A design method of a fresnel compound parabolic cylinder antenna

Abstract

This invention discloses a design method for a Fresnel-type composite parabolic cylindrical reflector antenna, applicable to the field of microwave energy space transmission, and particularly suitable for use as a large-size antenna operating at a fixed point frequency. The antenna utilizes a parabolic segment between the origin and point B0, and point B... n With point D n The straight line segment between them, and point D n With point B n+1 The parabola segment between and point B N‑1 The straight line segment between point E and point D and point E and point D N The straight segments between them form a composite curve. Extending along the curve's normal with the composite curve as the generatrix, a Fresnel-type composite parabolic cylindrical reflector antenna is obtained. When it needs to be used in an offset-feed mode, a portion of the surface can be truncated according to actual needs. By replacing the ordinary parabolic cylinder with a Fresnel composite parabolic cylinder, the overall thickness of the parabolic cylindrical reflector antenna is reduced, enabling the segmentation, splicing, and folding of large-size parabolic reflector cylinders. This significantly reduces the processing difficulty and cost of large-size parabolic cylindrical reflector antennas, while also facilitating transportation, assembly, debugging, and adjustment.

Description

Technical Field

[0001] This invention relates to the field of microwave energy spatial transmission technology, and in particular to a design method for a Fresnel-type composite parabolic cylindrical reflector antenna. Background Technology

[0002] A parabolic cylindrical antenna is a surface antenna consisting of a parabolic cylindrical reflector and an illuminator (feed) located on its focal line. The parabolic cylindrical reflector is a cylindrical surface formed by extending the normal to the plane containing the parabola along its generatrix. It is made of a good conductor. During transmission, electromagnetic waves radiate from the feed to the parabolic cylindrical reflector, are reflected, and then radiate into the air. Because the feed is located on the focal line of the parabolic cylinder, the electromagnetic waves, after reflection, radiate parallel to the axis of symmetry of the parabola. During reception, the electromagnetic waves, which are incident parallel to the axis of symmetry of the parabola, are reflected by the reflector and converge at the feed. Parabolic cylindrical antennas have advantages such as simple structure, high gain, strong directivity, and wide operating bandwidth. They are commonly used as high-gain antennas for point-to-point communication and are widely used in microwave relay communication, tropospheric scattering communication, satellite communication, radio telescopes, radar, and television.

[0003] The larger the size of a parabolic cylindrical antenna, the greater its gain. When the antenna width exceeds 2.428m (standard container size), it is usually necessary to manufacture it in modular form for easy vehicle mounting. This allows it to be folded up for transport to reduce space and unfolded for use. Larger antennas, to reduce weight, are typically made of carbon fiber, using ductile iron QT50-10 casting blanks and molds, manufactured through a composite molding process at around 200℃. In short, regardless of whether large parabolic antennas use aluminum or carbon fiber composite materials, their manufacturing presents challenges such as high processing difficulty, complex folding structures, large dimensions, inconvenience in use, and high cost. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a design method for a Fresnel-type composite parabolic cylindrical reflector antenna.

[0005] The objective of this invention is achieved through the following technical solution: a design method for a Fresnel-type composite parabolic cylindrical reflector antenna, comprising the following steps:

[0006] S1: Determine the working electromagnetic wave wavelength λ of the antenna and the distance h from the feed source to the antenna according to the usage requirements;

[0007] S2: Define the coordinate system and reference point: Take the axis of symmetry of the parabola as the X-axis, take the positive direction of the electromagnetic wave emission direction, take a point on the X-axis as the origin, the Y-axis passes through the origin and is perpendicular to the X-axis, and the normal direction of the XOY plane points in the direction of the drawer, where the coordinates of the origin are (0, 0) and the coordinates of the focus A are (h, 0).

