Vol 64, No 4 (2019)

A method of solving problems of calculating transfer characteristics of smooth junctions between two out-of-line screened waveguides having different cross-sections is suggested. The method results in the collocation algebraization of integral equations based on the Lorentz lemma.

The antenna characteristics of a hemispherical Luneburg lens with a flat screen on the lens side opposite to the position of the feed are studied. The hemispherical geometry of the lens allows the lens to be effectively used in the scan mode. In the scan mode of the antenna, it is possible to choose the shape and parameters of the radiation pattern depending on the position of the feed.

Formation of multibeam directional patterns in active phased antenna arrays (APAAs) with the known analog-digital signal control at the emitters is considered. Numerical simulation is used to study dynamics of interference of partial directional patterns (DPs) that leads to distortions and angular shift of the maxima and effects related to amplitude modulation of the emitter signals. A method to decrease the level of the DP side lobes using a system that forms intersecting subapertures in which a step of the digital-level subarray is less than the step of the analog-level subarray is proposed. Effect of peak correction of signal amplitudes at the emitters on the partial DPs of the multibeam APAA is studied.

Loss factor of supercooled pore water is studied at frequencies of 60–140 GHz at temperatures of down to –70°C using silica gel. It is shown that, with disregard of the effect of monomolecular nonfreezing layer of bound water, the loss factor of pore water in the silicate material is determined by the Debye relaxation of water corresponding to the properties of bulk water, additional loss in a temperature interval centered at ‒45°C owing to the effect of the second critical point of water, and the surface conduction at the interface due to the formation of ferroelectric ice 0 provided that the freezing point of water in pores is lower than ‒23°C. The experimental results can be used in the problems of radiation transfer in aerosols and porous wetted finely dispersed media.

A method for the formation of measurements of the angular coordinates of two closely spaced point targets by four independent receivers located at the same distance from each other is proposed. It is shown that the target angles are determined by the fixed points of some linear fractional transformation and can be found by solving a quadratic equation with complex coefficients. A method for calculating the accuracy of measuring the angular coordinates and a criterion for target resolution are substantiated. Results of numerical analysis on a model example are given. The method is designed for measuring the angular coordinates of two closely spaced targets and the elevation angle of a low-flying target against the background of the underlying surface (marine or terrestrial), as well as for measuring the coordinates of the target under the conditions of active interference.

A feasible design of a system with an allowed band with near-unity frequency-independent transmission utilizing the reflective properties of photonic crystals with dielectric filling and resonant irises in a setup with a Y-circulator is demonstrated. The existence of impurity modes of oscillation damping in the allowed band of this photonic crystal with disturbed periodicity is confirmed. Bandstop filters with parameters controlled by n–i–p–i–n diodes are constructed based on photonic crystals with resonant irises. These filters have a rejection level of >43.0 dB in the stop band and losses below 0.8 dB outside of it.

In this paper, we describe a method for restoring reflector motion using a radio-wave signal from a super high frequency (SHF) autodyne generator based on a Gunn diode. The proposed method consists in sequential emission and reception of an electromagnetic SHF signal reflected from an object using two channels that differ in electrical length providing the π/2-phase shift of interference signals. With this method, there is no ambiguity in determining the amplitude of reflector movement and no need to determine the initial phase of the detected signal.

The possibility of nonpulsed electron beam transport in a nonBrillouin magnetic field using a special forming electrode system has been investigated. Relativistic and nonrelativistic velocities are discussed.

Microstrip band-pass filters (BPFs) containing quarter-wavelength resonators and a Π-shaped half-wavelength resonator placed next to each other along the same line have been analyzed. These filters have more various frequency characteristics from the use of a Π-shaped half-wavelength resonator and spurious magnetic cross-talk coupling. The possibility of describing these filters using a coupling matrix is considered. The results of the simulation and measurement of the frequency characteristics of three microstrip BPFs with a central frequency of 2 GHz have been presented.