Rectangular Parasitic Stacked Layer on a Linearly Dual-Polarized Circular Patch Antenna

Achieving wideband performance while maintaining stable dual linear polarization remains a key challenge in mobile satellite communication antennas, as it directly impacts signal reliability, data throughput, and resistance to polarization mismatch in harsh and dynamic environments. This study investigates the effect of a rectangular parasitic structure on a circular patch with a rhombus-shaped feeding antenna designed for Ku-band satellite applications. The rectangular parasitic technique successfully increased the antenna bandwidth from 478 MHz to 1.76 GHz, and the gain improved from 6.283 dBi to 6.807 dBi, demonstrating significant improvement in frequency coverage. Simulation results also confirm the antenna's dual linear polarization capability, indicated by notably higher S21 values at vertical of −121.65 dB and horizontal of −31.28 dB orientations compared to the 45° slant position of −124.81 dB. This confirms strong coupling along orthogonal polarization axes and minimal transmission at mismatched angles. However, an anomaly in the horizontal polarization S21 value was observed, likely due to asymmetric field distribution or unintended resonance effects introduced by the parasitic structure. This irregularity suggests that while bandwidth performance improved, polarization isolation and balance require further refinement.