Measurement of the radiation efficiency of complex structures

This paper investigates the measurement of the radiation efficiency of complex structures with two constructions: metallic (flat and stiffened aluminum panels) and sandwich composite (honeycomb core). Two measurement methods are compared. The first is direct and is based on the simultaneous measurement of the vibration and acoustic response of the freely hanged structure in an anechoic room. The second is indirect and uses a statistical energy analysis (SEA) based model of the test article freely hanged in a reverberant room. For the latter two implementations are compared. The first is based on the SEA formulation, when only the test article is excited. The second is an inverse technique based on the SEA formulation, when both the test article and the reverberant room are excited. All methods are compared to analytical or numerical predictions. Results show that the experimental radiations efficiencies are in good agreement with theory for the studied constructions, especially when the inverse SEA method is used.