A Low-Cost Resistive Ink-Based Conformal Microwave Absorber

In this letter, a flexible radar absorbing structure is presented for applications in the lower microwave frequency spectrum (L, S, and C). The unit-cell patterns are printed in a multilayer configuration on thin, flexible FR4 sheets, with spacers used between the layers. Under normal incidence, the 90% absorptivity of the design lies from 1.56 to 7.31 GHz. The structure has an angular stability of 30° for transverse electric (TE) and transverse magnetic (TM) polarizations. Experimental validation of the fabricated prototype confirms the wideband absorption. The performance of the structure is further studied by mounting it on a cylindrical surface. The measured result shows that the absorber exhibits a 90% absorptivity bandwidth from 1.19 to 7.47 GHz, with an angular stability of 45°. The potential applications of the absorber include planar and conformal stealth technology, specifically targeting the low-frequency microwave bands.