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<blockquote data-quote="RimaNTSS" data-source="post: 1076852" data-attributes="member: 312276">I've found my several year old drawing about 1.2m CM antenna issue. I am pretty sure that 1.8m CM has more or less same problem (perhaps it is too strong word for this <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite53" alt=":confused" title="Confused&nbsp; &nbsp; :confused" loading="lazy" data-shortname=":confused" /> )So, what have I found out years ago: firstly, original LNB-holder does not hold LNB in the way that it's phase center (PC) co-located with antenna's focal point (FP). And it can not be corrected by moving LNB closer/further to the dish, there will always be distance between PC and FP. Secondly, feed pointing is too high and we get noise-catching and under-illuminated areas as [USER=175005]@John[/USER] rightly pointed earlier. I think that feed should divide opening angle of the antenna (AFB angle) exactly in halve. So, point G is proper point where to aim LNB. I also made some tests, and as far as I remember, pointing feed to G gave me best results. Another vital parameter of any offset antenna is it's offset angle. All CM antennas have 22.6* offset angle (if we go more precise it is 22.62*). I trully believe, producer really made antennas with 22.6* offset angles. So, if we have antenna pointed to satellite (maximum signal level) with elevation angle 30*, than antenna should be leaning&nbsp; backwards 7.4*. But....if original LNB-holder is used, antenna is pointed to satellite with 30* elevation after measuring leaning of antenna you will not get 22.6*. Moreover, when original LNB-holder is used and you move LNB closer/further from the dish, you will need to adjust antenna's elevation each time.</blockquote>

[QUOTE="RimaNTSS, post: 1076852, member: 312276"] I've found my several year old drawing about 1.2m CM antenna issue. I am pretty sure that 1.8m CM has more or less same problem (perhaps it is too strong word for this :confused ) So, what have I found out years ago: firstly, original LNB-holder does not hold LNB in the way that it's phase center (PC) co-located with antenna's focal point (FP). And it can not be corrected by moving LNB closer/further to the dish, there will always be distance between PC and FP. Secondly, feed pointing is too high and we get noise-catching and under-illuminated areas as [USER=175005]@John[/USER] rightly pointed earlier. I think that feed should divide opening angle of the antenna (AFB angle) exactly in halve. So, point G is proper point where to aim LNB. I also made some tests, and as far as I remember, pointing feed to G gave me best results. Another vital parameter of any offset antenna is it's offset angle. All CM antennas have 22.6* offset angle (if we go more precise it is 22.62*). I trully believe, producer really made antennas with 22.6* offset angles. So, if we have antenna pointed to satellite (maximum signal level) with elevation angle 30*, than antenna should be leaning backwards 7.4*. But....if original LNB-holder is used, antenna is pointed to satellite with 30* elevation after measuring leaning of antenna you will not get 22.6*. Moreover, when original LNB-holder is used and you move LNB closer/further from the dish, you will need to adjust antenna's elevation each time. [/QUOTE]

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