DEVELOPMENT OF 8×8 BUTLER MATRIX FOR BEAMSWITCHING APPLICATIONS IN WIRELESS COMMUNICATION

• Main Author: Manzil Karama, Muhammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87628
• Institution: Institut Teknologi Bandung

The increasing demand for high-capacity and spectrally efficient wireless communication systems has driven the development of beamswitching techniques, with the Butler Matrix being one of the most effective methods for directing signal beams without requiring mechanical antenna movement. However, the conventional 8×8 Butler Matrix design presents several major challenges, including a large physical size of 223 × 247.7 mm, high transmission losses due to multiple crossover elements, and fabrication complexity that affects beamswitching network performance. To address these issues, this study proposes the development of a crossover-free 8×8 Butler Matrix with further innovation through the integration of coaxial bridge strips. The methodology involves simulation, fabrication, and experimental measurements at an operating frequency of 2.4 GHz, using an FR-4 epoxy substrate with a dielectric constant of 4.3 and a thickness of 0.8 mm. The results indicate that the crossover-free design successfully reduces the overall size to 178.6 × 137.8 mm, achieving a 55.4% reduction compared to the conventional design, while improving transmission efficiency with an average insertion loss of ?3 dB and a return loss below ?15 dB. The integration of coaxial bridge strips further simplifies the feeding network by relocating the input/output ports to a single side, resulting in a 200 × 120 mm design, marking a 56.5% reduction compared to the conventional design, while maintaining optimal performance with a phase imbalance of ±15° from the theoretical value. The novelty of this research lies in the integration of coaxial bridge strips, which simplifies the design and enhances the efficiency of the crossover-free Butler Matrix, contributing to the advancement of beamswitching systems in Wi-Fi, radar, and 5G communication applications.