Design and electromagnetic wave absorbing properties of foam sandwich structure without reflective layer

For the purpose of electromagnetic requirement without reflective layer, the absorbing properties of sandwich structures were calculated. According to the calculated results, different kinds of absorbing foams were prepared and the electromagnetic properties of foams were characterized. The radar cross section (RCS) of wave absorbing foam sandwich structures was also investigated. The calculated results show that sandwich structure has the optimized broadband absorbing property, when dielectric constant is 2. 3-2. 7 and dielectric loss is 0. 24-0. 26. There is obvious change law for the dielectric constant of foam with carbon black absorber. The electromagnetic property of PMI foam is close to that of the optimized absorbing foam through calculation. The sandwich structure of wave absorbing PMI foam with 8% (mass fraction) carbon black absorber has the optimized broadband stealth performance, which is corresponding to the calculated result. The sandwich structure can achieve electromagnetic wave stealth through wave transmitting in low frequency band and wave absorbing in high frequency band.