Electrically Small Antenna Shape Synthesis That Approaches the Maximum Achievable Directivity

A unidirectional planar electrically small antenna shape synthesis method is proposed through the use of characteristic mode concepts. Antenna feed does not have to be specified beforehand, and can be easily selected on the synthesized conductor suggested by the eigencurrents distribution. The afforded freedom leads to potentially successful high-directivity electrically small antenna designs. By properly choosing the starting shape and size, the synthesized antenna can well approach the maximum achievable directivity, the associated gain, and
Q
-factor predicted by the circular plate of the same size.