High performance mobile communication radome

Abstract

The present invention discloses a high-performance mobile communication antenna cover. The antenna cover is composed of closely arranged periodic unit structures, and the entire antenna cover structure can be divided into a dielectric layer and a lossy layer and a lossless metal layer attached to both sides of the dielectric layer. The lossy layer is attached to the upper surface of the dielectric layer, and the lossless metal layer is attached to the lower surface of the dielectric layer. The present invention is suitable for the design of a high-performance mobile communication antenna cover for suppressing interference from stray signals of an antenna system, and has excellent polarization stability, a large passband width, and a small insertion loss within the band. When incident in the forward direction, an absorption band with a high absorption rate is formed at the second frequency of the passband, thereby suppressing stray signals of the antenna system. When incident in the negative direction, a highly suppressed reflection band is formed at the double frequency, thereby shielding interference signals in the external environment. It has great application value in modern commercial communications, radar, and military defense fields.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a high-performance mobile communication antenna cover, which can be applied to 5G communications and radar. Background Art

[0002] With the rapid development of communication technology, the performance requirements of communication systems are getting higher and higher. In traditional mobile communication systems, surface acoustic wave (SAW) filters and dielectric filters are usually used to suppress system stray signals. However, due to the large size of dielectric filters and the design concepts of high system integration and portability, the performance of SAW filters gradually deteriorates with the increase of frequency, so they can only be used in low-frequency band communications. In addition, due to the insufficient suppression ability of bulk acoustic wave (BAW) filters for stray signals at the multiple frequency, they cannot meet the requirements of current mobile communications. Therefore, how to improve the suppression of stray signals at the multiple frequency while ensuring the normal operation of the antenna system has become a major challenge in the design of current communication systems.

[0003] Traditional radomes are often just shells made of dielectric materials to protect the antenna and the entire communication system from environmental influences.

[0004] In recent years, the research on electromagnetic metasurfaces has attracted the attention of many scholars at home and abroad, and has also made many breakthroughs. The current research focuses more on the stability of transmission performance. The suppression of stray signals is generally achieved by designing a reflective resistance band. However, when this type of shielding cover is used in a communication system, due to the characteristics of reflection, although it can effectively suppress the radiation of stray signals into space, it will cause the stray signals to be reflected back to the communication system again, causing secondary radiation problems. A better way to suppress stray signals is to absorb and consume them, but absorptive shielding covers often affect the working performance of the antenna itself, which makes the design of absorptive antenna covers extremely difficult. Therefore, designing an antenna cover that can absorb and suppress stray signals at the multiples of the working frequency band while ensuring the stable operation of the antenna is crucial to the development of modern mobile communication technology. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a high-performance mobile communication antenna cover, which realizes efficient absorption of stray signals at the frequency multiples through the ingenious design of the top lossy layer and the bottom lossless layer, and at the same time has stable and efficient selective permeability to the working frequency band signals. The present invention can achieve a high degree of suppression of stray signals at the frequency multiples of the system, and at the same time improve the performance of the communication system itself to a certain extent.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] The antenna cover is composed of at least one periodic unit structure arranged closely, each periodic unit structure is mainly composed of a dielectric layer and a lossy layer and a lossless metal layer attached to both sides of the dielectric layer. The periodic unit structure includes a top lossy layer P 1 , dielectric layer D 0 and the bottom lossless metal layer P 2 ; There is a lossy layer P on the top 1 Attached to the dielectric layer D 0 Upper surface, bottom layer without lossy metal patch P 2 Attached to the dielectric layer D 0 Lower surface.

[0008] The top lossy layer P 1 It consists of a metal square ring and two resistors R welded on the square ring. es Composition: The metal square ring is located in the dielectric layer D 0 At the geometric center of the metal square ring, a rectangular opening is opened in the middle of two adjacent sides, and a resistor R is welded and arranged at each rectangular opening. es , resistor R es Connect the ends of the metal square rings on both sides of the rectangular opening. The side length of the metal square ring is smaller than the dielectric layer D 0 The bottom layer lossless metal patch P 2 The square ring metal patch T located on the periphery 0 And the "Jerusalem" cross metal patch T in the middle 1 Composition, including the "Jerusalem" shaped cross metal patch T 1 Located in square ring metal patch T 0 , is composed of four T-shaped units evenly spaced along the circumference in a centrally symmetrical manner; square ring metal patch T 0 The side length of the dielectric layer D 0 The side length of .

[0009] The dielectric layer D 0 Rogers RT5880 board is used, with a dielectric constant of 2.2 and a dielectric loss tangent of 0.0009.

