A method for cross-polarization and grating lobe processing of a coplanar KA flat antenna

Abstract

The present invention relates to the field of antenna technology, specifically to a method for processing cross-polarization and grating lobes of a coplanar KA flat-panel antenna for transmitting and receiving. The coplanar KA flat-panel antenna for transmitting and receiving refers to an antenna in which a waveguide and a microstrip coexist. For such an antenna, due to too many layers and serious mutual coupling, high cross-polarization lobes and grating lobes are easily present in the directional pattern radiated from the bottom excitation. In the present technical scheme, by optimizing the thickness and caliber of each layer of radiating waveguide, the high cross-polarization lobes appearing in the directional pattern radiated from the bottom excitation can be well improved. By thinning each layer of dielectric plate and opening windows, etc., the high grating lobes appearing in the directional pattern radiated from the bottom excitation can be well improved. Through this design, the antenna gain is greatly improved, and the problem of interference from neighboring satellites is solved.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a cross-polarization and grating lobe processing method of a coplanar KA flat antenna. Background Art

[0002] With the development of satellite communications, the Ka-band has attracted more and more attention due to its wide bandwidth, large capacity, and strong anti-interference ability, and its market share is also increasing. However, since the Ka-band adopts a dual circular polarization system, the number of flat antenna layers is large, and the mutual coupling between them is very serious. The directional pattern radiated from the bottom excitation is prone to high cross-polarization lobes and grating lobes, which seriously affects the communication quality of the system. A Ka-band coplanar antenna refers to an antenna with coexistence of waveguide and microstrip. For this type of antenna, due to the large number of layers and serious mutual coupling, the directional pattern radiated from the bottom excitation is prone to high cross-polarization lobes and grating lobes. A Ka-band coplanar antenna is needed to solve this problem. Summary of the invention

[0003] The object of the present invention is to provide a cross-polarization and grating lobe processing method for a coplanar KA flat antenna to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for cross-polarization and grating lobe processing of a coplanar KA flat antenna, comprising the following three steps: S1. First, the radiation pattern of the bottom excitation radiation, the cross-polarization lobe appears on the right side of the main lobe; and the thickness of the waveguide port is set to h, the side length is d, from top to bottom, the top three layers are h1, h2, h3; d1, d2, d3. By optimizing the values ​​of h1, h2, h3 and d1, d2, d3, the appearance of the right cross-polarization lobe is suppressed. Through continuous optimization in HFSS software, it can be found that the size of the side length d has no effect on the right cross-polarization lobe, but with the overall reduction of h, the right cross-polarization lobe is also constantly decreasing; S2, the radiation pattern of the bottom excitation, the cross-polarization lobe appears on the left side of the main lobe. Through continuous optimization in HFSS software, it can be found that the thickness h has no effect on the right cross-polarization lobe, but with the overall reduction of d, the right cross-polarization lobe is also decreasing; S3. Finally, in the directional pattern radiated by the bottom excitation, cross-polarization lobes appear on both the left and right sides of the main lobe. Through continuous optimization in HFSS software, it can be found that the thickness h and the side length d have no effect on the right cross-polarization lobe.

[0005] As a preferred technical solution of the present invention, in step S1, when h1 is reduced to 25%-35% of the wavelength corresponding to the center operating frequency of the antenna, h2 is reduced to 18%-30% of the wavelength corresponding to the center operating frequency of the antenna, and h3 is reduced to 18%-30% of the wavelength corresponding to the center operating frequency of the antenna, the cross-polarization lobe can be reduced to below -25dB. On this basis, when h continues to decrease, although the cross-polarization lobe will continue to decrease, the standing wave will quickly deteriorate.

[0006] As a preferred technical solution of the present invention, in step S2, when d1 is reduced to 61%-65% of the wavelength first corresponding to the central operating frequency of the antenna, d2 is reduced to 53%-58% of the wavelength first corresponding to the central operating frequency of the antenna, and h3 is reduced to 62%-66% of the wavelength first corresponding to the central operating frequency of the antenna, the cross-polarization lobe can be suppressed to below -25dB. On this basis, d continues to decrease, although the cross-polarization lobe deteriorates quickly again.

[0007] As a preferred technical solution of the present invention, frequency scanning is required in the step S3. If the cross-polarization lobe is more serious at the low frequency, the phase of the adjacent radiating units needs to be adjusted so that the phase difference increases; conversely, if the cross-polarization lobe is more serious at the high frequency, the phase of the adjacent radiating units needs to be adjusted so that the phase difference decreases.

