MAXIMUM-LIKELIHOOD BEAMFORMING IN THE PRESENCE OF MULTIPATH AND REFRACTION EFFECTS

The authors present a method of performing accurate tracking of low-al titude flying targets in the presence of multipath and refraction effe cts. The method applies maximum likelihood (ML) beamforming to an arra y radar having frequency agility in combination with a computational m ethod for predicting interference patterns which are affected by atmos pheric refraction. Tracking errors obtained when using the current ML technique under ducting conditions are shown. Then, the proposed metho d is described and examples of tracking improvement under ducting are given using experimental data in the X-band.