# What is the advantage of multiple antenna in receiver in energy harvesting ?harvested more power?

What is the advantage of multiple antenna in receiver in energy harvesting ?

Assume there are $$3$$ transmitted antennas in the A device,and $$1$$ received antenna in the B device,now assume A device use beamforming with $$3$$ antenna to transmit some signal to B device,and B device harvest $$0.1W$$ power from the signal.

Now if i add one more received antenna to device B,that is, there are $$2$$ antennas in B device now,and assume these two antennas are very closed,how much power will device B harvest now? still $$0.1W$$? or $$0.1W\times2$$ ?

I am confused about this question,because if device B still harvest $$0.1W$$,then what is the advantage of multiple antenna in receiver in energy harvesting ?

If device B harvest $$0.1W\times2$$,and this mean if i want to create power,i just use $$1$$ antenna to transmit 1W RF power to a receiver with $$\infty$$ antennas receiver,then i can get $$0.1W\times \infty$$ power ,but it is impossible .

• The harvested power would improve with more receive antennas, but I am not sure by how much exactly. You cannot use $\infty$ antennas at the receiver because of physical limitations, like device's size, and sometimes computational limitations. Also, after a certain number of antennas, the improvement may not be significant, as it's the case with receive diversity, for example. – BlackMath Nov 9 '19 at 12:39
• So if the antenna number of B become 2,will the harvested power become $0.1 \times 2$? if the device A just transmit the one signal to B – Sylvindrunner Nov 9 '19 at 13:22
• @BlackMath I have add my thinking in the answer,do you accept my thinking? – Sylvindrunner Nov 9 '19 at 13:30
• These questions are valid, but need research and mathematical derivations. I haven't worked on this topic before, but there should be improvement. The only thing to proof is by how much. I suggest to get a paper on the topic and read it. – BlackMath Nov 9 '19 at 19:22

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?
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