V.V. Voznuk1, D.A. Komlyk2, S.G. Vorona3

1 Military Space academy named after A.F. Mozhaisky (St. Petersburg, Russia)

The abstract is devoted to the topic of studying the effect of a defect in the shape of a parabolic antenna on the energy characteristics of satellite radio lines with broadband signals.

The introduction indicates the relevance of the article related to the absence of a correction factor in the currently used ratios for energy calculations of satellite radio lines associated with possible defects in the mirror-type antennas used for receiving and transmitting signals.

In the main part, the generally accepted calculation ratios for determining the power at the receiver input are given. However, such relations are true only for a class of narrow-band radiation whose energy is concentrated at the frequency of the carrier oscillation.

If broadband signals are used in satellite communication systems, the broadband coefficient (the ratio of the spectrum width to the carrier frequency of the transmitted signal) of which is > 0.01, the spectrum of such signals will experience nonlinear deformation. On the one hand, this will lead to distortion of the waveform on the time axis and, consequently, to a decrease in the noise immunity of their reception, and on the other hand, it will lead to inaccuracies in the energy calculations of parameters at the design stage of radio communication systems and facilities, which can also lead to a decrease in its quality.

Even under conditions of perfect matching of the frequency parameters of the transmitter and receiver, the expression for calculating the power of a narrow-band signal at the receiver input cannot be used to adequately calculate the power at the receiver input in relation to signals with a wide spectrum, since it contains a number of frequency-dependent parameters and coefficients, such as the carrier frequency, the gain coefficients of the transmitting and receiving antennas and, consequently, different spectral components of such signals will propagate with different attenuations.

In addition, with a sufficiently large ratio of the RMS deviation of the antenna shape from the ideal parabolic to the wavelength, the surface utilization factor and, accordingly, the gain factor decrease sharply due to antenna phasing. And also for each wavelength there is an optimal value of the relative diameter of the antenna, maximizing its gain.

Having made calculations taking into account these factors, the final expression for calculating the power at the receiver input in relation to signals with a wide spectrum is obtained, taking into account the broadband coefficient and the rms deviation of the shape of the receiving and transmitting antennas from the ideal parabolic one.

In conclusion, it is concluded that the ratios currently used for energy calculations of satellite radio lines are correct only for the class of narrowband signals. The resulting expressions obtained in the work are a complete form of the desired energy ratios for conducting radio engineering calculations in real radio lines with non-ideal parabolic antennas in a medium when transmitting broadband signals.

As the conducted studies show, when parabolic antennas of ideal shape are used in satellite radio lines, as the width of the spectrum of the signal transmitted in the radio line increases, estimates of its power at the receiver input made using refined ratios will differ (and in a big way) from similar estimates made using known expressions.

At the same time, it is also shown that the error of the power estimation performed using generally accepted expressions in comparison with the newly obtained ratios is characterized by a quadratic dependence on the broadband parameter of this signal.

Voznuk V.V., Komlyk D.A., Vorona S.G. Effect of a defect in the shape of a parabolic antenna on the energy characteristics  of satellite radio lines with broadband signals. Nonlinear World. 2021. V. 19. № 4. 2021. P. 32−45. DOI: https://doi.org/10.18127/j20700970-202104-04 (In Russian)

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