Dielectric rod antennas (DRAs) are commonly used as reflector feeds and nearfield probes because they exhibit single broadside beam, good polarization purity, wide bandwidth and low scattering cross section. Particularly for multiple reflector feeds, low cross-coupling and polarization purity of DRAs make them very attractive. More importantly, DRAs provide ultra-wideband (UWB) operation with a simple and easy-to-fabricate, cost-effective structure. However, the maximum achievable bandwidth is typically limited by the waveguide feed at the low end and the onset of higher-order modes of the dielectric rod at the high end of the frequency range. In the past, multi-layered DRA designs (C.-W. Liu and C.-C. Chen, “A UWB Three-Layer Dielectric Rod Antenna with Constant Gain, Pattern and Phase Center,” IEEE Transaction on Antennas and Propagation 60(10), Oct. 2012) have been utilized to increase the frequency coverage. However, this adds significantly to design and manufacturing complexity.