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# Satellite Communications/VSAT

Hugo wrote at 2009-05-13 14:20:20
Dear Luis, I have something to add or at least for you to clarify me.

You mentioned:

OFD = EIRP + G1m2 - Losses (1) and The gain of a reference 1m2 antenna is the tool used to convert from a flux density to effective power captured per m2, G1m2 = 10Log10(4PI) + 20LOG(F/c)=43,8 (2).

My questions/remarks, the antenna Gain formula you mentioned isn't considering efficiency aspects?

Also and more critical,

the POwer Flux Density (S) can be given by:

S (dBW/m^2)= PT x GT /(4*pi*d^2) where PT and GT are related with transmission EIRP, d is distance from the center of the antenna up to the spherical distance d in meters.

Arranging the formula you can get:

S = EIRP - 20 log d - 11 or

EIRP = S + 20logd + 11.

What I find strange in this EIRP calculation from one Power Flux density is that is not considering other variables from Friis Free Space loss formula like frequency.

Using both approaches we have completely differente values of required dish and amplifier sizes...so what is the correct approach?

ld wrote at 2015-07-29 14:01:57
check this: page 8, http://dsp-book.narod.ru/SolManComm/haykin8.pdf

Satellite Communications

Volunteer

#### Luis Emiliani

##### Expertise

Strengths - Satellite link design and analysis - Vsat network design and analysis - Propagation aspects for terrestrial and satellite links - ITU-R P recommendations Can not help with: - Questions related to TV receivers, TV kits, or specific networks such as DirecTV or DISH - Antenna pattern synthesis, RF MoM analysis, S-parameters.

##### Experience

My experience is in satellite communication networks and terrestrial microwave links.