Basic study for improvement of the performance of dielectric loaded small antennas
Details
The performances of the small dielectric antennas(DLAs)were evaluated using the FDTD method. The efficiency-fractional bandwidth(EB)product was used as a criterion of the evaluation. When applied to electrically small antennas, the EB product is equivalent to the PF proposed by Wheeler and easy to confirm by calculation and experiment. Several shapes of DLAs with almost the same volume were compared with a bare dipole using the EB product. The EB products were calculated both numerically and experimentally. As a result, it was found that the cylindrical DLA with relatively lower permittivity(ε_r less than about five)gives enhancement of the EB product over the bare dipole. This indicates the existence of the optimum values and shapes of dielectric loading to obtain the highest EB product.
