The Powder Toy

Spherical offset antenna by sentinal-5

sentinal-5
sentinal-5
70 / 4
13th Jan 2018
13th Jan 2018
i made this mostly to answer a question from NoVIcE about the spherical vs parabolic shape of antenna reflectors. this type of antenna uses a spherical reflector and you probably have one outside your house if you get sattelite tv.
radical dish antenna communication radio science

Comments

  • Epiclark
    Epiclark     6th Mar 2019
    This is the most accurate radio-related save i have seen so far. Kudos to you!
  • FlaxxDK
    FlaxxDK     16th Feb 2018
    I feel like using filt with tmp as 9 is better than using glass
  • Trigod
    Trigod     19th Jan 2018
    I put emp on the RX xD
  • sentinal-5
    sentinal-5     18th Jan 2018
    ID:2237590 hope this answers some questions
  • sentinal-5
    sentinal-5     18th Jan 2018
    ehh sort of. a parabola would work best in one very specific position. the benifit of a sphere is it works slightly worse from EVERY direction. so you don't need a tailor made reflector for every single lattitude and sattelite.
  • TheNik
    TheNik     17th Jan 2018
    So the sphere in this case is actually just an approximation of a parabola, which works well enough for the short path between the dish and the receiver?
  • sentinal-5
    sentinal-5     15th Jan 2018
    TL;DR spherical dish is only good for listening, but you can aim it by moving your reciever within the dish.
  • sentinal-5
    sentinal-5     15th Jan 2018
    PortalPlayer if you want to have Tx capability yes you need a paraboloid dish, but for Rx only a spherical reflector is cheaper, works almost exactly as well due to the extremely short distance, and allows for multiple recievers per dish. the Arecibo space telescope is a great example of a spherical reflector, but they use theirs to allow the reciever to be moved against a stationary reflector.
  • PortalPlayer
    PortalPlayer     15th Jan 2018
    NoVIcE: small antennae are offset so that the feed horn apparatus doesn't block the signal. They're not common for larger dishes because the shape is harder to manufacture. I don't know what this stuff about them being spherical is about, because spheres don't focus properly.
  • PortalPlayer
    PortalPlayer     15th Jan 2018
    Offset feed dishes are still parabolic, they just use the half of the curve on one side of the focus. No way would you use a spherical dish.