Grating lobe suppression technology for large-pitch array antennas based on metamaterial lenses

Abstract

The present invention provides a method for suppressing grating lobes of a large-spacing array antenna based on a metamaterial lens. The method comprises arranging a metamaterial lens (1) capable of transmitting antenna radio waves above a radiation surface of a large-spacing feed source array (2) of the antenna; the metamaterial lens comprises sub-wavelength metamaterial lens units (4) arranged densely and evenly at intervals; the lens units provide a compensation phase of the antenna radio waves for the area where the lens units are located by adjusting their radio wave transmission phases; when the radio waves of the large-spacing array feed source are incident on the metamaterial lens, the metamaterial lens provides the required compensation phases with each lens unit, so that the waves passing through the upper surface of the metamaterial lens are in phase, thereby suppressing the generation of grating lobes; the present invention can suppress antenna grating lobes based on a phase correction metasurface, and enhance the gain performance of large-spacing array antennas.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, in particular to a method for suppressing grating lobes of large-spacing array antennas based on metamaterial lenses. Background Art

[0002] High gain antennas have been widely used in many applications such as satellite communications, military radars, and earth and planetary coverage applications. To reduce the size, profile, and weight of these systems, planar array antennas are often used. The increase in operating range expands the aperture of the antenna array. According to antenna array theory, the distance between array elements in antenna arrays, especially beam scanning array antennas, should be around half a wavelength to avoid grating lobes. Therefore, large array antennas require a large number of array elements, which are densely arranged, increasing cost and design complexity.

[0003] Current and future wireless communication systems, such as the fifth and sixth generation wireless systems, have proposed the use of millimeter wave antenna arrays. When the antenna operates at millimeter wavelengths, other challenges are introduced, such as heat dissipation due to high packaging density, difficulty in coordination, and difficulty in reliability. In order to alleviate or even overcome these challenges, a simple and effective way is to reduce the density of array elements, that is, by using non-periodic or uniform large-spacing array antennas. However, this will lead to the appearance of larger grating lobes. Grating lobe suppression technology was developed as early as the 1970s to reduce the cost of limited scanning arrays. The emergence of technologies such as overlapping or staggered subarrays and non-periodic arrays has effectively solved this problem, but this will lead to the complexity of antenna design.

[0004] In recent years, metasurfaces have attracted great research interest due to their novel functions in manipulating electromagnetic waves. Phase gradient metasurfaces have been applied in practice. The present invention proposes a new method for suppressing antenna grating lobes and enhancing the gain performance of large-spacing array antennas based on phase correction metasurfaces. Unlike the existing grating lobe suppression methods, this method does not increase the design difficulty and can be flexibly applied to large or small, uniform or non-uniform, and periodic or non-periodic large-spacing arrays. Summary of the invention

[0005] The present invention proposes a method for suppressing grating lobes of large-spacing array antennas based on metamaterial lenses, which can suppress antenna grating lobes based on phase correction metasurfaces and enhance the gain performance of large-spacing array antennas.

[0006] The present invention adopts the following technical solutions.

[0007] A method for suppressing grating lobes of large-spacing array antennas based on metamaterial lenses, the method comprising arranging a metamaterial lens (1) capable of transmitting antenna radio waves above a radiation surface of a large-spacing feed source array (2) of the antenna; the metamaterial lens is composed of sub-wavelength metamaterial lens units (4) arranged densely and evenly spaced; the lens units provide a compensation phase of antenna radio waves for the area where the lens units are located by adjusting their radio wave transmission phases;

[0008] When the radio waves of the large-pitch array feed source are incident on the metamaterial lens, the metamaterial lens provides the required compensation phase with each lens unit, so that the waves passing through the upper surface of the metamaterial lens are in phase to suppress the generation of grating lobes.

[0009] The lens units are lens units with high radio wave transmittance and are evenly distributed directly above the feed source array. The transmission phase of each metamaterial lens unit can be adjusted individually to provide the required compensation phase within the range of 0-360 degrees or within a limited phase range.

