Frequency Diversity in Low-Angle Radar Tracking

Elevation angle errors due to sea-reflected multipath are evaluated theoretically for a radar operating in an off-boresight monopulse tracking mode. The computer simulation accounts only for specular reflection. Angle estimates at three frequencies are assumed to be available. It is shown that one can improve upon a simple average of the three indicated angles by unequally weighting them according to rank (lowest, middle, or highest). Some sample computations show that there is an optimum difference between the three frequencies.     

Antenna sidelobes in the presence of flat reflectors

Reflecting surfaces near the antenna may produce surprisingly large sidelobes even if the designed free-space sidelobes in the directions of these surfaces are very small. Calculations of such sidelobes are presented for an example of a linear aperture with a parabolic weighting function for the received signal amplitude     

Effective Sidelobe Levels Due to Scatterers

The far-field radiation patterns of radar antennas when installed aboard ships may differ substantially from their free-space or theoretical design radiation patterns. We obtain some estimates for the effective sidelobe levels generated by scatterers in the main beam of the antenna by 1) ships and other discrete scatterers in the far field; 2) the sea in the far field; and 3) the ship's own superstructure in the Fresnel region.