[0008] S3: Determine the opening width d of the composite parabola, the distance from the rear end face of the antenna to the center of the arc bottom of the composite parabola is g, the distance from the front end face of the antenna to the center of the arc bottom of the composite parabola is e, draw the antenna width reference line U parallel to the X-axis through the point with coordinate (0, d), draw the front end face limiting reference line M parallel to the Y-axis through the point with coordinate (e, 0), and the reference line U and the reference line M intersect at point E;

[0009] S4: Draw a straight line L parallel to the Y-axis, passing successively through points with coordinates (-h-nλ, 0) (n = 0, 1, 2, ...). n With focus A as the fixed point, L n Draw parabola C using the directrix as the reference line. n Parabola C n Intersects with the front face limit reference line M at intersection point B n When intersection point B n When the ordinate is greater than the antenna width d, stop drawing the parabola and denote n as N. The parabola C N The intersection point with the antenna width reference line U is D. N ;

[0010] S5: Sequentially draw the intersection points A and B from the series of intersection points in step S4. n Connect the two lines, and extend the line so that it intersects the parabola C. n+1 Intersect at point D n ;

[0011] S6: The parabola segment passing through the origin and point B0, and point B n With point D n The straight line segment between them, and point D n With point B n+1 The parabola segment between and point B N-1 The straight line segment between point E and point D and point E and point D N The straight line segments between them form a compound curve;

[0012] S7: Extending the composite curve along the curve normal, we obtain a Fresnel composite parabolic cylindrical reflector antenna.

[0013] Furthermore, in step S1, the electromagnetic wave wavelength λ of the antenna is...

[0014] λ = C / f;

[0015] Where C is the speed of light in the medium in which microwave transmission occurs, f is the frequency of the electromagnetic wave, and the focal diameter ratio h / d ranges from 0.3 to 0.5.

[0016] Furthermore, in step S3, the conversion formula for the opening width d of the composite parabola is:

[0017] d = ik / (kj);

[0018] Where i is the aperture width of a typical parabolic antenna that meets the requirements of the working environment, j is the depth of the parabola, and k is the focal length of the parabola.

[0019] Furthermore, in step S4, n takes continuous values.

[0020] Furthermore, in step S5, when n in step S4 is not a continuous value, the antenna thickness is selected to make the focal point A intersect with the series of intersection points B obtained in step S4. n The extension of the line connecting the two points intersects the parabola C. n+1 Intersection point D n The x-coordinate value is not less than the x-coordinate value of the antenna rear end face -g.

[0021] The present invention has the following advantages: by using the method disclosed in the present invention, a Fresnel-type composite parabolic cylinder is obtained by replacing the parabola with a composite curve as the generatrix of the reflective antenna, thereby reducing the overall thickness of the parabolic cylindrical reflective antenna, making it easier to divide, splice and fold large-size antennas, thereby reducing the antenna processing difficulty and cost, and at the same time the antenna is also easy to transport, assemble, debug and adjust. Attached Figure Description

[0022] Figure 1 A schematic diagram of the design process for a Fresnel-type compound parabolic cylindrical reflector antenna;

[0023] Figure 2 A schematic diagram of the process of drawing Fresnel-type composite surfaces;

[0024] Figure 3 A schematic diagram of the structure of the Fresnel-type composite surface plotted. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this invention, it should be noted that the coordinate system definitions, coordinate axes, and focal directrix selections described in this design and accompanying drawings are merely for the purpose of simplifying the description of this invention, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. The curve shape obtained by this design depends only on the spatial relative position of the focal point and the reference line. Furthermore, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0030] In this embodiment, as Figure 1 As shown, a design method for a Fresnel-type composite parabolic cylindrical reflector antenna includes the following steps:

[0031] S1: Determine the antenna's operating electromagnetic wave wavelength λ and the distance h from the feed source to the antenna based on usage requirements; that is, the antenna focal length is h.

