let's consider the following blocks diagram for a receiver of a pulse RADAR (but I suppose my question regards many kinds of receivers)
My book says that T/R Lim means a power limiter which is inserted after the duplexer (which is after the antenna) in order not to burn the receiver.
Well, my simple questions are:
Is such a power limiter realized with an attenuator (e.g. a voltage divider, or a microwave resistive attenuator etc)? Simply put, is it a resistive attenuator or a voltage/current limiter (e.g. diodes)?
If it is an attenuator, how does it affect the SNR ratio? Does it reduce both noise and signal powers?
If it is an attenuator, why should we attenuate and then amplify with LNA? Why can't we attenuate less (just less than the maximum power the system may work with) and save space and money by avoiding the Low Noise Amplifier?