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Pictures of Members' Setups and general satellite
My 2 dishes in Cyprus
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<blockquote data-quote="Orthoclipse" data-source="post: 410853" data-attributes="member: 190790"><p>@bignick - I have looked through some old books I have on satellite reception and I can only see f/D ratio being focal length divided by diameter.</p><p></p><p>If you add the panels to the dish, and the focal length stays the same, the f/D ratio must decrease. </p><p></p><p>Famaval list the focal length as 93cm. So for 230cm, f/D is 93/230 = .404 and for 310, f/D = 93/310 = 0.3.</p><p></p><p>This is the same figure quoted on the famaval website:</p><p>h**p://www.famaval.pt/en/tiki-index.php?page=antenas_310</p><p></p><p>The other way to think about it - if the focal length stays the same but the diameter increases, you need a wider illumination angle to cover all the surface of this dish. The illumination angle increases as f/D decreases.</p></blockquote><p></p>
[QUOTE="Orthoclipse, post: 410853, member: 190790"] @bignick - I have looked through some old books I have on satellite reception and I can only see f/D ratio being focal length divided by diameter. If you add the panels to the dish, and the focal length stays the same, the f/D ratio must decrease. Famaval list the focal length as 93cm. So for 230cm, f/D is 93/230 = .404 and for 310, f/D = 93/310 = 0.3. This is the same figure quoted on the famaval website: h**p://www.famaval.pt/en/tiki-index.php?page=antenas_310 The other way to think about it - if the focal length stays the same but the diameter increases, you need a wider illumination angle to cover all the surface of this dish. The illumination angle increases as f/D decreases. [/QUOTE]
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Pictures of Members' Setups and general satellite
My 2 dishes in Cyprus
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