A novel high-isolation, monostatic, circularly polarized (CP) simultaneous transmit and receive (STAR) anisotropic dielectric resonator antenna (DRA) is presented. The proposed in-band full-duplex (IBFD) CP-DRA system consists of two identical but orthogonally positioned anisotropic annular sector dielectric resonators composed of an alternating stack of different dielectric with relative permittivity of 2 and 15 and excited by coaxial probes. The element spacing is selected to maximize the IBFD DRA radiation performance. In addition, a simple square absorber is carefully placed between the resonators to realize high Tx/Rx isolation. Measurement results exhibit high Tx/Rx isolation better than 50 dB over the desired operating bandwidth (5.87 to 5.97 GHz) with 98% total efficiency and a peak gain of 5.49 and 5.08 dBic for Ports 1 and 2, respectively.