This paper demonstrates the development of the analytical method of suppression of radiation pattern (RP) side lobes which is based on Woodward-Lawson method with three basic functions. The considered method allows to suppress the side lobes of the RP in a wide range of angles. It also allows to suppress RP side lobes in a desired direction. This approach can be used in digital antenna systems and the multibeam active phased antenna arrays. In the first part of the paper, linear phased antenna array (LPAA) consisting of isotropic equispaced radiators and methods of suppression of side lobes and creation of the operated minimum in a LPAA radiation pattern are considered. In the second part of the paper partial diagram method is considered. It is shown how to control the RP side lobes in wide range of angles. In the third part of the paper it is shown how to suppress RP side lobes in a desired direction. The fourth part of the paper shows how to synthesize amplitude and phase distribution to control RP side lobes. The method presented in this work allows to reduce the level of the side lobes of the radiation pattern by more than 50 dB in a wide range of angles, or in a given direction. Expressions for calculating the amplitude and phase distributions forming a minimum RP in a given direction are presented. Using LPAA with a given number of emitters, the use of the technique is demonstrated.
A study of the microwave absorbing properties of coatings based on bulk samples of W-type hexaferites is presented. The link between dielectric and magnetic permeability makes it possible to control their magnetic properties by doping the original composition. Hexaferrites are the most stable system, showing a good rate of absorption and reflection of electromagnetic radiation in the microwave range. The substantiation of the choice of material for the manufacture an absorber of electromagnetic radiation and a brief description of the technology of obtaining a composite absorber based on W-type hexaferrite are given. The results of studying the characteristics of reflection and absorption of electromagnetic radiation based on W-type hexaferrite powder in the frequency range 1 MHz –40 GHz are presented. Recommendations are given on the use of the proposed composite material as an absorber of electromagnetic radiation. It is shown that the use of a composite material for shielding and absorbing EMP has great prospects, while the shielding efficiency depends, first of all, on the type of ceramic material.
The results of the influence of Ti4+ + Сo2+ ions on the magnetic properties of ferrites are presented. It is shown that the increase in the content of Со2+ + ions Ti4+ in the structure of spinel ferrites can be controlled to change as the values of magnetic permeability and temperature of the phase transition to the paramagnetic state. Magnetic and dielectric properties of ferrites are closely related to their chemical transformations during synthesis and temperature treatment. Temperature treatment, provides homogenization and formation of ceramic structure. The paper considers ferrite systems as phases of variable composition formed in the process of temperature treatment. Specific examples are given of modern ideas about the physic-chemical nature of the processes of synthesis of ceramics. The obtained samples are characterized by high density, micron size of crystallites, uniform distribution of alloying impurities, chemical homogeneity.
Development of the integration variable selection method for the numerical solution of the Cauchy problem is demonstrated. This method is applicable for the simulation of electromagnetic wave propagation in inhomogeneous media by geometric optics approximation. Usually, in the methods of the numerical solution of the Cauchy problem, the integration is carried out according to one pre-selected variable. This approach does not seem to be the most cost-efficient in terms of computing resources.
The equations of rays and eikonal in finite differences are considered, taking into account the anisotropy of the refractive index. The paper presents a block diagram of the algorithm for choosing the variable of integration. The integration is carried out on the variable selected at the current step, which is assigned the specified step value. The increments of the remaining variables are calculated by expressions depending on the selected integration variable so that the increments on the remaining variables do not exceed the value of the integration variable. The integration variable is selected again and the increments are calculated. This method saves computational resources and minimizes the risk of transition to adjacent phase trajectories. The paper presents a general flowchart of the selection algorithm and expressions for calculating the increments of other variables at each step. The algorithm for calculating increments for each variable is demonstrated. The variable selection algorithm is developed for the case of a 7-dimensional phase space. It includes the projection of the pulse on the three axes of the Cartesian coordinate system, the projection of the coordinate and the phase component. The phase component describes the phase of the wave at the selected point and is analogous to the time dependence.
The results of numerical electrodynamic modeling and experimental research of slotted waveguide radiator is presented. The operational frequency was decreased on 25%. It was found that the differences between the experimental and calculated characteristics are associated with the following factors: the inaccuracy of manufacture of the geometric dimensions of the slotted waveguide radiator, methodical error of the finite element method in calculating the characteristics, inaccuracy of the values of the relative permittivity and magnetic permeability.
The results of the study saturation magnetization and crystallographic anisotropy doped with diamagnetic ions of hexagonal ferrites are presented. It is shown that the impedance matching properties of ferrimagnetic fillers depend on equality values of magnetic and dielectric permittivity composite material in the working wave band. The contribution of the proposed replacement complexes to the magnetic and dielectric permittivity resulting materials is determined. Magnetostatic and electrodynamic properties of composites based on doped hexaferrites type M and Z are studied. Hexagonal ferrites, which play the role of an impedance matching medium in frequency range 0.1-3 GHz, are obtained. Recommendations are offered on the possibility using impedance matching composite hexagonal ferrites in the development filtering and frequency separation systems.
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