The port substitution technique is used to enhance and alter the impedance properties of fixed antenna geometry templates. Generic ports are first introduced into a geometry model, where arbitrary lumped elements can be placed. Next, an impedance matrix is generated through a full-wave simulation technique. The covariance matrix adaptation evolutionary strategy (CMA-ES) is then employed with the port substitution technique to quickly find a set of lumped elements that best fulfills the design criteria. Two examples with a single fixed geometry are given that demonstrate the ability to quickly design multi-band antennas by optimizing a set of capacitors. Broadband designs can be realized with the same technique by selecting a more flexible geometry and altering the cost function.