MI-STAR: Mitigation of Self-Interference in Simultaneous Transmit and Receive Array via Evolutionary Optimization

Simultaneous Transmit and Receive (STAR) technology is a promising alternative to conventional communication systems, offering improved spectral efficiency and capacity. However, self-interference (SI) remains a major challenge. This paper proposes a shared aperture array design optimized using Genetic Algorithm (GA) to minimize SI ensuring a balanced distribution of transmit and receive elements. A $10 \times 10$ antenna array with two coaxial ports per unit cell is used for validation, incorporating two unit cell designs: a square patch antenna for higher frequencies and a crossbow-shaped patch antenna for lower frequencies. GA-based optimization achieves substantial SI reduction, with -4.846 dB for the square patch and -4.595 dB for the crossbow structure. The results demonstrate that aperture optimization effectively enhances isolation, making STAR systems more effective for wireless communication, radar, and spectrum-sharing applications.