A wireless device includes at least one slim radiating system having a slim radiating structure and a radio-frequency system. The slim radiating structure includes one or more booster bars. The booster bar has slim width and height factors that facilitate its integration within the wireless device and the excitation of a resonant mode in the ground plane layer, and has a location factor that enables it to achieve the most favorable radio-frequency performance for the available space to allocate the booster bar. The at least one slim radiating system may be configured to transmit and receive electromagnetic wave signals in one or more frequency regions of the electromagnetic spectrum.