Abstract In this article, a single feed antenna design which consists of a parasitic patch slot with an I-tree shaped fractal defected ground structure for circularly polarized radiation is presented. In the proposed design, circular polarization characteristics are achieved by deploying fractal slotted defected ground structures. The antenna design with a third iterative I-tree shaped fractal slot on an Fr4 substrate is fabricated and tested for verifying the simulated results. The circular polarization mechanism is performed using parametric studies. The measured and simulated results confirmed that the proposed structure can adequately generate an impedance bandwidth of 10.6% with 3 dB axial ratio bandwidth of 4.89%, with the measured peak gain of the proposed antenna being 5.16 dBic. The proposed article is suitable for C-band and CA-band applications.