[0008] As a preferred technical solution of the present invention, the appearance of the grating lobe is related not only to the distance between the units but also to the structural factors. In this technical solution, it is found through HFSS software calculation that the thickness of the dielectric plate will also cause the grating lobe in the directional pattern radiated from the bottom excitation. When the thickness of each layer of the dielectric plate is reduced to 0.127mm and grooves are dug on both sides of the dielectric plate feed line, the grating lobe can be significantly reduced.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention is a method for processing cross-polarization and grating lobes of a coplanar KA flat antenna. The present invention can effectively improve the high cross-polarization lobes in the directional pattern radiated from the bottom by optimizing the thickness and diameter of each layer of radiation waveguide. The high grating lobes in the directional pattern radiated from the bottom by thinning each layer of dielectric plate and opening windows can effectively improve the high grating lobes in the directional pattern radiated from the bottom. Through this design, the antenna gain is greatly improved and the problem of interference from neighboring satellites is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 is the directional pattern radiated by the initial excitation according to the present invention; Figure 2 is a schematic diagram of the structure from top to bottom showing the thickness and side length of the waveguide port according to the present invention; Figure 3 is the directional pattern radiated by the intermediate excitation according to the present invention; Figure 4 is the directional pattern radiated by the final excitation according to the present invention; Figure 5 is a schematic diagram of a radiation horn and a coupling feed line of an antenna according to the present invention; Figure 6 is a diagram showing the relationship between the distances between the grating lobes and the units according to the present invention; Figure 7 is a schematic diagram of a slot beside a feeder according to the present invention; Figure 8 Schematic diagram of the grooves on the grid medium plate according to the present invention. DETAILED DESCRIPTION

[0012] The invention is further described below in conjunction with specific implementation methods: Example 1

[0013] Example 1 is described, comprising the following three steps: S1, first the radiation pattern of the bottom excitation, the cross-polarization lobe appears on the right side of the main lobe; Set the thickness of the waveguide opening to h and the side length to d. From top to bottom, the top three layers are h1, h2, h3; d1, d2, d3. Suppress the appearance of right cross-polarization lobes by optimizing the values ​​of h1, h2, h3 and d1, d2, d3. Through continuous optimization in HFSS software, it can be found that the size of the side length d has no effect on the right cross-polarization lobe, but the size of h has a significant effect on the right cross-polarization lobe. The initial value of h is set to the wavelength first corresponding to the working center frequency of the antenna. As h decreases overall, the right cross-polarization lobe is significantly reduced. When h1 is reduced to 25%-35% of the wavelength first corresponding to the central working frequency of the antenna, h2 is reduced to 18%-30% of the wavelength first corresponding to the working center frequency of the antenna, and h3 is reduced to 18%-30% of the wavelength first corresponding to the working center frequency of the antenna, the cross-polarization lobe can be suppressed to below -25dB. On this basis, when h continues to decrease, although the cross-polarization lobe will continue to decrease, the standing wave will quickly deteriorate; S2, the radiation pattern of the second bottom excitation, the cross-polarization lobe appears on the left side of the main lobe; Through continuous optimization in HFSS software, it can be found that the thickness h has no effect on the right cross-polarization lobe, but the size of d has a significant effect on the left cross-polarization lobe. The initial value of d is set to the wavelength first corresponding to the working center frequency of the antenna. As d decreases overall, the left cross-polarization lobe is significantly reduced. When d1 is reduced to 61%-65% of the wavelength first corresponding to the central working frequency of the antenna, d2 is reduced to 50%-58% of the wavelength first corresponding to the working center frequency of the antenna, and d3 is reduced to 62%-66% of the wavelength first corresponding to the working center frequency of the antenna, the cross-polarization lobe can be suppressed to below -25dB. On this basis, d continues to decrease, and the left cross-polarization lobe quickly deteriorates; S3, the radiation pattern of the last bottom excitation, has cross-polarization lobes on both the left and right sides of the main lobe; Through continuous optimization in HFSS software, it can be found that the thickness h and the side length d have no effect on the right cross-polarization lobe. At this time, frequency sweeping is required. If the cross-polarization lobe is more serious at low frequencies, the phase of adjacent radiating units needs to be adjusted to increase the phase difference; conversely, if the cross-polarization lobe is more serious at high frequencies, the phase of adjacent radiating units needs to be adjusted to reduce the phase difference.

