Radio wave transmissive metallic member and method for manufacturing the same

A metallic member comprising:

• a substrate body;
• an ion-exchange resin layer formed on the substrate body;
• and
• a metal particle layer formed on the ion-exchange resin layer,
• wherein gaps are provided between metal particles in the metal particle layer,
• wherein a maximum length a (nm) in a horizontal direction of the metal particle, a maximum length b (nm) in a perpendicular direction of the metal particle, and a length c (nm) in the perpendicular direction of a portion embedded into the ion-exchange resin layer of the metal particle satisfy 1.5 nm≤a≤200 nm, b/a≥1.25, and c≥0 in a cross-sectional surface of the metallic member, and
• wherein an inclination θ (°) of the metal particle with respect to a bottom surface of the ion-exchange resin layer satisfies 60°≤θ≤90° in the cross-sectional surface of the metallic member.