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Satellite TV receivers & systems support forums
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: 1124766" data-attributes="member: 332642"><p>Hello and welcome to the forum, [USER=414694]@st2@88e[/USER]! </p><p></p><p>Well yes, there is:</p><p><strong>Diameter.of.mother.PF.parabola = ( 4 * focal.length * abs(tan(offset.angle)) ) + Width.of.offset.dish.</strong></p><p></p><p>(where "abs" means the 'absolute' value, and assuming the dish face of the offset dish is flat. </p><p>The 'abs'-function is only needed for possible negative offset angles.)</p><p></p><p><strong>The derivation of the equation is discussed in this blog:</strong> <a href="https://ftapinamar.blogspot.com/2021/11/antenas-offset-8.html?showComment=1638279867072#c3203251010676321325" target="_blank">Antenas Offset (8)</a></p><p></p><p>Of course, the <em>focal length</em> and the <em>offset angle</em> can be calculated with the 'common' equations.</p><p>So, if wanted, you could also derive the above equation to an equation, that just needs inputs Height, Width, and Depth at the center. (Not so difficult....)</p><p></p><p>Is this what you want/mean?</p><p></p><p>Greetz,</p><p>A33</p></blockquote><p></p>
[QUOTE="a33, post: 1124766, member: 332642"] Hello and welcome to the forum, [USER=414694]@st2@88e[/USER]! Well yes, there is: [B]Diameter.of.mother.PF.parabola = ( 4 * focal.length * abs(tan(offset.angle)) ) + Width.of.offset.dish.[/B] (where "abs" means the 'absolute' value, and assuming the dish face of the offset dish is flat. The 'abs'-function is only needed for possible negative offset angles.) [B]The derivation of the equation is discussed in this blog:[/B] [URL="https://ftapinamar.blogspot.com/2021/11/antenas-offset-8.html?showComment=1638279867072#c3203251010676321325"]Antenas Offset (8)[/URL] Of course, the [I]focal length[/I] and the [I]offset angle[/I] can be calculated with the 'common' equations. So, if wanted, you could also derive the above equation to an equation, that just needs inputs Height, Width, and Depth at the center. (Not so difficult....) Is this what you want/mean? Greetz, A33 [/QUOTE]
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Satellite TV receivers & systems support forums
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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