If you had two exact same antennas next to each other, say 10cm, or even wound together. Would they see the exact same noise?

I'm thinking whether it would be possible to amplify a signal by amplifying the common signal and removing the noise in the case the input signal is of unknown frequency and amplitude.

The reason I ask is that types of noise are inherently random such that an antenna with an unknown signal on it would have a hard or impossible time differentiating the desired signal from noise, whereas dual antennas could see a common signal and be able to remove/cancel the noise out by differntial signal rejection methods if said noise was random or different in each antenna.

  • \$\begingroup\$ Noise is unwanted signal. It doesn't have to be random. Another transmitter could produce a signal that, for you antennas, would be noise. Or isn't power line hum noise? \$\endgroup\$ – RaphaelP Apr 25 '19 at 13:23

Treating the signals received on more than one antenna is known as beamforming. It relies on the antennae being in different places, so that aspects of the noise and signal they receive are sufficiently different to be suitable for processing, usually to enhance the SNR (signal to noise ratio).

The two most common processes are to steer a beam in the direction of the wanted signal, and to steer a null in the direction of an identified unwanted signal source. 'Steering' is achieved by giving the signals different delays, and adding them, sometimes with weights other than unity.

This is a much-studied technique, and there is a huge amount of literature out there. Many people have done their PhDs in this field.

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