Leaky Horns: A New Paradigm of Developing Electromagnetic Horns Based on Leaky-Wave Structures

More than one-century history of microwaves has witnessed two seemingly unrelated developments of leaky-wave and horn antennas. While conventional horns cannot be made free from phase error even though the optimum horn criterion is adopted, this problem can theoretically be tackled by artfully exploiting the plane-wave nature of near-field wedge-shaped regions of leaky-wave antennas/structures to create an intrinsically phase-error-free horn. This special horn class is comprised of a pair of properly aligned leaky-wave structures and is thus named “leaky horn” to imply its hybrid attribute inherited from both leaky-wave and horn communities. From the authors’ perspective, the leaky horn presents a paradigm shift in developing electromagnetic horns, which will be a competitive rival over conventional horns in wireless applications and thus merits close attention.