Evaluation for dielectric loaded small dipole antennas using efficiency-bandwidth product

The efficiency-fractional bandwidth (EB) product is used to evaluate the performance of small dielectric antennas (DLAs). When applied to electrically small antennas, the EB product is equivalent to the radiation power factor (PF) proposed by Wheeler (1947) and easy to confirm by calculation and experiment. Several shapes of DLAs with almost the same volume are compared with a bare dipole using the EB product. As a result, it was found that a rectangular dielectric coating of lower permittivity (/spl epsiv//sub r/ less than about four) gives an enhancement of the EB product over the bare dipole.