This chapter explores the fundamental concepts of antenna design critical for beyond 5G (B5G) and anticipated 6G technologies. It delves into various antenna types, including microstrip antennas, metamaterial-based designs, reconfigurable antennas, phased array antenna, and lens antennas, highlighting their role in achieving the ultra-high data rates, ultra-low latency, and massive device connectivity envisioned for B5G and 6G networks. The discussion covers key aspects such as beamforming, beam steering, and pattern reconfigurability of antenna arrays, along with interference mitigation strategies. By understanding these diverse antenna systems, researchers and engineers can contribute to shaping the future of wireless communication in the B5G and 6G era.