What are you basing your statement on? have you actually done the math?
All I'm saying is I hope you have a background in EM. There's lots of stuff that sounds great in approximation and models, but breaks down in reality.
[1] G=4piA/lambda^2 - I tacked on 70% eff which is mid-high for a parabolic dish
for instance. Put in a 3 by 5 meter aperture, and bam, 40dB on the nose.