An Ultra‐Wideband MIMO Antenna With Multi‐Substrate Compatibility for Vehicular Communication

This work presents a compact semicircular patch antenna with a microstrip feed and partial ground plane, designed for vehicular applications. Fabricated on a Rogers RT/Duroid 5880 substrate with overall dimensions of 30 × 30 × 0.578 mm 3 , radiator uses a unique semicircular geometry to achieve wideband performance. The partial ground plane enhances bandwidth at lower frequencies while maintaining high isolation up to 52 dB within an Ultrawide impedance bandwidth from 7.5 GHz to 60 GHz (155.5%), with main resonance at 25 GHz. The antenna exhibits stable gain (7–8 dBi), high efficiency (89%–92%), and bidirectional radiation, making it suitable for 5 G FR‐2 communication. A key contribution of this work is the investigation of antenna performance across different vehicular substrate materials, including PTFE, ABS, windshield glass, and tempered glass. The results demonstrate that the proposed antenna maintains stable characteristics irrespective of substrate variations, making it highly suitable for practical affordable automotive integration. The proposed antenna thus offers a compact, high‐isolation, and material‐resilient solution for next‐generation vehicular communication systems.