Noise sensitivity PRRU (real)

This value is characterized by the minimum required power or EMF of the signal in the antenna, at which a given signal-to-noise ratio is provided at the output of the receiver’s linear path:

This takes into account the noise of the antenna, feeder and the receiver itself.

In the matching mode, the noise power of the antenna transmitted to the input of the feeder is defined as

In the negotiation mode, the maximum rated power is given

Denote the transmission coefficient of the feeder through , then at the receiver input the noise power of the antenna will be .

Feeder noise power at receiver input in matching mode

Here - feeder noise ratio. If W is the receiver noise figure, then the receiver’s own noise power, reduced to its input, is defined as

Then the total noise power at the output of the linear path with power transfer coefficient at

Where - relative noise temperature of the antenna.

To ensure the specified reception quality, the signal power at the output of the path must be equal to

Therefore, the signal power in the antenna, which characterizes the sensitivity of the receiver

With we get the expression for the limiting or threshold sensitivity

Accordingly, the emf signal in the antenna for real sensitivity

        ,

for threshold sensitivity

        .

Often the receiver sensitivity is expressed through noise temperature.

For simplicity, we assume = 1.

Comparing and it is easy to determine to what extent the real sensitivity of the receiver depends on its own noise.