# 2005

**Project “BUKSIR-2”**

The new configurations of FSSs that provide simultaneous narrow-band reflection of the plane wave at one or several frequencies are proposed. They are made of metal strips with the periodical sets of single (or multiplet) rectangular slots. Kirilenko A.O., Mospan L.P.

The exact 2D model of the phenomenon that describes the slow-wave to volumetric wave conversion has been created. The main properties of corresponding leaky-wave antennas are investigated in dependence on geometrical parameters. Kirilenko A.O., Steshenko S.A.

**INTAS **

The created mathematical model has allowed synthesizing a composite double-choke type flange units in rectangular waveguides with essential gaps between flanges at saving the low level of microwave radiation. They are the DC(direct current)-breaks with improved characteristics for different types of particle accelerators. Kirilenko A.O, Tkachenko V.I.

**CRDF **

The software for analysis, synthesis and optimization of double-band circular-polarization antennas has been created. Such antennas consist of septum polarizer, polarization corrector and corrugated horn. Kirilenko A.A., Tkachenko V.I., Rud L.A., Perov A.O.

# 2006

**Project “Buksir 2”**

The novel constructions of (ТЕ10 to ТЕq0, q<19) mode convertors have been designed. They can be used at the development of microwave units for summation (division) of the microwave power. A simple geometry dealing with ТЕ60-mode of rectangular waveguide is exploited now at Drugkovka’s faience factory for uniform distribution of microwave heating energy. The ТЕ10-ТЕ30- converter supplied with matching transformer to desired cross-section has been designed for prof. K. Mizunu laboratory (Japan) to add the powers of microwave oscillators. Rud L.A., Tkachenko V.I., Kirilenko A.A.

The development of mathematical models and corresponding software for the waveguides with arbitrary smooth boundaries and the fragments of them has been completed. Don N.G., Kirilenko A.A.

The novel configuration of the band-stop iris in circular waveguide that provides the narrow-band reflection at single or several frequencies has been proposed. The peculiarity of such an iris consists in the usage of the arc=shaped slots that allows to improve their properties in the view of breakdown resistance 5-8 times. Don N.G., Kirilenko A.A., Mospan L.P.

# 2007

**Project “Buksir 3**

The “enhanced transmission phenomenon” of the waveguide dominant mode total transmission through the iris having a below-cutoff hole has been found. Such an effect is manifested at a frequency near cutoff of the first higher mode exciting at given symmetry and is associated with excitation of the plane-junction eigen oscillation (“aperture eigenoscillation”). This phenomenon extends essentialy the set of in the waveguides and has to be included into classical ones. N.G.Don, A.A.Kirilenko

# 2008

**Research project “Buksir-3”**

For the first time, original electromagnetic explanation for the total transmission through the set of below cut-off openings was proposed. The explanation is based on the excitation of high-quality eigen oscillations of the junction plane between a perforated metallic screen and a free space. Basing on proposed explanation, new topologies of grating, providing the total transmission through the set of below cut-off openings were proposed. The resonant frequency of the grating is less significantly than known grating’ operating frequency А.А.Kirilenko, А.О.Perov.

# 2009

**Research project “Buksir-3”**

The existence of eigen oscillations with the real eigen frequencies (i.e, without radiation losses) is proven for the waveguide or doubly periodic nanostructures (theoretically even of zero volume). For example, it was proven for a thin wire with a step connecting the waveguide walls and for a plane grating of conductors with periodic steps. The respective resonance frequency is characterized by total reflection of a waveguide mode or a plane wave from the structure. It can be placed in any position of a wide band of the single-mode frequency range. For the first time the objects of ultra-small volume were demonstrated that has the oscillations with Q-factor limited only by ohmic losses. These oscillations are not related to any symmetry of the object or to the proximity to any critical point. They owe their existence only by the geometry of the selected planar waveguide object or the planar doubly periodic grating. Applied significance of the result is the ability to create new types of filters and frequency-selective structures with very narrow pass band, photonic crystals based on the appropriate nanostructures, virtually single-mode open resonators, and the super Q open resonators based on the superconducting nano-gratings. S.A. Prikolotin, A.A. Kirilenko

