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

Abstract

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.

Polarization‐insensitive frequency selective rasorber with broad absorption band and two‐sided transmission bands

“…The proposed FSR is a thin, polarizationinsensitive and exhibits dual transmission property as compared to the reported FSRs. [24][25][26][27][28]…”

“…[21][22][23] The reported FSRs have been classified into different categories depending upon the relative positions of the absorption and transmission bands. This include, the FSRs with lower transmission band relative to the absorption band (T-A FSR), 24 higher transmission band above the absorption band (A-T FSR), 25 transmission band in between two absorption bands (A-T-A) 26,27 and dual absorption and dual transmission bands in an alternate arrangement (A-T-A-T). 28 A FSR designed with meander-line square loop, 24 achieves a low-pass transmission window below 1.5 GHz and broad absorption band at a higher frequency.…”

“…Another polarization-insensitive A-T-A FSR designed using a crossdipole pattern has been reported. 27 The reported FSRs [24][25][26][27] have single transmission bands and thus have limited applications. With the growing use of multi-band radiating systems, the FSR with multiple transmission bands can provide an enhanced performance.…”

Dual‐polarized frequency selective rasorber with broadband absorption and transmission

“…It consists of resistive sheet, dielectric layer and metallic ground plane), the lossless layer almost totally reflects the incident EM wave to perform a metallic ground plane of CAA, and the lossy layer absorbs the incident EM wave 9 . Various 2‐D FSRs have been reported recently, which possess excellent spatial filtering and absorption performances 10–22 . For example, the FSRs with absorption bands located on both sides of the transmission band are presented in Han et al 10–13 But their transmission bandwidth is generally narrow, which will result in wide transition bandwidth between passband and absorption, thus causing rise of reflection in the transition band.…”

“…Various 2‐D FSRs have been reported recently, which possess excellent spatial filtering and absorption performances 10–22 . For example, the FSRs with absorption bands located on both sides of the transmission band are presented in Han et al 10–13 But their transmission bandwidth is generally narrow, which will result in wide transition bandwidth between passband and absorption, thus causing rise of reflection in the transition band. There are also many FSR designs with the absorption band above the passband, 14–16 these FSRs used slot‐type FSSs for passband generation and cascaded CAA structure for absorption implementation.…”