Novel power recycling schemes for enhanced radiation efficiency in leaky-wave antennas

Two novel power recycling schemes for enhancing the radiation efficiency of leaky-wave antennas are proposed and demonstrated both theoretically and experimentally. The first scheme enhances the radiation efficiency of a single leaky-wave antenna by feeding the energy remaining at the output of the antenna back into its input terminal via a rat-race hybrid coupler. In this manner, the power associated with each information symbol loops several times along the structure until all its energy has been fully radiated, leading ideally to a 100% radiation efficiency. This is the self-recycling scheme. The second scheme enhances the radiation efficiency of a leaky-wave antenna array by re-injecting the energy remaining at the output of the excited element into the adjacent elements of the array via a series feeding network, and possibly including phase-shifters for full-space pencil-beam scanning. This is the cross-recycling scheme.