Utilization of U-Slot on 30-Star Microstrip Antenna for CP-SAR Antenna Performance Enhancement

CP-SAR (Circularly Polarized Synthetic Aperture Radar) utilizes circularly polarized signals, enabling penetration through obstacles such as fog, clouds, and rain. One type of antenna that can be used in CP-SAR applications is the microstrip antenna, which generates circularly polarized signals due to its advantages of compact size, simplicity, lightweight construction, low production cost, and ease of fabrication. This research chose the 30-star microstrip antenna because its performance aligns with the desired parameters. The U-slot method is proposed to demonstrate its impact on circular polarization. U-slot is a U-shaped gap in the main antenna element, which enhances bandwidth, modifies radiation patterns, and reduces the antenna's dependency on the center frequency. The analyzed performance parameters for the antenna include VSWR < 3 dB, return loss < -12 dB, gain> 3 dB, efficiency> 80%, and axial ratio < 3 dB. Simulations were conducted using CST Studio Suite 2019 with an FR-4 substrate. The simulation results show that the 30-star microstrip antenna with the U-slot achieved an axial ratio of < 3 dB, confirming the presence of circular polarization. This finding is crucial for effective signal transmission in CP-SAR.