[0032] S2: Define the coordinate system and reference point: Take the axis of symmetry of the parabola as the X-axis, take the positive direction of the electromagnetic wave emission direction, take a point on the X-axis as the origin, the Y-axis passes through the origin and is perpendicular to the X-axis, and the normal direction of the X0Y plane points in the direction of the drawer, where the coordinates of the origin are (0, 0) and the coordinates of the focus A are (h, 0).

[0033] S3: Determine the opening width d of the composite parabola, the distance g from the rear end face of the antenna to the center of the bottom arc of the composite parabola, and the distance e from the front end face of the antenna to the center of the bottom arc of the composite parabola. Draw an antenna width reference line U parallel to the X-axis through the point with coordinates (0, d), and a front end face limiting reference line M parallel to the Y-axis through the point with coordinates (e, 0). Reference line U and reference line M intersect at point E. Specifically, the distance g from the rear end face of the antenna to the center of the bottom arc of the parabola is flexibly selected and determined by the antenna material and structural strength requirements, while the distance e from the front end face of the antenna to the center of the parabola is flexibly selected and determined by the material, weight, thickness, and other requirements.

[0034] S4: Draw a straight line L parallel to the Y-axis, passing successively through points with coordinates (-h-nλ, 0) (n = 0, 1, 2, ...). n With focus A as the fixed point, L n Draw parabola C using the directrix as the reference line. n Parabola Cn Intersects with the front face limit reference line M at intersection point B n When intersection point B n When the ordinate is greater than the antenna width d, stop drawing the parabola and denote n as N. The parabola C N The intersection point with the antenna width reference line U is D. N Specifically, due to parabola C n Symmetric about the X-axis, therefore only the upper half of the curve with a positive ordinate is plotted.

[0035] S5: Sequentially draw the focal point A and the series of intersection points B from step S4. n Connect the two lines, and extend the line so that it intersects the parabola C. n+1 Intersect at point D n ;

[0036] S6: The parabola segment passing through the origin and point B0, and point B n With point D n The straight line segment between them, and point D n With point B n+1 The parabola segment between and point B N-1 The straight line segment between point E and point D and point E and point D N The straight segments between them form a composite curve; specifically, since the straight segments do not participate in electromagnetic wave reflection, they can be made into hollow structures as needed to reduce weight and wind resistance and improve the aerodynamic characteristics of the antenna.

[0037] S7: Extending the composite curve along its normal, a Fresnel-type composite parabolic cylindrical reflector antenna is obtained. When it needs to be used in an offset-feed configuration, a portion of the surface can be cut out according to actual needs. Using the method disclosed in this invention, the composite curve is used to replace the parabola as the generatrix of the reflector antenna to obtain a Fresnel-type composite parabolic cylindrical reflector antenna. This reduces the overall thickness of the parabolic cylindrical reflector antenna, facilitating the segmentation, splicing, and folding of large-size antennas, thereby reducing the antenna's manufacturing difficulty and cost. The antenna is also easier to transport, assemble, debug, and adjust. The reflector antenna obtained by this method retains the high gain and strong directivity of a parabolic antenna, but changes its wide operating bandwidth, becoming a frequency-sensitive antenna. Electromagnetic waves reflected from different positions form coherent interference in space, constituting a spatial resonant frequency-selective cavity with a high Q value, thus achieving spatial filtering. When the electromagnetic wave frequency matches the antenna's operating wavelength, coherent superposition enhancement is achieved; when the electromagnetic wave frequency does not match the antenna's operating wavelength, coherent cancellation occurs, facilitating the elimination of adjacent frequency interference.

[0038] Furthermore, in step S1, the electromagnetic wave wavelength λ of the antenna is...

[0039] λ = C / f;

[0040] Where C is the speed of light in the medium through which the microwave transmission occurs, f is the frequency of the electromagnetic wave, and the focal diameter ratio h / d ranges from 0.3 to 0.5. Specifically, when the focal diameter ratio h / d is less than 0.3, the thickness compression effect is better, but the antenna diameter is larger than that of a conventional parabolic cylindrical antenna with the same efficiency; when the focal diameter ratio h / d is greater than 0.5, the thickness compression effect is worse. Therefore, in this embodiment, the focal diameter ratio h / d is 0.4.

