Keywords: satellite antenna homemade
Author: Jiang Zhiqiang
There is no need for cumbersome calculations, just one ruler and two thin lines, you can draw a precise parabolic! The drawing process is described in detail below. First, the quasi-line parabola undergoing a parabola and parabolic refers to a trajectory of a point to a point to a point F and a fixed line L distance. As shown in FIG. 1, the trajectory (or set) of a point (or set) that is equal to a point of fixed point F and a fixed point L distance, but f, is called a parabolic. This fixed point is the focus of the parabolic, which is the parabolic line. F is called "the focus of the parabola", which is called "quasi line". The distance to the quasi-line of the parabola is "coke" and is represented by P. P>0. Second, the parabolic parabolic is a parabolic surface to rotate 1800 in its axis of symmetry. Third, the first wife finds the focus of the parabola when manufacturing or installing the parabolic antenna, can generally calculate its focus position from the caliber and depth. The focal length diameter of the parabola antenna has a fixed formula: f / d = 0.38-0.4, common feedforward antenna's focal length diameter ratio f / D between 0.3-0.4, when F / D = 0.38, rotate the parabolic antenna The best performance, the general finished feedforward parabolic antenna is mostly the focal length / diameter ratio, so as long as the antenna diameter D, according to the experience formula F = 0.38d, the focal length of the antenna can be roughly judged. Similarly, you can find the parabola of the antenna to find the focus (or focal length) and antenna caliber. The attached table is the specific parameters of the Zhongwei feedback antenna. Fourth, the success or failure of the self-made parabolic antenna is to draw a precise parabolic because the arc is used, which causes the edge of the light wave to get down in focus, and the antenna that is not possible is impossible. We already know the distance between the parabolas to its quasi-line and focus. Moreover, there is also the diameter and focal length of the finished large diameter feedback antenna, so it can draw a precise parabolic according to this condition. Referring to the 1.80-meter airfoil antenna to do demonstration, the specific steps are as follows: Step 1: Find a 3m-faced flat air, draw L. The focus F, vertex O, quasi-line L, caliber AB of 80m antenna. If you make a larger parabolic, you can select the focal length and caliber according to the parameters of Table L. Quasi-line L can also be replaced with a wooden strip, vertex 0 to focus f can be vertically planted with a whole woodworking board (width L220mm, length 2440mm), replace (F11) 2440mm this side is placed on the vertex 0), so that the parabola is directly painted On the wooden board to make a parabolic template. Step 2: A-B will be parallel to the parabolic axis PF with a plurality of horizontal lines with a certain distance (e.g., L0CM or 5 cm). Step 3: Look for two thin lines or line rules, wireless wire can be used in accordance with LCM distance, and L0CM is using L0 color (if there is conditional can be used, the line itself has dimensions) Then, then fix one of the blue line fk in Figure 5 in focus f, and another red line AK selects a point between the A-B, fixed straight to parallel, fk and When the AK two-wire cross-and length is equal, the corresponding is a point K on the parabola, and this point is drawn on the wooden board. Reputable, draw K ', K "..., etc., you can draw an extremely precise parabolic. The template accuracy of this can be compared with the Zhongwei Antenna. ! Note: Be sure to parallel the red line AK in the figure, the red line AK coin i3 blue line FK intersection must ensure the value of the value. If the method of drawing the parabolic line does not require formula, it is extremely simple, easy to operate, can draw the line People who can understand the size will do. Step 4: Painting a straight line between the painted parabolic KG, then tailoring on the woodworking board, make an antenna with round steel, flat iron or stainless steel The skeleton, the antenna surface can be made of wire, stainless steel net, and its production method can find a large number of tutorials online, and will not be described here.
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