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Admin

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Posts posted by Admin

  12. Posted

    It was interesting to design a small and lightweight antenna from available materials for FPV.
    After looking at what is available in household stores, I decided to stop at zinc/brass for the antenna elements and a canister cover as a radom.
    And so everything is in order - as it seemed to me, a lid from paint cans / mounting foam / air fresheners is perfect for radom. Its diameter is 77 mm external and 84 mm internal. Height from 12 to 40 mm. Material-polypropylene.
    Based on this, the dimensions of the entire structure were selected.
    you will need brass / galvanized 0.25 mm thick, brass tube diameter 4 mm external (wall thickness 0.25 mm), screw m3 -40 mm. cap nut m3, SMA connector, pipe cutter, metal scissors, drills with a diameter of 1.4 and 3 mm.
    The reflector is made of sardine cans.
    General view of the structure and results:

    screenshot_967.png

    3 people like this

  19. Posted

    Coaxial cables with an impedance of 50 ohms (Ω) are used to connect the transceiver to the antenna. The most common cables are RG 58 and RG 213:The RG 58 cable is used for use, which has a diameter of 5 mm and the losses it introduces are insignificant, due to the small length of the cable. One detail that you MUST keep in mind is that a cable must be equal in length to multiples of ½λ to properly transfer the impedance of the antenna. If the length is different then the cable will work as an impedance transformer. In this case, a properly tuned antenna will have a high SWR at the transceiver output. The shortening factor (k) has a special importance in the calculation of the cable length. It differs depending on the dielectric of the cable.

    -shortening factor(k) -Solid Polyethylene (PE):  66 %

    1 person likes this