High-Isolation SIW-Based MIMO Antenna for Mid X-Band Wireless Applications

This paper presents a substrate-integrated waveguide (SIW) based multiple-input multiple-output (MIMO) antenna operating in the X-band frequency range from 9.4 GHz to 10.5 GHz. The design excited by a coaxial cable feding technique to achieve efficient feeding, wide impedance bandwidth around 12%, and compact planar integration. Simulation results demonstrate a high isolation level exceeding –25 dB between antenna elements, effectively minimizing mutual coupling. The antenna exhibits an average radiation efficiency of approximately 90%, highlighting the low-loss characteristic of the SIW configuration. Moreover, the gain remains above 6.66 dBi across the entire operational band, ensuring satisfactory radiation performance for high-frequency wireless applications. These caracteristics make the proposed antenna as a strong candidate for many applications like radar, satellite communication, and advanced wireless systems requiring compactness, high isolation, and robust performance within the mid X-band spectrum.