A Wideband Frequency-Selective Rasorber Based on Interdigital Resonator and Fractal Shaped Slot

A two-layer design which has a wideband transmission window within an ultra-wide absorption band, named as frequency-selective rasorber (FSR), is presented. This structure enables small insertion loss in the wide transmission window, with two absorption bands below and above the passband. The equivalent circuit (EC) is employed to make the design clearer and straightforward. Compared with other FSRs, it has a much wider transmission band with an ultra-wide absorption band and relative low profile. The simulated results exhibit that the insertion loss is less than 3 dB from 9.59 to 12.16 GHz (23.6%), while the frequency for –10dB reflection coefficient ranges from 5.4 to 17GHz (103.6%) with a thickness of 0.106λL (λL is wavelength at the lowest working frequency).