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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="archive10" data-source="post: 913799"><p>I think you need to factor in that the CM120 (100 and 90 too) have the feed arms attached to the front of the dish.</p><p>The active area of the dish probably does not include the points where the feed-arms are attach to the dish.</p><p>This means that the active area is offset upwards in relation to the dish face.</p><p>The G-point of the active area is therefore *higher* than the "offset center" of the reflector (your green dot).</p><p>It may be close, if not spot-on the red dot..</p><p>(After all, somebody thought long and hard about this when designing the antenna...)</p><p></p><p>See attached modified drawing for putting this visually.</p><p></p><p>This does not detract from the CM120 being a 120, IIRC the reflector is in fact 125 x 134 or something like that.</p><p>This probably will include an (almost) full 120 cm working area of the reflector.</p><p></p><p>It could be different on reflectors sich as the Echostar, where the feedarms attach to the sides of the dish.</p><p>But we need to measure...</p></blockquote><p></p>
[QUOTE="archive10, post: 913799"] I think you need to factor in that the CM120 (100 and 90 too) have the feed arms attached to the front of the dish. The active area of the dish probably does not include the points where the feed-arms are attach to the dish. This means that the active area is offset upwards in relation to the dish face. The G-point of the active area is therefore *higher* than the "offset center" of the reflector (your green dot). It may be close, if not spot-on the red dot.. (After all, somebody thought long and hard about this when designing the antenna...) See attached modified drawing for putting this visually. This does not detract from the CM120 being a 120, IIRC the reflector is in fact 125 x 134 or something like that. This probably will include an (almost) full 120 cm working area of the reflector. It could be different on reflectors sich as the Echostar, where the feedarms attach to the sides of the dish. But we need to measure... [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
Tests of 120cm antennas
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