Two variants of dual-band antenna systems with a common aperture are considered and compared. The common is that in the both variants there are used: two-reflector system with rotation of polarization plane for exсitation of extremely high frequency band electromagnetic waves and slotted-waveguide array for excitation of microwave frequency band electromagnetic waves. Twist-reflector of extremely high frequency band is combined with aperture of slot-waveguide array. The difference of the proposed variant of antenna system is use of a flat transreflector and a twistreflector, which is a multi-element polarization array and has little effect on the characteristics in the microwave range. The structure of flat transreflector is based on multi-layer zoned Frenel antenna. The both variants of antenna system allow to realize a wide-angle space scanning. Manufacturing of antenna system with flat multi-layer transreflector is greatly simplified with the help of well-developed technology for the production of printed circuit boards. There are presented the results of computer simulation that show the possibility of practical realization of the proposed antenna systems.

The paper considers an embodiment of the antenna design based on a flat non‑axis‑symmetrical transreflector made by using multilayer printed circuit board technology. The construction principle of a flat non‑axis‑symmetrical transreflector by cutting it from the flat polarizing structure is given. The form of the flat multi‑layer non‑axisymmetric transreflector board is determined by the projection of the non‑axisymmetric parabolic transflector onto a plane perpendicular to the focal axis. An electrodynamic model of the antenna with a flat non‑axis‑symmetrical reflector to study the radiation characteristics in the UHF range was constructed. A comparative analysis of the radiation characteristics of antennas on the basis of planar multilayer axisymmetric and flat multilayer non‑axis‑symmetrical transreflectors was performed. A number of technological advantages of the developed flat structure over a non‑axis‑symmetrical parabolic transreflector due to use of the known technology of multilayer printed circuit boards is also described.

Technical solution that allows reduce mutual influence of «waveguide‑slot array antenna/twistreflector» system elements due to the use of a microstrip diffraction grating with rectangular elements as a twistreflector is given. The geometrical dimensions of the elements ae calculated in such a way that the diffraction grating converts a falling linearly polarized field into a field with orthogonal polarization at the working frequency band. Polarization characteristics angular dependence of twistreflector in EHF and radiation characteristics of waveguide‑slot array antenna multi‑element in SHF of investigated system was performed using FDTD method. The possibility of the system functioning in both working frequency range with an insignificant mutual influence is shown. The low level of mutual influence is explained by the significant difference in the resonant frequencies being combined.

A new type of single‑layer transrefleсtor structure based on microstrip reflective antenna array is described. The developed device is a single‑layer printed circuit board on one side of which a system of printed reflectors is located, and on the other is a polarization structure consisting of parallel metal conductors, in contrast to a microstrip reflectarray antenna. The shape and geometrical dimensions of printed reflectors arranged in a rectangular or hexagonal (triangular) pattern are chosen in such a way that they transform a spherical front of an incident vertically polarized electromagnetic wave into a flat front of reflected wave. In the case of irradiation of the developed transreflector with a horizontal polarization wave, the printed structure makes minimal electromagnetic energy loss during its passage. The results of characteristics modeling (including phase curves) of an element of the reflective lattice in the W‑band for different angles of incidence of the wave on the planar structure under study are given. Based on the results obtained, the sizes of the reflective elements of the transreflector, which provide for the correction of the incident wave with the necessary phase discrete, are determined and an electrodynamic model of the transreflector antenna is built. The simulation of the main radiation characteristics of the antenna with the developed single‑layer transreflector was carried out.