[0010] The lens unit is a lens unit that converts linear polarization waves into circular polarization waves. A rotatable metal patch is provided at the exit surface of the lens unit, and the transmission phase of the lens unit changes with the rotation of the metal patch.

[0011] When the metal patch of the lens unit rotates, the transmittance of the lens unit remains approximately unchanged.

[0012] The lens unit spacing is less than 0.7 wavelength.

[0013] The distance between the metamaterial lens and the large-pitch array feed source is adjustable, and the grating lobe suppression effect of the metamaterial lens on different large-pitch array antennas can be adjusted by adjusting the distance.

[0014] The medium between the metamaterial lens and the large-pitch array feed source is an air medium, and the distance between the metamaterial lens and the large-pitch feed source array is one working wavelength of the antenna.

[0015] The large-spacing feed array includes a plurality of feeds, and the spacing between the feeds is greater than an operating wavelength of the antenna; the initial amplitudes of the feeds may be the same or different, and the phases of the feeds may be the same or different.

[0016] The side length or diameter of the metamaterial lens is greater than the side length or diameter of the feed source array, and the difference is at least two working wavelengths of the antenna.

[0017] A reflective ground (3) is provided below the large-pitch feed source array; the reflective ground is a metal layer, which reflects electromagnetic waves radiated downward from the large-pitch feed source array, so that the main radiation working area of ​​the antenna is located above the reflective ground and the metamaterial lens, and the gain performance of the array antenna is improved.

[0018] In the present invention, the metamaterial lens and the large-pitch feed array are not limited to specific lenses and feeds, and the metamaterial lens and feed can be replaced with lenses of different structures and feeds of different structures. In the large-pitch array, the feed spacing can be uneven, which can make other sparse array antennas that produce grating lobes.

[0019] The present invention belongs to the field of antenna engineering technology and can be flexibly applied to large or small, uniform or non-uniform, periodic or non-periodic large-pitch array antennas. In the above scenario, according to array antenna theory, when the array element spacing of the array is greater than an operating wavelength, a grating lobe will be generated in the radiation pattern, and according to the Huygens principle, the working far field above the lens is formed by the lens array rather than the original large-pitch array. Since the unit spacing on the lens is half a wavelength, if the amplitude and phase on the lens array unit are appropriate, the grating lobe from the original large-pitch array will be suppressed; the present invention uses a metamaterial lens to control the phase of an electromagnetic wave so that the waves passing through the upper surface of the lens are in phase, which can suppress the generation of grating lobes; the large-pitch array grating lobe suppression method based on a metamaterial lens described in the present invention starts from a uniform sparse array, but can be used for a non-uniform or uniform sparse array, the method is practical and simple, and can suppress the grating lobe of the array antenna without significantly increasing the cross-sectional size of the array, while also greatly improving the gain of the array antenna.

[0020] The present invention proposes a new method for suppressing antenna grating lobes and enhancing the gain performance of large-spacing array antennas based on phase-corrected metasurfaces. Unlike the existing grating lobe suppression methods, this method does not increase the design difficulty and can be flexibly applied to large or small, uniform or non-uniform, and periodic or non-periodic large-spacing arrays.

[0021] The innovation of the present invention lies in that the traditional array antenna grating lobe suppression method is to use overlapping or staggered sub-arrays, or to use non-periodic arrays. However, these designs will lead to efficiency loss. In order to solve the loss problem, an array synthesis method with an optimization strategy has been developed, such as using global optimization or optimization evolution algorithm. These designs will cause the complexity of the design and the problem of the feed network requires a large amount of computing resources. In the design method involved in the present invention, no overlapping staggered or non-periodic arrays are used, but a metamaterial lens with good transmission performance is used. The design can be completed by only optimizing and compensating the metamaterial lens unit. This will not only reduce the complexity of the design, but also make it easy to process. The use of sub-wavelength metamaterial lenses will not reduce the working frequency band of the array antenna, and at the same time, it can improve the gain performance of the antenna. The feed module uses a large-pitch array or other sparse array. The spacing and size of the feed source and the spacing between the feed source array and the metamaterial lens can be adjusted according to actual conditions.

