Compact wideband multi-layer cylindrical dielectric resonator antennas

Homogenous dielectric resonator antennas (DRAs) have been studied widely and their bandwidth have been reached to the possible upper limit. A new non-homogenous DRA, multilayer cylindrical DRA (MCDRA), is designed and fabricated to achieve wider bandwidth. The antennas consist of three different dielectric discs, one on top of the other. Two different excitation mechanisms are studied here. As much as 66% of impedance bandwidth with a broadside radiation pattern has been demonstrated using a 50 Omega coaxial probe placed off the antenna axis. More than 32% of impedance with a broadside radiation pattern has been achieved when the antenna is excited by an aperture coupled 50 Omega microstrip feedline. Mode analysis is carried out to investigate the natural resonance behaviours of the MCDRA structure.