A frequency-tunable capacitively-loaded magnetic dipole antenna includes a
transformer loop having a balanced feed interface, and a
capacitively-loaded magnetic dipole radiator with a tunable effective
electrical length. In one embodiment, the capacitively-loaded magnetic
dipole radiator includes a tunable electric field bridge. For example,
the capacitively-loaded magnetic dipole radiator may comprise a quasi
loop with a tunable electric field bridge interposed between the quasi
loop first and second ends. The electric field bridge may be an element
such as a ferroelectric (FE) tunable capacitor or a
microelectromechanical system (MEMS) capacitor, to name a couple of
examples. In certain embodiments, the capacitively-loaded magnetic dipole
radiator includes a quasi loop with a loop perimeter. The effective
electrical length of the radiator is changed by adjusting the perimeter
using an element such as a MEMS switch, or a semiconductor switch.