Polarization Insensitive Broadband Frequency Selective Rasorber with Improved Selectivity for Stealth Applications

This article describes a broadband polarization-insensitive Absorption-Transmission-Absorption (A-T-A) rasorber for stealth applications. The proposed structure is a two-tiered structure comprised of one lossy layer with lumped resistors for broadband absorption and one lossless layer for transmission. Under normal incidence, the proposed rasorber has two absorption bands and one transmission band (A-T-A), with the first absorption band being from 4.12 GHz to 7.85 GHz with 62.32% of bandwidth and the second absorption band being from 9.3 GHz to 13.82 GHz with 39.1% of bandwidth. The transmission band spans from 8.08-9.04 GHz with 11% fractional transmission bandwidth with improved selectivity and the lowest IL of 1.64 dB at 8.49 GHz. The measured reflection and transmission coefficients of the structure correspond well with the results of the simulation when fabrication and alignment errors being taken into account.