Monopole Antenna Loaded by a Stepped-Radius Dielectric Ring Resonator for Ultrawide Bandwidth

A coax-fed thin-wire monopole antenna loaded by an annular cylindrical dielectric ring resonator (DRR) containing a step in its outer radius is studied numerically. The results obtained with computations based on bodies of revolution (BoR) followed by the method of moments (MoM) procedure are compared to the results of commercially available software tools for verification. The new hybrid antenna can easily offer a fractional bandwidth up to 110% for the magnitude of the input reflection coefficient, vertical bar S(11)vertical bar < -10 dB. The vertical bar S(11)vertical bar response of the newly proposed antenna shows an additional resonance compared to its cylindrical ring counterpart without the step, resulting in at least 10% larger impedance bandwidth.