Abstract: A method and apparatus for estimating the trajectory of a projectile using two interferometric radar antennas each producing a group of interferometric antenna lobes forming intersecting solid angles, and being directed at an elevation angle so that the projectile passes through each interferometric antenna lobe. Each radar antenna transmits a different frequency of pulsed RF power and receives pulsed RF signals reflected from the projectile whenever the projectile passes through the antenna lobes of the radar antennas. Based on the received signals of respective radar antennas, the range and time information for the projectile passing through the antenna lobes of the respective radar antennas can be obtained. From this range and time information, the three-dimensional coordinates, speed and acceleration at the points in the antenna lobes through which the projectile passes can be obtained.