Wide Harmonic-Band Absorbed Frequency Selective Rasorber With Enhanced Angular Stability Based on Equivalent Circuit Synthesis

In this article, we proposed a wide harmonic-band absorbed frequency selective rasorber (FSR) with improved angular stability based on equivalent circuit model. An equivalent circuit model with nonresonant branches is established to synthesize the FSR structure. In addition, the scan compensation theory and step impedance matching technique are introduced to improve the angular stability of the FSR. The wide harmonic-band absorption is realized by a capacitive-resistive model and the transmission is realized by adding nonresonant inductive and capacitive branches. Since all the branches are free of resonant LC characteristics, the circuit model can effectively synthesize the desired FSR over a wide frequency range. The synthesized FSR has a transmission window at 10 GHz, and a wide absorption band with the absorptivity of more than 90% ranges from 18.6 GHz to more than 40 GHz under normal incidence. The transmission and absorption performances can maintain stable within 50° of oblique incidence under both transverse electric (TE) and transverse magnetic (TM) polarizations. The proposed FSR can be used for stealth radar radome and interference suppression of wireless communication system.