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DISH SETUP: Single sat, Multi-Sat & Motorised
Dish Setup Guides, Information threads and FAQs
Calculation of the focal length of an offset satellite dish antenna, Revisited
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<blockquote data-quote="a33" data-source="post: 1120938" data-attributes="member: 332642"><p>Thank you, [USER=415308]@ozumo[/USER]!</p><p></p><p>Here are the calculated specs (in column V).</p><p></p><p>The clearance of this dish is about zero: y-null is -0.25. That means that a multifeedholder, when taking space above the LNBs, will take away signal from the dish.</p><p>( I don't know if that also is the case with the Sky dish in this recent topic: <a href="https://www.satellites.co.uk/forums/threads/multi-sat-on-a-sky-dish.179830/" target="_blank">Multi sat on a sky dish</a> But it might indeed be an issue, as this dish shows! )</p><p></p><p></p><p>[ATTACH=full]139469[/ATTACH]</p><p></p><p></p><p>NB LNB viewing angle, etc, is calculated for a flat-faced dish with height 55.3, and corresponding width 51.43</p><p>Focal point position can be found by top string length, and bottom string length.</p><p></p><p>In the (small) collection of offset dishes specifications that I now have, LNB viewing angle is usually between 70 and 80 degrees (or, average, about 73 to 74). (But a few exceptions below 70, or above 80. And I'm not an expert on this!)</p><p>This dish has 77 degrees. I guess this would mean, that a normal Ku LNBf (as opposed to a special feedhorn Sky LNB ) would 'see' the whole vertical part of the dish (no spill-over), but just a small horizontal part of the dish.</p><p></p><p>Specification of the indicated points is shown in this picture (I guess I must try to make it a bit smaller, I think...?) :</p><p></p><p>[ATTACH=full]139470[/ATTACH]</p><p></p><p></p><p>So I'm curious now, whether the LNB holder actually puts the LNB in the right position?</p><p></p><p>Greetz,</p><p>A33</p><p></p><p><em>Edit: a few additions, to clarify.</em></p></blockquote><p></p>
[QUOTE="a33, post: 1120938, member: 332642"] Thank you, [USER=415308]@ozumo[/USER]! Here are the calculated specs (in column V). The clearance of this dish is about zero: y-null is -0.25. That means that a multifeedholder, when taking space above the LNBs, will take away signal from the dish. ( I don't know if that also is the case with the Sky dish in this recent topic: [URL='https://www.satellites.co.uk/forums/threads/multi-sat-on-a-sky-dish.179830/']Multi sat on a sky dish[/URL] But it might indeed be an issue, as this dish shows! ) [ATTACH type="full" alt="Zone2 dish Parabolic Specs Dish ozumo Schermafdruk_2021-11-16.png"]139469[/ATTACH] NB LNB viewing angle, etc, is calculated for a flat-faced dish with height 55.3, and corresponding width 51.43 Focal point position can be found by top string length, and bottom string length. In the (small) collection of offset dishes specifications that I now have, LNB viewing angle is usually between 70 and 80 degrees (or, average, about 73 to 74). (But a few exceptions below 70, or above 80. And I'm not an expert on this!) This dish has 77 degrees. I guess this would mean, that a normal Ku LNBf (as opposed to a special feedhorn Sky LNB ) would 'see' the whole vertical part of the dish (no spill-over), but just a small horizontal part of the dish. Specification of the indicated points is shown in this picture (I guess I must try to make it a bit smaller, I think...?) : [ATTACH type="full" alt="A33 Offset satellite dish specs calculator Picture of the relevant points.png"]139470[/ATTACH] So I'm curious now, whether the LNB holder actually puts the LNB in the right position? Greetz, A33 [I]Edit: a few additions, to clarify.[/I] [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
Dish Setup Guides, Information threads and FAQs
Calculation of the focal length of an offset satellite dish antenna, Revisited
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