To meet the demand for multifunctional antennas in shipborne communication systems, this paper proposes a novel high gain four-beam reconfigurable patch antenna based on the Yagi antenna.

The proposed antenna is composed of four symmetrical sector elements, with four PIN diodes loaded between the central patch and the sector components. These PIN diodes are used to control the radiation pattern by switching their on/off states, allowing the antenna to achieve four distinct directional patterns. Additionally, arc-shaped parasitic units are incorporated as reflectors or directors to enhance the antenna's gain and suppress sidelobes. The antenna is fabricated on a single-layer PTFE substrate with a dielectric constant of 2.2 and a loss tangent of 0.001, with overall dimensions of 80 mm × 80 mm × 4 mm. The design process involved optimizing various parameters, such as the radius of the sector patches (R1) and the spacing between the parasitic units and the sector patches (D1), to achieve the desired performance. The antenna's performance was evaluated through both simulation and experimental testing, with detailed analysis of its radiation patterns, gain, and impedance characteristics.

Experimental results demonstrate that the antenna can achieve beam pointing at four specific azimuth angles (45°, 135°, 225°, and 315°) across four operating modes. Within the frequency range of 5.47 to 6.05 GHz, the antenna exhibits a high average gain of 7.46 dBi, with a measured impedance bandwidth of 10.07%. The measured gain is consistent across all four modes, with a maximum gain of 8.68 dBi observed within the operating band. The introduction of parasitic elements significantly enhances the antenna's directional radiation pattern, reducing sidelobes and improving gain. The optimized antenna demonstrates excellent impedance matching and radiation characteristics, with the measured results closely matching the simulated performance.

The proposed antenna has the advantages of high gain, low profile and simple control. Its radiation direction can be dynamically adjusted according to the communication needs of ships in order to reduce signal interference and improve communication quality.