[0010] The frequency of the electromagnetic waves incident on the antenna cover is 2GHz-9GHz.

[0011] When electromagnetic waves in free space are incident on the radome, they will be selective for electromagnetic waves of specific incident frequencies, so that the signals in the working frequency band can be transmitted normally: for signals incident in the positive direction on the lossy layer on the upper surface of the radome, an absorption band with high absorption rate will be formed at the double frequency of the antenna working frequency band: for signals incident in the negative direction on the lossless layer on the lower surface of the radome, a highly suppressed reflection band will be formed at the double frequency, thereby suppressing the stray signals of the antenna system. The positive incidence refers to the electromagnetic wave incident from the lossy layer on the top of the radome, and the negative incidence refers to the electromagnetic wave incident from the lossless layer on the bottom of the radome.

[0012] In the specific implementation, the lossy layer of the top layer of the present invention only has a great consumption on the stray signal at the antenna frequency doubling, but has little effect on the antenna working signal, thereby achieving the absorption of stray signals while ensuring the normal operation of the antenna. For electromagnetic waves with positive incidence (incident from the lossy layer of the antenna cover), the antenna cover will allow the working signal of the 3.2GHz-3.8GHz frequency band to pass normally, and its loss is less than 0.2dB. The 6.5GHz-7.5GHz frequency band will form an absorption band with a high absorption rate, which absorbs the electromagnetic waves in this frequency band, and the absorption efficiency is greater than 90%, so that it cannot be transmitted through the antenna cover. For electromagnetic waves with negative incidence (incident from the lossless layer of the antenna cover), the antenna cover will allow the working signal of the 3.2GHz-3.8GHz frequency band to pass normally, and its loss is less than 0.2dB. The 6.5GHz-7.5GHz frequency band will form a highly suppressed reflection band, and the suppression effect is more than 20dB, thereby realizing the shielding effect of the antenna cover on this section of the signal.

[0013] The high-performance mobile communication antenna cover of the present invention can be applied to modern communications such as 5G, radar and military communications.

[0014] The working principle of the antenna cover of the present invention is as follows:

[0015] In a communication system, when the antenna is in operation, in addition to radiating useful signals in the operating frequency band, there are also stray signals at the multiples of the antenna's operating frequency band, which will have a serious impact on the antenna system. Traditional antenna covers are usually designed to form a reflective stopband to suppress stray signals. Although the reflective stopband can effectively suppress stray signals, it will cause the stray signals to be reflected back to the antenna system, thereby causing electromagnetic pollution and forming secondary interference. In order to overcome the drawbacks of traditional reflective stopbands, the present invention adopts the following structural design to absorb and suppress stray signals at the multiples while allowing the operating frequency band signals to pass normally to improve the performance of the communication system.

[0016] In the present invention, the top of the antenna cover is a lossy layer with a resistor element. The careful design of the structure enables it to form an absorption effect at the double frequency of the antenna operation, thereby achieving absorption and suppression of stray signals; while the bottom of the antenna cover is a lossless layer structure. On the one hand, it forms a stop band at the double frequency, and cooperates with the lossy layer on the top layer to form an absorption effect. On the other hand, it forms a low-loss wide passband in the antenna operating frequency band, so that the working signal passes through the antenna cover without being affected, thereby ensuring the normal operation of the antenna.

[0017] Top lossy layer P 1 It is mainly composed of a metal square ring and two resistors R welded on the square ring. es Composition: The metal square ring is located at the geometric center of the structural unit, and has two rectangular openings in the middle of its two adjacent sides; two resistors R es Welded to the rectangular opening of the metal square ring. From the perspective of equivalent circuit, the metal square ring can be equivalent to an inductor L 0 , and the gap between the unit and the unit structure can be equivalent to the capacitor C 0 , plus the resistor R soldered to the metal square ring es , forming an RLC series circuit. Figure 5 The current distribution at the double frequency of the antenna working frequency band is shown. It can be found that at a specific frequency, the RLC series circuit forms a resonance effect, and a strong current is formed on the square ring. es Make the stray signal energy consumption, realize the absorption and suppression of stray signals; Figure 6 The current distribution at the antenna operating frequency is shown. It can be seen that the current intensity is small at this time, so it will not cause too much consumption to the antenna working signal, ensuring the normal operation of the antenna.

