on the outer surface of the dielectric layer and the metal gap patch between the adjacent dielectric layers; after the electromagnetic wave in the free space is selectively filtered by the radome, the remaining clutter is filtered out, and the electromagnetic wave in the required working frequency band is output .

The invention is designed for the ultra-wideband radome with high angle and polarization stability requirements in high-frequency communication. The insertion loss in the passband is small and stable. Fast speed with excellent angular and polarization stability and frequency selectivity.

The periodic unit includes an upper metal patch P ₁ , an upper thin dielectric D ₁ , an upper metal gap P ₂ , a middle thick dielectric D ₂ , a lower metal gap P ₃ , a lower thin dielectric D ₃ and a lower metal patch P ₄ ; The upper metal patch _P1 is attached to the upper surface of the upper thin medium _D1 , the upper metal gap piece _P2 is located between the upper layer thin medium _D1 and the middle thick medium _D2 , and the lower metal gap piece _P3 is located in the lower layer thin medium Between D ₃ and the middle thick medium D ₂ , the lower metal patch P ₄ is pasted on the lower surface of the lower thin medium D ₃ ; the upper metal patch P ₁ and the lower metal patch P ₄ have the same structure size, and the upper metal gap piece P ₂ has the same structural size as the lower metal gap sheet P ₃ , and the upper thin dielectric D ₁ has the same structural size as the lower thin dielectric D ₃ .

The upper metal gap piece _P2 and the lower metal gap piece _P3 are mainly composed of a duplex-shaped metal patch structure, a peripheral square ring metal patch and the gap between the two: the duplex-shaped metal patch is The Jerusalem cross shape is located at the center of the outer square ring metal patch; the outer square ring metal patch is located at the outer ring of the duplex-shaped metal patch, and the outer side length is the same as the period unit side length.

The upper layer metal patch P ₁ and the lower layer metal patch P ₄ are respectively placed in the centers of the upper layer metal patch P ₁ and the lower layer metal patch P ₄ .

Preferably, the dielectric constant of the upper thin dielectric D ₁ , the middle thick dielectric D ₂ and the lower thin dielectric D ₃ is 3.5, and the dielectric loss tangent is 0.0015.

In the case of vertical incidence of space electromagnetic waves, the insertion loss is less than 0.4dB in the passband range of 27.15GHz-29.65GHz, and the suppression is greater than 20dB in the stopband range of 31.15GHz-33.52GHz; space electromagnetic waves are within ±45° When incident, the insertion loss is less than 1.5dB in the passband range of 27.08GHz-29.80GHz; and when the incident electromagnetic wave changes within the range of ±85° incident angle, the transmission pole and zero point basically do not change, and the angle and polarization stability Extremely high, realizes the fast transition from band-pass to band-stop working state, and has excellent frequency selection performance.

2. The radome is applied to 5G modern communication, radar and military communication.

The radome design of the present invention adopts a miniaturized design, and the unit size is three times smaller than the structural size designed in the traditional scheme, but it is still suitable for processing and production in the traditional PCB process.

Compared with prior art, the beneficial effect of the present invention is:

The upper and lower layers of the square metal patch antenna of the present invention and the outer metal square rings of the middle two layers of slit layers provide the radome with a passband with very large bandwidth and extremely small insertion loss. For the electromagnetic wave perpendicularly incident on the radome, After successively passing through each layer structure of the radome, the passband insertion loss in the 27.15GHz-29.65GHz frequency range is less than 0.4dB.

The two metal gap layers in the middle of the present invention provide the radome with a wide bandwidth range and a high suppression band, and the design concept of the two metal gap layers further improves the conversion speed of the pass band to the stop band. For the electromagnetic wave vertically incident on the radome, the stop band suppression is greater than 20dB in the frequency range of 31.15GHz-33.52GHz.

The unique structural design of the present invention makes the present invention have extremely high angle stability performance, and the electromagnetic waves in space are very stable in the range of incident angles of ±60°, and within the range of incident angles of ±85°, the transmission pole transmission The zero point is quite stable and basically does not shift. In addition, the electromagnetic dual-polarization performance of the present invention is stable, and simultaneously supports two polarization modes of TE and TM.

The present invention has extremely high application value in miniaturization of antenna devices, 5G and other modern communications, radar and military communications.

Description of drawings

Fig. 1 is a three-dimensional structure diagram of a radome according to an embodiment of the present invention.

Fig. 2 is a three-dimensional structure diagram of the unit structure of the present invention.

Fig. 3 is a front view of the unit structure of the present invention.

Fig. 4 is a top view of the unit structure of the present invention.

Fig. 5 is a view of the middle metal gap layer of the unit structure of the present invention.

