The method of phased array altimeter beamforming based on rotation platform

In this paper, a phased array beamforming method based on the rotational platform is proposed. According to this method, the height of a platform can be measured accurately by adjusting the azimuth and elevation angles to keep the beam always point to the nadir point. Thus, the phased array altimeter needs to compensate the intersection change of the beam-point and the nadir point as a consequence of the platform translation and rotation. This paper deduces functions of angle error and phase compensation to calibrate the beam-point by establishing motion model of the platform, provides the method of weight calculating, and analyzes the update rate of weight. The curves illustrating the changes in directions of beam point as azimuth and elevation change respectively are provided by simulating. Finally, by means of simulation, making comparison between compensated and non-compensated antenna beam direction, we find the non-compensated beam is off nadir point with the changing motion of platform, while after compensating, the beam can be calibrated and pointed to the nadir again.