A helical shaped broadband circularly polarized dielectric resonator antenna

By modifying the shape of a rectangular dielectric resonator antenna (DRA), a wideband circularly polarized (CP) radiator is introduced. The modified structure is composed of two L-shaped dielectric pieces stacked onto each other. The resulting geometry is similar to a two-turn helix with a rectangular cross section. Placing a coaxial probe adjacent to the sidewall of the DRA excites multiple orthogonal modes in the antenna which in sequence leads to a wideband CP DRA. The special geometry of the DRA provides the required quadrature phase difference between the orthogonal components of the electric fields. The measured input scattering parameter,, is below -10 dB from 3 to 4.6 GHz (42%). Also, the frequency band in which axial ratio (AR) is lower than 3 dB extends from 3.1 to 3.83 GHz (21.07%), which is suitable for WIMAX applications. The measured results of the fabricated prototype are presented to verify the simulations.