Okay. So i am planning to make this project in which i want to use two transmitters and two receivers. I want to make one of them to transmit waves that go only for say 3+ feet and another than can only transmit around 1 feet. 4 Is it possible? I know frequency plays an role and so does the power, but how should i exactly get the distances my wave can travel? Is there a precise way? If not how i should work it out? if i get the frequency i can work on the component values of my wave generator. Please need help fast. Secondly, Is there a simple way in which i can know whether the wave i transmitted is being recieved.. i want to know it on the transmitter side.. (maybe getting it back from reciever).. But exactly how? Is there any other method?