EMC Considerations in Transponder Antenna Design for Tactical Automatic Landing Systems

Integration of omni-directional transponder antennas into unmanned aerial vehicles (UAVs) becomes an important task since the adjacent conducting elements and UAV payloads significantly degrade the antenna performance. In this paper, an electromagnetic compatible (EMC) transponder antenna for tactical automatic landing system (TALS) is presented. The proposed transponder antenna has a monopole-like radiator designed to operate in X-band for UAV guidance applications, and is backed by a shielding metal cover to suppress the unwanted radio-frequency interference. In addition, with the use of the streamlined dielectric cover, the aerodynamic drag of the antenna can be mitigated. To substantiate the proposed antenna design, an electromagnetic simulation software that uses moment method (MoM) numerical computation and a 3D simulation model of large-sized military UAV are employed. Electromagnetic coupling mechanisms between the antenna and the adjacent conducting devices are also studied for the development of layout rules for transponder antenna.