Fig. 6 is a graph showing the influence of the size of the square metal patch on the transmission performance of the radome in the present invention.

Fig. 7 is a graph of transmission performance curves of the radome of the present invention for normal incidence TE and TM polarization modes.

Fig. 8 is a graph showing the effect of the incident angle of electromagnetic waves in the TE polarization mode on the performance of the radome in the present invention.

Fig. 9 is a graph showing the effect of the incident angle of electromagnetic waves in the TM polarization mode on the performance of the radome in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, a radome is a frequency selective surface mainly composed of an array of periodic elements. Each periodic unit is divided into a dielectric layer and a metal layer. The dielectric layer includes the upper and lower dielectric layers and a dielectric layer in the middle. The metal layer includes the complete metal patch on the outer surface of the upper and lower dielectric layers and the gap between the adjacent dielectric layers. between the metal gap patch.

As shown in Figure 2 and Figure 3, the periodic unit includes the upper metal patch P ₁ , the upper thin dielectric D ₁ , the upper metal slot piece P ₂ , the middle layer thick dielectric D ₂ , the lower metal slot piece P ₃ , and the lower thin dielectric D ₃ and the lower metal patch _P4 ; the upper metal patch _P1 is attached to the upper surface of the upper thin medium _D1 , the upper metal gap piece _P2 is located between the upper thin medium _D1 and the middle thick medium _D2 , and the lower metal gap The sheet _P3 is located between the lower thin medium _D3 and the middle thick medium _D2 , and the lower metal patch _P4 is attached to the lower surface of the lower thin medium _D3 ; the upper metal patch _P1 and the lower metal patch _P4 have a structure The size is the same and the position on the surface is also the same. The upper metal slot _P2 and the lower metal slot _P3 have the same structural size, and the upper thin dielectric _D1 and the lower thin dielectric _D3 have the same structural size.

The upper and lower surfaces of the thick medium D ₂ in the middle layer of the radome are respectively pasted with an upper metal slot piece P ₂ and a lower metal slot piece P ₃ , wherein the upper metal slot piece P ₂ and the lower metal slot piece P ₃ are mainly composed of a double-shaped metal patch structure a and the peripheral square ring metal patch b and the gap between the two. As shown in Figure 5, the duplex-shaped metal patch a is in the shape of a Jerusalem cross and is located in the center of the outer square ring metal patch b. Specifically, four T-shaped units are evenly spaced along the circumferential direction in a spiral center-symmetrical manner. made. The peripheral square ring metal patch b is located on the outer ring of the duplex-shaped metal patch a, and the outer side length is the same as the side length of the periodic unit, which is a standard metal square ring.

As shown in Figure 4, the upper metal patch _P1 and the lower metal patch _P4 are square metal patches located in the center of the unit structure, and are respectively placed in the center of the upper metal patch _P1 and the lower metal patch _P4 .

The working principle of the radome of the present invention is as follows:

When the incident angle of electromagnetic waves in space is θ, the periodic size of the radome unit determines the phase difference between the electromagnetic waves reaching the surface of each unit. The larger the phase difference, the greater the deviation of the transmission performance when it is perpendicular to the incident electromagnetic wave. In order To overcome the impact of electromagnetic waves on the transmission performance of the radome in the case of multi-angle incidence, the radome in the present invention uses capacitive and inductive surface coupling technology to realize the miniaturization of the unit structure, thereby improving the angular stability of the radome in the present invention .

Among them, the square metal patch layers on the outermost two sides of the radome are periodically arranged to form a capacitive surface to store electric field energy; while the outer square ring metal in the middle two metal gap layers can be equivalent to an inductance to form a perceptual surface , to store magnetic energy. This coupling mechanism of capacitive and inductive surfaces suppresses the fluctuation of electromagnetic waves, breaks the limitation that the unit size is consistent with the resonant wavelength, and thus realizes the miniaturization design of the structural unit.

The square metal patch layers on both sides of the outermost sides can be regarded as transmitting and receiving antennas respectively, which themselves can be equivalent to a series resonant circuit. The outer square ring metal of the middle two metal gap layers is an inductive structure, which forms an LC parallel resonant circuit with the square metal patches on both sides of the outermost side, forming a band-pass effect. The gap between the outer square ring metal of the middle two metal gap layers and the double-shaped structure of the middle metal gap layer forms a capacitive structure, and the "duplex"-shaped structure itself is inductive, so it is regarded as an LC series connection The resonant tank, in turn, generates a transmission zero at the drop of the passband, which realizes the rapid drop of the passband edge.

