A Broadband Multilayer Absorber With Switchable Function of Radiation

This article presents a novel dual-functional reconfigurable integrated structure in which p-i-n diodes switch the two operating states. The proposed structure consists of a periodic arrangement of square loops printed on dielectric substrates separated by an air spacer. The lumped resistors and switchable p-i-n diodes are soldered at the center of each of the four arms of the squares on the top and bottom layers, respectively. When p-i-ns are on, the designed structure is considered a high-gain antenna array operating within the absorption band. A wideband absorber covering C- and X-bands is constructed using a multistacked circuit analog (CA) absorption structure when p-i-ns are resistors. Besides, the ray-tracing method and the equivalent circuit model are utilized to analyze the operating principle of the states of radiation and absorption, respectively. Finally, a sample of $4 \times 4$ integrated units is fabricated and measured. Both simulated and experimental results demonstrate the excellent performance of the proposed structure with a peak measured gain of 13.1 dBi at 8.2 GHz and the reflectivity below −10 dB in the frequency range between 4.02 and 13.82 GHz (fractional bandwidth of 109.8%) under normal incidence.