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This paper includes two new microstrip filter configurations for high frequency and ultra-wideband applications. The first proposed filter is a composition of four parallel open-circuited stubs connected by optimized fractal-structured microstrip line. The filter response is a combination of three passing regions, namely, low pass from 0.1 GHz to 3 GHz, band-pass from 4.5 GHz to 9 GHz, and high pass from 10.5 GHz to 13 GHz, separated by two rejection regions from 3 GHz to 4.5 GHz and 9 GHz to 10.5 GHz. Deep and sharp rejection regions reaching up to -44.6 dB with 40 % fractional bandwidth (FBW) are observed with a good electrical performance. Furthermore, with a comparative table, the advantages of this proposed BSF in terms of FBW, compactness, and insertion loss are compared with recently reported related studies. Secondly, a dual-band band-pass filter implementing a stepped-impedance resonator (SIR) and a modified H-shaped structure is presented. This filter is designed to operate in a low pass region up to 3.58 GHz and a band-pass region from 15.38 to 21.65 GHz, with a wide stopband region between 4.46 and 14.07 GHz. The simulated and measured results are in good agreement. Compared to its peers, the compact size and low price allow for a wide application of these filter configurations, while passing frequencies allow operation in the unlicensed frequency spectrum, which is popular for high-speed communication. [ABSTRACT FROM AUTHOR]

Due to the properties of inverse refraction, the metamaterials can focus the incident wave and can be used as a lens for high directive antennas. For this purpose, in this study, initially, a metamaterial unit cell is designed to exhibit metamaterial feature at 12 GHz and converted into a periodic layer. The reference antenna and the proposed metamaterial layers are simulated and fabricated. It is observed that the directivity of the reference antenna is increased by 2.74 dB with one layer of the proposed metalayer according to the measurement results. Finally, a double lens layer is used and an increase of 4.08 dB is observed. In the literature, the dimensions of metalayers, that is, used to achieve directivity enhancement, are larger than the patch size, but in this study we achieve a significant improvement with metalayers that have almost the same dimensions as the patch. However, the proposed antenna system is more effective than Ku-band antennas in the literature due to its high directivity compared to similar ones. [ABSTRACT FROM AUTHOR]