Design of a Non-Uniform Depth Corrugation Structure for Enhanced Broadband Isolation Between Transmit and Receive Antennas

It is essential to ensure sufficient isolation between antennas in transmission and reception systems for stable operation. When two antennas are connected by a metallic ground plane, unintended electromagnetic coupling can significantly degrade isolation. While corrugation has been widely used as a simple yet effective means of reducing mutual coupling, uniform-depth designs are optimized for specific frequencies and thus limited in wideband applications. To address this limitation, a non-uniform depth corrugation structure with stepwise variation in slot depth is proposed, designed to enhance isolation across the entire X-Ku band. Its performance is validated through simulation and measurement results confirm that the inserted structure generates a radiation null, effectively suppressing mutual coupling. Accordingly, an average isolation improvement of 17.9 dB is obtained over the entire X-Ku band when compared to a conventional metallic ground plane, demonstrating the effectiveness of the proposed structure.