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DISH SETUP: Single sat, Multi-Sat & Motorised
Calculating waveguide size
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<blockquote data-quote="s-band" data-source="post: 1079461" data-attributes="member: 407744"><p>Coverage of <3.7 depends on your need for Russian satellites, mainly.</p><p>The filter in the Tit is OK but if you really want to get rid of Wimax, you need a waveguide or other good quality filter.</p><p></p><p>As long as the pipe is above the lower cut off and below higher multi-modes, the diameter doesn't matter too much. The problem is with the depolariser. If it has a wide phase/frequency bandwidth you're OK. Some of the best ones are like this one <a href="https://www.satellites.co.uk/forums/threads/a-prodelin-gd-satcom-tripoint-global-c-band-offset-feed-omt.176306/#post-1076402" target="_blank">A prodelin / gd satcom / tripoint global c band offset feed / omt - SatsUK</a> or with scaled lengths to the pins in the pin pipe type.</p><p>It's hard to get a usable, frequency independent, phase shift over more than about 10-15% of centre frequency. You can adjust the feed skew to recover some circularity as you move away from the precise +/-45 deg frequency (see [USER=175005]@John[/USER] posts)</p><p></p><p><Edit>I didn't see [USER=178786]@moonbase[/USER] post till now - yes, changing the dimensions of the pipe squeeze will improve it if you want to change the frequency a lot.</p><p></p><p>If your depolariser is a bit off you'll get elliptical polarisation which will still work OK as long as you don't need much X polar rejection</p></blockquote><p></p>
[QUOTE="s-band, post: 1079461, member: 407744"] Coverage of <3.7 depends on your need for Russian satellites, mainly. The filter in the Tit is OK but if you really want to get rid of Wimax, you need a waveguide or other good quality filter. As long as the pipe is above the lower cut off and below higher multi-modes, the diameter doesn't matter too much. The problem is with the depolariser. If it has a wide phase/frequency bandwidth you're OK. Some of the best ones are like this one [URL='https://www.satellites.co.uk/forums/threads/a-prodelin-gd-satcom-tripoint-global-c-band-offset-feed-omt.176306/#post-1076402']A prodelin / gd satcom / tripoint global c band offset feed / omt - SatsUK[/URL] or with scaled lengths to the pins in the pin pipe type. It's hard to get a usable, frequency independent, phase shift over more than about 10-15% of centre frequency. You can adjust the feed skew to recover some circularity as you move away from the precise +/-45 deg frequency (see [USER=175005]@John[/USER] posts) <Edit>I didn't see [USER=178786]@moonbase[/USER] post till now - yes, changing the dimensions of the pipe squeeze will improve it if you want to change the frequency a lot. If your depolariser is a bit off you'll get elliptical polarisation which will still work OK as long as you don't need much X polar rejection [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
Calculating waveguide size
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