On the one hand, the radome of the present invention adopts the design of the bimetal gap layer, which forms a high-order filtering effect, widens the bandwidth, increases the flatness in the working frequency band, and improves the selectivity of the radome; on the other hand, it adopts a completely symmetrical The design idea realizes the dual polarization stability design under the TE and TM modes of electromagnetic waves.

The embodiment of the present invention takes the radome applied to the 5G communication industrial frequency band as an example, and specifically elaborates the implementation of each part of the present invention and the influence of each structural parameter on the transmission performance of the radome:

With the rapid development of 5G communication technology, its related standards are gradually taking shape. Now it seems that the 2GHz frequency band around 28.5GHz is most likely to become the working frequency band of 5G communication. At the same time, the passband insertion loss in this frequency band needs to be less than 0.8dB. In addition, It also has good angle and polarization stability. The invention adopts capacitive and inductive surface coupling and AFFA technology to realize the miniaturization and high-performance design of the radome in the high frequency band of 5G communication. The radome in the invention has stable transmission performance of electromagnetic waves within the range of ±60° incident angle , realizes the fast conversion from band-pass to band-stop working state, and has good frequency selection performance.

As shown in FIG. 1 , the embodiment adopts a 32*32 periodic unit array, and the square metal patches P ₁ and P ₂ on both sides of the outermost sides of the periodic unit structure are squares with a side length of 1.73 mm. In practical applications, the size can be selected according to the specific design passband target. Its size changes affect the change of the two transmission poles in the passband. When the size of the square metal patch increases, the entire passband will move towards the low frequency direction, and the passband bandwidth will decrease, but the passband insertion loss will decrease. This is mainly because as the size of the square metal patch increases, its resonant frequency will decrease, so the passband shifts to the low frequency direction; without changing the size of other parts, due to the increase in the size of the square patch , so that the coupling strength between it and the metal gap layer is increased, and then the insertion loss of the passband is reduced, and the improvement of the stability in the passband is at the expense of the bandwidth of the passband. But the size change of the square metal patch has no effect on the transmission zero point of the radome, which is mainly because the transmission zero point is mainly controlled by the middle metal gap layer. Figure 6 specifically describes the influence of the size change of the square metal patch on the passband effect.

The upper thin medium D ₁ , the middle thick medium D ₂ and the lower thin medium D ₃ are all made of Rogers RO3035 plates, and the size of the periodic unit is 2.53mm. The characteristic of this plate is that its dielectric loss is small, so it has less influence on the insertion loss of the passband. However, the price of this plate is relatively high, and in practical applications, a plate with a dielectric constant similar to this material can also be selected for design and processing, thereby reducing the production cost.

As shown in Figures 2, 3, and 4, the surface on both sides of the thick medium D ₂ in the middle layer of the radome is respectively pasted with an upper metal gap sheet P ₂ and a lower metal gap sheet P ₃ , and these two metal gap layers are the design core of the present invention . Firstly, for the outermost square annular metal patch structure b, its outer side length is 2.53 mm, which is the size of the periodic unit structure. The size of the structure b and the size of the two outermost square metal patches P ₁ and P ₄ determine the working frequency band of the radome. The increase in the size of the periodic unit structure will cause the passband to move to the low frequency direction, and the insertion loss in the passband will increase. Passband bandwidth widening. This is mainly due to the increase of the unit period, which reduces the coupling strength between units and increases the insertion loss of the passband; the increase of the outer length of structure b causes the resonant frequency to decrease and the passband to move to the low frequency direction. Similarly, the change of the length of the inner side of the outermost square annular metal patch will also affect the passband.

In addition to the influence on the passband, the two metal gap layers _P1 and _P2 in the middle also have a decisive significance on the stopband after the passband. As shown in Figure 5, the size of the middle duplex metal structure a determines the change of the stop band. When the main structure length L of structure a increases, the stop band will move to the low frequency direction. This is mainly because when the structure of other parts does not change and L increases, the gap between structure a and structure b decreases, and the distance between the two plates equivalent to the capacitance decreases, which in turn increases the capacitance and makes the LC series The resonant frequency generated by the resonant tank is reduced, which shifts the stop band to the low frequency direction. When the arm length J of the duplex metal structure a increases, the corresponding stop band will also move to the low frequency direction. This is mainly due to the increase of J in structure a, which is equivalent to the increase of the plate area of the capacitor, which increases the capacitance and reduces the resonance frequency. Table 1 specifically describes the impact of the size change of the "duplex" metal structure a on the stop band effect.