[0018] Bottom layer lossless metal patch P 2 It is mainly composed of the outer square ring metal patch T 0 And the "Jerusalem" cross metal patch T in the middle 1 From the perspective of equivalent circuit, the outer square ring metal patch T 0 Can be equivalent to inductance L 1 The gap between the metal square ring and the Jerusalem cross metal patch is equivalent to a capacitor C 2 , and the Jerusalem cross metal patch itself can be equivalent to the inductor L 2 Capacitor C 2 With inductance L 2 The LC series circuit is formed to resonate at the antenna frequency doubling to form a stop band, which cooperates with the lossy layer on the top layer to achieve an absorption band, thereby absorbing stray signals. 1 With capacitor C 2 and inductor L 2The series circuit is formed into an LC parallel circuit, which forms resonance in the antenna working frequency band, forms a passband in the working frequency band, realizes a transparent effect on the antenna working signal, and ensures the normal operation of the antenna. Finally, the equivalent circuit model of the present invention is as follows Figure 7 As shown. Figure 7 Z in the equivalent circuit shown 0 is the impedance in free space, Z h0 is the equivalent impedance of the dielectric layer.

[0019] The antenna cover in the present invention adopts a completely symmetrical design concept, and realizes a dual-polarization stability design in the TE and TM modes of electromagnetic waves.

[0020] The present invention is suitable for the design of high-performance mobile communication antenna covers that suppress stray signals and have high polarization stability. The insertion loss in the passband is small and stable, and a high-suppression wide stopband is formed at the second frequency of the passband (a reflection band is formed for positive incidence and an absorption band is formed for negative incidence). The polarization stability is excellent. It has great application value in modern communications, radar, military defense and other fields.

[0021] The beneficial effects of the present invention are:

[0022] The present invention realizes the design of the antenna shielding cover of the 5G communication system, which is suitable for the design of high-performance mobile communication antenna cover for suppressing the interference of stray signals of the antenna system. It has excellent polarization stability, a large passband width and a small insertion loss in the band. When the incident direction is forward, an absorption band with high absorption rate is formed at the second frequency of the passband, so as to suppress the stray signals of the antenna system. When the incident direction is negative, a highly suppressed reflection band is formed at the double frequency, so as to suppress the interference signals in the external environment. It provides a feasible solution for solving the problems of suppressing stray signals in the 5G antenna system, secondary radiation caused by traditional lossless reflective FSS antenna cover and large loss of working signals by traditional absorbers.

[0023] The antenna cover of the present invention has the structural characteristics of a frequency selective absorber. The final antenna cover thickness is only 0.037λ, which is much smaller than the design requirement of 1 / 4λ of a traditional absorber. This greatly reduces the volume of the antenna cover and the weight of the antenna system, making its application in a new generation of mobile communication systems possible.

[0024] In addition, the present invention adopts a completely symmetrical design, so that its electromagnetic dual-polarization performance is stable, and both TE and TM polarization modes are supported.

[0025] The present invention has extremely high application value in miniaturization of antenna devices, modern communications such as 5G, radar and military communications.

[0026] In summary, the present invention is suitable for the design of high-performance mobile communication antenna covers that suppress stray signals and have high polarization stability. The insertion loss in the passband is small and stable, and a high-suppression wide stopband is formed at the second frequency of the passband (a reflection band is formed for positive incidence and an absorption band is formed for negative incidence), and the polarization stability is excellent. It has great application value in modern communications, radar, military defense and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a three-dimensional structural diagram of a radome according to an embodiment of the present invention;

[0028] Figure 2 It is a front view of the unit structure of the present invention;

[0029] Figure 3 is a top metal structure view of the unit structure of the present invention;

[0030] Figure 4 is a view of the underlying metal structure of the unit structure of the present invention;

[0031] Figure 5 This is a current distribution diagram of the top structure of the present invention at 7 GHz (the antenna operating frequency multiple);

[0032] Figure 6 This is a view of current distribution in the top metal structure of the unit structure of the present invention at 3.5 GHz;

[0033] Figure 7 is an equivalent circuit model diagram of the antenna cover of the present invention;

[0034] Figure 8 is the distance S from the top metal square ring to the edge of the unit structure t The influence curve of transmission performance when the change occurs;

[0035] Fig. 9 is the transmission performance curve of the radome of the present invention under forward incidence TE and TM polarization modes;

[0036] Fig.10 is the transmission performance curve of the radome of the present invention for reverse incident TE and TM polarization modes;

[0037] Fig.11 It is the absorptivity curve of the antenna cover of the present invention when the electromagnetic wave is incident in the forward direction under the TE polarization mode. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings.

