A new implementation of a beam-steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard-wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase-shifts, can be assembled in a prescribed spatial phase-modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full-wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 × 10-element 1-bit beam-steering transmitarray is presented and its performance benchmarked against the conventional single-panel, i.e., unibody, counterpart. Prototypes of the tiled and single-panel C-band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth-generation (5G) communication systems.

The paper presents a reconfigurable linear polarized transmitarray unit cell design with 1-bit phase quantization for C-band applications. The unit-cell structure consists of two square ring patches of reduced size, which are connected using a coupling element. Incorporating p-i-n diodes inside the coupling element allows controlling the current flow direction in the antennas and providing a 180° phase difference. An analysis of the unit-cell insertion loss contributed by small-size antennas and coupling between them is discussed. The p-i-n diode parasitic parameters are taken into consideration of the unit cell performance simulation. It was shown that the insertion loss caused by the p-i-n diodes parasitic parameters can be reduced. The original biasing circuitry providing p-i-n diodes control voltage is proposed. Simulation results of the reconfigurable unit cell are validated by measurements in a waveguide. As a result of measurements, the insertion loss is −2.3 dB at 5.9 GHz, the reflection coefficient module is less than −20 dB, the phase difference error does not exceed ± 1° in the passband, while 3-dB bandwidth corresponds to 180 MHz (3.4%).

Electromagnetic (EM) wave propagation inside and along the surface of the human body is the subject of active research in the field of biomedical applications of microwaves. This research area is the basis for wireless monitoring of biological object parameters and characteristics. Solutions to the following problems are crucial for achieving the stated goals in the area of wireless monitoring: EM wave propagation inside and on-body surface. The biological object monitoring is based on a consideration of the following problems: (i) dielectric properties of a biological issue; (ii) EM wave propagation in biological medium; (iii) propagation of EM waves across the boundary of two media (biological medium–air): wave reflection and refraction; (iv) EM wave propagation in a multilayer biological medium; (v) EM wave propagation along the plane or curved surface of biological objects.

Introduction. Due to the increasing number of users, growing rates of data transmission, and rapid advancement of the Internet of Things, the parameter of channel capacity is acquiring greater importance in modern communication systems. In wireless communication systems, capacity limitation occurs due to a low signal-to-noise ratio, one reason for which consists in high losses associated with the propagation of electromagnetic waves. These losses can be compensated using high-gain antenna systems, such as metasurfaces, transmitarrays, or reflectarrays.Aim. Development and research of a one-bit transmit phased antenna array with spatial excitation for use in wireless communication networks across sub-6 GHz frequencies. The issues of reducing the insertion losses associated with the cell geometry and control components are discussed. Account is taken of the parasitic parameters of p–i–ndiodes used as control elements for phase adjustment in a unit cell. Methods for suppressing cross-polarization in a unit cell with the purpose of reducing insertion losses are studied.Materials and methods. The characteristics of unit cells in a transmit antenna array were studied by numerical electrodynamic modeling in the CST Microwave Studio computer-aided design system. The obtained results were confirmed by an experimental study of samples.Results. A unique design of a unit cell comprising the main element of a transmitarray was proposed. On its basis, a transmitarray was designed and manufactured, whose measurements proved the level of insertion losses to be lower than 1.5 dB in the operating frequency band of 210 MHz (3.6 %). The level of cross-polarization was found to be lower than 24 dB, and the gain attenuation did not exceed 2.5 dB in the range of beam deflection from 45° to -45°.Conclusion. The design simplicity, low losses, and acceptable cross-polarization levels of the developed one-bit transmit phased antenna array with spatial excitation confirm its feasibility for modern communication systems.