Table 1 The influence of the size change of "duplex" metal structure a on the stop band effect

The transmission characteristic curve of this embodiment at the time of vertical incidence of electromagnetic waves is shown in Figure 7. The insertion loss in the passband of 27.45GHz to 29.52GHz is less than 0.4dB, and the insertion loss in the bandwidth of 27.19GHz to 29.64GHz is less than 5G communication insertion loss. The loss requirement is 0.8dB; in addition, this example has excellent frequency selectivity, which is manifested in the very fast falling speed of the passband falling edge, realizing the fast conversion from passband to stopband; in the bandwidth of 31.18GHz to 33.53GHz The stopband suppression is greater than 20dB. At the same time, it can be found that the transmission effects of the two polarization modes of TE and TM are completely consistent, which well meets the design requirements of 5G communication radome.

As shown in FIGS. 8 and 9 , the influence of the radome of the embodiment on the transmission performance of the radome when the incident angle of electromagnetic waves changes is described. It can be found in the figure that within the range of the incident angle of ±45°, the transmission characteristic curve basically coincides with the transmission characteristic curve under normal incidence, and has quite stable transmission performance. In addition, with the further increase of the incident angle, the wave impedance changes when the incident angle increases, resulting in an inevitable increase in the passband insertion loss in the TE mode and a decrease in the passband bandwidth in the TM mode. The problem, however, is that as the angle increases, no matter in TE mode or TM mode, the transmission poles and zeros basically do not shift.

Therefore, it can be seen from the above implementation that the present invention realizes a high-performance miniaturized radome design with wide passband insertion loss, wide stopband high rejection, passband steep falling edge, and stable angle and dual polarization performance in high frequency band communication.

Claims (5)

1. A capacitive, inductive surface coupling mechanism miniaturization high-performance high-frequency communication radome, is characterized in that: said radome is a frequency selective surface mainly composed of periodic cell arrays, and each periodic cell is divided into dielectric layer and The metal layer, the dielectric layer includes the upper and lower dielectric layers and a dielectric layer in the middle, the metal layer includes the complete metal patch on the outer surface of the upper and lower dielectric layers and the metal gap patch between the adjacent dielectric layers; free space After the electromagnetic wave is selectively filtered by the radome, the electromagnetic wave of the required working frequency band is output; The periodic unit includes an upper metal patch P ₁ , an upper thin dielectric D ₁ , an upper metal gap P ₂ , a middle thick dielectric D ₂ , a lower metal gap P ₃ , a lower thin dielectric D ₃ and a lower metal patch P ₄ ; The upper metal patch _P1 is attached to the upper surface of the upper thin medium _D1 , the upper metal gap piece _P2 is located between the upper layer thin medium _D1 and the middle thick medium _D2 , and the lower metal gap piece _P3 is located in the lower layer thin medium Between D ₃ and the middle thick medium D ₂ , the lower metal patch P ₄ is pasted on the lower surface of the lower thin medium D ₃ ; the upper metal patch P ₁ and the lower metal patch P ₄ have the same structure size, and the upper metal gap piece P ₂ has the same structural size as the lower metal gap sheet P ₃ , and the upper thin dielectric D ₁ has the same structural size as the lower thin dielectric D ₃ ; The upper metal gap sheet _P2 and the lower metal gap sheet _P3 are mainly composed of a duplex-shaped metal patch structure (a) and a peripheral square ring metal patch (b) and the gap between the two: The duplex-shaped metal patch (a) is in the shape of a Jerusalem cross and is located in the center of the outer square ring metal patch (b); the outer square ring metal patch (b) is located in the duplex-shaped metal patch The outer ring of sheet (a) has the same outer side length as the periodic unit side length. 2. A kind of capacitive, inductive surface coupling mechanism miniaturization high-performance high-band communication radome according to claim 1, is characterized in that: described upper layer metal patch P ₁ and lower floor metal patch P ₄ are placed respectively In the center of the upper thin medium _D1 and the lower thin medium _D3 . 3. A capacitive and inductive surface coupling mechanism miniaturized high-performance high-frequency communication radome according to claim 1, characterized in that: the upper thin medium D ₁ , the middle thick medium D ₂ and the lower thin medium The dielectric constant of the medium _D3 is 3.5, and the dielectric loss tangent is 0.0015. 4. A capacitive and inductive surface coupling mechanism miniaturized high-performance high-band communication radome according to any one of claims 1-3, characterized in that: for the electromagnetic waves perpendicularly incident on the radome, they pass through the antenna successively After each layer structure of the cover, its passband insertion loss in the 27.15GHz-29.65GHz frequency range is less than 0.4dB, and the stopband suppression in the 31.15GHz-33.52GHz frequency band is greater than 20dB; When the angle range changes, its transmission pole and zero point do not change, and the angle and polarization stability are extremely high. 5. The application of a capacitive and inductive surface coupling mechanism miniaturized high-performance high-band communication radome according to claims 1 to 4, characterized in that: the radome is applied to 5G modern communications, radar and military communications .

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