Described herein are antenna designs and configurations that provide flexible solutions for creating compact antennas with multiple-band capabilities. For example, a hybrid PIFA-monopole antenna configuration and design is described. As another example, non-planar (e.g., orthogonal) and composite radiating structures incorporating various radiating element and ground plane configurations are described. Connective structures are also described for providing physical rigidity and ground plane connectivity to composite radiation elements. In embodiments described herein of composite radiating structures, multiple antennas may be included through passive radiating elements potentially combined with active circuitry. Composite radiating structures with multiple antennas may be used in multiple-in and multiple-out (MIMO) antenna applications. For example, multiple different antennas within the composite radiating structures may be created using radiating elements on one or more of the vertical and/or horizontal portions of the composite radiating structure.