Design and Experimental Demonstration of Non-Foster Active Absorber

This paper presents a non-Foster active absorber with ultrawideband and extremely low profile, which can effectively break the Rozanov limit for passive absorbers. The design concept is explained using transmission line theory and the matching process is interpreted by plotting field distributions. To facilitate the design and optimization of the active absorber, a cosimulation method and simple guidelines are proposed. Measured results show that the absorber can achieve a wide bandwidth with at least -10 dB reflectivity from 150 to 900 MHz and its thickness is only 1/100 lambda(0) at the lowest operating frequency. This is the first experimental demonstration of the non-Foster active absorber.