A segmented aperture imaging/positioning method of a multi-rotor unmanned aerial radar. A target echo is acquired based on an unmanned aerial vehicle-borne synthetic aperture radar system. An echo signal estimated from the motion state of a manoeuvring platform is segmented. Motion compensation is performed on each echo signal segment. A two-dimensional spectrum is obtained by performing a two-dimensional Fourier transform on each compensated echo signal segment. A series inversion method to decompose the two-dimensional spectrum is used to obtain a phase filter of each segment. The two-dimensional spectrum of each segment is multiplied by the phase filter, and an image of each segment is obtained by performing two-dimensional inverse Fourier transform on the two-dimensional spectrum. A full-aperture imaging result is obtained by performing geometric corrections on the images and splicing them. The trajectory of each segment of the platform is spliced to obtain complete trajectory coordinates of the platform.

Synthetic aperture radar (SAR) imaging systems that transmit repeated waveforms based upon pseudonoise sequences to generate SAR imaging data in accordance with various embodiments of the invention are disclosed. A synthetic aperture radar in accordance with one embodiment of the invention includes: a transmitter configured to transmit superchirps, where the superchirp is generated by convolving a kernel with a pseudonoise modulated impulse sequence having a flat power spectrum; a receiver configured to receive backscatters of transmitted superchirps and digitize the received backscatters; and signal processing circuitry configured to perform matched filtering on digitized backscatters.

A SAR imaging method performs N SAR acquisitions in stripmap mode of the earth's surface using a synthetic aperture radar transported by an aerial or satellite platform and including a single, non-partitioned antenna and a single receiver coupled thereto. All N SAR acquisitions are performed using the same predetermined elevation angle relative to the nadir of the synthetic aperture radar and using a respective squint angle relative to the flight direction of the synthetic aperture radar. Radar transmission and reception operations are time interleaved with other N-1 SAR acquisitions, resulting in the respective acquisition directions being parallel to each other and not parallel to acquisition directions of other N-1 SAR acquisitions. Radar beams in two immediately successive time instants and related to two different SAR acquisitions are contiguous along the azimuth. SAR images may be generated using all the N SAR acquisitions having an enhanced azimuth resolution.

A SAR imaging method is provided that performs N SAR acquisitions in stripmap mode of areas of the earth's surface by means of a synthetic aperture radar transported by an aerial or satellite platform and which includes a single, non-partitioned antenna and a single receiver coupled to the single, non-partitioned antenna, N being an integer greater than one. Each SAR acquisition in stripmap mode is performed using a respective squint angle with respect to the flight direction of the synthetic aperture radar and a respective elevation angle with respect to the nadir of the synthetic aperture radar. The method may further generate SAR images of areas of the respective swath observed via the SAR acquisition in stripmap mode. All SAR images have the same azimuth resolution that is equal to half the physical or equivalent length along the azimuth direction of the single, non-partitioned antenna of the synthetic aperture radar.

A method of operating a Synthetic Aperture Radar SAR to acquire image data of a swath comprising one or more subswath(s) is provided, wherein the SAR is carried on a platform moving along a flight direction and a radiated beam is directed towards the swath, the method comprising: electronically steering the beam in azimuth direction along one subswath for each burst; and mechanically steering the beam in a direction opposite to the flight direction during each burst. The method allows to obtain an improved swath to resolution ratio.

A method of operating a synthetic aperture radar SAR to acquire image data, comprises steering the SAR beam in azimuth with respect to the direction of travel during a first time period to acquire image data for a first area on Earth to be imaged; steering the SAR beam in azimuth during one or more additional time periods to acquire image data for one or more additional areas on Earth to be imaged; and steering the SAR beam in azimuth in a rearward direction with respect to the direction of travel, during a time period including the first and one or more additional time periods, to reduce the speed of travel of the beam with respect to Earth.