1. A two-port linear passband network has a bandwidth B = 50 kHz. The network has a 6 dB noise…

1. A two-port linear passband network has a bandwidth B = 50 kHz. The network has a 6 dB noise figure. It has equal input and output impedances  (purely resistive), and it is perfectly matched. Calculate the input signal power (in dBm) and the corresponding source statistical power (in V2) that guarantees an output SNR of 40 dB.

2. Consider a receiver consisting on the cascade of: (1) an antenna with noise temperature Ta = 50 K; (2) an amplifier, directly connected to the antenna, with gain (g1)dB = 20 dB and noise temperature T1 = 40 K; (3) a second amplifier with gain (g2)dB = 30 dB and noise figure (F2)dB = 6 dB; (4) a device consisting of a converter to an intermediate frequency and of a series of amplifiers, with a total noise figure (F3)dB = 15 dB. Assume each device to be matched. Determine:

a) The noise figure of the receiver.

b) The average power (in dBm) of the input signal, Ps,in, to guarantee an output SNR of 30 dB (assume the system bandwidth B = 100 kHz).

c) How do the above results change if the second amplifier at item (3) is removed from the receiver?