Abstract: Two kinds of radomes with different structure used in a radar antenna array are formed by plastic extrusion molding and plastic injection molding with modified polyphenylene oxide (MPPO) alloy. Electrical performance test of MPPO material, standing wave test of antenna array and five-year radar outdoor operation show that main electrical performances (such as dielectric constant (ε), dielectric loss tangent (tan δ), VSWR) as well as weatherability of the radome can well satisfy the technical requirements of the products.