http://radioelektronika.org/issue/feedRadioelectronics and Communications Systems2017-09-22T02:23:26+03:00Fedor Dubrovkafedor.dubrovka@gmail.comOpen Journal Systems<p>Radioelectronics and Communications Systems, ISSN 1934-8061 (Online), ISSN 0735-2727 (Print) is a monthly peer-reviewed international scientific journal on electrical engineering, electronic engineering, and electronics. It is English version of the journal <strong>Izvestiya Vysshikh Uchebnykh Zavedenii. Radioelektronika</strong>, ISSN 2307-6011 (Online), ISSN 0021-3470 (Print). The journal is indexed in SCOPUS, INSPEC, Google Scholar, Academic OneFile, EI-Compendex, Gale, OCLC, SCImago, Summon by Serial Solutions, VINITI, RSCI. <strong>Сites per Doc. = 0.3</strong> (Cites per Doc. (2y) = Impact Factor WoS, 2016). <strong>SJR = 0.2, Q3, SNIP = 0.46</strong> (Scopus, 2016).</p>radiocurrenthttps://feedburner.google.comhttp://radioelektronika.org/article/view/S0735272717090011Varicap-tuned narrowband filters with extended rejection band based on U-shaped microstrip resonators2017-09-22T02:23:13+03:00Alexander V. Zakharovazakharov@bk.ruMykhailo Ye. Ilchenkoazakharov@bk.ruA resonance equation for the first unwanted resonant frequency of tunable microwave U-shaped loop-type resonator with variable capacitance has been derived. This frequency does not depend on the variable capacitance value; it is invariable and proportional to λ-type oscillations. The ascertained feature makes it possible to determine the ratio of the first unwanted resonant frequency to the frequency of the main resonance and control the rejection bandwidth of tunable filters with U-shaped resonators. A narrowband (2%) varicap-tuned filter with extended rejection band has been built and its experimental data are presented. The experimental four-resonator filter could be tuned in the frequency range 225–400 MHz. The filter rejection band in terms of the attenuation level of –40 dB was located in the frequency range 420–1290 MHz, i.e., <em>f</em><sub>max</sub>/<em>f</em><sub>min</sub> = 3.07. Varicap-tuned filters with microstrip U-shaped resonators are shown to have a good potential for their practical use.<img src="http://feeds.feedburner.com/~r/radiocurrent/~4/R3X3HfVdhbQ" height="1" width="1" alt=""/>2017-09-21T00:00:00+03:00Copyright (c) 2017 Radioelectronics and Communications Systemshttp://radioelektronika.org/article/view/S0735272717090011http://radioelektronika.org/article/view/S0735272717090023Polarized X-band Doppler radar scatterometer for investigation of microwave scattering of the wavy water surface in laboratory conditions2017-09-22T02:23:15+03:00V. I. Abramovvicabr@mail.ruE. M. Zuikovazuikova@hydro.appl.sci-nnov.ruD. A. Sergeevdaniil@hydro.appl.sci-nnov.ruYu. I. Troitskayayuliya@hydro.appl.sci-nnov.ruA. V. Ermoshkineav@hydro.appl.sci-nnov.ruV. I. Kazakovkazakov@hydro.appl.sci-nnov.ruThe paper describes an experimental model of continuous wave X-band Doppler radar scatterometer (sine frequency modulation) designed for physics investigation of radio waves scattering from sea surface in controlled conditions. The prototype is developed and fabricated at the IAP RAS. Its main feature is adaptation to the conditions of a laboratory modeling in the wind-wave flumes to investigate the dependence of the normalized radar cross-section (NRCS) on the wind speed. The design of the microwave and antenna systems allows measurement of scattered radiation power and its Doppler spectrum both at linear co- and cross-polarizations (in a sequential switching mode). This is important from the viewpoint of studying the waves at high wind speeds. The detailed description of the design and its specifications are presented. Also the problems of calibration and results of experimental operation on the high-speed wind-wave flume of IAP RAS are discussed.<img src="http://feeds.feedburner.com/~r/radiocurrent/~4/dtL372OUZoU" height="1" width="1" alt=""/>2017-09-21T00:00:00+03:00Copyright (c) 2017 Radioelectronics and Communications Systemshttp://radioelektronika.org/article/view/S0735272717090023http://radioelektronika.org/article/view/S0735272717090035Radiation sensitive detector based on field-effect transistors2017-09-22T02:23:21+03:00I. М. Vikulinphysonat@gmail.comV. E. Gorbachevphysonat@gmail.comА. А. Nazarenkophysonat@gmail.comThe possibility of developing radiation detectors based on field-effect transistors (FET) is investigated. Transistor saturation current is chosen as an informative parameter for modeling. Experimental results show that the drain saturation current of the FET with <em>p-n</em> junction as a gate is decreasing after irradiation. In metal-oxide-semiconductor (MOS) FETs during radiation-induced defect formation two