Problem 1: Antenna gain is usually given in relation to an isotropic antenna (radiating/receiving equally in all directions). It can be shown that the effective area of such an antenna is Aiso = λ2/4π.
Compute the antenna gain Gpar of a circular parabolic antenna as a function of its radius r, where the effective area is Ac = 0.55 A is the physical area of the opening.
Problem 2: When communicating with a geostationary satellite from Earth, the distance between transmitter and receiver is approximately 35,000 km. Assume that Friis' law for free space loss is applicable (ignore any effects from the atmosphere) and that stations have parabolic antennas with gains 60dB (Earth) and 20dB (satellite), respectively, at the 11-GHz carrier frequency used.
a. Draw the link budget between transmitted powers PTX and received power PRX.
b. If the satellite receiver requires a minimum received power of -120 dBm, what transmit power is required at the Earth station antenna?