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• SHAPING OF CONTOURED-BEAM ANTENNA MAIN LOBE BY PROFILING OF REFLECTOR ANTENNA

  К.М. Zanin, D.D. Gabrielyan, Y.V. Kuznetsov, S.Е. Mishenko

  2024-10-08

  Abstract ▼

  In satellite communication complexes, it is required to ensure a given level of the gain of the space
  antenna in a given serviced area. A lower level of gain beyond this area is also required. The boundary of
  the coverage area may have a complex shape that does not change during the operation of the communication
  system. To meet these requirements, reflector antennas with a profiled reflector are used. The law
  of profiling the reflector surface is described by smooth analytical functions. However, when forming a
  contour lobe with a more complex shape, the required phase distribution may have discontinuities during
  the transition through the period 2π. These gaps cannot be eliminated by smooth functions without distortion.
  In this case, the known approaches to profiling reflectors of reflector antennas do not allow obtaining
  a radiation pattern with a given quality. The goal of the work was constructing a reflector of a reflector
  antenna, which provides the formation of a radiation pattern with specified parameters. To achieve
  this goal, the following tasks have been solved: 1. Development of an algorithm for profiling the reflector
  of a reflector antenna, taking into account the shape of the boundary of the serviced area and taking into
  account the given law of distribution of the gain; 2. Conducting numerical simulations on the construction
  of the reflector profile. In the course of the research, an algorithm has been developed that allows you to
  obtain the reflector profile of a reflector antenna. This reflector antenna generates a field distribution at
  the aperture corresponding to the radiation pattern with the required parameters. To do this, the calculation
  of the field distribution on the plane was performed, and the surface of the reflector was synthesized
  based on the calculation results. Numerical simulations have confirmed the possibility of constructing a
  reflector antenna that forms a radiation pattern with specified parameters.

• INFLUENCE OF FREQUENCY NOISE IN A COMMUNICATION CHANNEL ON THE PROBABILITY OF A BIT ERROR DURING TRANSMISSION OF SIGNALS

  I. А. Alferova, О. А. Safaryan, D.D. Gabrielyan, B.K. Kulbikayan, L.N. Stazharova

  2023-06-07

  Abstract ▼

  The purpose of the article is to analyze the combined effect of amplitude white Gaussian noise
  (AWGN) present in the communication channel and frequency noise (FN) resulting from fluctuations in
  the frequency of the signal in the communication channel on the probability of bit error when processing
  QAM signals. Research tasks to be solved: 1. Development of a mathematical model for processing the
  QAM signal, taking into account the combined effects of AWGN and FN in the communication channel.
  2. Numerical study of the combined effect of AWGN and FN on the probability of bit error when processing
  QAM signals. A mathematical model is proposed that establishes the relationship between the
  signal-to-noise ratio in the channel and the mean square deviation of the signal frequency, on the one
  hand, and the probability of bit error during A mathematical model is proposed that establishes the
  relationship between the signal-to-noise ratio in the channel and the mean square deviation of the signal
  frequency, on the one hand, and the probability of bit error during QAM signal demodulation, on the
  other. The visualization of the effects associated with the presence of AWGN and FN in the channel on
  the signal constellation of the received QAM signal is given. The main patterns associated with joint
  action AWGN and FN in the communication channel are: - the appearance of FN in the communication
  channel leads to a decrease in the signal level in the channel during the correlation processing of the
  received signal and a corresponding decrease in SNR; - In addition to the blurring of the signal constellation
  in the azimuthal direction, associated with the appearance of an integral phase fluctuation due to
  frequency fluctuations during the pulse, an increase in the blurring of the signal constellation in the
  radial direction causes a decrease in the SNR. Based on the results obtained, it is concluded that it is
  necessary to take into account more fully the deviations of the signal parameters in the channel due to
  both the presence of AWGN and FN.