V.Yu. Loskutov¹, S.A. Rastvorov², M.V. Rodin³, V.V. Chapurskiy⁴

¹−⁴ Bauman Moscow State Technical University (Moscow, Russia)

To analyze the resolution of interference measurements by the angle of the place in coherent systems of two or three radars with narrowly directed headlights and LFMS, analytical expressions are obtained for the generalized correlation integral (RCI) of joint coherent signal processing from the output of the radar receiving channels when they operate in a non-cooperative mode. Using this result, in the conditions of free space, different variants of the arrangement of systems of the same type of C-band radar when working in the landing zone of aircraft on the runway of the airfield are analyzed. The initial version of a single-position radar and 4 variants with different spatial separation of the positions of two and three radars with headlights or their AC, potentially allowing to measure the height (angle of position) of the aircraft in the interferometric mode with increased accuracy, are considered.

In the basic version of a single-position radar, in the section of the module of the generalized correlation integral «range–seat angle», there is a lobe of the order 2 o wide in the seat angle, due to the vertical size of the AU, which does not provide the required accuracy of measuring the height of the aircraft in the landing zone.

The variant with the placement of two radars on the same vertical with a height difference of 5 m when operating in the interferometer mode leads to a large number of interference lobes narrow in height (seat angle) within the main lobe of the bottom of the radar AC. The interference lobe has a width at the angle of the place of the order of 0.25 o, and all side lobes lead to ambiguity in the measurements of the angle of the place. In the variant of two radars with a reduced vertical base between the phase centers of their AC to the size of the vertical aperture of the AC, the width of the main interference lobe was about 1.0 o. At the same time, there is a large level of the first side lobes as remnants of the first interference lobes suppressed by the decline of the main lobe of the DN AC. This situation is permissible only for the far border of the aircraft descent zone at a range of 5000 m and is not satisfied at the near border 2000 m from the middle of the runway 2000 m long at an aircraft height of 60 m.

The option when two radars form a parallel runway bistatic base with a length of 25 or 50 m leads to acceptable results for the length of the main lobe in height and the angle of the place of the order of 0.5 o at the far and near borders of 5000 m and 2000 m from the middle of the runway when the aircraft is lowered from a height of 200 m to a height of 60 m. At the same time, a solution to the problem of increasing the accuracy of measurements based on sum-difference algorithms for modules of the generalized correlation integral is proposed, similar to the principles of using sum-difference directional diagrams in monopulse angular measurements. The variant using the case of a system of three radars with a longitudinal (parallel to the runway) location and the same height of the location of their AF equal to 3 m to increase the efficiency of angle-angle measurements showed an improvement in the resolution and accuracy of measurements compared to the variants of two radars.

Loskutov V.Yu., Rastvorov S.A., Rodin M.V., Chapurskiy V.V. Principles of aircraft height precision measurement in a non-cooperative system of spaced radars with phased array antennas. Information-measuring and Control Systems. 2022. V. 20. № 1‑2. P. 25−36. DOI: https://doi.org/10.18127/j20700814-202201-03 (in Russian)

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