Abstract: A radar attenuator panel incorporating reactive elements is provided comprising a composite of electrically semiconductive or reactive layers separated by relatively non-conductive layers with the entire structure bonded together with compatible thremosetting resins. The electrically reactive attenuator layers have a complex admittance wherein the imaginary portion is substantial compared with the real portion. A sheet having a ratio of the imaginary portion to the real portion of complex admittance in the range of 0.7 to 2.0 throughout the frequency range from S-Band through X-Band is provided by impregnating a glass fabric with a phenolic resin having amorphous carbon and aluminum particles dispersed therein. The carbon is preferably present in the range of 9 to 18 parts by weight and the aluminum is preferably present in the range of 5 to 42 parts by weight per 60 parts by weight of resin.