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https://www.satsig.net/cgi-bin/yabb/YaBB.pl VSAT technology and installation >> Dish pointing and alignment >> Formula for dB down off axis https://www.satsig.net/cgi-bin/yabb/YaBB.pl?num=1252873255 Message started by chumleymobile on Sep 13^th, 2009 at 9:20pm

Title: Formula for dB down off axis
Post by chumleymobile on Sep 13^th, 2009 at 9:20pm

Sirs/Ma'ams,

I've got the formula for dB down off axis for 3 db beamwidth ie (theta/3db beamwidth)^ x 12, anyone have the formula for dB down ref to 10 dB beamwidth? Many thanks.

Chumleymobile

Title: Re: Formula for dB down off axis
Post by Forum Admin on Sep 14^th, 2009 at 11:17pm

You may try this beamwidth calculator but please be aware that the result is approximate.

The shape of the main beam is affected by the power illumination distribution across the dish. The feed has higher gain towards the centre of the dish and lower gain towards the edge of the dish. The effect is to greatly reduce the off-axis sidelobe levels with some limited on-axis gain reduction.

Best regards, Eric.

Title: Re: Formula for dB down off axis
Post by chumleymobile on Sep 15^th, 2009 at 3:24pm

Eric,

Good stuff, thanks.

Br's,

C'mobile