In this work, broadband linear to cross and circular to circular polarization converter for K and Ka-band applications is proposed. The metasurface comprises a novel H-shaped unit cell printed on 1.2 mm thin FR-4 grounded dielectric substrate. It exhibits 90% polarization conversion ratio (PCR) over a bandwidth of 22.26 GHz (17.97-40.23 GHz) with 76.5% FBW maintaining a minimal PCR of 92.5%. The converter also maintains handedness for circularly polarized incident wave. Surface current distributions at different resonant frequencies are analyzed to illustrate the reason behind the broadband behavior.The converter design is simple with the cell periodicity of 0.209λ o and thickness of 0.071λ o , where λ o is the free-space wavelength corresponding to the lowest frequency of the band. Monostatic and Bistatic RCS analysis of the designed converter is performed, demonstrating greater than 10 dBsm RCS reduction over all the frequency range. It shows 16 to 30 dBsm at resonant
This paper presents a new compact ultra-thin triple-band absorber which shows near-unity absorption in C, X and Ku-bands. It consists of an inductive stub loaded circular ring resonator and a flower-shaped resonating patch on top of 0.8 mm thin FR-4 grounded dielectric substrate. A transmission line equivalent is proposed, and circuit simulation response is in good agreement with the full-wave analysis. The unit-cell architect's 4fold symmetry makes it polarisation-insensitive for different polarisation angles in the azimuthal plane (? = 0 ) under normal incidence. Its good shows angular stability up to 45 under TE (75 under TM) incidences for all three frequencies. Surface current patterns are analysed at resonant frequencies to illustrate the mechanism behind the electromagnetic absorption. This design's novelty lies in the centre patch's dual-resonating behaviour, making this design compacted one. The absorber has low-profile nature with cell periodicity of 0.163λ L and thickness 0.013λ L , where λ L is the lowest resonating peak wavelength. An X-band conventional MSA is fabricated on a thin FR-4 substrate. In-band RCS reduction (nearly 18 dBsm) of the antenna is verified after loading with the proposed absorber. The absorptivity peaks are optimised such that the same structure would be used in different applications like RF energy harvesting, RCS reduction and sensor applications.
This work presents a compact broadband wide angular stable polarization‐insensitive circuit analog absorber at sub 6 GHz. It shows almost 95% absorption from 2.26 to 5.76 GHz over the entire operating range. A transmission line equivalent circuit is modeled, and the response is validated. The design is obliquely stable up to 45° for both transverse electric and transverse magnetic incidences. The analysis of surface current distributions at two resonant frequencies confirming magnetic resonances' role in near‐unity absorption. It is compact with a periodicity of 0.1 λL and thickness of 0.08 λL. Finally, bistatic radar cross section reduction of the proposed absorber attached with an antenna is measured.
A novel broadband linear‐circular and linear‐cross polarization converter for K to Ka‐band applications is demonstrated in this work. The proposed structure primarily consists of an inductive grid in orthogonal with an H‐shaped dipole as top Frequency Selective Surface (FSS) and a modified horizontal dipole as bottom FSS; a 1 mm thin FR‐4 substrate is separating both. During transmission, it can convert the linearly polarized EM wave to a circular one, with Axial Ratio (AR) ≤ 3 dB from 13.08 to 25.13 GHz with 63.07% Fractional Bandwidth (FBW). In addition, this polarizer can work in reflection mode also when the bottom FSS is replaced by a Perfect Electrical Conductor (PEC), demonstrating the linear‐circular polarization with AR (≤3 dB) from 16.94 to 18.64 GHz (RHCP/LHCP) and 24.5–40.32 GHz (LHCP/RHCP) with FBW 9.56% (Ku‐band), and 48.81% (K‐ and Ka‐band), respectively. Besides, linear‐circular conversion, it performs linear‐cross conversion in reflection mode with polarization conversion ratio (PCR) above 90% from 19.71–22.22 GHz, 43.57–48.81 GHz, 53.50–55.32 GHz with 13.89%, 11.34%, 3.32%, FBW, respectively. The equivalent circuit model of the proposed converter is extracted. Surface current distribution profiles at multiple plasmonic resonances are investigated to understand the reason behind the multi‐polarization conversion. The performance is angular stable up to 45° for both transverse electric (TE) and transverse magnetic (TM) incidences for reflection as well as transmission modes. The unitcell is compact with periodicity 0.114λL × 0.114λL and a thickness of 0.044λL, where λL is the free‐space wavelength of the lowest frequency. This design's novelty lies in dual‐mode stable angular performance in both reflection and transmission cases. Also, highly miniaturized architecture and circular rotation switching in the consecutive bands make this design suitable for real‐time scenarios.
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