Kharkiv National University of Radio Electronics

At present time, a widespread type of antenna systems is represented by wave-guide-slotted antenna arrays (AA) [see, for example, 1–30] which have several ad-vantages over other antenna systems. These AA are characterized by following fea-tures: absence of protruding parts, simple excitation of AA with large number of radiators, and possibility to realize a wide range of amplitude-phase distribution of fields and currents over the AA aperture. This Chapter presents results concerning electrodynamic characteristics of some waveguide-slotted AA obtained by the au-thors.

Let us consider the system, consisting of N of the parallel impedance vibrators, located in free space. We introduce numeration of the vibrators and designate the length and the radius of the vibrator with the number n via $2L_{n}$ and $r_{n}$, correspondingly, and the corresponding coordinates of the vibrator centre in the Cartesian coordinate system—via $z_{n}$, $x_{n}$, $y_{n}$.

This Chapter briefly presents basic equations, boundary conditions and tensor Green’s functions for studying electromagnetic fields, which will be used throughout the book. This chapter with comments on some aspects of electrodynamics theory, will allow a reader to read the book without searching for additional references.

Ultrawideband technologies are growing significantly in the last decades. The efforts were aimed at creating both efficient single impulse antennas, such as IRA (Baum in Radiation of impulse-like transient fields, pp 1–29, 1989 [1]; Baum et al. in Proc IEEE 92:1096–1109, 2004 [2]; Miletic and Olcan in IEEE Trans Antennas Propag 70:6414–6422, 2022 [3]), and antenna arrays. For example, there are MIMO communication systems that need to develop ultra-wideband antenna arrays.

In this Section the dual-frequency antennas based on vibrator-slot structures with similar RP in main polarization planes are suggested. Such antennas can be realized by diode switching the activity of slot and vibrator elements. The traditional combined radiators with passive vibrators are proposed to use at the main frequency. The work at alternative frequency is provided by active vibrators. The formation of radiation fields by the combined structures at the main and alternative frequencies is analyzed.

Let us formulate in the most general form the problem of excitation, scattering and radiation of electromagnetic fields by material bodies of finite size in the presence of the coupling holes between the two electrodynamic volumes. Let there be an arbitrary volume $V_{1}$ bounded by a perfectly conducting, impedance, or partially impedance surface $S_{1}$, some parts of which can be removed to infinity. The volume $V_{1}$ is coupling with another arbitrary volume $V_{2}$ through holes $\Sigma_{n}$ $(n = 1,2 \ldots N)$ cut in the common surface between the two volumes. The boundary wall between the coupling volumes $V_{1}$ and $V_{2}$ has an infinitely small thickness in the region of the coupling holes.

In this Section a problem of impedance synthesis for a 2D antenna arrays consisting of narrow linear slots with magneto-dielectric filling is solved. The slots are cut in a perfectly conducting screen, which geometric centers coincide with nodes of a rectangular grid with double periodicity. The slots are excited by voltage δ-generators in the center of the slot apertures. The slot cavities are represented by rectangular resonators with magneto-dielectric filling which control the induced magnetic impedance of the radiators by varying the material parameters of the slots filling. The problem solution is based on the approach proposed by the authors for the impedance synthesis of vibrator arrays (Chap. 6) and based on the electrodynamic principle of permutation duality (Sect. 1.4.2).

In this Section a new method of impedance synthesis of antenna array radiation fields based on a single methodological conception is presented. At first, an approximate solution for the current in the thin vibrator with variable impedance was obtained using the partial averaging operation of the integral–differential equation.

Rectennas are part of wireless power transmission (WPT) systems and are intended to receive microwave energy and convert it to DC energy. Efficiency of the WTP system is largely determined by the rectenna, which is an unphased array of receiver-rectifier elements (RREs), each of which consists of a receiving antenna and a rectifier circuit. Parameters of RRE mainly determine such indices of rectenna quality as efficiency, level of over-radiation at frequencies of higher harmonics, reliability, cost and suitability for serial production. Today, the optimization of both the parameters of individual RRE and the characteristics of the entire array as a whole remains relevant for the array. Of course, such optimization can be implemented only as a result of mathematical modeling.

Wireless electrochemiluminescence (ECL) device employing the wireless reverse charging function or On-The-Go (OTG) USB transmission function of smartphones is designed. It was coupled with a multi-channel single-electrode electrochemical system based...

We propose a novel sparse array design method to address the problem of the direction of arrival error caused by the difficulty in achieving synchronous optimization of uniform degrees of freedom and mutual coupling effects in existing sparse arrays. Unlike traditional sparse array design methods, the proposed method is based on an array sparse optimization model, with the optimization goal of improving uniform degrees of freedom and reducing mutual coupling. The Grey Wolf Optimizer with adaptive weights is used to optimize the distribution of array sensors under a given array aperture and sensor quantity, and then the designed array is obtained. Compared with existing sparse arrays, the sparse array derived by the proposed method possesses flexible sensor distribution and maintains a higher uniform degree of freedom while significantly reducing mutual coupling effects. Simulation experiments are conducted, and the results show that the designed sparse array performs better in the direction of arrival estimation, verifying the effectiveness of the design.