The paper proposes a theoretical model of self-oscillators based on resonant tunneling diodes. Numerical modeling of the synchronization band of the oscillator was carried out on its basis. The effect of spreading resistance and resonator inductance on the synchronization band is analyzed. It is shown that at a low quality factor, as well as taking into account the nonlinearity of the capacitance and auto-bias, the frequency characteristics of the self-oscillator will be asymmetric and the instability regions of synchronous stationary oscillations will have a complex shape.

Keywords: theoretical model, numerical simulation, quality factor of an oscillatory system, synchronization bandwidth, capacitance nonlinearity, auto-bias, frequency characteristics, instability region, spreading resistance, resonator inductance

In this work, a theoretical determination of the transfer coefficient of millimeter-wave mixers based on resonant tunneling diodes is carried out. The analysis of the conditions for optimizing the transmission coefficient of microwave mixers using resonant tunneling diodes as nonlinear elements is carried out. The optimal constant voltage is determined, at which the amplitude of the local oscillator, required to obtain the maximum transfer coefficient of the mixer, will have the smallest value, and the coefficient itself will be the largest.

Keywords: gain, mixer, millimeter wave, frequency conversion, local oscillator amplitude, modified Bessel functions, stability factor, resonant frequency, bandwidth

In this work, R, L, C - parameters of spiral structures with sizes l and S were determined to obtain artificial chiral substrates. This made it possible, given the parameters of the polarizability of the helical structures αij, to use these features to determine the conducting properties of metamaterials. The basic relationships have been determined (for determining the electrophysical parameters of spirals (left- and right-handed) that are included as chiral inclusions in the metamaterial. An algorithm for calculating conducting structures using the proposed equations is proposed.

Keywords: biological liquid medium, dielectric constant, complex dielectric constant, loss tangent, medium conductivity, frequency response, fluctuation, frequency range, biophysical parameter

In the work, a microwave balanced mixer based on transmission line combinations has been designed and investigated. Two developed layouts of balanced mixers on boards of different dielectric materials are investigated. The results of measuring the parameters of the mixers showed results that are better than those of mixers built according to traditional schemes on microstrip lines.

Keywords: balanced mixer, combination of transmission lines, hybrid device, electric circuit, ring bridge, quarter-wave open loop, conversion loss, dielectric, microstrip line, slot line

The work investigated the behavior of volumetric electrical conductivity (and its components) of various biological liquid media in order to determine the possibility of influencing the processes of life. In the frequency range 0-50 GHz, the following biological liquid media were studied: cold-pressed sunflower oil; sunflower oil obtained using heat treatment; fresh egg yolk and protein; Bacillus amyloliquifaciens bacteria; bacteria Escherichia coli MG1655 pXen-lux. The presence of fluctuations in the dielectric permittivity parameters, the unevenness of the frequency characteristics, in the range of 35-37 GHz, the “bursts” of values ​​characteristic of the resonance nature of this dependence were observed on the frequency characteristics of the loss angle tangents.

Keywords: biological liquid medium, dielectric constant, complex dielectric constant, loss tangent, medium conductivity, frequency response, fluctuation, frequency range, biophysical parameter

The paper considers methods of taking into account the energy dependence of the effective mass of hot carriers in the volume of semiconductors of the AIIIBV type for three different cases of dispersion. The classical deviation of the dispersion from the quadratic law, the Kane deviation of the dispersion from the quadratic law and the dependence m (W), connected with the two-valley representation of semiconductors of the AIIIBV type, are analyzed. Energy dependences of the normalized effective mass for the main valley, lateral valley, and total energy are calculated, taking into account the intervalley transition and also the energy dependences of the normalized effective mass calculated by the equations. An estimation of the effect of an external electric field on the average carrier energy taking into account different dispersion mechanisms is made.

Keywords: dispersion characteristic, effective mass, quadratic law, Keynes deviation of dispersion, effect of "weighting" of electrons, energy dependencies, heating effects

The characteristics of amplifiers on resonant-tunnel diodes (RTDs) are analyzed using the method of approximation to them and operating at frequencies close to resonant. It was revealed that the nonlinear and resonant properties of the amplifier on the RTD are related and determined from each other; the nonlinearity of the current-voltage characteristics of the RTD imparts a resonant curve to the form that usually occurs in the case of nonlinear reactivity. It is established that for large signals it is necessary to take into account the frequency dependence, which will complicate the course of the resonance curves. In this question, the most complete equivalent RTD scheme without simplifications.

Keywords: amplifier on resonant-tunnel diodes, equivalent circuit, amplitude-frequency characteristic, instability region, oscillatory characteristic, regeneration parameter

The effect of auto-displacement in a resonant-tunnel diode (RTD) on the dynamic range of amplifiers on these diodes is considered. Taking into account autosplacement, two possible types of amplitude characteristics and boundaries of their existence were revealed. For these two types of amplitude characteristics, expressions were obtained that determine the dynamic range of the amplifier. When using the amplitude characteristic of the first type, the auto-shift expands the region of existence of this amplitude characteristic and leads to a decrease in the dynamic range. For amplitude characteristics of the second type, a certain expansion of the dynamic range can be achieved.

Keywords: a resonance-tunnel diode, a current-voltage characteristic of a diode, a dynamic range, a gain factor, the degree of regeneration, and the power supply mode of an amplifier for an RTD.