[0014] In the above figure, each polarization layer contains a dielectric plate and a waveguide, and there are coupling lines on the dielectric. From bottom to top, all the waveguides combined together form an open horn. The specific method of suppressing the cross-polarization lobe depends on the characteristics of the cross-polarization lobe. Example 2

[0015] Description of Example 2, this implementation further describes Example 1, including grating lobes; The appearance of grating lobes is related not only to the distance between units, but also to structural factors. In this technical solution, it is found through HFSS software calculation that the thickness of the dielectric plate will also cause grating lobes in the directional pattern of the bottom excitation radiation. When the thickness of each layer of dielectric plate is reduced to 0.127mm, and grooves are dug on both sides of the network dielectric plate feed line, the grating lobes can be significantly reduced.

[0016] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for cross-polarization and grating lobe processing of a coplanar Ka flat antenna, characterized in that: It includes the following three steps: S1. First, the radiation pattern of the bottom excitation radiation, the cross-polarization lobe appears on the right side of the main lobe; and the thickness of the waveguide port is set to h, the side length is d, from top to bottom, the top three layers are h1, h2, h3; d1, d2, d3. By optimizing the values ​​of h1, h2, h3 and d1, d2, d3, the appearance of the right cross-polarization lobe is suppressed. Through continuous optimization in HFSS software, it can be found that the size of the side length d has no effect on the right cross-polarization lobe, but with the overall reduction of h, the right cross-polarization lobe is also constantly decreasing; S2, the radiation pattern of the bottom excitation, the cross-polarization lobe appears on the left side of the main lobe. Through continuous optimization in HFSS software, it can be found that the thickness h has no effect on the right cross-polarization lobe, but with the overall reduction of d, the right cross-polarization lobe is also decreasing; S3. Finally, in the directional pattern radiated by the bottom excitation, cross-polarization lobes appear on both the left and right sides of the main lobe. Through continuous optimization in HFSS software, it can be found that the thickness h and the side length d have no effect on the right cross-polarization lobe.

2. The method for cross-polarization and grating lobe processing of a coplanar Ka-type planar antenna according to claim 1, characterized in that: In step S1, when h1 is reduced to 25%-35% of the wavelength corresponding to the center operating frequency of the antenna, h2 is reduced to 18%-30% of the wavelength corresponding to the center operating frequency of the antenna, and h3 is reduced to 18%-30% of the wavelength corresponding to the center operating frequency of the antenna, the cross-polarization lobe can be reduced to below -25dB. On this basis, when h continues to decrease, although the cross-polarization lobe will continue to decrease, the standing wave will quickly deteriorate.

3. The method for cross-polarization and grating lobe processing of a coplanar Ka-type planar antenna according to claim 1, characterized in that: In step S2, when d1 is reduced to 61%-65% of the wavelength first corresponding to the center operating frequency of the antenna, d2 is reduced to 53%-58% of the wavelength first corresponding to the center operating frequency of the antenna, and h3 is reduced to 62%-66% of the wavelength first corresponding to the center operating frequency of the antenna, the cross-polarization lobe can be suppressed to below -25dB. On this basis, d continues to decrease, although the cross-polarization lobe deteriorates quickly again.

4. The method for cross-polarization and grating lobe processing of a coplanar Ka-type planar antenna according to claim 1, characterized in that: Frequency scanning is required in the step S3. If the cross-polarization lobe is more serious at low frequencies, the phases of adjacent radiating units need to be adjusted to increase the phase difference. Conversely, if the cross-polarization lobe is more serious at high frequencies, the phases of adjacent radiating units need to be adjusted to reduce the phase difference.

5. The method for cross-polarization and grating lobe processing of a coplanar Ka-type planar antenna according to claim 1, characterized in that: The appearance of the grating lobe is related not only to the distance between the units but also to the structural factors. In the present technical solution, it is found through calculation in HFSS software that the thickness of the dielectric plate will also cause the grating lobe in the directional pattern radiated from the bottom excitation. When the thickness of each layer of the dielectric plate is reduced to 0.127 mm and grooves are dug on both sides of the dielectric plate feed line, the grating lobe can be significantly reduced.

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