I have seen in many places were empty 1.5 ltrs coke or pepsi bottles being cut into half and placed on the top of the LNB in dish to protect it from rain/snow so that there would be no signal loss of minimum signal loss. Does this really work?
It is unnecessary. LNB is already weatherproof. Unless heavy downpour from rooftop directly on the LNB, it does not help. May be you are avoiding this situation with bottle cover.
Yes it does not block signal.