In this article, a wideband circularly polarized rectangular dielectric resonator antenna (RDRA) with broadside radiation characteristics has been proposed. By using modified ground plane having an F-shaped slot, the proposed structure able to generates three sets of modes i.e., fundamental as well as higher order modes. To obtained circular polarization, an orthogonal mode (TE113) in the RDRA has been generated by using the F-shaped slot on the modified ground plane. The resonance frequency of fundamental mode (TE111) in the rectangular dielectric resonator (DR) has been calculated by using dielectric waveguide model method. The same has been confirmed through E-field distribution in RDRA. Here, wide axial ratio (AR) bandwidth of the proposed antenna is due to the generation of (TEx 121 and TEy 121 modes) modes. It is observed that input impedance bandwidth has been broadening with a pair of excited modes (TEx 121 and TEy 121 modes) in the proposed antenna structure. All these modes have been excited and merged to form a wide input impedance bandwidth and wide AR bandwidth of the designed antenna. The proposed antenna shows measured input reflection coefficient (S11< −10 dB) of 50.55% and measured AR bandwidth (AR < 3 dB) of 14.28%. The designed antenna shows left-handed circular polarization in broadside direction and offering an average gain and radiation efficiency of 4.29 dBic and 92.22% respectively. © 2018 Wiley Periodicals, Inc.