A 30 km microwave link design will use a 10 GHz carrier frequency and have a maximum acceptable path loss of 169 dB. The transmit antenna is 20 m above the ground but the height of the receive antenna is to be determined. The ground between the antennas is flat except for a knife-edge ridge line which is 80 m high and located 10 km from the transmitter. 

Find: 

(a) the total path loss assuming the receive antenna is mounted 20 m above the ground and 

(b) the height of the receive antenna that will produce a path loss exactly equal to the maximum acceptable value.