Bessel beam radar system using sequential spatial modulation

Abstract

A spatially modulated Bessel beam radar system for enhancing the resolution with which a range and an azimuth of a plurality of closely spaced targets is determined. In a Bessel beam radar system, a Bessel beam is generated by sequential spatial modulation of the radar signal while maintaining a constant spatial polarization, and the return signal from one or more targets is processed to determine its Bessel function content. To spatially modulate the radar beam, the point at which the radar signal is transmitted is moved around a circular orbit. In a first embodiment of the spatially modulated Bessel beam radar system (80), a radar dome (86) mounted on the distal end of a mast (84) is pivoted around an orbit (90). The radar signal is transmitted in a predefined direction, along a Poynting vector that is generally aligned with the plane of the orbit. In a second embodiment (110), a plurality of parabolic antennas (116) are arranged in a spaced-apart circular array around a common center. The radar signal is sequentially spatially modulated as it is transmitted from each of the parabolic antennas in sequence around the circular array, and the Poynting vector of the spatially modulated Bessel beam radar signal is generally transverse to a plane in which the parabolic antennas are disposed. The signal reflected back from plural targets comprises a complex phase history. To determine a range and azimuth for each target, a controller/processor (180), processes this signal to develop closed form Bessel functions from which target azimuth and range are determined. Alternatively, target azimuth is determined from a convolution of the complex phase history using a dot product detector (202).

Dependencies are inferred from the claim text.