Phase Control in Multibeam Arrays

The phases of the radiation fields in a multibeam antenna are analyzed and their relations to the feed network are established. A method of phase control is proposed and applied to the case of cophasal beams radiated from an array for which the feed network is a lossless Butler matrix.     

Moving target imaging and trajectory computation using ISAR

Novel algorithms for moving target imaging and trajectory computation using a two-receiver radar are presented. The range-bin alignment is implemented with an adaptive method using the envelope correlation feature of different returns and the angular trajectory equation is solved using a linear least squares method combined with a unique phase-unwrapping technique. The angular positions of the synthetic array elements are determined from the trajectory computation. Three target models moving along a perturbed straight line are used to verify the proposed algorithms     

Precision tracking algorithms for ISAR imaging

The simultaneous imaging and tracking of a moving target is one of the most difficult problems in inverse synthetic aperture radar (ISAR) signal processing. The problem is addressed here using a two-antenna imaging radar. The target range shift is sensed with an exponentially averaged envelope correlation algorithm while the angle change is measured with a differential phase shift algorithm. The three state Kalman filters are used in range and azimuth dimensions to provide both a filtered estimate and a one-sample-ahead prediction for the purpose of target tracking. The filtered range shift provides an accurate information for range bin alignment, and the target angle change provides the angular positions of the synthetic array elements. Therefore, the ISAR imaging simply becomes processing of a circular-arc aperture. The algorithms are verified both by computer simulations and also with experimental data processing