||Image of the Monopole DRA antenna.
The Hybrid monopole dielectric resonator antenna is an attractive option for designers who want a simple, compact antenna that can achieve wider bandwidths. This antenna uses an annular ring dielectric resonator (DRA) with a reported bandwidth of up to 3:1. The wide bandwidth performance is actually achieved by 3 distinct resonances (f1, f2 and f3) with associated omnidirectional patterns. These resonances can be associated with the physical dimensions of the antenna: the height of the monopole (f1), combined effect of the monopole and DRA (f2) and the DRA by itself (f3). The middle resonance (f2) is achieved by the DRA effectively loading the monopole so that it achieves the current distribution of a slightly shorter monopole.
The following figures show the radiation performance and reflection coefficient in a 50 Ω system of a design for 2:1 bandwidth using a DRA with εr = 20. The last figure compares near field cuts at different frequencies. Note how the positions of the peak radiation change with frequency. ...