Wideband Reconfigurable Multifunctional Absorber/Reflector With Bandpass/Bandstop Filtering and Band-Notch Absorption for RCS and EMI Shielding

A novel multifunctional frequency selective surface (FSS) based switchable absorber/reflector is demonstrated. The design consists of a resistor-loaded resonating patch, p-i-n diodes loaded inductive grid (IG) printed on different substrates, and a ground plane separated by air spacers. In the diode's
on
state, it works as a wideband absorber from 2.30 to 5.95 GHz [88.48% fractional bandwidth (FBW)], and 3-dB reflector at different air-spacers thicknesses between FSS and IG. It also behaves as a band-notch absorber at 3.5 GHz (sub-6 GHz) and a perfect reflector for a similar configuration in the diode's
off
state. In the absence of the ground and air spacers, it works as a spatial bandpass filter with a 3-dB insertion loss from 5.50 to 7.58 GHz and a bandstop filter with a transmission zero at 4.5 GHz (3-dB return loss with 124.65% FBW) for the
on
and
off
conditions, respectively. The design periodicity is compact (0.068 × 0.068
${\bm{\lambda }}_{\bm{L}}^2$
) and performance is obliquely stable. The authors strongly believe that the proposed design performs multiple operations, such as absorbing, reflecting, and filtering with stable angular performance. The miniaturized architecture makes this design a potential candidate and can be easily integrated for radar cross section, electromagnetic interference shielding, and real-time wireless applications in the Sub-6 GHz range.