Mikhail E. Zamarin − Deputy Director General for Science  E-mail: m.zamarin@mail.ru

Nowadays information systems of next generation with ultrawideband radars are being extensively designed to obtain spatial radar images of given objects that gives a better effectiveness of their detection, tracking and identification.

For practical purposes one has to obtain images with possibly better resolution and minimum background level. To fulfill this, it is necessary to define ambiguity function of the radar signal synthesized using inverse aperture principle for any frequency range of probing signal and any elevation angle.

The purpose of this paper is to obtain 2-D radar images using inverse aperture synthesis with potentially maximal resolution and minimal background level.

Ambiguity function is basis for system analysis and for finding of best signals for a given application. To suppress side-lobe level and to broaden dynamic range of radar cross section to resolve centers of local scattering when range and azimuth resolution are at minimum it is appropriate to use weighting processing. When weighting processing is used, probability of detecting of desired signals becomes somewhat lower due to energy loss. As a result, main lobe of ambiguity function becomes wider that makes worse range and azimuth resolution and increases measurement error for range and azimuth. At the same time after weighting processing linear dimensions (in range and azimuth) for area of synthesis of a 2-D radar image don’t change.

Range and azimuth resolution in radar imaging using chirp signal is determined by instantaneous frequency of a chirp signal and sector in which radar image is synthesized. Azimuth resolution can be better if tuning range of a chirp signal is shifted toward more higher frequencies and if sector in which radar image is synthesized is widened.

In this paper it shown that after weighting processing range and azimuth resolution in radar imaging using chirp signal became two times worse but dynamic range of radar cross section to resolve centers of local scattering when range and azimuth resolution are at minimum rose to 30,5 dB.

Zamarin M.E. Some features of a 2-d frustration function for a chirp signal in radar imaging. Radiotekhnika. 2020.  V. 84. № 10(20). P. 23−. DOI: 10.18127/j00338486-202010(20)-03 (In Russian).

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