Design of Compact, Broadband Polarization Insensitive Dual-Circular Circuit Analog Absorber for X, Ku and Ka-Band Applications

Int. J. Microw. Wireless Technol.

2022

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In this study, a compact modified circular ring-based circuit analog absorber (CAA) is proposed. It comprises a resistor-loaded frequency selective surface (FSS) underneath an FR-4 substrate, and the other end is terminated with a perfect electric conductor (PEC) separated by an air-spacer. The proposed design shows a minimum −10 dB reflectance from 10.55 to 36.03 GHz (25.48 GHz bandwidth and 109.4% fractional bandwidth) with two dips at 13.5 GHz and 35.23 GHz having reflectivity −17.18 dB and −24.9 dB, respectively. The existing four-fold circular symmetry architecture shows insensitivity for different polarization angles under normal incidences and up to 45° stability for Transverse Electric (TE) and Transverse Magnetic (TM) modes under oblique incidences. The proposed cell is compact with a periodicity of 0.193λL, and a thickness of 0.09λL, where λL is the free-space wavelength corresponding to the lowest frequency of the absorption band. The novelty of the design lies in the topology of using an underneath FSS to take advantage of effective permittivity control for both broader bandwidth and better angular stability. To demonstrate the ability of the proposed design, a 28 GHz microstrip patch antenna prototype is fabricated, and its radar cross section (RCS) is measured after loading with the absorber. A 15.15 dBsm RCS reduction is observed in comparison with the PEC. The authors strongly believe that the proposed design has potential applications such as RCS reduction and radio-frequency energy harvesting.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A novel modified circular ring-based broadband polarization-insensitive angular stable circuit analog absorber (CAA) for RCS applications

Int. J. Microw. Wireless Technol.

2022

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“…In addition, metamaterial enabled structures for various absorption mechanisms are also proposed 5–7 . A simple electric field‐driven LC resonator for near‐unity microwave absorption is demonstrated in Landy et al 8 Different absorbers for triple, 9 quad and multi‐bands 9–13 have been reported from microwave to optical regimes 14 . However, the high Q‐factor of resonator‐based architecture is limiting its usage in real‐time.…”

Section: Introductionmentioning

confidence: 99%

Compact, broadband, wide angular stable circuit analog absorber at sub‐6 GHz for radar cross section reduction

Micro & Optical Tech Letters

2021

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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.

“…20 In CAAs, the non-zero reactive part of the impedance adjusts resonant frequencies for uniform absorption. 21 A single-layered dual octagonal loop CAA loaded with eight lumped resistors for X and Ku-band (having 73.68% fractional bandwidth [FBW] and 20 angular stability) is illustrated in Li et al 22 Ghosh et al proposed a multilayer squared array CAA with 12 lumped resistors loaded on the unit cell, exhibiting broadband absorption from 4.96 to 18.22 GHz with 114% fractional bandwidth. 23 Lumped resistors with vias have also been used in many designs for wide angular stability under TM oblique incidence and broader bandwidth.…”

mentioning

confidence: 99%

Broadband polarization insensitive wide angular stable dual‐split square ring circuit analog absorber for radar cross section and electromagnetic interference shielding applications

Int J RF Mic Comp-Aid Eng

Koul

2022

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This work presents a simple broadband polarization-insensitive circuit analog absorber (CAA) with wide angular stability. It comprises of dual-cut square loop resonator loaded with eight lumped resistors as top patch and an inductive grid. The normal incidence reveals a 90% absorption bandwidth of 20.51 GHz (110% fractional bandwidth) covering the entire X to K-band with a minimum flat absorption rate of 92.82%. Equivalent circuit analysis is carried out, and responses are validated with full-wave simulations. The proposed prototype is insensitive to different polarization angles under normal incidence and stable with 45 in transverse electric (TE) and transverse magnetic (TM) incidences. The design's novelty lies in using two resistors on each side of the square ring, which improves the absorptivity performance. The inductive grid enhances TM mode's angular stability. The proposed absorber is fabricated, and the measured results are in good agreement. In-band bistatic radar cross section reduction of 12.97 dBsm is obtained with the absorber using an X-band antenna. The temperature profile of the prototype is illustrated using near-in-lock infrared thermography, and 2.1 F of temperature rise is noticed in the absorption band. The proposed structure possesses a low profile, broad bandwidth, polarization insensitivity, and wide angular stability to the best of the author's knowledge.absorber, broadband, IR imaging, lumped resistor, radar cross section | INTRODUCTIONElectromagnetic (EM) wave absorption has gained significance in applications like RF energy harvesting, photodetectors, micro-bolometers, biological image sensing, EM shielding, and radar cross section (RCS) reduction in stealth technology. 1 Salisbury screen was the first traditional microwave absorber, 2 consisting of a flat resistive sheet coated on a λ g =4 ground dielectric spacer. Dependence of effective impedance on substrate thickness confines Salisbury screen to a narrow band. Jaumann absorber, 3 where stacking of different resistive on λ g =4 spacers was proposed for uniform absorption over a wideband. However, the physical size of the Jaumann screen is limiting its usage. Earlier, the EM wave absorption were also focused on pyramidal foam absorbers, carbon