HDTVFanAtic said:What percentage should a Ku 0.3db lnb increase your signal over a 0.6db lnb?
k2ue said:Noise Figure is based a terrestrial ambient temperature reference of 290K, and is defined as how much noise is added by passing thru the amp. So 0.3 dB adds 21 degrees K, 0.6 dB add 43 degrees K. The unknown is the Antenna temperature at your elevation angle above the horizon (the higher, the more you see of the cold of space, and the less of the 290K terrestrial heat. But if were to say it was 30K, then the NF improvement calulation would be 10*log ((30+21)/(30+43)) = 1.55 dB improvement in CNR (Carrier to Noise Ratio). Commercial antennas (as opposed to consumer) usually have a graph of noise temp as a function of elevation above horizon on their data sheet, to facilitate the calculation I made above.
HDTVFanAtic said:If I were at sea level (thus not in the cold air) - what % improvement should that 1.55db give me over a 0.6?
HDTVFanAtic said:Thanks for the input/
There are several articles that i have found that lead on to believe that the 0.3 db signal spec is just marketing hype - that the real figure needed is the maximum - worse case scenario.
Right now I have a usable 74 from E* 148 with a toroidal T90 and a 0.6 lnb. When I used a .5 meter Dish 500 I was able to get a 55, so the move from a .5 meter to .9 meter gave me about 35% additional signal. I was curious what a move to a 0.3 lnb would yield, but that seems to be trick question if I believe everything I read.
HDTVFanAtic said:Thank you for your knowledgable info on this.
If I could ask you one last thing, how much gain should I net going from a 24" dish to a 30" dish.
Also, how much should I net if I move from my .9 Meter to 1.2 Meter?
Are the increases linear and consistent?