Wednesday, January 14, 2015

RFs from satellite dishes

RFs from satellite dishes


Andre,
 
I solved the puzzle of the internet dishes last night. The power density of a dish has to be the actual power divided by the area of the beam. That's 2.8 watts divided by pi R squared. Not a big number. That means the ERP (Effective Radiated Power) near the dish can't be a big number either. That's reassuring.
 
The published ERP of a dish seems to be the ERP at the satellite, not the ERP here on earth. I did the trigonometry and calculated that the radius of the beam at the satellite would be about 1 km if it has an ERP of 100kW. 
 
Arthur

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