Get access

Antenna-induced range smearing in ST and MST radars


  • B. J. Watkins,

  • P. E. Johnston


For ST and MST radars, finite antenna beam width causes range-smearing that depends on observation range and antenna pointing angle. This effect is examined by first developing a range-smearing function and then applying this function to model atmospheric turbulent structures for two typical antenna systems. The effect is most severe at mesospheric heights (80–100 km) for off-vertical antenna directions and for broader-beam antennas. This has implications for radar design and the scientific interpretation of the data when high resolution is a goal. The results emphasize the need for the narrowest antenna beam that the design and budget will permit. For data interpretations, a highly discontinuous turbulent structure (in the vertical direction) may be recorded, and interpreted, as a continuous height distribution. This will affect the interpretation of measured parameters such as the occurrence of turbulence, Doppler velocity, spectra widths, and calculations of turbulent diffusion rates. For situations when there are very strong returned signals from some heights (i.e., signals ≥26 dB above the minimum detectable level), the antenna side lobes extend the smearing and it may be difficult or impossible to discriminate against these false signals.

Get access to the full text of this article