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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Tests of 120cm antennas
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<blockquote data-quote="battenfan" data-source="post: 913964" data-attributes="member: 239108"><p>I don't know what equipment one would need but I guess they define illumination angle as where the signal lost 10 dB compared to the aiming point which is close to the theoretical compromise between spillover and illumination.</p><p><img src="http://www.nitehawk.com/rasmit/IMUFIG3.JPG" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p><a href="http://www.nitehawk.com/rasmit/offset.html" target="_blank">(Image source)</a></p><p></p><p>What I was getting at <a href="https://www.satellites.co.uk/forums/threads/lnbs-aiming-point.160762/page-2#post-875208" target="_blank">here...</a> if one imagines a polar plot beam as the one above. To illuminate the dish evenly top and bottom, maybe one needs to aim a little higher than our calculated g-spot. The next image shows the aiming point higher than the projected aperture center.</p><p></p><p><img src="http://elektroarsenal.net/img/1011/image600.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p><a href="http://elektroarsenal.net/the-parabolic-reflector-antenna-and-other-single-reflector-systems.html" target="_blank">(Image source)</a></p></blockquote><p></p>
[QUOTE="battenfan, post: 913964, member: 239108"] I don't know what equipment one would need but I guess they define illumination angle as where the signal lost 10 dB compared to the aiming point which is close to the theoretical compromise between spillover and illumination. [IMG]http://www.nitehawk.com/rasmit/IMUFIG3.JPG[/IMG] [URL='http://www.nitehawk.com/rasmit/offset.html'](Image source)[/URL] What I was getting at [URL='https://www.satellites.co.uk/forums/threads/lnbs-aiming-point.160762/page-2#post-875208']here...[/URL] if one imagines a polar plot beam as the one above. To illuminate the dish evenly top and bottom, maybe one needs to aim a little higher than our calculated g-spot. The next image shows the aiming point higher than the projected aperture center. [IMG]http://elektroarsenal.net/img/1011/image600.jpg[/IMG] [URL='http://elektroarsenal.net/the-parabolic-reflector-antenna-and-other-single-reflector-systems.html'](Image source)[/URL] [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Tests of 120cm antennas
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