A lightning protection design method for multi-reflecting surface antenna

Abstract

The application discloses a lightning protection design method of a multi-rod lightning protection of a double-reflector antenna, and relates to the antenna safety protection technology in the fields of communication, measurement and control, radar and radio astronomy, and aims to provide a lightning protection design method with small rod size, large protection range, design method conforming to international norms, easy manufacturing and low cost. The application is realized by the following technical scheme: firstly, a three-dimensional model of the double-reflector antenna under different elevation angles is established, the three-dimensional model is projected into a two-dimensional front view and a side view respectively, then a basic design elevation angle is determined and an outline envelope is drawn; secondly, the outline envelope is rolled on both sides to determine the position of the lightning rod and establish the lightning rod to obtain a protection area; finally, the lightning protection area under other elevation angles is checked. The method is simple and easy to operate, has high reliability and credibility in lightning protection, is suitable for different types of double-reflector antennas, and is especially suitable for the design and manufacturing of lightning protection of medium caliber antennas.

Description

Technical Field

[0001] This invention relates to antenna safety protection technology in the fields of communication, measurement and control, radar and radio astronomy, and more specifically, to a lightning protection design method for dual-reflector antennas, which is particularly applicable to the lightning protection design and manufacturing of small and medium-diameter antennas. Background Technology

[0002] Reflector antennas are widely used as transmitting or receiving devices in fields such as communications, telemetry, radar, and radio astronomy. Dual-reflector antennas, by increasing geometric parameters, allow for more flexible design to meet diverse needs. Among these, the dual-bias antenna is an important type. This type of antenna eliminates the obstruction of the aperture by the sub-reflector and feed, and also eliminates the reaction force of the sub-reflector to the feed, improving the matching of the feeding system. Therefore, dual-bias antennas are more suitable for applications requiring high gain, low sidelobes, and low cross-polarization.

[0003] As outdoor equipment, reflector antennas must withstand various natural challenges during operation, with lightning being a particularly dangerous natural disaster. Lightning strikes are divided into two main parts: direct lightning strikes and induced lightning strikes, with direct lightning strikes being the most damaging. Installing lightning rods on buildings and electrical equipment effectively prevents damage from both direct and induced lightning strikes. Lightning rods directly conduct current to the ground during a direct lightning strike, preventing damage to equipment. For induced lightning strikes, lightning rods conduct static charge to a pointed tip for discharge, neutralizing the charge in the thundercloud and achieving lightning protection.

[0004] Lightning protection for dual-reflector antennas is primarily achieved through the installation of lightning rods and down conductors. The placement of the lightning rods determines the protection range against lightning strikes and is a key technology in antenna design and manufacturing. Traditional lightning protection designs for dual-reflector antennas typically employ a dual-lightning-rod method or a separate lightning protection tower. While these two methods offer some protection, they have the following drawbacks:

[0005] (1) Insufficient protection range. In the traditional dual lightning rod method, one lightning rod is usually located at the top edge of the main reflector and the other is located at the back of the sub-reflector. Due to the limitations of antenna aperture and rotation space, the height of the lightning rod will be relatively low, which will result in the risk of insufficient lightning protection range.

[0006] (2) Independent lightning protection towers are expensive. In traditional methods, independent lightning protection towers are also used to increase the protection range. However, lightning protection towers are generally quite tall, which greatly increases the construction cost.

[0007] (3) The lightning protection calculation method is not standardized. The traditional double-mounted lightning rod method uses a broken line calculation method, which is only applicable to the fields of power system and electrified railway, and is not applicable to the field of antenna technology that can rotate.

[0008] Chinese patents CN107834199A and CN207009667U disclose an intelligent active lightning protection antenna and lightning protection system; CN107895836A discloses an omnidirectional antenna and its lightning protection structure; CN202871975U discloses a lightning protection antenna that can shield from wind and rain; and CN202871975U discloses a novel lightning protection device for antenna systems. While the lightning protection methods mentioned in these patents can solve some engineering problems, they have the following shortcomings for reflector antennas:

[0009] (1) Applicable only to linear antennas or printed circuit board antennas. The antennas involved in the above patents are all linear antennas or printed circuit board antennas. Not only are the antennas small in size, but they also operate at lower frequencies. Signal transmission is carried out through cables, and lightning protection can be achieved by adding filtering components in the circuit. Reflector antennas are usually larger in size and operate at higher frequencies, and the above patent methods cannot meet the usage requirements.

