Ultrawideband Frequency-Selective Absorber Designed With an Adjustable and Highly Selective Notch

In this article, the working mechanism of a wideband absorber designed with an adjustable and highly selective notch band is studied, in which narrow independently controlled by lower lossless layer absorber, whereas upper lossy loaded lumped resistors realizes absorption. We present two instances geometrically electrically bands, respectively. Without decreasing absorption performance, position can be flexibly adjusted throughout entire frequency simply modifying dimension frequency-selective surface (FSS) or changing capacitance varactor, i.e., using geometric control electrical control. The allows wide bands to retained on both sides; therefore, good stealth performance still guaranteed. Equivalent circuit models (ECMs) are proposed further explain principle. frequency-domain simulation, ECM, time-domain experimental results agreement validate adjustability high selectivity notched absorbers. At end FSA-backed monopole antenna simulated measured, clearly illustrates that these FSAs serve as ground plane for antennas realize out-of-band RCS reduction.