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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
Deep Dish - Low f/d ratio feed
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<blockquote data-quote="Channel Hopper" data-source="post: 1144907" data-attributes="member: 175144"><p>A 0.25 f/d ratio dish has an efficiency of little more than 50% even with a matched feed.</p><p></p><p>The gain will be reduced slightly further when receiving LH/RH signals as a result of the dielectric plate creating its own phase changes in the feed port (I believe vertical polarised signals will also be lower than horizontal ones but it was a long time ago since I carried out tests).</p><p></p><p>Elsewhere on the forum I have mentioned fitting a microwave skirt/sleeve on the outer rim of the reflector to lower the effects of 5G at the feed, on a deep dish this will mean moving the feed away from the true focal point by a small distance to retain overall performance.</p></blockquote><p></p>
[QUOTE="Channel Hopper, post: 1144907, member: 175144"] A 0.25 f/d ratio dish has an efficiency of little more than 50% even with a matched feed. The gain will be reduced slightly further when receiving LH/RH signals as a result of the dielectric plate creating its own phase changes in the feed port (I believe vertical polarised signals will also be lower than horizontal ones but it was a long time ago since I carried out tests). Elsewhere on the forum I have mentioned fitting a microwave skirt/sleeve on the outer rim of the reflector to lower the effects of 5G at the feed, on a deep dish this will mean moving the feed away from the true focal point by a small distance to retain overall performance. [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
Deep Dish - Low f/d ratio feed
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