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In this paper, an electrically small tunable microstrip bandpass filter with two concurrently tuned transmission zeros (TZs) is presented. The filter consists of two coupled resonators and varactors as tuning elements. An application of a multipath coupling network results in TZs on both sides of the passband. The filter controlled by a single voltage has a wide tuning range from 370 MHz to 800 MHz and a low insertion loss ranging from 1.9 dB to 3.4 dB. To achieve high attenuation in the stopband, two sections of the designed filter were cascaded. Both one-section and two-section filters were validated by measurements. The obtained results are in a very good agreement with simulations.

Shielding of instruments and humans from electromagnetic interference (EMI) has become increasingly important during the last decades due to more and more machines and devices radiating electromagnetic waves. While several applications can use rigid shields, more flexibility is enabled by developing bendable, drapable, ideally even stretchable EMI shielding. Textile fabrics can have these properties, combined with potentially good mechanical properties, depending on the textile structure and the chosen material. On the other hand, the necessary physical properties, especially conductivity and magnetic properties, cannot be taken for granted in normal textile fabrics. These properties have to be added by conductive yarn or layer coatings, integration of conductive or magnetic fibers, producing intrinsically conductive or magnetic fibers, etc. The article gives a critical comparison of the properties of materials typically used for this purpose, such as intrinsically conductive polymers, metal-coated fabrics and metal wires, MXene coatings, MXene fibers, carbon coatings, and fibers. The review concentrates on thematically suitable papers found in the Web of Science and Google Scholar from the last five years and shows that especially MXenes are highly investigated recently due to their high conductivity and EMI shielding effectiveness, while other conductive and magnetic coatings and fibers are nevertheless still interesting for the preparation of EMI shielding textile fabrics.

SnO 2 nanocrystalline thin films have been deposited on oxidized silicon substrates by spin-coating from a precursor solution, followed by slow thermal annealing in oxygen atmosphere at different temperatures (500 to 900°C). The precursor solution consisted of 1.0 to 2.0 M SnCl 4 ·5H 2 O in isopropanol. It was shown that the concentration of the precursor solution, annealing temperature and heating rate had a significant effect on the structural, optical and electrical properties of the studied thin films. The topography of SnO 2 thin films was examined by scanning electron microscopy (SEM). Furthermore, as-deposited films were characterized by X-ray diffraction (XRD), UV-Vis and impedance spectroscopy.

This article presents a novel compact widely tunable bandpass filter. The filter consists of two resonators that are double-coupled, inductively, where the coupling inductances are elements of the input and output networks. The application of double-coupling enabled the transmission zero next to the upper cutoff frequency. This makes the filter useful for applications in preselector networks used in receiving systems with a low to intermediate frequency with the desired channel frequency lower than the image channel frequency. The article shows the practical realisation of the varactor-tuned example filter fabricated as a microstrip planar network of an overall size of 0.03λg × 0.045λg. The tuning range of the proposed filter is from 410 MHz to 880 MHz with the fractional bandwidth equal to 7.5–8.1% and an in-band insertion loss better than −3.4 dB. The achieved IP3 value exceeds 17.5 dBm.

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In this study, a method to identify the impedance of the sample composed of Sn02 nanowires (NWs) has been presented. The studied sensor structures were based on one dimensional (ID) Sn02 NWs grown by thermal deposition on silicon substrate. The topography of Sn02 NWs was investigated by means of scanning electron microscopy (SEM).The results of qualitative and quantitative analysis in selected micro region have been presented. Furthermore, the electrical properties of the NWs were measured. The base of the measurement comprised impedance spectroscopy, Pade data approximation restrained by passivity condition. This study demonstrates that it is possible to separate the characteristic parameters for various transport phenomena in the NW. R EFERENCES[1] A. Gurlo, "Nanosensors: towards morphological control of gas sensing activity. Sn02, In203, Zno and W03 case studies," Nanoscale, 3,2011, pp. 154-165.