[0039] The embodiment of the present invention takes the radome applied to the industrial frequency band of 5G communication as an example to specifically explain the implementation methods of various parts of the present invention and the influence of various structural parameters on the transmission performance of the radome:

[0040] The Rogers RT5880 plate material used in the dielectric plate of the present invention has a periodic unit size of 15.5 mm. The characteristic of the plate material is that its dielectric loss is very small, so the insertion loss of the passband is less affected. However, the price of the plate material is relatively high. If the insertion loss requirement of the passband is low, in actual applications, a plate material with a dielectric constant close to that of the material can also be selected for design and processing, thereby reducing the production cost.

[0041] like Figure 1 and Figure 2 As shown, there is a lossy layer P on the top of the radome 1 , dielectric layer D 0 and the bottom lossless metal layer P 2 ; Top lossy layer P 1 Attached to the dielectric layer D 0 Upper surface, bottom layer without lossy metal patch P 2 Attached to the dielectric layer D 0 Lower surface.

[0042] like Figure 3 As shown, there is a lossy layer P on the top 1 It consists of a metal square ring and two resistors R welded on the square ring. es Composition: The metal square ring is located in the dielectric layer D 0 At the geometric center of the metal square ring, a rectangular opening is opened in the middle of two adjacent sides, and a resistor R is welded and arranged at each rectangular opening. es , resistor R es Connect the ends of the metal square rings on both sides of the rectangular opening. The side length of the metal square ring is smaller than the dielectric layer D 0 The side length of .

[0043] like Figure 4 As shown, the bottom layer has no lossy metal patch P 2 The square ring metal patch T located on the periphery 0 And the "Jerusalem" cross metal patch T in the middle 1 The "Jerusalem" cross metal patch T 1 Located in square ring metal patch T 0 , is composed of four T-shaped units evenly spaced along the circumference in a centrally symmetrical manner; square ring metal patch T 0 Located in the outer ring of the unit structure, the square ring metal patch T 0 The side length of the dielectric layer D 0 The side length of the square ring metal patch T 0 Outer edge and dielectric layer D 0 It is aligned with the outer edge of a standard metal square ring.

[0044] Table 1 Dimensions of various parts of the structure of the present invention

[0045] P <![CDATA[S t ]]> <![CDATA[W 0 ]]> <![CDATA[h 0 ]]> <![CDATA[R es ]]> 15.5mm 3.5mm 1.1mm 3.175mm 145Ω <![CDATA[W 1 ]]> <![CDATA[W 2 ]]> <![CDATA[W 3 ]]> <![CDATA[L 0 ]]> <![CDATA[S 0 ]]> 0.55mm 1.25mm 2.9mm 9mm 0.84mm

[0046] like Figure 1 As shown, the embodiment adopts a 20*20 periodic unit array. The unit period in the present invention is 15.5mm. The structural dimensions of each part are shown in Table 1. In practical applications, the corresponding dimensions can be selected according to the specific design goals. 1 The gap S between the metal square ring and the edge of the unit structure t Or the width W of the metal square ring 0 When the absorption band decreases, it will move to low frequency, which is mainly due to the gap S t The reduction of the equivalent capacitance C 0 and inductor L 0 increases, thus making the capacitance C 0 With inductance L 0 The series resonance frequency formed becomes smaller. Similarly, if the square ring width W 0 Reduce, can make the inductance L 0 increases, thus causing the resonant frequency to move to a lower frequency. 2 The width of the outer metal square ring is W 1 When it decreases, the passband will move to lower frequencies, which is mainly due to the width W 1 The reduction of the equivalent inductance L 1 becomes larger, making it larger than the capacitance C 2 With inductance L 2 The transmission pole controlled by the LC parallel circuit composed of the series circuit becomes smaller, so the passband moves toward the low frequency direction. Figure 8 Specifically describes the gap S from the top square ring metal patch to the edge of the structural unit t The effect of changes on the transmission performance of the radome in the present invention.

[0047] The asymmetric arrangement of the two resistors in the top lossy layer is a design innovation of the present invention. First, the top resistor R es Distributed at the midpoint of two adjacent edges of the top metal square ring, the existence of inductance will destroy the metal integrity of the original metal square ring. When all four edges are loaded with resistors, the metal square ring will have very poor inductance, making the absorption band unable to meet the requirements; at the same time, if only one side is loaded with resistors, the structure will be asymmetrical, which will destroy the dual-polarization stability of TE and TM. Through a large number of simulation verifications and theoretical derivations, asymmetric resistor loading is the best design solution.

