The speech quality for a particular mobile communication system is just acceptable when the received power at the terminals of the mobile receiver is -104 dBm. Find the maximum acceptable propagation loss for the system, given that the transmit power at the base station is 30W, base station feeder losses are 15 dB, the base station antenna gain is 6 dB, the mobile antenna gain is 0 dBi and the mobile feeder losses are 2 dB. Express the field strength at the receiver antenna in dBμV m-1.