In this paper, a broadband metamaterial microwave absorber is designed, simulated and measured. Differently from the traditional method which is only based on unit cell boundary conditions, we carried out full-wave finite integration simulations using full-sized configurations. Starting from an elementary unit cell structure, four kinds of coding metamaterial blocks, 2 × 2, 3 × 3, 4 × 4 and 6 × 6 blocks were optimized and then used as building blocks (meta-block) for the construction of numerous 12 × 12 topologies with a realistic size scale. We found the broadband absorption response in the frequency range 16 GHz to 33 GHz, in good agreement with the equivalent medium theory prediction and experimental observation. Considering various applications of metamaterials or metamaterial absorbers in the electromagnetic wave processing, including the radars or satellite communications, requires the frequency in the range up to 40 GHz. Our study could be useful to guide experimental work. Furthermore, compared to the straightforward approach that represents the metamaterials configurations as 12 × 12 matrices of random binary bits (0 and 1), our new approach achieves significant gains in the broadband absorption. Our method also may be applied to the full-sized structures with arbitrary dimensions, and thus provide a useful tool in the design of metamaterials with specific desired frequency ranges.

A simple design of a broadband multifunctional polarization converter using an anisotropic metasurface for X-band application is proposed. The proposed polarization converter consists of a periodic array of the two-corner-cut square patch resonators based on the FR-4 substrate that achieves both cross-polarization and linear-to-circular polarization conversions. The simulated results show that the polarization converter displays the linear cross-polarization conversion in the frequency range from 8 to 12 GHz with the polarization conversion efficiency above 90%. The efficiency is kept higher than 80% with wide incident angle up to 45°. Moreover, the proposed design achieves the linear-to-circular polarization conversion at two frequency bands of 7.42–7.6 GHz and 13–13.56 GHz. A prototype of the proposed polarization converter is fabricated and measured, showing a good agreement between the measured and simulated results. The proposed polarization converter exhibits excellent performances such as simple structure, multifunctional property, and large cost-efficient bandwidth and wide incident angle insensitivity in the linear cross polarization conversion, which can be useful for X-band applications. Furthermore, this structure can be extended to design broadband polarization converters in other frequency bands.

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We investigate theoretically and numerically the tunability of the magnetic property of metamaterial in the THz region via thermal control. One component of the meta-atom is InSb, playing an important role as an alterable metal. When the temperature of the InSb stack increases from 300 to 350 K, the resonance peak of the transmission spectra shows a shift from 0.6 to 0.85 THz accompanied by a stronger magnetic behavior. The S-parameter retrieval method realizes the tunability of the negative permeability achieved in the above heating range.