Antenna system embodiments are illustrated that include a planar, top-loaded dipole antenna and a planar elliptical dipole antenna arranged substantially coplanar and within the top-loaded dipole antenna. These antenna structures facilitate their combination with tuning coil chains, baluns and impedance matching circuits to operate over multiple frequency bands. System embodiments exhibit high gain and selectivity and may be digitally tuned over wide frequency bands (e.g., 30-600 MHz). The embodiments may be digitally tuned to support operational modes such as frequency hopping to thereby realize a secure communication system. Because these embodiments are configured to operate in the absence of a ground plane, they are especially suited for mounting on various portions of an aircraft's structure. For example, they may be configured as winglets and situated far out on wingtips to thus free the remainder of an aircraft's structure for other operational systems.