An RFID tag or label includes a wireless communication system that is mounted in electrical proximity to the dielectric material. The wireless communication system includes a wireless communication device associated with an antenna system that has at least one conductive tab, including: a plurality of electrical components forming an impedance matching network, coupled to the conducting tab and wireless communication device, that electrically interact with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device; and/or a structural element forming a frequency selective by-pass trap circuit formed in the conducting tab, and electrically interacting with the dielectric material to maintain a substantial impedance match. The antenna system may be directly mounted on a dielectric substrate, which serves as the dielectric material, or alternatively may be mounted on a backing layer intermediate the dielectric substrate and the antenna system.