Cubecell: RSSI and SNR

The SNR factor is the ratio between signal and noise.

I have two HTTC-AB01 boards, one as a transmitter (without antenna) and the other as a receiver (with antenna). I use the “LoRaWan_APP.h” library. The distance between the boards is two meters.

I receive the packet with RSSI = -75dB and SNR = 12 dB.

When I put the antenna on the transmitter board I get RSSI = -40dB and SNR = 12 dB.

Can someone explain to me why the SNR value doesn’t change?

Does this mean that the noise is amplified to the same extent when we place the antenna?

That is, the noise occurs on the transmitter board?