Some Siretta antennas, because of their construction, require a ground plane beneath them to achieve their data sheet specifications. A ground plane means that the antenna needs to be placed on a surface that will reflect the radio signals. The data sheet often specifies the size needed, which should be read as a minimum size. If a ground plane is needed but not specified, then it should extend at least ¼ of the antenna’s wavelength from the antenna in all directions on the plane on which the antenna is mounted.