Theoretical study of tunable tripling octave frequency to ultra-wideband low-profile metastructure absorber based on brick splicing method

• The bricks splicing method is used. • Tripling octave frequency absorption is obtained. • The column resonators increase the resonance. • The profile of theabsorber is breaking the Rozanov limit. Designing low-profile absorbers with octave frequency characteristics in the microwave range remains challenging, particularly in the L-band and lower frequency ranges. A tunable tripling octave frequency metastructure absorber (TOFA) is proposed to overcome this challenge. TOFA can be converted into an ultra-wideband metastructure absorber (UWA) through a novel brick splicing (BS) method. As the brick structures are inserted, the operating state is TOFA, and the absorption bandwidths are 0.71–6.06 GHz and 8.99–12.49 GHz. The tripling octave frequency absorption bandwidths are 3.00–4.16 GHz and 8.99–12.49 GHz. Notably, the profile of the designed TOFA is only 0.041 times the maximum absorption wavelength, breaking the Rozanov limit. As the brick structures are pulled out, TOFA can convert to UWA, and the UWA’s absorption bandwidth is 2.5–20 GHz. When the brick structures are inserted, the UWA can convert to TOFA. Finally, the radar cross section (RCS) reduction capabilities of both UWA and TOFA are investigated, and it is found that both structures exhibit excellent RCS reduction. According to these properties, the TOFA can be used in signal encryption, intelligent stealth technology, and spectral analysis. Additionally, the BS method introduced a novel approach for the design of multifunctional metastructures.