[0022] The beneficial effects of the present invention are as follows: a grating lobe suppression technology for large-spacing array antennas based on metamaterial lenses is proposed. The use of subwavelength metamaterial lenses can suppress the grating lobes of the antenna without reducing the operating frequency band of the array antenna, so that the antenna has better radiation performance when using large-spacing feed sources, solving the problems of complex structure and poor actual operating performance caused by the traditional use of large-spacing feed array grating lobe suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0024] Attached Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0025] Attached Figure 2 It is a schematic diagram of the structure of a metamaterial lens unit in a preferred embodiment of the present invention;

[0026] Attached Figure 3 A schematic diagram of the amplitude and phase distribution of eight units obtained by rotating the upper metal patch of the metamaterial lens unit in a preferred embodiment of the present invention;

[0027] Attached Figure 4 This is a schematic diagram of the E-plane direction calculated by the large-spacing array antenna without a metamaterial lens loaded in a preferred embodiment of the present invention;

[0028] Attached Figure 5 This is a schematic diagram of the H-plane direction calculated by the large-spacing array antenna without a metamaterial lens loaded in a preferred embodiment of the present invention;

[0029] Attached Figure 6 This is a schematic diagram of the E-plane direction calculated after the large-spacing array antenna is loaded with a metamaterial lens in a preferred embodiment of the present invention;

[0030] Attached Figure 7 This is a schematic diagram of the H-plane direction calculated after the large-spacing array antenna is loaded with a metamaterial lens in a preferred embodiment of the present invention;

[0031] Attached Figure 8 It is a schematic diagram of the working principle of the present invention;

[0032] In the figure: 1-metamaterial lens; 2-large-pitch feed source array; 3-reflective ground; 4-lens unit; 5-metal patch. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments, rather than schematically limiting the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form, and it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] As shown in the figure, a method for suppressing grating lobes of large-spacing array antennas based on metamaterial lenses is provided. The method is to set a metamaterial lens 1 that can transmit antenna radio waves above the radiation surface of the large-spacing feed source array 2 of the antenna; the metamaterial lens is composed of sub-wavelength metamaterial lens units 4 that are densely arranged at uniform intervals; the lens unit provides a compensation phase of antenna radio waves for the area where the lens unit is located by adjusting its radio wave transmission phase;

[0036] When the radio waves of the large-pitch array feed source are incident on the metamaterial lens, the metamaterial lens provides the required compensation phase with each lens unit, so that the waves passing through the upper surface of the metamaterial lens are in phase to suppress the generation of grating lobes.

[0037] The lens units are lens units with high radio wave transmittance and are evenly distributed directly above the feed source array. The transmission phase of each metamaterial lens unit can be adjusted individually to provide the required compensation phase within the range of 0-360 degrees or within a limited phase range.

[0038] The lens unit is a lens unit that converts linear polarization waves into circular polarization waves. A rotatable metal patch 5 is provided at the exit surface of the lens unit, and the transmission phase of the lens unit changes with the rotation of the metal patch.

[0039] When the metal patch of the lens unit rotates, the transmittance of the lens unit remains approximately unchanged.

[0040] The lens unit spacing is less than 0.7 wavelength.

[0041] The distance between the metamaterial lens and the large-pitch array feed source is adjustable, and the grating lobe suppression effect of the metamaterial lens on different large-pitch array antennas can be adjusted by adjusting the distance.

[0042] The medium between the metamaterial lens and the large-pitch array feed source is an air medium, and the distance between the metamaterial lens and the large-pitch feed source array is one working wavelength of the antenna.

[0043] The large-spacing feed array includes a plurality of feeds, and the spacing between the feeds is greater than an operating wavelength of the antenna; the initial amplitudes of the feeds may be the same or different, and the phases of the feeds may be the same or different.

[0044] The side length or diameter of the metamaterial lens is greater than the side length or diameter of the feed source array, and the difference is at least two working wavelengths of the antenna.

