A polarization-insensitive broadband rasorber with in-band transmission response

In this letter, a polarization-insensitive broadband rasorber structure with in-band transmission response has been presented. The proposed structure comprises a periodic arrangement of convoluted cross-dipole pattern in the top layer and square slot geometry in the bottom layer. Lumped resistors are symmetrically mounted across the top pattern to result in wideband absorption, whereas in-band transmission is obtained by careful design of the square slot in the bottom layer. The overall structure exhibits a broad absorption band (having reflection coefficient below -10 dB) in the range of 2.18 to 9.80 GHz, and the transmission band appears at 6 GHz with an insertion loss of 0.56 dB. The novelty of the proposed design lies in its compact topology, polarization-insensitivity, angular stability, and in-band transmission response unlike the existing rasorber structures. Surface current distribution, equivalent circuit model, and several parametric variations have also been illustrated for in-depth analysis. A sample prototype has been fabricated and the measured results show a good agreement with the simulated responses, under normal as well as oblique incidence.