Abstract: This paper presents the design of a multiport microstrip antenna featuring tri-polarization capability, high port isolation, and wide beam coverage in a two-dimensional space, based on characteristic mode analysis (CMA). By selectively exciting different ports to excite distinct modes, the radiation patterns of these modes are effectively combined to achieve a wide beam coverage of ±80.75°. Furthermore, the integration of a choke structure enhances port isolation, achieving a maximum isolation of 28 dB and maintaining more than 23 dB across the operating bandwidth. Prototype measurements are subsequently conducted, and the experimental results are in agreement with the simulation data.