This study aims to develop and evaluate the multibeam one-third Radial Line Slot Array (RLSA) antennas. The various techniques used include: a) slot implementation on the background surface for the design of multibeam, b) cutting the full circle of RLSAs for the simplification of the antenna size, and c) slot deletion for the formation of bandwidth. Approximately 40 multibeam one-third RLSA models were designed and simulated, with the best being fabricated and measured to verify the simulation. The results showed that the antenna had symmetrical beams regarding the gain, direction, and beamwidth at 9 dBi, 20 and 160°, as well as 38°, respectively. The antenna also had a low reflection of -22 dB at the centre frequency of 5.8 GHz, with a broad bandwidth of approximately 1.2 GHz, which was highly sufficient for Wi-Fi application. The gain of 9 dBi was 3 dB lower than that of a simulated single-beam antenna, which was suitable for the theory of splitting. Based on these findings, the agreement between measurement and simulation verified the design of the antenna.
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