A Low-Profile and Ultrawideband Capacitive Circuit Absorber Empowered by Enlarged Unit Periodicity

In this letter, alow-profile and ultrawideband capacitive circuit absorber with enlarged unit periodicity is developed by using impedance sheet model for
RC
synthesis and grating lobes suppression. The developed absorber achieves a simulated (measured) 10 dB absorption bandwidth ratio of 12.4:1 (12.5:1) at 0.093 λ
_L
, and its unit size is 0.3 × 0.3 × 0.093 λ
_L
³
, where λ
_L
corresponds to the lowest 10 dB absorption frequency. By taking advantage of the enlarged unit periodicity to directly improve realizable capacitance diversity, the developed absorber can be realized conveniently without high dielectric substrate and complex frequency selective surface patterns, which makes it lightweight, cheap, easy to design, and thus, suitable for many low-frequency applications.