How can I calculate signal strength decrease for non-focus sats, in multifeed system?

BombedOne

Let's say, I have a dish pointing at 13E. I've mounted another LNB on it, pointing on 5E, adjusted to maximum signal strength. What will be decrease of signal strength in dB in such case? is there any way to calculate it mathematically?

For larger/brandname dishes, in user manual you can find sidelobe attenuation level, which can be used as reference for placing additional LNB. But generally, such info is available for large (over 180cm) and high-end dishes only, leaving most consumer dishes market outside.

Vipersan

..Hi m8 ..
Don't know if it helps but might give an approximate relative sidelobe gain reduction ..
Smaller dishes would be presumably of a similar ratio.
The result may not be exact ..but maybe close enough.

These are figures quoted for the Gibby 1.2

F/D ratio: 0.66 - Offset angle: 21.3 degrees - Frequency range: 10.00 - 13.00 GHz - Illumination Efficiency: 70% - Gain: @ 10.95 GHz: 41.5 dB - Elevation angle range: 20 - 50 degrees - Beam width: 1.37 degrees - Cross pol. discrimination on main axis: > 30 dB - Mast clamp for: 55 - 100 mm - Wind pressure: @ 120 km/h: 145 Kg - First side lobe: 26 dB -

rgds
VS

BombedOne

Thanks for information. But we're missing additional data. The power of 1st sidelobe is given, but it's angle is unknown...

deepbluesky

As far as i remember Satmaster Pro should be able to give you a table based on your data input: _http://www.arrowe.com/linkbudget.html

Also take a look here if you find something: _http://www.satellite-calculations.com/

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