# 2010

**Research project “Buksir-3”**

The effect of “enhanced transition” of electromagnetic waves through small holes of a grating with regular defect was revealed. It observed at significantly lower frequencies in comparison with the already known effect for the regular structures. The resonance in the “old” frequency point is preserved. On this basis the double-band metamaterials, whose properties are based on the effect of “enhanced transition,” can be constructed.

If the holes of the grating are comparable with the wavelength and have their own resonance, then the defect in the geometry of a periodic cell results in the resonance of total reflection between two pass bands. This effect opens the way for the introduction of attenuation poles in the characteristics of spatial frequency- or angular-selective filters to improve their selectivity. A.O. Perov, A.A. Kirilenko.

The “electrodynamic” nature of the phenomenon of “optical activity” was clarified for metamaterials formed by a grating of periodically arranged plane-chiral objects and dielectric layers, or arrays of objects with rotational symmetry of the fourth order. It was found that the structural reason of the effect consists in the desymmetrization of the object in the longitudinal direction and in its transformation from a “planar-chiral” to 3-D-chiral with characteristic for “optical activity” rotation of the plane of polarization. As it turned out, the internal mechanism consists in the presence of the higher backward waves between the layers of the structure. They generate the cross-polarized field, while the planar-chiral layer cannot generate it by itself. N.G. Kolmakova (Don), A.A. Kirilenko, S.L. Prosvirnin (Institute of Radio Astronomy.)

# 2011

**Research project “Buksir-3”**

The generalized approach for solution of the vector boundary value problems in the waveguides with piecewise coordinate boundaries was built, implemented, debugged and verified on a wide variety of practical and fundamental problems. The essential advance is the account of the electromagnetic field behavior on the edges, which dramatically improves the performance of numerical algorithms and greatly expands the range of their application in the analysis of problems of propagation and diffraction of waves and the problems of eigen oscillations and waves in the configurationally complex systems. A.A. Kirilenko, S.O. Steshenko, S.A. Prikolotin, L.A. Rud.

The properties of the near-field enhancement and sub-wavelength focusing by the single- and multilayered gratings of silver nanospheres were investigated in the optical wavelength range. It has been shown that the frequencies of the pronounced phenomena correspond to flat zones of the dispersion curves for the modes polarized orthogonally to the grating. S.O. Steshenko.

The eigen oscillations of a pair of tightly coupled silver nanospheres were considered based on the approximate dipole model. It was shown that this structure can support the longitudinal and transverse, symmetric and antisymmetric oscillations. The relative positions of these four eigen frequencies were described. S.A. Steshenko.

It has been found that the asymmetric waveguide-dielectric insert can greatly absorb the energy of the fundamental wave from one arm and strongly reflect it from another one at the resonant frequency. Maximum absorption occurs when the sum of the coupling coefficients of the resonators with the supply waveguides is equal to one. A physical interpretation of the mechanism of resonant absorption was suggested based on the study of field diffraction. Such an effect can be expected in optics in the problems of excitation of the dielectric layers with periodic gratings. L.A. Rud.

**Research project “Grіd-ІRE” (project director is P.N. Melezhik) **

Adaptation of the system of electrodynamic modeling to distributed computing environment.t D.Y. Kulik.

# 2012

**SRW “BUKSIR- 4”**

The new principle to build-up metamaterial structures providing a “huge” optical activity is found and explored. It is based on alternation С4-symmetrical plain chiral irises with different chirality signs. From the electromagnetic point of view, it is based on close interaction of the components with specific a spatial spectrum. As an example plain chiral irises in a square wave guide are considered to show the application of this principle for build-up of the newest microwave devices for the polarization plane rotation of the electromagnetic wave. It allows essentially (by orders) reduce the longitudinal sizes of such devices for ultrahigh frequencie technique and offer new types of metamaterials. Kirilenko A.A., Don Н.Г., Perov A.O.

