Vol 23, No 2 (2020)

The paper considers the influence of a rough surface on the propagation of waves in shielded structures, taking into account the finite conductivity of the metal. A brief overview of the most significant models of such structures is presented and a new calculation method is proposed, which is based on the principle of a gradient model of a rough surface and the concept of partial Brillouin waves. Using the developed method, a simple expression is obtained for the equivalent conductivity of a rough surface, which can be used in well-known formulas for linear losses of various guide structures.

The signal-coded-construction with higher stability of fading is are presented. The base of this construction is sequential (mono-carrier) transmission-method, turbo-trellis-coded-modulation and high specific keying rate. The base-peculiarity of this signal-coded-construction is time-diversity of code-symbols. For decoding the iterative procedure is used. The turbo-decoder consists of two maximum a posteriori decoding, those a priory knowledge through pseudo-random interleaver are exchanges. The probability-performance, those findings by the use of imitation-modeling are presented. These performance confirm the efficiency of introduced method.

The spectrum sensing at the frequencies of «white spaces» is an important feature for cognitive radio networks. The characteristics of detection of licensed primary users by single secondary users will deteriorate under the influence of fading in the radio channels, both in the sensing channels and in the reporting channels of results. Reliable detection of licensed primary users is implemented on the basis of the secondary users cooperative spectrum sensing. The article considers the possibility of constructing the reporting channel based on the scheme of regenerative relaying of «hard» single-bit local solutions in the form of binary phase-shift keying of signals from remote secondary users to a Central Station, which forms a global decision about the result of sensing. The potential value of the gain of the scheme with relay in relation to the scheme with direct transmission and the conditions for optimal placement of the repeater in channels with Rayleigh fades are determined.

Switching of power semiconductor devices in secondary power supplies is the main source of electromagnetic interference. The level of conductive interference must be lowered to meet standards of electromagnetic compatibility. This lowering can be achieved by various methods, including radio interference filters, that are built mainly from inductor coils (chokes) and capacitors. Chokes and capacitors are key elements to design radio interference filters and knowledge of their accurate high-frequency models is required for a wide range of frequencies up to 100 MHz and higher. The article is devoted to development of high-frequency models of capacitors and chokes based on equivalent electric circuits, which parameters are expressed either through electrical-physical values, or through frequency-dependent dielectric permittivity of the dielectric material and magnetic permittivity of the core. Results of modelling are confirmed by impedance measurements of a capacitor with ferroelectric and pyroelectric material used as capacitor’s dielectric and a choke with a core made of nanocrystalline alloy based on GM414 iron. An example of radio interference filter for attenuation of balanced and unbalanced conductive interference is used to consider the negative impact of «spray inductance» of capacitors and «spray capacitance» of chokes.

The paper is devoted to the technique of the forecast models for the integrated circuits of 564 series based on the methods of the theory of pattern recognition. Methods of regression models and discriminant functions were used for the model-building. Analysis of the obtained models was carried out. The optimal threshold values of the discriminant and regression functions were determined. The values of the risk of incorrect decision, producer’s risk (α-risk) and consumer’s risk (β-risk) were estimated.