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Pictures of Members' Setups and general satellite
SMW OA 1600 dish
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<blockquote data-quote="a33" data-source="post: 954891" data-attributes="member: 332642"><p>Hi,</p><p>I came to this thread following RimaNTSS' picture of the SMW1600, in my thread <a href="https://www.satellites.co.uk/forums/threads/multifeed-installation-and-exact-calculation-of-lnb-position.167435/" target="_blank">Multifeed installation and exact calculation of LNB position</a></p><p></p><p>As we know a purely toroidal dish is parabolic in het vertical plane, and spheric(or better: circular) in the horizontal plane.</p><p>In a circular mirror the length of the radius is two times the focal distance: <u><strong>r = 2 f</strong></u>.</p><p>That means the red line in the drawing of RimaNTSS should just go till <u>twice</u> the distance from the dish to the LNBs, that is: just to the centre of the circle. (In his drawing he seems to go more than three times the distance from dish to LNBs; that is much too far!)</p><p></p><p>[ATTACH]88667[/ATTACH]</p><p></p><p>Aiming of LNBs should ideally follow the (corrected) red line from centre of circle, through LNB, to dish.</p><p></p><p>However, as the drawings of the manual in an earlier post show: You can aim two or three LNBs with very small azimuth differences <u>towards</u> each other. <strong>Placement of the head of the LNB in the phase centre is much much more important than the aiming angle of the LNB!</strong> Didn't Paul Wade say so, already? (Or was it some other dish-guru? I'm not quite sure.)</p><p></p><p>That means the aiming on this picture of RimaNTSS isn't ideal <img src="https://www.satellites.co.uk/styles/default/xenforo/smilies/sad.png" class="smilie" loading="lazy" alt=":(" title="Sad :(" data-shortname=":(" />. However because he has extended the range of the multifeed bracket, the outer LNBs should of course NOT point mostly outside the dish; there he should aim the LNB a bit more inward...;).</p><p></p><p>Greetz,</p><p>A33</p></blockquote><p></p>
[QUOTE="a33, post: 954891, member: 332642"] Hi, I came to this thread following RimaNTSS' picture of the SMW1600, in my thread [URL='https://www.satellites.co.uk/forums/threads/multifeed-installation-and-exact-calculation-of-lnb-position.167435/']Multifeed installation and exact calculation of LNB position[/URL] As we know a purely toroidal dish is parabolic in het vertical plane, and spheric(or better: circular) in the horizontal plane. In a circular mirror the length of the radius is two times the focal distance: [U][B]r = 2 f[/B][/U]. That means the red line in the drawing of RimaNTSS should just go till [U]twice[/U] the distance from the dish to the LNBs, that is: just to the centre of the circle. (In his drawing he seems to go more than three times the distance from dish to LNBs; that is much too far!) [ATTACH]88667[/ATTACH] Aiming of LNBs should ideally follow the (corrected) red line from centre of circle, through LNB, to dish. However, as the drawings of the manual in an earlier post show: You can aim two or three LNBs with very small azimuth differences [U]towards[/U] each other. [B]Placement of the head of the LNB in the phase centre is much much more important than the aiming angle of the LNB![/B] Didn't Paul Wade say so, already? (Or was it some other dish-guru? I'm not quite sure.) That means the aiming on this picture of RimaNTSS isn't ideal :(. However because he has extended the range of the multifeed bracket, the outer LNBs should of course NOT point mostly outside the dish; there he should aim the LNB a bit more inward...;). Greetz, A33 [/QUOTE]
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SMW OA 1600 dish
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