This work presents a detailed analysis of the susceptibility of LoRa communications in the presence of intentional jamming signals. The analysis is performed with a periodic frequency-sweeping intentional electromagnetic interference, corresponding to the most common jamming signals. Such a waveform faithfully represents the signals emitted by commercial jammers. As the sweep period of the jamming signals may vary from one such device to another, the analyses are conducted with different sweep period values, from 1 μs to 50 μs. The experimental results indicate that the impact varies significantly according to the sweep period of the jamming signal. The detailed analysis allows us to identify the jamming signals to which LoRa communications can be resilient or not as well as to identify which LoRa channels are less affected during an attack.