Full-wave analysis of Compensated Compact Ranges including absorber structures

The Compensated Compact Ranges (CCRs) of Airbus Defence & Space form a dual-reflector arrangement to create a cross-polar-compensated electromagnetic field in an indoor facility which shows far-field characteristics in close proximity to the reflectors. Serrations are mounted on the reflectors to mitigate diffraction of the waves. The serrations of the main reflector which face the illuminating antenna feed, however, cause diffracted field components. Thus, it is necessary to shadow these serrations with a specially designed absorber cylinder, which is called SERAP (Serration Radiation Protection), in order to prevent the undesired field components from radiating into the quiet zone. In addition, the direct leakage of the feed into the test zone is suppressed by a cylinder covered with absorbers called Baffle. In a detailed simulation model of a CCR the absorber structures have to be considered in order to reflect the physics accurately. Hence, models of the absorber cylinders are developed in FEKO and GRASP. By using the existing reflector models and the Multi-level Fast Multipole Method (MLFMM) in combination with the Surface Equivalence Principle (SEP), a strong correlation between simulation results and probing measurements is shown at lower frequencies.