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• MODELLING AND EXPERIMENTAL RESEARCH OF MICROSTRIP MIMO-ANTENNA SYSTEM’S CHARACTERISTICS

  V.О. Ignatovich , N.N. Kisel

  2026-02-27

  Abstract ▼

  The paper presents the results of a comprehensive study of the characteristics of a microstrip MIMO antenna system intended for application in fifth-generation communication equipment operating within the n79 frequency band (4.4–5.0 GHz). The purpose of the research was to develop a compact 1×2 antenna array on a single dielectric substrate and to evaluate its electrodynamic properties, taking into account factors capable of influencing matching and radiation parameters under real operating conditions.
  The proposed design incorporates two radiating elements, four excitation ports, and a modified ground plane, which provides enhanced functional stability and improved operational characteristics. Numerical modelling demonstrated that the developed antenna system ensures stable standing-wave ratio values, high antenna gain, and consistent radiation patterns across the entire operating frequency band. Particular attention was devoted to assessing the influence of external environmental effects, especially the formation of a thin water film on the radiating surface. The study revealed that the presence of moisture results in an SWR increase of more than 0.5, a decrease in antenna efficiency, and degradation of radiation characteristics at higher frequencies, highlighting the necessity of employing protective structural solutions when operating under humidity-prone conditions. Additionally, the feasibility of replacing copper with an ideal conductor in electromagnetic simulations was examined. The difference in SWR between the realistic and idealized models did not exceed 0.006, confirming that such a simplification may be applied during early design stages without significant loss of accuracy. An experimental prototype of the antenna was fabricated and tested under laboratory conditions. The obtained measurements demonstrated a high degree of agreement with the modelling results, validating the proposed mathematical model and confirming the practical applicability of the developed MIMO antenna system in next-generation communication infrastructures

• BROADBAND DOU BASED ON ROTHMAN'S PRINTED LENS FOR MULTIBEAM ANTENNA ARRAYS

  D.Е. Gubarev, Y.V. Yukhanov

  154-164

  2025-08-01

  Abstract ▼

  The most well-known beamforming device (DOU) (for linear and flat MAR) is the Rothman
  lens, which is of great interest because it allows you to form a fan of MAR rays in a wide spatial
  sector of angles (wide-angle scanning), has a fairly high efficiency and MAR with a lens Rothman
  has a low level of side lobes. Another advantage of the MAR with a Rothman lens is the weak dependence
  of the position of the rays in space on frequency, in contrast to the MAR with a Butler
  matrix DOE, in which, at a high efficiency (theoretically 100%), the position of the rays depends
  on the frequency. However, the previously developed analogs of the Rothman lens are large and
  require additional components in the design, which affects the transmission coefficient of the lens
  in the operating frequency range from 2 GHz to 20 GHz and the consistency of the device with
  other components of the transceiver equipment. It follows that the study and modernization of lens
  structures in relation to multibeam antenna arrays (MAR) is a topical topic for research. The purpose
  of the work is to propose a method for calculating the Rotman lens, modernize the lens design,
  make a lens model and conduct an experimental study of the lens in order to obtain constructive
  methods for optimizing the characteristics of the Rotman lenses for use in MAP in the frequency
  range from 2 GHz to 20 GHz. In the results of the article, the dimensions of the lens, the
  mass of the lens, the transmission coefficient, and the simplicity of the design are estimated in comparison with the previously developed analogues. A technique for calculating the geometry of
  a Rotman lens is proposed, the SWR of a printed Rotman lens is experimentally studied on a vector
  network analyzer, constructive methods are obtained for optimizing the characteristics of Rotman
  lenses for use in multibeam antenna arrays. A model of a broadband Rotman lens in microstrip
  design with a maximum SWR of 1.3 (S21) in the operating frequency range from 2 to 20 GHz was
  made, the lens size was 150x100, and the lens weight was 0.4 kg. According to these parameters,
  the Rothman lens surpasses the analogues developed earlier