[0041] Furthermore, in step S3, the conversion formula for the opening width d of the composite parabola is:

[0042] d = ik / (kj);

[0043] Where i is the aperture width of a typical parabolic antenna that meets the requirements of the working environment, j is the depth of the parabola, and k is the focal length of the parabola.

[0044] In this embodiment, n takes continuous values ​​in step S4.

[0045] In this embodiment, in step S5, when n in step S4 is not a continuous value, the antenna thickness is selected so that the focal point A intersects with the series of intersection points B obtained in step S4. n The extension of the line connecting the two points intersects the parabola C. n+1 Intersection point D n The x-coordinate value is not less than the x-coordinate value of the antenna rear end face -g.

[0046] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a Fresnel-type composite parabolic cylindrical reflector antenna, characterized in that: Includes the following steps: S1: Determine the operating electromagnetic wave wavelength of the antenna based on usage requirements. and the distance from the feed to the antenna ; S2: Define the coordinate system and reference point: with the axis of symmetry of the parabola as... axis, The positive direction of the axis is taken as the direction of electromagnetic wave emission. Take a point on the axis as the origin. The axis passes through the origin and is parallel to... The axis is perpendicular. The normal to the plane points in the direction of the draftsman, where the coordinates of the origin are ( ),focus The coordinates are ( ); S3: Determine the opening width of the composite parabola The distance from the rear end face of the antenna to the center of the bottom of the composite parabola is The distance from the front surface of the antenna to the center of the bottom of the composite parabola is The coordinates are ( The point is drawn parallel to ) Antenna width reference line of the axis The coordinates are ( The point is drawn parallel to ) Shaft front end face limit reference line Reference line With reference line Intersection point ; S4: Passing through coordinates in sequence ( ) points, do and A straight line parallel to the axis ,in, With focus For fixed point, Draw the parabola using the directrix as the reference line. ,parabola With front face limit reference line Intersect at the intersection point When the intersection The vertical axis is greater than the antenna width. When, stop drawing the parabola and Recorded as ,parabola With antenna width reference line The intersection is ; S5: Focusing sequentially Intersection with the series of points in step S4 Connect the two lines, and extend the line so that it intersects the parabola. Intersection point ; S6: Through the origin and point parabolic segments and points between With point straight line segments and points between With point parabolic segments and points between With point The straight line segment and point between With point The straight line segments between them form a compound curve; S7: Extending the composite curve along the curve normal as the generatrix, a Fresnel composite parabolic cylindrical reflector antenna is obtained.

2. The design method of a Fresnel-type composite parabolic cylindrical reflector antenna according to claim 1, characterized in that: In step S1, the electromagnetic wave wavelength of the antenna... for ； in, The speed of light in the medium in which microwave transmission occurs. Electromagnetic wave frequency, focal diameter ratio The range of values ​​is .

3. The design method for a Fresnel-type composite parabolic cylindrical reflector antenna according to claim 2, characterized in that: In step S3, the opening width of the composite parabola The conversion formula is: ； in, To meet the aperture width requirements of a typical parabolic antenna in the working environment, For the depth of the parabolic surface, The focal length is the parabolic focal length.

4. The design method of a Fresnel-type composite parabolic cylindrical reflector antenna according to claim 1, characterized in that: In step S4 It takes continuous values.

5. The design method of a Fresnel-type composite parabolic cylindrical reflector antenna according to claim 1, characterized in that: In step S5, when the step S4 When the values ​​are not continuous, the focal point is adjusted by selecting the antenna thickness. Intersection points with the series obtained in step S4 The extension of the line connecting the parabola intersection The x-coordinate value is not less than the x-coordinate value of the antenna rear end face. .

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