[0010] (2) Not applicable to reflector antennas with rotational movement. The above patents are all for fixed antennas or antennas that do not involve rotational movement. In operation, reflector antennas usually need to rotate to align with the target. During this process, the protection range of lightning protection will change. Therefore, the above patents are not applicable.

[0011] (3) It will affect the electromagnetic performance of the antenna. The above patents also involve using a protective cover for lightning protection. However, this method will affect the electromagnetic performance of the antenna. Summary of the Invention

[0012] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-lightning rod lightning protection design method for dual-reflector antennas. Compared with existing technologies, this method features small lightning rod size, large protection range, design method conforming to international standards, ease of manufacturing, and low cost. The lightning protection design method for dual-reflector antennas of this invention employs a rolling sphere design for antennas at different elevation angles to obtain the position and size of the lightning rod, and verifies the lightning protection area at other elevation angles. This design method can meet the lightning protection requirements of reflector antennas at different elevation angles, while reducing the size of the lightning rod, making it particularly suitable for lightning protection design of dual-reflector antennas.

[0013] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solutions.

[0014] A lightning protection design method for a dual-reflector antenna with multiple lightning rods includes the following steps:

[0015] (1) Establish a three-dimensional model of the dual-reflector antenna at different elevation angles, and project the three-dimensional model into a two-dimensional front view and side view at different elevation angles respectively;

[0016] (2) Compare the antenna heights at different elevation angles in step (1) and select the elevation angle with the maximum height as the basic design elevation angle;

[0017] (3) Based on the basic design elevation angle obtained in step (2), make the outline envelope diagram of the front view and side view under that elevation angle;

[0018] (4) Select the rolling sphere radius, denoted as hr, according to the lightning protection level of the dual-reflector antenna;

[0019] (5) Roll the ball on both sides of the main view shape envelope obtained in step (3). The radius of the ball is the value hr given in step (4). The contact point between the ball and the main view shape envelope is the lightning rod setting point.

[0020] (6) Set up the lightning rod at the lightning rod position point obtained in step (5);

[0021] (7) Connect the lightning rod apex obtained in step (6) to form a line segment. Make the perpendicular bisector of the line segment and intersect it with the horizontal line at a height of hr above the ground to form an intersection point. With the intersection point as the center and the lightning rod apex as the radius, draw an arc so that the envelope of the main view is located outside the arc.

[0022] (8) Repeat steps (5) to (7) for the side view shape envelope obtained in step (3);

[0023] (9) Check the lightning protection area at other elevation angles so that the front view and side view at different elevation angles are all outside the arcs of the radii hr and R.

[0024] Specifically, the dual-reflector antenna is a circularly symmetrical antenna or a dual-biased antenna.

[0025] Specifically, in step (7), the envelope of the main view is not allowed to intersect with the arcs with radii hr and R; otherwise, the height of the lightning rod in step (6) is increased.

[0026] Specifically, in step (8), the side view envelope is not allowed to intersect with arcs with radii hr and R; otherwise, the height of the lightning rod at the corresponding position is increased.

[0027] Specifically, in step (9), the main view and side view are not allowed to intersect with arcs with radii of hr and R; otherwise, the height of the lightning rod at the corresponding position of the view under that elevation angle is increased.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) Wide range of applications. The background technology only involves lightning protection methods for linear antennas or printed circuit board antennas, and does not involve reflector antennas and fully movable antennas. The method of the present invention is not only applicable to dual reflector antennas, but can also be extended to other types of antennas, such as single reflector antennas, printed circuit board antennas, etc., so it has a wider range of applications.

[0030] (2) Small lightning rod size and large protection range. Traditional methods use single or double lightning rods, which have a small protection range and cannot cover lightning strikes from different directions, making the antenna susceptible to damage. This invention uses a multi-lightning rod method, which not only reduces the size of the lightning rod but also increases the protection range.

