We report on the design, fabrication, and measurement of a triple-band absorber enhanced from a planar two-dimensional artificial metamaterial transmission line (TL) concept. Unlike previous multiband absorbers, this implementation incorporates fractal geometry into the artificial TL framework. As a consequence of the formed large LC values, the utilized element is compact in size, which approaches λ 0 /15 at the lowest fundamental resonant frequency. For independent control and design, a theoretical characterization based on a circuit model analysis (TL theory) is performed and a set of design procedures is also derived. Both numerical and experimental results have validated three strong absorption peaks across the S, C, and X bands, respectively, which are attributable to a series of self-resonances induced in the specific localized area. The absorber features near-unity absorption for a wide range of incident angles and polarization states and a great degree of design flexibility by manipulating the LC values in a straightforward way.

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A novel miniaturized microstrip bandpass filter (BPF) has been proposed by using coupled simplified composite right/left-handed (SCRLH) zeroth-order resonators (ZORs). The SCRLH ZOR consists of microstrip high/low-impedance short-line elements, grounded stub, and transmission line sections. Being one of the artificial metamaterials, the SCRLH ZOR resonates when the phase constant equals to zero. Compared with the conventional half-wavelength resonator, the superiority of the proposed ZOR mainly lies in its compact size. In addition, it is easy to tune the zeroth-order resonant frequency, thanks to its simple structure and easy fabrication. In this article, the performance and design of the novel ZOR is first studied in detail. Then, the ZOR is exploited to devise a three-order Chebyshev coupled microstrip BPF. Different coupling schemes are adopted, including interdigital capacitor coupling for the interstages and aperture-backed dual-finger parallel-coupled line structures at the terminals, thus, the specified coupling strengths can be conveniently satisfied. Finally, a prototype device filter operative at S-band is provided to illustrate the proposed techniques. Salient feature of the size reduction of the novel filter is achieved (more than 70%) when compared to a conventional structure.ABSTRACT: A novel design of a compact bandpass ring slot filter for achieving dual-mode operation is proposed and experimentally studied. By using an arrow-shaped slot structure as a resonator, the resonant frequency of the proposed filter is significantly lowered, which can lead to a large filter size reduction for a fixed frequency operation. Two degenerate modes are achieved by loading with proper asymmetry, which can be placed at the corner of diagonals. A prototype of the proposed design is implemented and measured. From the measured results, the proposed filter has about 5.2% bandwidth at the center frequency of 0.97 GHz and a minimum insertion loss of 1.07 dB within passband.