**SRW “Radiator” **

Development of the basic building blocks of the three-band radiator for a radio telescope antenna is carried out. Among them: septum polarizers for Ка-band with circular waveguide out, phase rotators for the Х-band in coaxial a waveguide, corners, rotational displacements, and another ones. The set of the five septum polarizers and corrugated horns for measuring and testing in the five frequency bands is designed as well. Kirilenko A.A., Steshenko S.A., Perov A.O., Rud L.A.

**SRW “GLOESS” (under the order of Ukraine State committee on questions of a science, innovations and information, as a part of the design “Dnepr” with France) **

The methods and algorithms of global optimization were the object of research, namely: genetic algorithm (GA) and algorithm on the basis of swarm particle method (SPM), being the most popular tools of electromagnetic synthesis. In addition to development and verification of the algorithms in actual practical problems, the procedure of parameter adaptation is designed for the goal of optimum allocation of efforts on global and local searches. Some schemes of coding of physical problem properties for diminution of its dimensions and computing complexity are offered. Combination opportunities of various global and local algorithms for search under various requirements (such as criterion function, such as variable, etc.) are investigated. The hybrid algorithm on basis GA, capable to optimization of functions with many local extremes. Boriskin А., Galan A.Yu., Prikolotin S.A. is designed.

# 2013

**SRW «BUKSIR-4»**

The simulation system MWD 2 based on numerical- analytical methods, is substantially extended with a package of algorithms for calculation of the plane junctions and the mode spectrums in waveguides with piecewise-smooth cross-section in cylindrical coordinate system. Steshenko S.A., Prikolotin S.A.Kirilenko А.О, Rud L.A., Senkevich S.L., Kulik D.Yu.

The new dihedral D4 (2) symmetry eigenoscillations of the open waveguide resonators are found, which are responsible for a rotation of the polarization plane by plane-chiral waveguide structures or two dimensional gratings. Their existence is based on nearfields, that has allowed implement a new polarization plane rotator with the considerable decrease of the longitudinal sizes in comparison with existing devices. The result has separate value for main principle explanation and developing of the metamaterials with a huge optical activity. Кolmakova N., Prikolotin S.A., Perov A.A., Kirilenko A.A., Derkach V.N.

The original construction of reflective waveguide init is realized, which provides simultaneous transmission on a given frequency and the complete locking of the waveguide transmission line on the other frequency. The unit represents a piece rectangular waveguide with a pair metal rods of the unequal height in the waveguide cross-section. Kirilenko A.A., Mospan L.P.

**SRW «RADIATOR»
(« Development of the cooled three-band radiator with partitioning circular polarizations », the Contract № To 20/12 is made with ПАО ” Research-and-production enterprise ” Saturn “. Kiev (II Stage)) **

In the framework of the project it is designed three-band (S- X- Ka-band) coaxial radiator for radio telescopes compatible with international design VLBI2010 (radio interferometers with superlong basis). Steshenko S.A., Perov A.O., Prikolotin S.A., Kirilenko A.A.,Rud, L.А., Kulik D.Yu.

# 2014

**SWR “BUKSIR- 4”**

The zones of the eigenfrequency coincidence for dihedral eigenoscilations are revealed. The later are shaped in the vicinity of the conjugate chiral metasurfaces. That provides wide bands of “optical activity”, and for the scattering problems generates 5-10 % bands of the transparence with polarization plane rotation on the arbitrary angle. A.Kirilenko, A.A.Perov, N.Kolmakova (Don)

The actual opportunity for polarization plane rotation through the fixed angles is discovered. It is realized on the base of two and four-element chiral irises providing the matching in a frequency band, middle frequency control, and high stability of the rotation angle in the frequency band. D.Yu.Kulik, A.A.Kirilenko.