[0045] A reflective ground 3 is provided below the large-spacing feed array; the reflective ground is a metal layer, which reflects electromagnetic waves radiated downward from the large-spacing feed array, so that the main radiation working area of ​​the antenna is located above the reflective ground and the metamaterial lens, and improves the gain performance of the array antenna.

[0046] Example:

[0047] Figure 1 It is a schematic diagram of the three-dimensional structure of the antenna loaded with a metamaterial lens for phase compensation in a specific embodiment of the present invention. The feed source is composed of 8×8 ideal feed sources, the spacing of which is set to 1.5 working wavelengths, the amplitude of the feed source is set to 1, and the phase is set to 0°. Then the metamaterial lens is evenly placed directly above the feed source array. The period of the metamaterial lens unit is 0.4 working wavelengths, the overall size of the metamaterial lens is 32×32, and the distance between the metamaterial lens and the large-pitch feed source array is 1 working wavelength. Adjusting the distance between the metamaterial lens and the large-pitch feed source array can achieve different grating lobe suppression effects.

[0048] Figure 2 Schematic diagram of the structure of the metamaterial lens unit in a specific embodiment of the present invention. Figure 2 As shown, the unit can convert linear polarization waves into circular polarization waves, which can reduce the system's sensitivity to the antenna orientation. And the phase of the output wave can be controlled by rotating the upper metal patch. When the upper metal patch is rotated, the transmission phase of the unit will change, and the transmittance of the unit will remain almost unchanged. This not only ensures that the metamaterial unit has a high transmittance within the designed frequency band, but also produces different transmission phases. The period and implementation effect of the metamaterial lens unit can be optimized according to specific requirements. The optimization of the periodic unit can enable it to have stronger radiation within a certain space, and also enable it to have a wider axial ratio and greater transmission efficiency, thereby improving the overall antenna performance.

[0049] Figure 3 The amplitude and phase distribution diagrams of eight units of the metamaterial lens unit in the specific embodiment of the present invention are obtained by rotating the upper metal patch at intervals of 45°. Figure 3As shown, the transmission amplitudes of the eight metamaterial lens units at the operating frequency are very high, all above 0.9. The transmission phases of the eight metamaterial lens units also change linearly at intervals of 45°, covering a range of 0-360°. At the same time, when the upper metal patch of the unit is rotated at any angle, different transmission phases will be generated in the range of 0-360°, which means that the metamaterial lens unit can generate transmission phases at any angle individually, so that each metamaterial lens unit can perform phase compensation individually according to the phase that needs to be compensated, so that the phase of the wave passing through the upper surface of the metamaterial lens is consistent, achieving the purpose of grating lobe suppression. The transmission amplitude and transmission phase of the metamaterial lens unit can be optimized according to the needs of the unit.

[0050] The metamaterial lens placed directly above the large-spacing feed source needs to be adjusted according to the specific situation during design. In a specific embodiment of the present invention, when placing the metamaterial lens, it is first necessary to use simulation software to read the near field of the metamaterial lens position directly above the large-spacing feed source array, and then perform data processing based on the read near field to obtain the phase distribution of the metamaterial lens position directly above the large-spacing feed source array, and use the phase compensation function of the metamaterial lens to perform corresponding continuous phase compensation on the phase of the metamaterial lens directly above the large-spacing feed source, so that the phase of the wave passing through the upper surface of the metamaterial lens is the same. The phase compensation method can also be changed accordingly according to the performance of the metamaterial lens, for example, 3-bit phase (eight phases with a step length of 45) compensation can also be performed.

[0051] Figure 4 This is the E-plane radiation pattern calculated by software simulation without loading the metamaterial lens (i.e., without performing phase compensation) in a specific embodiment of the present invention. As can be seen from the figure, the radiation pattern has two very high-level grating lobes at 50° and 125°.

[0052] Figure 5 This is an H-plane radiation pattern calculated by software simulation without loading a metamaterial lens (i.e., without performing phase compensation) in a specific embodiment of the present invention. As can be seen from the figure, the radiation pattern has two very high-level grating lobes at 50° and 125°.

