Conventionally, to measure the electrical characteristics of a reflector antenna panel made of a composite material, a flat sample was separately manufactured with the same material as the panel or a part of the antenna panel was cut to make it flat. In this study, it was confirmed that the electrical characteristics of the curved sample can be accurately analyzed without deformation by performing measurements using an electromagnetic interference shielding foam adapter and a vertical-type measurement device. It is possible to efficiently analyze the electrical characteristics of the composite reflector panel by manufacturing a measurement device for curved panels to overcome the size limit of the vertical-type measurement device and enable measurement by angle at an arbitrary position.