Algorithms of S-matrix recalculation for waveguides and Floquet chanels rotated relatively to base element are implemented, which accelerates calculations in some times. (A.Perov, S.L.Senkevich).

Algorithms for eigenmode calculations in waveguides with cylindrical coordinate boundaries are created, which includes analysis mirror symmetry planes. Their realization within the framework of electrodynamic modeling system MWD-3 has considerably increased efficiency of calculations. S.A.Steshenko, S.Prikolotin.

The realization of the MWD-4 system has started, that will wide an application of the numerical – analytical algorithms on the waveguides with particular dielectric filling. S.A.Steshenko, S.Prikolotin.

The spectral theory of the open waveguide resonators is applied for resonant property investigation of the traversal rod waveguide sections. Physical mechanisms of formation of resonances of the complete reflection are revealed. It is shown, that the estimation of their quantity indicators is better on the order than for well-known ones. L.P.Mospan

Within the framework of competitive SWR « the Multifrequency radiator inside cryogenic focal blocks for reflective-type antenna of the new generation VLBI2010-network radio telescopes: synthesis, designing, experiment» (« Target complex program of NASU on scientific space investigations on 2012-2016 » (В33) (the Code SPACE. К.) ):

– the geometry configuration S / X / Ka the radiator inside cryogenic focal block is proposed. V.Skresanov, A.A.Kirilenko;

– the computer codes for calculation three-band (S / X / Ka) antenna, which have to be used in multistage optimization are prepared, numerically implemented and verified. S.A.Steshenko, A.A.Perov, S.A.Prikolotin;

– the algorithms of eigenmode and eigenvector search for two-layer circular or coaxial waveguides, which will be used at examination and designing of coaxial antennas with the dielectric lens are analytically formulated and numerically implemented. S.A.Steshenko, A.A.Perov, S.A.Prikolotin.

# 2015

**Scientific research project “BOOKSIR-4”**

An analytical explanation is given to the phenomenon of “optical activity” in the metamaterial structures based on conjugate waveguide diaphragms or periodic screens. The theory of groups and the spectral theory have been applied in order to reveal a relation between the regimes of the total transformation of the incident wave and the excitation of a special class of dihedral eigenmodes due to the spatial symmetry of the structures under consideration. (Perov A.O., Kirilenko A.A.)

By using a pair of conjugated screens, joint manifestation of two properties of metamaterials, namely “extraordinary transmission” and “optical activity” was found theoretically and experimentally confirmed (Perov A.O., Kirilenko A.A. Derkach V.N.)

It is proved that the cutting an additional centered hole in the composite two-layered four-slot diaphragm as a rotator of the plane of polarization, allows us to dose the ratio of the copolarized and the cross-polarized components of the electromagnetic field in a passband. It improves the matching characteristics and / or reduces the frequency dispersion of the angle of rotation of the plane of polarization essentially (Kulik D.Yu.)

An algorithm for calculating the planar junction of a circular waveguide that surrounds arbitrary waveguide with coordinate boundaries in a Cartesian coordinate system was developed, implemented and verified. (Steshenko S.A., Prikolotin S.A. Kirilenko A.A.)

An algorithm for searching the eigenmodes of a circular two-layer waveguide is developed, that makes it possible to use a uniform representation of the modes in the entire range of transverse wave numbers. Algorithms for calculating the planar junction of such a waveguide with a round, coaxial or other circular two-layer waveguides have been developed, implemented and verified (Steshenko S.A., Prikolotin S.A.)

To explain all the features of a frequency response, a complete spectral portrait of a rectangular waveguide section with rectangular posts of different symmetry and topology was established. (Mospan L.P.)

The full spectrum of natural waves of a periodic comb was studied at various dimensions and wavelength proportions. On this basis, a relationship was established between the directivity pattern of a waveguide opening with a finite corrugated flange and the modes of a comb. Operating regimes of the antenna were studied and described. (Steshenko S.A., Boriskin A.V., Kirilenko A.A.)

