Abstract-Impact of electromagnetic interference on front-end receiver behaviour is theoretically and experimentally studied outside the bandwidth of the antennas. Microwave chaotic generation is observed. Under certain conditions, reflected waves combined to the non linearity of the front-end receiver leads to a chaotic signal generation between the antenna and the front-end receiver. Different antennas, such as patch, loop, monopole and horn, are tested. Theoretical and experimental results are presented for each antenna.