effects are competing, therefore the result of radiation influence is highly dependent on the electro-physical properties of transistors before irradiation and on the absorbed radiation dose. It is shown that saturation current increases with absorbed radiation dose for all the transistors with low electron concentration in a channel above certain levels of absorbed radiation. While the opposite effect is observed for high electron concentration in a channel, i.e. the saturation current drops. Obtained dependences of the drain saturation current of FET on the irradiation dose facilitated development of simple detector design for low levels of radiation. The bridge circuit is used in the radiation sensor to minimize the effect of temperature fluctuations. The sensitivity of the detector is enhanced several times with the help of two pairs of FETs with the opposite sign of radiation sensitivity.<img src="http://feeds.feedburner.com/~r/radiocurrent/~4/3hKbL1sZNSA" height="1" width="1" alt=""/>2017-09-21T00:00:00+03:00Copyright (c) 2017 Radioelectronics and Communications Systemshttp://radioelektronika.org/article/view/S0735272717090035http://radioelektronika.org/article/view/S0735272717090047Analysis of electrocardiosignals for formation of the diagnostic features of post-traumatic myocardial dystrophy2017-09-22T02:23:23+03:00N. G. Ivanushkinan.ivanushkina@gmail.comK. О. Ivankokoondoo@gmail.comYe. S. Karplyukkoondoo@gmail.comО. V. Chesnokovaolga4ec@yandex.uaI. А. Chaikovskiyillya.chaikovsky@gmail.comS. V. Sofienkoillya.chaikovsky@gmail.comG. V. Mjasnikovillya.chaikovsky@gmail.comThe possibilities of high-resolution electrocardiography (HR ECG) application for diagnostics of post-traumatic myocardial dystrophy having multifactorial genesis is considered in this paper. Numerical processing and analysis of electrocardiograms that belong to patients from armed forces after explosive-driven injuries have been performed based on clinical studies. Complex method of cardiosignal analysis based on combination of wavelet analysis, eigenvector decomposition and principal component analysis is developed. This method revealed that low-amplitude deviations in ECG signal in case of post-traumatic myocardial dystrophy have low-frequency nature that is linked to slow electro-physiological processes. It is shown that these low-frequency, low-amplitude components appear at a high levels (8th and 9th) of decomposition in case of 9-level wavelet decomposition of averaged cardio cycles. Integral parameters for identification of post-traumatic myocardial dystrophy features are suggested and determined on the basis of principal component analysis. These parameters are squared sum of signal projections to eigenspaces <em>H<sub>k</sub></em> and mean eigenvalues of covariance matrices of electrocardiosignals ensembles λ<sub>mean</sub>.<img src="http://feeds.feedburner.com/~r/radiocurrent/~4/9WxUp5SxPso" height="1" width="1" alt=""/>2017-09-21T00:00:00+03:00Copyright (c) 2017 Radioelectronics and Communications Systemshttp://radioelektronika.org/article/view/S0735272717090047http://radioelektronika.org/article/view/S0735272717090059Design of a negative conductance dielectric resonator oscillator for X-band applications2017-09-22T02:23:25+03:00Seyi Stephen Olokedesolokede@gmail.comSyasana Basyirah Zakisyazanabasyirah@yahoo.comNor Muzlifah Mahyuddinsolokede@gmail.comMohd Fadzil Aineemfadzil@usm.myZainal Arifin Ahmadsizainal@usm.my<p>An X-band tunable microwave low-phase noise planar oscillator employing a novel-fed dielectric resonator (DR) with a single transistor has been investigated and realized. A ZrSnTi oxide composite ceramic-based DR with dielectric permittivity of 95 enclosed in a metallic cavity with an unloaded Q factor of 5,000 at 10 GHz is proposed. The resonant frequency affinity with respect to geometric parameters is established by using the compensation technique based on dual negative conductance feedback, the outputs of which are combined via a Wilkinson power divider (WPD). The feedback parallel-coupled DR oscillator is incorporated into a laminate microwave board using the photolithographic technique. The oscillator includes a pseudomorphic low noise amplifier based on a high-electron-mobility transistor. Hence, the proposed oscillator with mechanic tuning is measured, and the results show that DR resonates at TE01d mode with frequency of 10 GHz. The measured phase noise of the oscillator is –81.03 dBc/Hz at a 100 kHz offset.</p><img src="http://feeds.feedburner.com/~r/radiocurrent/~4/lkgAb4vhfmM" height="1" width="1" alt=""/>2017-09-21T23:29:00+03:00Copyright (c) 2017 Radioelectronics and Communications Systemshttp://radioelektronika.org/article/view/S0735272717090059