Air Traffic Control (ATC) radar, military Air Traffic Surveillance (ATS) radar and meteorological radar operate in S-Band frequency range. In fact 4G communication systems such as Long Term Evolution (LTE) make also use of these frequencies. Test and measurement of their coexistence is absolutely essential as performance degradation of mobile devices and networks and even malfunction of ATC radars has been proven. This application note describes LTE and S-Band radar coexistence test and measurement. It addresses LTE user equipment, base stations and S-Band radars and presents test solutions.