[0031] (3) The design method is standardized and conforms to international standards. The traditional lightning rod design method is a broken line calculation method, while the present invention adopts the rolling sphere method in the design process, which conforms to international lightning protection standards and domestic design specifications, and improves the reliability and dependability of lightning protection.

[0032] (4) Protection is achieved at different antenna elevation angles, improving lightning protection safety. The lightning protection methods involved in the background technology are all designs under fixed elevation angles. This invention proposes a method of "basic design elevation angle" and "verification of other elevation angles", which improves the safety of lightning protection.

[0033] (5) The method is simple and easy to operate. The design presented in this invention adopts a geometric method, with a clear protection range and detailed and highly operable steps.

[0034] In summary, this invention is ingeniously conceived, has a clear approach, and is easy to implement. It not only solves the problems of small lightning protection range and non-standard design methods of traditional reflector antennas, but also improves the reliability and dependability of lightning protection, representing an important improvement over existing technologies. Attached Figure Description

[0035] Figure 1 (a) is a two-dimensional front view at a 15° elevation angle in an embodiment of the present invention;

[0036] Figure 1 (b) is a two-dimensional side view at a 15° elevation angle in an embodiment of the present invention;

[0037] Figure 2 (a) is a two-dimensional front view at a 45° elevation angle in an embodiment of the present invention;

[0038] Figure 2(b) is a two-dimensional side view at a 45° elevation angle in an embodiment of the present invention;

[0039] Figure 3 (a) is a two-dimensional front view at a 90° elevation angle in an embodiment of the present invention;

[0040] Figure 3 (b) is a two-dimensional side view at a 90° elevation angle in an embodiment of the present invention;

[0041] Figure 4 (a) is the front view envelope diagram of the basic design elevation angle in the embodiment of the present invention;

[0042] Figure 4 (b) is the side view of the outer shape envelope under the elevation angle of the basic design in the embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the lightning rod setting point in step (5) of this embodiment of the invention;

[0044] Figure 6 This is a geometric schematic diagram of step (7) in an embodiment of the present invention;

[0045] Figure 7 This is the lightning protection area obtained in step (8) of this embodiment of the invention;

[0046] Figure 8 (a) is the lightning protection area of ​​the main view under a 15° elevation angle verified in step (9) of the embodiment of the present invention;

[0047] Figure 8 (b) is the lightning protection area of ​​the 15° elevation angle lower side view checked in step (9) of the embodiment of the present invention;

[0048] Figure 9 (a) is the lightning protection area of ​​the main view under a 90° elevation angle verified in step (9) of the embodiment of the present invention;

[0049] Figure 9 (b) is the lightning protection area of ​​the 90° elevation angle side view checked in step (9) of the embodiment of the present invention. Detailed Implementation

[0050] Dual-reflector antennas are the most widely used type of reflector antennas, and they include several forms such as Cassegrain, Gregorian, and dual-biased. This invention covers the above-mentioned types of dual-reflector antennas.

[0051] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0052] This invention takes the lightning protection of a dual-biased 15-meter aperture antenna as an example, and includes the following steps:

[0053] (1) Establish a three-dimensional model of the dual-reflector antenna at different elevation angles, and project the three-dimensional model into a two-dimensional front view and side view at different elevation angles.

[0054] In this embodiment, the antenna's operating elevation angle is 15° to 90°. Figures 1-3 Two-dimensional front and side views of the antenna at different elevation angles are given.

[0055] (2) Compare the antenna heights at different elevation angles in step (1) and select the elevation angle with the maximum height as the basic design elevation angle.

[0056] The antenna in the embodiment has a maximum height at an elevation angle of 45°, therefore, this elevation angle is selected as the basic design elevation angle.

[0057] (3) Based on the basic design elevation angle obtained in step (2), make the shape envelope diagram of the front view and side view under that elevation angle.

[0058] Figure 4 This is an envelope diagram of the antenna's front view and side view at a 45° elevation angle in the embodiment.

[0059] (4) Select the rolling sphere radius, denoted as hr, according to the lightning protection level of the dual-reflector antenna.

[0060] The antenna in this embodiment is of Class II lightning protection level, and the rolling sphere radius hr is selected as 45m.

