Broadband/multiband printed antennas

Broadening the frequency bandwidth of antennas has been one of the major subjects concerning antenna design technologies. Two of the major subjects for microstrip antennas, which appeared in the 1970s, have also been the broadening of the frequency bandwidth and the sharing of multifrequency bands. In this paper, we describe the broadband and multiband techniques of printed antennas, and show the configurations of realized broadband and multiband antennas and their characteristics. Here, resonant-type microstrip antennas, planar monopole antennas, fractal antennas and ultra-wideband printed antennas are introduced. The optimum design techniques using a genetic algorithm are introduced for developing broadband and multiband printed antennas. The usefulness of this method is verified by the simulation and experimental results of the fabricated planar monopole antenna which has ultrawide-band characteristics.