The LNA boosts the antenna signal to beat feed line losses involving the antenna as well as receiver. To simplify the noise obtain calculation, the sounds resources in The easy amplifier circuit in Figure one might be lessened to just one whole RTI sounds supply (Vni, Overall), as demonstrated in https://low-noise-amplifier78898.alltdesign.com/low-noise-amplifier-can-be-fun-for-anyone-56265510