[0053] Figure 6 This is the E-plane directional diagram obtained by software simulation calculation after loading the metamaterial lens for phase compensation in a specific embodiment of the present invention. Figure 4 It can be seen that the two grating lobes with high levels at 50° and 125° are significantly suppressed after loading the metamaterial lens for phase compensation, and the grating lobe level is below -20dB. This verifies that the use of a metamaterial lens with phase compensation function can suppress the grating lobes of the antenna, thereby improving the gain of the antenna.

[0054] Figure 7This is the H-plane directional diagram obtained by software simulation calculation after loading the metamaterial lens for phase compensation in a specific embodiment of the present invention. Figure 5 It can be seen that the two grating lobes with high levels at 50° and 125° are significantly suppressed after loading the metamaterial lens for phase compensation, and the grating lobe level is below -20dB. This verifies that the use of a metamaterial lens with phase compensation function can suppress the grating lobes of the antenna, thereby improving the gain of the antenna.

[0055] In summary, the technical means proposed in the present invention solves the problem that the grating lobes of large-spacing antenna arrays are too high in practical applications, thereby affecting the antenna gain, and the design difficulty is small and the adjustability is strong.

[0056] The above is a description of the preferred implementation of the present invention and its specific implementation scheme provided to the engineering and technical personnel familiar with the field of the present invention. It should be noted that these descriptions should be regarded as illustrative rather than restrictive. For the engineering and technical personnel in this field, without departing from the principle of the present invention, the central idea of ​​the invention can also be combined with specific problems to make specific operations, several improvements and embellishments, and naturally a series of changes can be made to the implementation scheme according to the above. The above contents should also be regarded as the protection scope of the present invention.

Claims

1. A method for suppressing grating lobes of large-spacing array antennas based on metamaterial lenses, characterized in that: The suppression method comprises arranging a metamaterial lens (1) capable of transmitting antenna radio waves above the radiation surface of the antenna's large-spaced feed source array (2); the metamaterial lens is composed of sub-wavelength metamaterial lens units (4) arranged densely and evenly spaced; the lens units provide a compensation phase of the antenna radio waves for the area where the lens units are located by adjusting their radio wave transmission phases; When the radio waves of the large-spaced feed source array are incident on the metamaterial lens, the metamaterial lens provides the required compensation phase with each lens unit, so that the waves passing through the upper surface of the metamaterial lens are in phase to suppress the generation of grating lobes; The lens units are lens units with high radio wave transmittance, which are evenly distributed directly above the feed source array. The transmission phase of each metamaterial lens unit can be adjusted individually to provide the required compensation phase within the range of 0-360 degrees or within a limited phase range; The lens unit is a lens unit that converts a linear polarization wave into a circular polarization wave. A rotatable metal patch is provided at the exit surface of the lens unit, and the transmission phase of the lens unit changes with the rotation of the metal patch. When the metal patch of the lens unit rotates, the transmittance of the lens unit remains approximately unchanged; The lens unit spacing is less than 0.7 wavelength; The distance between the metamaterial lens and the large-pitch feed source array is adjustable, and the grating lobe suppression effect of the metamaterial lens on different large-pitch array antennas can be adjusted by adjusting the distance; The medium between the metamaterial lens and the large-pitch feed source array is an air medium, and the distance between the metamaterial lens and the large-pitch feed source array is one working wavelength of the antenna; The large-spacing feed source array comprises a plurality of feed sources, and the spacing between the feed sources is greater than an operating wavelength of the antenna; the initial amplitudes of the feed sources may be the same or different, and the phases of the feed sources may be the same or different; The side length or diameter of the metamaterial lens is greater than the side length or diameter of the feed array, and the difference is at least two working wavelengths of the antenna; A reflective ground is provided below the large-spacing feed array; the reflective ground is a metal layer, which reflects electromagnetic waves radiated downward from the large-spacing feed array, so that the main radiation working area of ​​the antenna is located above the reflective ground and the metamaterial lens, and improves the gain performance of the array antenna.

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