An apparatus transmits and/or receives radio waves in the UHF band and is configured for installation in an elastic structure. The apparatus includes at least one electronic component and an antenna embedded in the elastic structure. The antenna is connected to the electronic component and includes at least one filament configured to be plastically deformable and/or elastically deformable. The filament is helically wound to a predetermined antenna length (L) and defines an antenna winding turns density per cm of the antenna length. The antenna length (L) is between 4 cm and 10 cm and the antenna winding turns density lies in a range of 5 to 15 winding turns per cm of the antenna length.