# 2016

**Scientific research project “Start-4”**

**Scientific research project “Buxir-3”**

The phenomenon of a transmission of the electromagnetic waves through a cut-off hole grating accompanied by the simultaneous rotation of the polarization plane up to the orthogonal one was revealed and experimentally confirmed in the microwave range (A.Kyrylenko, V.Derkach, A.Perov).

New designs of the dihedral cells allowing a rotation of the polarization plane for arbitrary angle and having satisfactory reflection characteristics in a given frequency band (A.Kyrylenko, D.Kulyk) were proposed.

On the example of a rectangular waveguide section with rectangular posts, the possibility of a complex quasi-elliptic frequency response due to the involvement of higher modes in the process of electromagnetic interaction (L.P.Mospan) was investigated.

# 2017

**Scientific research project “START- 4”**

The boundary value problems were formulated to describe the propagation and scattering of waves of different polarization in 2D periodic gratings, taking into account the exact boundary conditions on the ideally conducting elements and the conditions of quasi-periodicity on the boundary of the cell. Appropriate algorithms for automated partitioning of the elementary cell of 2D periodic grating consisting of the metal elements into a set of partial regions were developed. Each partial region allows separating the variables in the boundary-value problems describing the propagation and the scattering of waves on the gratings of the type under consideration. The algorithms are implemented in the MWD modeling system. The results allow conducting electromagnetic analysis as single grating with complex structure of the period, as well as complex multilayer gratings with dielectric filling. The study of the polarization dependencies of the perforated screens, depending on the layout of the periodic cell and the relative arrangement of the screens, was carried out. A theoretical and experimental study of the transformation of electromagnetic fields in polarization rotators and polarization transformers of complex cross-sections was carried out. The structure of the fields of appropriate natural proper oscillations in the corresponding resonators was investigated and its conformity to the resonance phenomena was established. The investigated devices are original and can be widely used in angular- and frequency-selective units of antenna-feeding circuits in a wide frequency range up to subTHz one (A.P.Kirilenko, D.Yu.Kulik, L.P.Mospan, A.O.Perov, S.A.Steshenko).

The rigorous solution to the problem of scattering of a wave falling on a half-infinite periodic lattice, and the solution of the problem of scattering a plane wave on a semi-finite system of ribbon lattices are the most significant results. The obtained result makes possible the simulation of complex combs and waveguide devices with a super-order period, has a world scientific level of significance and has no analogues. (S.O.Steşhenko)

**Scientific research project “Vetka”( project leader O. M. Kuleshov. IRE NAS of Ukraine)**

The effective algorithm for calculation of three-dimensional electromagnetic system of a clinotron hardly demanded in the terahertz frequency range as a power supply was developed

The clinotron electromagnetic system is a complex combination of a number of waveguide components, including T-junctions in the irregular cross section waveguides and 3D comb.

Integration of appropriate program modules into the system of electromagnetic modeling of the clinotron resonators was carried out. The result is the possibility of to perform a fundamental research, in particular modeling of the power characteristics of a clinotron in a “hot” (electron beam) regime and optimization of its electromagnetic system to improve its output characteristics. (S.O.Steshenko, L.P.Mospan)

Scientific research project (HF OTR-II) (project leader GI Khlopov. IRE NAS of Ukraine)

The numerical simulation of the frequency selective screen was made in order to reduce the reflection of the external information sensor in the low frequency part of the microwave range and to reduce the loss in the millimeter range. Numerical simulations of a mm range diplexer were performed to ensure the joint operation of the active and passive channels of the external information sensor on the common antenna. The calculations were performed using the MWD software developed in the department (now laboratory) of computational electromagnetics. The algorithms integrated in MWD software allow carrying out the numerical simulation and optimization of microwave devices with given output characteristics. (A.O.Kirilenko, D.Yu.Kulik, L.P.Mospan, S.O.Steşhenko)