[0048] The functional innovation of the present invention is that the signal in the working frequency band is almost completely transparent, and the stray signal absorption at the double frequency of the forward incident frequency and the reflection suppression of the external environment interference signal at the double frequency of the reverse incident frequency are absorbed. The lossy layer on the top layer only works at the double frequency of the antenna working frequency band, so as to absorb the stray signal without attenuating the working signal; for the interference signal from the external environment, the radome will reflect it and it cannot enter the antenna system through the radome, thus better ensuring the stable operation of the antenna system. Fig. 9 and 10 The transmission effect of the radome is specifically demonstrated when electromagnetic waves are incident in the forward and reverse directions.

[0049] The transmission characteristic curve of this embodiment when the electromagnetic wave is incident vertically in the forward direction is as follows: Fig. 9 As shown in the figure, the insertion loss in the 3.05GHz–3.99GHz frequency band is less than the 5G communication requirement of 0.8dB, and the insertion loss in the 3.4GHz–3.6GHz frequency band is less than 0.15dB; in addition, this example has a good suppression effect on the stray signals in the antenna working frequency band, and the reflection in the 6.5GHz–7.5GHz frequency band is less than -10.4dB, and the transmission is less than -13.2dB, as shown in the figure. Fig.11 As shown in the figure, the absorption efficiency in this frequency band is greater than 90%, while the absorption rate in the working frequency band is less than 2%. At the same time, it can be found that the transmission effects in the TE and TM polarization modes are completely consistent, which well meets the design requirements of the 5G communication antenna cover.

[0050] like Fig.10 As shown in the figure, the effect on the transmission performance of the antenna cover when the electromagnetic wave is incident on the antenna cover in the reverse direction is described. In the 3.07GHz-4.05GHz frequency band, the insertion loss is less than the 0.8dB requirement of 5G communication, and the insertion loss in the 3.4GHz-3.6GHz frequency band is less than 0.19dB; in addition, this example has a good suppression effect on the stray signals in the antenna working frequency band, and the reflection is greater than -0.48dB in the 6.5GHz-7.5GHz frequency band. The electromagnetic waves incident in this frequency band are basically all reflected, which well covers the frequency band range of the stray signals of the 5G communication system, thereby avoiding the influence of interference signals from the external environment on the antenna system and achieving high stability of the antenna system.

[0051] Therefore, the present invention realizes low loss of working signals in 5G communication, absorption of forward incident spurious signals at the frequency doubling of the working signal, reflection suppression of reverse incident external environmental interference signals, and a high-performance antenna shielding cover design with fairly stable dual-polarization performance.

Claims

1. A high-performance mobile communication antenna cover, characterized in that: The antenna cover is composed of a periodic unit structure arranged closely, and the periodic unit structure includes a top lossy layer P1, a dielectric layer D0 and a bottom lossless metal patch P2; the top lossy layer P1 is attached to the upper surface of the dielectric layer D0, and the bottom lossless metal patch P2 is attached to the lower surface of the dielectric layer D0; the top lossy layer P1 is composed of a metal square ring and two resistors R welded on the square ring. es Composition: The metal square ring is located at the geometric center of the dielectric layer D0. A rectangular opening is opened in the middle of two adjacent sides of the metal square ring. A resistor R is welded and arranged at each rectangular opening. es , resistor R es The metal square ring ends connected to the two sides of the rectangular opening have a side length smaller than the side length of the dielectric layer D0; the bottom layer lossless metal patch P2 is composed of a square ring metal patch T0 located at the periphery and a "Jerusalem" shaped cross metal patch T1 located in the middle, wherein the "Jerusalem" shaped cross metal patch T1 is located at the center of the periodic unit structure, and is composed of four T-shaped units evenly spaced along the circumference in a centrally symmetrical manner; The side length of the square ring metal patch T0 is equal to the side length of the dielectric layer D0; The dielectric layer D0 is made of Rogers RT5880 plate, with a dielectric constant of 2.2 and a dielectric loss tangent of 0.0009.

2. A high performance mobile communication antenna cover according to claim 1, characterized in that: The frequency of the electromagnetic wave incident on the radome is 2 GHz-9 GHz.

3. The high performance mobile communication antenna cover according to claim 1, characterized in that: When electromagnetic waves in free space are incident on the antenna cover, it will be selective for electromagnetic waves of specific incident frequency, allowing the working frequency band signals to pass normally; for signals that are positively incident on the lossy layer on the upper surface of the antenna cover, an absorption band with high absorption rate will be formed at the twice frequency of the antenna working frequency band; for signals that are negatively incident on the lossless layer on the lower surface of the antenna cover, a highly suppressed reflection band will be formed at the double frequency, thereby achieving the suppression of stray signals of the antenna system.

4. A high-performance mobile communication antenna cover according to any one of claims 1 to 3 can be used in 5G modern communications, radar and military communications.

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