Problem
1. Early satellite communications systems often used large 20-m-diameter parabolic dishes with an efficiency of approximately 60% to receive a signal at 4 GH2. What is the gain of one of these dishes in dB?
2. In terrestrial microwave links, line-of-sight transmission limits the separation of transmitters and receivers to about 40 km. If a 100-milliwatt transmitter at 4 GHz is used with transmitting and receiving antennas of 0.5-m2 effective area, what is the received power level in dBm? If the receiving antenna terminals are matched to a 50-ohm impedance, what voltage would be induced across these terminals by the transmitted signal?