Background. Diagnosis of genital prolapse (GP) and stress urinary incontinence (SUI) in women is a complex clinical problem. Aim. To improve the efficiency of diagnosis of cystocele and SUI by using methods of diagnostic radiology. Material and methods. Data of comprehensive examination of 73 female patients suffering from GP and SUI with the help of a modified one-hour pad test and MRI. Results. A positive modified one-hour pad test is a documentary confirmation of minimum volume SUI and an indication for an MRI investigation. If, according to the results of static MRI, there is a damage of the ligaments of the urethra and/or the value of the urethral inclination angle (UIA) is more than 30o, a dynamic MRI needs to be done. At values of UIA over 35o, as revealed by dynamic MRI, cystocele is diagnosed and classified. Conclusions. The modified one-hour pad test confirms and documents the minimum volume SUI. MRI of the pelvis detects and documents all cases of SUI in women with GP, and allows for an objective diagnosis of cystocele as well as its stage.

COMPACT The paper considers design of the dual‑band horn operating in significantly spaced frequencies. In W‑band part of the system represents as a conical horn. In X‑band part of the system represents as distributed aperture microwave feed system based on an improved waveguide tee is described in detail. In the proposed design of the waveguide tee at the junction point of the waveguides, a dual resonant iris is used as a mismatch compensator. This waveguide tee design has a small size, a wide working band and a large variability in matching of horn channels in antenna systems. Waveguide corners with a bend in a wide and narrow wall are also used in each channel to reduce overall dimensions of the radiation system. Two paired pyramidal horns forming a linear antenna array were used to obtain large directivity values and highly expressed directional properties. The numerical simulation of the system under study was carried out by the finite difference method in the time domain. The simulated results of the radiation system main characteristics are given.

The paper presents the results of computer simulation of the developed dual‑frequency antennas with a common radiating aperture, operating in the millimeter and centimeter wavelength range. The operation of antennas in the Kaand W‑bands is based on the well‑known dual reflector polarization rotating antennas constructing principles. The twistreflector of the considered antennas is combined with the radiation surface of the centimeter wavelength range (X‑band) waveguide‑slot array. Transreflector is made by offset scheme. For the Kaand X‑bandsantenna, the transreflector is a paraboloid of rotation part. In the case of the Wand X‑band antenna, the transreflector has a flat Fresnel zoned antenna structure. Computer simulation is based on the method of finite integrals, which provides a reliable result at an appropriately chosen sampling step. The calculated characteristics confirm the operability of the considered antenna options.

The dual-band antenna system design for an onboard dual-channel front-looking radar and its computer simulation results are considered in this paper. The advantages of a two-channel radar with significantly spaced carrier frequencies are briefly described. A dual-band antenna system consists of a centimeter-wave band waveguide-slot array and a millimeter-wave band dual-reflector polarization-rotating antenna. The surface of the scanning millimeter-wave twist-reflector is combined with the radiating surface of the waveguide-slot array. The dielectric edges of the slotted holes in the twist-reflector are metallized to eliminate surface excitation. Dual-reflector antenna of millimeter range is made by offset scheme. Trans-reflector representing a segment of a paraboloid of revolution, has a polarization structure, radio transparent only for the horizontal polarization electromagnetic waves. The dual-band antenna system provides the ability 90-degree angular range scan in azimuth and elevation. Effectiveness of the proposed technical solutions confirmed by computer simulated radiation characteristics.

Results of the densitometrical characteristic of bone structures of vertebral segments are presented in article at 175 patients with cervical osteochondrosis aged from 19 to 76 years were collected a film X-ray, the X-ray computed tomography and the quantitative computed tomography (QCT). By results of the analysis of the obtained data dependence of the mineral density of a bone on features of biomechanics of cervical vertebrae in norm is established and at osteochondrosis.

The work is dedicated to the development of the technological mode gear cutting coupling sleeve with a spatial geometry by running on an existing standard equipment standard cutting tool. The method relies simultaneously changing axial distance between the tool and the billet and the billet message further rotational movement.

In work the main features of gears production on the basis offunction-oriented technologies are considerate. There are classification of gears and their elements based on their functions. Schemes technological actions for the work surface layers of gears, and using these schemes based on vacuum ion-plasma coatings are shown. The device for orientation workpieces and motion of gears in coating is proposed.