N.V. Povarenkin1

1 St. Petersburg State University of Aerospace Instrumentation (SUAI) (St. Petersburg, Russia)

The problem of measuring the angular coordinates of low-flying radar targets located at a great distance from the radar station is currently a priority. The difficulty of solving such a problem is largely determined by the impossibility of resolving this goal at small viewing angles, when the target practically merges with the underlying surface. The developed algorithms of super-resolution show their effectiveness in conditions when the observed objects are at a distance not less than the width of the radiation pattern of the antenna system. In addition, for the normal operation of super-resolution algorithms (Canon, ESPRIT, MUSIC, Root-MUSIC), sufficient accumulation time is required to obtain a correlation matrix. In addition, to ensure the operation of such algorithms, it is necessary to create special antenna systems with which it would be possible to increase the resolution at the apparate level.

The applicability of the multichannel method of measuring the coordinates of a low-flying target in the case of its flight over a surface characterized as a mirror using digital antenna arrays is evaluated. Multipath distribution is implemented using a fan of needle-shaped directional patterns formed in the angular plane using a digital processing unit of the received radio signal. This approach made it possible to conduct a joint analysis of the signal re-reflected from the direction of the target and multiple re-reflections created by the same signal, but from the rising surface. The use of joint processing according to the criterion of maximum similarity of the copies of the reflected signal received in each channel, but coming along their own path, allows us to obtain the best estimate from the point of view of the main parameters of the signal, corresponding to the angular position of the low-flying target being tracked.

One of the main problems of existing radar systems for detecting low-flying targets is their wide directional pattern. The beam width equal to 0,5 degrees for bearing the target at the distance of decision-making from the radar station becomes so wide that it begins to irradiate not only the radar target being targeted, but also the underlying surface located under it. In this case, direct and re-reflected signals from the underlying surface begin to arrive at each emitter of the antenna array. Since the path traversed by each signal is different, the resulting phase front becomes rugged and unpredictable at the point of their impact. Because of this, it becomes extremely difficult to deter-mine the true direction.

Povarenkin N.V. Direction finding of small-sized low-flying targets over a surface close to a mirror. Achievements of modern radioelectronics. 2023. V. 77. № 8. P. 33–39. DOI: https://doi.org/10.18127/j20700784-202308-05 [in Russian]

1. Ermakov A.K., Povarenkin N.V. Modelirovanie signala, pereotrazivshegosya ot podstilayushchey poverkhnosti, pri zondirovanii nizkoletyashchego vozdushnogo ob"ekta s ispol'zovaniem metoda Kirkhgofa. M.: Radiotekhnika. 2020. [in Russian]
2. Griesser T. Oceanic Low-Angle Monopulse Radar Tracking Errors, Oceanic Engineering. IEEE Journal. 1987. V. 12. № 1. P. 289–295.
3. Spravochnik po radiolokatsii. Kn. 1. Pod red. M. Skolnika. Izd. 3-e. Per. s angl. pod obshchey red. B.C. Verby. V 2-kh knigakh. M.: Tekhnosfera. 2014. [in Russian]
4. Bokhovkin D.V., Korobkov Yu.Yu., Mushkov A.Yu., Yangovatova O.A. Metod zashchity vysokoskorostnykh ob"ektov, letyashchikh na maloy vysote. Antenny. 2022. № 3. S. 78–85. [in Russian]
5. Ostrovityanov R.V. Statisticheskaya teoriya radiolokatsii protyazhennykh tseley. M.: Radio i svyaz'. 1962. [in Russian]
6. Tagaev T.I., Povarenkin N.V., Ermakov A.K., Muzafarov D.A. Sravnenie posledovatel'nykh algoritmov sverkhrazresheniya dlya resheniya zadachi razresheniya tseley, raznesennykh na maloe uglovoe rasstoyanie. Sb. «Volnovaya elektronika i infokommunikatsionnye sistemy». Materialy XXV Mezhdunar. nauch. konf. Sankt-Peterburg. 2022. S. 247–253. [in Russian]
7. Govard D.D. Monoimpul'snyy radiolokator slezheniya s vysokim razresheniem po dal'nosti. IEEE Transactions on Aerospace and Electronic Systems. 1975. V. AES-11. № 5. P. 749–755. Doi: 10.1109/TAES.1975.307984. [in Russian]