A horn antenna configured for use in a radio frequency (RF) anechoic test chamber is provided. The horn antenna includes one or more conductive radiating elements. The horn antenna further includes an electromagnetic interference (EMI) suppressing material covering at least a portion of a surface of the one or more conductive radiating elements such that the EMI suppressing material at least partially suppresses a surface current associated with the surface of the one or more conductive radiating elements during a test operation.