Ship radars generally operate in the X, C, S, L bands, and in these frequency bands they only travel in a straight line, some emitted signals can interact with the atmosphere and refract, in this way the range below the horizon can be extended. The radio waves that normally propagate beyond the horizon are the HF down bands (HF, MF, LF, VLF) that go around the world reflecting off the ionosphere.
A coastal search and tracking complex such as Mineral-U that operates in passive mode from band I (X-band or SHF band) to D-band (L-band or UHF band) could use atmospheric ducts to passively search and track waves. emitted by on-board naval radars that also operate in this frequency band to detect and track their targets. Enemy radar location plays an important role in modern warfare.
For example, the AN/SPS-67(IFF antenna operates in the L-band - D-band or UHF band) and claims to have a detection range >104 km, this is the Arleigh Burke surface search radar but can also detect air targets at low altitudes and cruise missiles, it is found that the radar is at an altitude position of 30 to 40 meters on the ship, calculating the radar horizon for a radar position at 40 meters and the target also at a height than 40 meters, the horizon detection range is half the effective range of the radar which is >104 km. This means that naval radars propagate electromagnetic wave radiation through the troposphere generating "footprints" that an enemy radar could track and detect through atmospheric ducts.
I think that in the same way that a Mineral-M uses atmospheric ducts to extend the detection range, the AN/SPS-67 also does it in the same way, but its range is much smaller than the Mineral-M. In this way, a Mineral-U could passively detect the signal from enemy naval radars (L, S, C and X bands) at long distances.
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