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This study introduces a new broadband hybrid perfect absorber (HA) that includes metamaterial absorber (MA) and a lossy composite. The unit cell of the MA is in the form of two concentric ring-based structures fabricated on an FR4 substrate, which provides a broadband absorption band because of two neighbouring resonance frequencies. The composite layer is built by mixing the carbon black powder and epoxy resin in an optimised weight percentage. By modelling the structure with multiple transmission line sections, a closed-form procedure has been proposed to optimise the HA parameters. The final tuning of the HA parameters is performed using HFSS. A prototype of the HA is fabricated and measured. The results indicate that the proposed HA provides nearly perfect absorption (absorption ratio over 99%) in the frequency range of 2–2.8 GHz. It is, also, polarisation-insensitive due to its symmetrical design. The total thickness of the proposed structure is 12.5 mm, which is acceptable concerning the absorption rate and the operational frequency bandwidth. [ABSTRACT FROM AUTHOR]

This article introduces a recursive formula, in which any approximate method can, iteratively, be incorporated to solve electromagnetic scattering problems. The use of extended Born approximation and quasi-analytical approximation in this formula results in two series (algorithms), whose convergence properties are discussed. Numerical examples are given to demonstrate merits and the range of applicability of the new series. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2425–2429, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22781 [ABSTRACT FROM AUTHOR]