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<blockquote data-quote="Channel Hopper" data-source="post: 757066" data-attributes="member: 175144">The gain increase looks about right for the two dish sizes, the 1.8m being about 40% more area.As for surface areas, only the two dimensional area is valid for any communication requirement, as the signal is derived from the aperture that observes the satellite. The effective area of a prime focus dish would therefore be D/2 x D/2 x 3.1415926 etc, minus the outer rim that isn't part of the parabola, the shadows caused by the feedarms, feed, LNB and any cable dangling in front of the dish. If you did want to work out the total surface area you would need to look at the work of Archimedes and his calculations using the mathematics behind cross sections through cones (parallel to the slant edge), which can be found on the following link._http://docs.google.com/viewer?a=v&amp;q=cache:ligSYIx17aIJ:<a href="http://www.shsu.edu/~mth_jaj/math467/tate_final.pdf+equilibrium+of+planes+parabola&amp;hl=en&amp;gl=uk&amp;pid=bl&amp;srcid=ADGEESiaJuXS5c61b5hwx-67XbmL0dFb0mkrgh5tg7KK21DnNxwmZJtUoKvpugRPkrtbtYftgfekwua1mnVo8zEuWtPOXRpw53orTLbT1lAcmT9bdjUfD1YQgSPVEmgqO8nCLq_i8D5w&amp;sig=AHIEtbQHQ6cNA1I9rs4Dxsk-A6LM3uQ8jQ" target="_blank">www.shsu.edu/~mth_jaj/math467/tate_final.pdf+equilibrium+of+planes+parabola&amp;hl=en&amp;gl=uk&amp;pid=bl&amp;srcid=ADGEESiaJuXS5c61b5hwx-67XbmL0dFb0mkrgh5tg7KK21DnNxwmZJtUoKvpugRPkrtbtYftgfekwua1mnVo8zEuWtPOXRpw53orTLbT1lAcmT9bdjUfD1YQgSPVEmgqO8nCLq_i8D5w&amp;sig=AHIEtbQHQ6cNA1I9rs4Dxsk-A6LM3uQ8jQ</a>Every PC I've had has a calculator within the 'start/programmes/accessories' link, and can be set to 'scientific' which brings up the 'Pi' button</blockquote>

[QUOTE="Channel Hopper, post: 757066, member: 175144"] The gain increase looks about right for the two dish sizes, the 1.8m being about 40% more area. As for surface areas, only the two dimensional area is valid for any communication requirement, as the signal is derived from the aperture that observes the satellite. The effective area of a prime focus dish would therefore be D/2 x D/2 x 3.1415926 etc, minus the outer rim that isn't part of the parabola, the shadows caused by the feedarms, feed, LNB and any cable dangling in front of the dish. If you did want to work out the total surface area you would need to look at the work of Archimedes and his calculations using the mathematics behind cross sections through cones (parallel to the slant edge), which can be found on the following link. _http://docs.google.com/viewer?a=v&q=cache:ligSYIx17aIJ:[url]www.shsu.edu/~mth_jaj/math467/tate_final.pdf+equilibrium+of+planes+parabola&hl=en&gl=uk&pid=bl&srcid=ADGEESiaJuXS5c61b5hwx-67XbmL0dFb0mkrgh5tg7KK21DnNxwmZJtUoKvpugRPkrtbtYftgfekwua1mnVo8zEuWtPOXRpw53orTLbT1lAcmT9bdjUfD1YQgSPVEmgqO8nCLq_i8D5w&sig=AHIEtbQHQ6cNA1I9rs4Dxsk-A6LM3uQ8jQ[/url] Every PC I've had has a calculator within the 'start/programmes/accessories' link, and can be set to 'scientific' which brings up the 'Pi' button [/QUOTE]

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