A radar cross section (RCS) measurement setup for the characterization and measurement of periodic structures is presented. The idea is to modify an existing spherical range in an anechoic-chamber setup, allowing scattered-field measurements of PEC and artificial magnetic conductor prototypes. With the proposed setup, the scattered field of the object under test (OUT) can be measured for different azimuth and roll angles, as well as for any incident wave polarization. The measurement setup's performance is validated by comparing simulations and measurements. Finally, a combined PEC-artificial magnetic conductor surface, intended for RCS reduction, was measured with the proposed setup.