[0061] (5) Roll the ball on both sides of the main view shape envelope obtained in step (3). The radius of the ball is the value hr given in step (4). The contact point between the ball and the main view shape envelope is the lightning rod setting point.

[0062] like Figure 5 As shown in the figure, points A and B are the lightning rod setting points.

[0063] (6) Set up the lightning rod at the lightning rod position point obtained in step (5).

[0064] Figure 6 Two lightning rods are shown in the embodiment.

[0065] (7) Connect the lightning rod apex obtained in step (6) to form a line segment. Draw the perpendicular bisector of the line segment and intersect it with the horizontal line at a height of hr above the ground to form an intersection point. With the intersection point as the center and the lightning rod apex as the radius, draw an arc so that the envelope of the main view is located outside the arc.

[0066] like Figure 6As shown, the vertices of the two lightning rods are C and D, respectively. The perpendicular bisector of line segment CD intersects the horizontal line at a height of hr above the ground at point O. Then, an arc is drawn.

[0067] (8) Repeat steps (5) to (7) for the side view shape envelope obtained in step (3).

[0068] Figure 7 It is the lightning protection area obtained in step (8) of the embodiment.

[0069] (9) Check the lightning protection area at other elevation angles so that the front view and side view at different elevation angles are all outside the arcs of the radii hr and R.

[0070] Figure 8 , Figure 9 These are the lightning protection areas in the main view and side view at elevation angles of 15° and 90°, respectively, as verified in step (9) of the embodiment.

[0071] It should be noted that the lightning rod height given in the embodiment satisfies the requirement that the front view and side view at different elevation angles are located outside the arcs with radii hr and R, without intersecting with them, thus meeting the lightning protection requirements and eliminating the need to increase the height of the lightning rod.

[0072] The above description is merely the preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A lightning protection design method for a dual-reflector antenna with multiple lightning rods, characterized in that, Includes the following steps: Step 1: Establish a 3D model of the dual-reflector antenna at different elevation angles, and project the 3D model into a 2D front view and side view at different elevation angles respectively; Step 2: Compare the antenna heights at different elevation angles in Step 1, and select the elevation angle with the maximum height as the base design elevation angle; Step 3: Based on the basic design elevation angle obtained in Step 2, create the shape envelope diagrams of the front view and side view at that elevation angle; Step 4: Select the rolling sphere radius, denoted as hr, based on the lightning protection level of the dual-reflector antenna; Step 5: Roll the main view shape envelope obtained in Step 3 on both sides. The radius of the rolling ball is the value hr given in Step 4. The contact point between the rolling ball and the main view shape envelope is the lightning rod setting point. Step 6: Set up the lightning rod at the lightning rod location point obtained in step 5; Step 7: Connect the apex of the lightning rod obtained in Step 6 to form a line segment. Draw the perpendicular bisector of this line segment and intersect it with a horizontal straight line at a height of hr above the ground to form an intersection point. With this intersection point as the center and the apex of the lightning rod as the radius, denoted as R, draw an arc so that the envelope of the main view is located outside the arc. Step 8: Repeat steps 5 to 7 for the side view shape envelope diagram obtained in step 3; Step 9: Verify the lightning protection area at other elevation angles, ensuring that the front view and side view at different elevation angles are all outside the arcs of the radii hr and R.

2. The lightning protection design method for a dual-reflector antenna with multiple lightning rods according to claim 1, characterized in that, The dual-reflector antenna is either a circularly symmetrical antenna or a dual-biased antenna.

3. The lightning protection design method for a dual-reflector antenna with multiple lightning rods according to claim 1, characterized in that, In step 7, the envelope of the main view is not allowed to intersect with the arcs with radii hr and R; otherwise, the height of the lightning rod in step 6 is increased.

4. The lightning protection design method for a dual-reflector antenna with multiple lightning rods according to claim 1, characterized in that, In step 8, the side view envelope is not allowed to intersect with arcs of radius hr and R; otherwise, the height of the lightning rod at the corresponding position is increased.

5. The lightning protection design method for a dual-reflector antenna with multiple lightning rods according to claim 1, characterized in that, In step 9, the front view and side view are not allowed to intersect with arcs of radius hr and R; otherwise, the height of the lightning rod at the corresponding position of the view under that elevation angle is increased.

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