What is the advantage of multiple antenna in receiver in energy harvesting ?harvested more power?
After thinking,i think when the antenna number of device B become 2,the harvested power of B will not become $0.1W \times 2$,WHY?

Because when there is just one antenna in B device,the beamforming direction just aim that antenna,because just that antenna has to receive or harvest the signal,so that antenna can harvest all the RF energy

However,if the antenna number become two,device A has to let both of two antenna of B receive or harvest the signal,so the beamforming direction has to change,maybe the middle of these two antenna,so now first antenna will harvest about $0.05W$,and the other will receive $0.05W$ as well.Or perhaps $0.06W$ and $0.04W$,but the total power will not be larger than 0.1W